Hi-Fi Blog... Page 6 - 2022

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January 2022 Blog

More Horrible 1980s Amps, No-One Will Want To Try To Repair These.
1989 180w Akai AM-95 & 1988 100w Akai AM-73 "Digital Integrated Amplifiers". These were likely sold as Something Special back in the day. We're asked about these, not tried later Akai so to see these are Heavily Stuffed with ICs means they are unrepairable & to even bother with them is just not what we as Hifi techs would want to get involved with. A Non Working One will never find anyone to dare fix it, so it's Disposable. Put it on ebay as 'Not Working' & let someone take it cheaply for parts. There seem to be a deluge of these type of unrepairable amps, in reality you got 30 years use, well done, get rid & buy something New or try Proper Vintage that can be forever repaired. You can see they tried others to repair it, unaware that a Tech has to think there will be success to tackle an amp like this & they've had time enough to realise these amps are best avoided. As for asking for Repairs & Servicing, just not worth the aggro, these are 30+ years old & probably need recapping plus the risk of worn out controls. A Harsh Reality.

Non-Working Amps Can Often Be Too Risky To Try To Repair.
Worth Trying. An old amp that Powers Up & Lights Bulbs if is otherwise Very Rough & Noisy in use at least has it's Status Known: It Does Work even if not useable. An Amp that Blows Fuses & gives nothing in terms of life could be absolutely anything wrong. Signs of Damage can help narrow it down, if seeing nothing that looks faulty leaves the Tech to fault find, which can take ages as much testing is needed. The 1971 Marantz 2270 arrived like this. We take the challenge as this is Our Era & one of those 'Forever Repairable' type amps. We got it going as our review tells. Getting a Dead Amp going is a great thing & what causes it to blow the Main Fuse can be a lot more obscure than expected. Not Worth Trying. The type of amp like the 1989 Akai ICs amps above is where Techs don't want to spend your Money on what is a pure gamble. It may be a repair that could work out, or it could end up finding one Bad IC that makes the Amp useless. Would you Spend Hundreds to "Try" to Repair an amp & then be satisfied the Gamble failed & you have a Dead Amp & Wasted Money? It's where 'Beyond Economical Repair' comes in & not to spend is wisest. For Less Money than a Gamble you could buy another working one & swap the best external parts to it, knowing the Amp was a working one. But the 1980s IC stuffed amp isn't a good buy thesedays, maybe it's time to buy a better amp, as in easier to repair.

A Few 1963 & 1965 Valve Receivers With Updated Years.
The More We See in the Early years, the better to date them, with HFN reviews & ads helping. A Big Design Change is a small slider that Fisher & Akai used in 1963, the big ranges of USA Fisher valve amps are therefore all 1963, if continued to be made & sold into 1966. Those saying Fisher valves are late 1960s are clearly just guessing the first year of manufacture. By 1964 Fisher were onto versions of Early Transistor Amps like the Fisher 440-T with better rocker switches. The sliders on the Akai AA-5000 date it to 1963 too perhaps, the 1966 Akai AA-5000 S is a sneaky 'rebadging', the manuals show several versions of Transistor used with Germaniums still in both models. 1965 Trio WX-400U, 1965 Trio W-41U plus backdating 1963 Akai AA-5000, the non 'S' version.

Five Amp Compare On Original Amplifiers Not Yet Upgraded.
Makes a change to have 5 Amps to actually be working & test together as Original. Two more 1963 Akai AA-5000 & 1966 Sanyo DC-60 aren't useable. These following are ones that are Ours plus two Customer's Amps. To compare these Five Quality Amps to give an idea of what we hear & consider them to sound like, being Worthy of Upgrading. On Headphones only, we don't trust old amps on our Tannoys until rebuilt, if have tried a few in earlier blogs. Treble & Midrange quality the main idea, on Original Amps Bass is usually lacking in the Deep Bass under 50Hz range. This weak Bass upgrades well & always much improves, it's why we upgrade. Using only two test tracks "Uptown Top Ranking " and JJ's "Crimson & Clover". Two have slight transistor noise Pioneer & JVC. In no particular order, 1971 Sony STR-6065 70w. USA-EU if non UK model, was trashed beyond repair on the power amp if amazingly we got a spare working amp board & haven't altered anything else beyond the repairs. Bass limited, so about +2 on Bass fills it out better. This is a high quality sound with Treble & Midrange sounding very decent, wide Stereo on Rock it is detailed if not the bass weight yet, some treble slurring is noticeable as it is aged. This will upgrade to probably be the Best Sony integrated. 1967 Trio-Kenwood TK-140X 53w the Black label 1st version. This has 2 nasty Bass Filters in the design & has No Bass really below 100Hz, +2 on Tone isn't great. But it has a nice clean sound, Treble & Midrange as good as the Sony if not quite the open sound. Receiver version of the KA-6000 & is a great amp upgraded, bettering the KA-6000 in either version. 1966 Pioneer SX-1000TA 40w-50w actually still works as original. A different sound here, a more refined crisp smooth sound with more kick to it. Not the Bass weight if otherwise this isn't the more sweet sound of the 1967 range. Will probably be the best sounding Transistor Pioneer once upgraded & we have the 1969 SX-2500 too. Next is a bit Different, the 1973 JVC 4VN-880 25w x4, 55w x 2. A 4 Channel Bridgeable Amplifier. This all original if very rough on arrival, much work needed. Not the typical SEA Equaliser as the 4VN-990 we have has, this has standard Tone Controls. Sounds like the Pioneer for the crisp smooth sound & at last Some Bass & more weight on Rock. Very punchy sound for 25w. This does sound the best one here so far not taking Bass into consideration, the others are still The Best in Vintage & not as Serviced as the JVC needed as unusable originally. Last one is a 1971 Marantz 2270 70w. This has the Retro Bass that upset the 1977 Marantz 2235B. Quality sound here, a little flatter than the JVC, Bass here +2 is a bit Retro lumpy, if otherwise another of The Best Vintage, rather different to the soft 2245 as we had years back. 2270 needed some repair to try & may still be lacking until recapped-upgraded as a little 'shoutiness' noticeable in comparing to the JVC which has different design. Interesting Batch of Amps, some of The Best there Are. The JVC one wins as original, if to be fair it's much serviced, some of the others aren't much serviced yet. To rate 1-5 is a bit pointless as such quality in the amps. The STR-6065, 4VN-880 & SX-1000TA were ones we purposely got for seeing their circuit designs.

Auctioneers Like Easy Wins Only?
Plenty you see on TV & for those taking 'Bargain Hunt' items they are aware it's dealing with low value uninteresting items, but they get seen on TV so Free Advertising. 'Dickinson's Real Deal' is more interesting as it features higher value interesting items, often 'sleepers' that can do well or fail badly. Notice how displeased they are if the seller sets a Reserve too high as they get no commission as Unsold. Our first taste of Auctions was in 1987 with a Cliff Richard 'Taxi' acetate, hear it on Youtube. It made £750 which is very high & Cliff wouldn't make that price these days. 30% commission at Sothebys plus Insurance for them to store is very expensive, today 10-15% is typical, if the high rates get the best prices, we got back about £480. We've got a Paul Simon acetate, to see prices on Popsike for released ones are around £200 as only Unissued Acetates make big money. Paul Simon a low profile artist currently if an important one. To be lazily told it's a £100-200 item shows they've not understood what it is & even with all the info we've found, to not even try it at a better reserve is sadly the sort of way we find others deal. We continued by asking them about Auctioning Vintage Hifi, not that we'd do that with our Upgraded Rebuilds, but generally with the main money items like Garrard 301-401, Lowther valve amps, Tannoy Golds etc, the more established prices. Even offered them 'Hifi Shark' as a pricing site. To try to further Vintage Hifi, but not even a reply shows these 'hipsters' are no different to any auction house. Our Website in Records & Hifi has Always been about Promoting The Sleeper. To Keep Music & Hifi alive with interest in things previously bypassed. The Auction House should be more willing to take chances, but the reality is the Old Sniffy ways of decades ago are much there still.

1959 Garrard 4HF Turntable on 'The Repair Shop'
This turntable we've mentioned on the Turntables page before. It was a Popular one with UK's Jamaican Reggae scene in later years, the D-shaped one that came on a similar Garrard plinth. Uses a nice Garrard motor & bearing which is why it was picked & it has a captive arm that's of good quality for the age as we had the seperate arm to try. But Old it is now, Steel Turntable platter no good for Magnetic Cartridges & the Wire Wound Speed Control will always be long burnt out & leaving it run too fast. The Garrard spares guy we rang about 30 years ago groaned about that long unavailable part, we had a nice grade one back then. So to see what the TV show does with a tatty one wil be interesting. The Love the UK based Jamaicans have for Music & the home-made Sound System is great, if not so widely known outside music circles. The 4HF here was in bad condition, no slip mat, parts seized, no cartridge & said to be 'burnt out' on the motor, possibly the speed controller. It's too far gone & to buy a better working one, ebay has ones £200-£300 plus extras like a PVC cover. A working one sold £205 recently. Motor was fine, he didn't strip it down to service like we did on the 301 & 401s, big job but to do it properly. Mechanics quite basic, motor similarly a more budget version if the Bearing on the Platter & Spindle is more like the 301 style, the oil version. To build a new plinth makes it a neater piece. To see what they do for a mat & the badly corroded aluminum arm plus the speed controller. Mat they use isn't the right one, these you'd never find unless you get a parts unit & some do crack badly. No mention of the speed controller. They use a crystal flip over cartridge, the sort still buyable in the 1980s & old stock around, you'd never find an original beyond parts units. Makes a decent job of it, arm polished bright & the owner is 'well pleased' playing Don Drummond 'Man In The Street' a classic 1965 Island Ska 45, speed a bit wrong shows the speed controller was broken.

The Problems Recapping & Upgrading Some Amps We've Had.
We've bought amps for several years now to Upgrade them to see if we can get 'Excellent' from them, as in just scrapes it or a High Excellent. Problems meaning 'Overcoming Poor Design' rather than just having a faulty one needing more done. Some Amps Upgrade well, others are Obviously with Rubbish design such as Overheating Power Supplies that knock the amp out, others with Low Spec Cost Cutting & the Ridiculous amount of Bass Filtering in amps of all years 1965-1982 which may surprise. One such amp that did give an Excellent after much more work we got asked about, Akai AA-8080 from 1973 on reading the review to remember how much it took to be it's best & then another one we upgraded too must be an altered design mid run as it wouldn't upgrade the same way, to update that review. Then the 1973 Pioneer SA-9100 we aren't pleased with as the Review tells, it has some awful design plus the extreme Bass Filters, plus a hard one to work on. Question asks if £450 will upgrade it is way short of what any 'better' 60w amp would cost to Rebuild to 'Use Daily' quality & no point not doing the job right. No point saying what it'll really cost as you can tell a 'no sale' as they didn't even bother to see if we'd had it to Review. Note the '1973' and both brands in the Comet cost cutting problem that upset the Hifi Market as much blogged about.

The Idea A Full Recap With Design-Based Upgrades, Full Service & Testing
... on a complex 60w amp is only £450 shows too many not reading much or anything to realise this is Not Cheap Work, do it properly or don't, go sell it on ebay. A quick reply to see if they even reply back & then say more as many just disappear, ones thinking even £200 rebuilds a complex amp to realise they'll never become customers. '£450 Won't Even Touch It' is a good line to at least get a reply, if usually they can't really afford that. To say 'Cheaper Rebuilt Amps On Our Sales Page' rarely gets a reply. A Sense of Reality & Worth in Upgraded & Recapped Amps for The Costs & Skilled Work including Redesign is not an easy Concept to get through. Imagine if Hundreds realised how Great our Work is & having a possible 30 Amps to work on, no good to us as it's only one person doing this.

Ferranti Mid 1930s Bakelite Desktop Radio Wireless.
We've had lots of Old Radios & Radiograms over the years, if only keep the 1932 Pye G/RG Radiogram as it's a smart looker. Old Radios as Valves & early Transistor Portables you see on TV fairly often. Are they that interesting anymore? The Stylish ones are, the vast majority are pretty dull & most will never work again as they probably will Cost Too Much To Fix, the age old issue. 'The Repair Shop' has the Ferranti, here it's got the full set of control knobs & in decent grade externally which often isn't what you find. As with Hifi not worth fixing, the Radios still stay around in hope. Usual Valves, Outsize Capacitors inside, 'Goodmans' speaker the electromagnet type that was out of date by about 1936-37. Also the Tuner Glass lettering still good keeps it more worth keeping. 'The Usual Suspects' replaced, not as neat as we'd do it. But then Powered Up it burns an internal Transformer, so it needs a donor, which for the amount of tatty-cased unwanted Radios is probably not too hard, as is finding NOS Valves as there are enough of ones past mid 1930s to last forever, in terms of Radio ones. Amplifying ones may be much more difficult if over 5w. It does risk Unobtainable parts & as it's a Tuner, to need the right Test Gear. He sounds worried. Once done, said to be a big job as it needed a better tuner chassis as the other one too damaged, the Speaker replaced & a part of one front control knob found. It works, owner very pleased. Originality. Collectors like as much Original on early valve Radios. This may need several Parts Units. Our Pye has a very high grade outer, original cloth, original electromagnet speaker if reconed as it crumbled. To get a Pye G radio to swap the main block as it had a replaced transformer, still had the 'pepperpot' capacitors that are left for looks & all resistors and other capacitors as original which must be rare. This is how you want these early items. A piece of card as a base to keep the spiders out, we've not plugged it in for ages after getting it right adding the old style cloth cable as 3 core to have it grounded. It worked in an eerie 'lost' sound, if not to pretend it works perfectly as so original, Volume Control not great. It's 90 years old now. What's Not Good on old radios, radiograms & radio console units is the wood stripped giving a much darker finish than the sunfaded old one & the speaker cloth being tatty or replaced with something too new, even if a good pattern.

February 2022 Blog

People Just Don't Read Things. To Not Understand What They've Bought.
This is a Vintage Hi-Fi website. We Do Hi-Fi Jobs. It involves Recapping & Updating the Amp or Receiver. We Always Add Design Based Upgrades to improve the amp. Your Hifi as original will use parts to keep to a price to match the competition at the time, plus them being Decades old, they're past their best. Some amps we've heard that were being used still are very far gone, yet still used. Like you & others getting old, changes if seen often aren't noticed. Since 1973 Cost Cutting due to "Comet" wholesale pricing almost upset the scene. This means the Amp may be a great design but made on The Cheap so it's far from it's best. To see there are certain great amps 1969-71 that are made penny pinched & deliberately dumbed down to be 'not too good' is what we've discovered. We Question anything we don't see as right, clearly not a popular way of thinking as life over the last two years shows. To be Spoon Fed others ideas is basically what all Shop Bought Hifi is. All Designs of Anything are other people's ideas & the amount they change shows no-one is ever happy, if to see these changes over years shows the Best Ideas soon get forgotten. Our Unique Design Based Upgrades put back an amount of what was dumbed down at a Reasonable Price. We have gone a lot further to see how much better amps can be, with ideas added to the work we do over time & still realising new ones. Most Hifi people just Recap 'Like For Like' as the manual schematics show. This is Not Upgrading, it's Renewing parts. To Alter Designs as we do in our Custom Upgrades is a very different thing. To keep an amp hum free & stable can be a real problem which is why old time techs won't even recap, scared of issues. To send one of our Amps to a Book Smart Tech will not be understood, they'll foolishly say it's wrong as they can't think there's any other way than Booksmart. They'll do things wrongly & even totally trash the amp, as the poor Sony STR-6120 got as blogged before. It still lives. We have complex amps from as early as 1966 in 'use daily' quality with advanced rebuilds. The amount of work in some amps we sell is way ahead of the selling price, look at the Trio-Kenwood KR-6170 on our sales page. We bought it as it's Rare & looked interesting. Perhaps the grade should have left it, but we wanted it & now price to sell it. Profits nowhere in this one, many hours work, if it was an interesting one.

Cheap Modern Valve Amps, Oh Boy...
We get messages. They are only asking, but some are a bit unaware. To Blog it to Tell the ideas we get are sometimes Difficult as with the Blog above. We're here to do worthwhile Hifi Jobs, not just take in Anything that will likely be a Big Problem based on previous experiences. An Audio Innovations Series 300 Mk2 is some modern Class A 25w thing. Said to be 'hissy'. No circuit manuals on these if they are usually nothing special, made with Cheap Parts & to see the resale price of these tells they are Budget items. Then they think it'll be fixed for £200. Probably the sort of amp that is for Newbies to try the valve scene. To offer budget valve gear to one like us once it goes faulty, having had a couple of ones well over £1000 new to find they aren't made well. Our 1992 Tube Technology Genesis were over £4000 RRP when we got them, if to get ex-demo hugely cheaper shows the mark up on these. After over 20 years we've changed so much & to think a PCB is good on High Power for an amp used often tells us to Be Wary of any more modern valve amps. Better ones can be rebuilt as with that EAR Yoshino one, to then realise the lousy design. We don't want High Risk jobs on Budget gear. £200 wouldn't touch a rebuild, no Manuals, Compromised design. To learn it would take time & the Results even if you spent a more realistic £1000 may not be so good, so to just tell it how we see it, and never get a reply back...

The Problem Of Retro Bass.
On this one again. The Marantz 2235B guy we upgraded his well used amp to give a nice use daily joy with new bulbs making it a nice unit. 2235B has Retro Bass & why they liked the sound so asked it to stay if upgrade the rest. Amp returned sounding Hugely Better if the Retro Bass became a problem, they heard it as we Reviewed it. They thought to get it done further without the Retro Bass, if to be fair, we can't be totally sure how it would sound, it could need a lot more Upgraded to sound like other Marantz do. We liked the 4ch Receiver sound, if the 4ch Amp we heard their bassier sound if weren't pleased seeing it's 'Sound Shaping' similar to Retro Bass, so sold it on. We have been doing EQ for ages, so to know which sounds need boosting or cutting to sound more Natural. Retro Bass involves 'Ringing' on Audio, which makes a One-Note Bass. It has No Focus in lower Bass & you miss all the deeper bass as it's 'squashed up' by the Ringing Effect. The 2235B owner said it's like 'Having Loudness' on all the time, we suggested to use the Tone more to adjust. Currently they'll keep it as-is, if the Midrange (500Hz-2kHz) won't be affected by Retro Bass. We have the 1971 Marantz 2270 here, it amazingly for a top 70w model has this Retro Bass, so we'll upgrade it to Our Ideas, rather than risk a confused buyer. The 2235B owner can see our Review when it's done & maybe decide again. More in a Blog next Month.

Retro Bass Is A Cheap Way To Get A Punchy Sound That Can Please.
We first knew it with the Hacker GAR record players & it made 1950s & 1960s Singles sound more punchy & to EQ things today, to remember this sound on the same 45s decades later is a strange one. They Sound Better for a fuller sound, if in reality we have far better Record Playing Gear now, they can sound a bit thin. Bass has to be limited on Vinyl else the grooves would be with too much movement so Tracking would be a problem. A reason why a 12" single version of vinyl by the 1970s Disco era was popular as grooves more spaced gives a louder bassier cut, in theory. One recent amp that had us Questioning this was the 1969 Sanyo DC-66. We had no Manuals, but it had a well crafted sound, it had Retro Bass, if with no info best to leave it with the Retro Bass. We tried it without it & it was very thin if clean sounding. Not knowing what else to safely alter as the circuits were far from any designs we'd seen in some ways. But the Funny Thing is is actually Sounded Good on speakers, the Marantz 2235B & others were awful on our Tannoys. The customer who sent it for a Rebuild liked the sound too as it had when returned done. What in the design balanced it is still unknown.


March 2022 Blog

Retro Bass: Test It Out With Sine Waves.
In Hi-Fi mags you'll see amps tested with Square Waves & showing degrees of tilt & more, showing Poor Response & RF issues. We understand it, but like all those endless stupid graphs in the Media for the last 2 years, to learn what it all means is often not worth the effort knowing. Theory has a base in Hifi, if Listening is the real way to describe, backed up with Test Results to confirm things. Some play Musical instruments like a Master without understanding the formal notes & sheet music meanings. We've tested Hifi a lot to see How Good our upgrades are, that 1971 Sony TA-1130 we had a few times a few years back got tested & was found flat 20Hz to 20kHz. What it was like Original we never tested, but as Upgraded it was as it should be. But to upgrade it to be that good, it has to be kept stable with other ideas. The TA-1130 power amp is like the STR-6065 & TA-3200F power amp, it's a very good one. So to test an amp similarly with known Retro Bass, to see what it actually does, knowing how it sounds on Speakers & how a similar Marantz 2235B sounds & confuses the owner who initially liked the Retro Bass sound. See what it reads at from Input to Speaker Output as was the TA-1130. The Marantz 2270 is the one we use, what we've done already won't affect the readings, to read Sine Waves on the Speaker Outputs using Test Tones into the Aux with the level set to match what you'd use it on Speakers at mostly, ie 3-4. What will it test like? Typing this before trying anything. You could test only the section with the Retro Bass, if having tried similar, it doesn't quite tell true as impedance can affect outputs, so Aux in to Speaker out is the way you use the amp after all. Test It. Set all controls Flat, Loudness & Filters off. Set 1kHz as a 10.02v reference on the Velleman battery scope using the Soundcard. Not the most accurate, if a quicker way than Generator & Proper Scope, if we're looking at the Below 1kHz ranges, this way shows over 1kHz less accurately as the readings always rise, which isn't as wanted. See the Graph Here. Quite obviously an Uneven Bass, the 'Ringing Effect' will pull the Frequencies into a 'One Note' Bass with a clear Boost in the 40Hz-80Hz range reading around 11v with 50Hz going as high as 11.82v. This eases back to 'Flat' only by 300Hz, so a thickening of the Sound will be Obvious. It does as it says, as 'Retro Bass' but it's artificial if will please on cheaper speakers that are playing 50Hz much reduced. 'Retro Bass' can fool you that it's Bassier, but here we show the Blurred Poorly-Defined Bass Under 80Hz is shaped into a Peak of 10%-18% which is quite a way off Flat. An amp should Ideally be Flat on Preamp & Power Amp, with Phono obviously different. If you want more Bass or Treble, use Tone, we do, but to have the Option of Hearing It Flat as all Rooms differ in sound. Retro Bass is what it says, an Old Fashioned 'Cheap' way of getting Bass of sorts. The Marantz 2270 upgraded well to bring a fresher Bass & doesn't need it as the basic design is good.

Another Radiogram On 'The Repair Shop'.
This time a Grundig one looking mid 1960s. It's nice the Owner is sentimental about it, the outer case looks in good order. But the insides are broken she said & the Turntable a replaced one. Nightmare job, the replaced Turntable usually means the space has been cut bigger as soon revealed & having had this on older Grams, to get it to look right is tricky. The Tuner cord sounds broken, can be restrung if this can be difficult even with the Repair Manual. The innards are budget EU TV-grade quality & to even get it working will be a big job. How will our guy do, he's not the best Tech from previous jobs, bit of a Bodger. Better to look online for a complete & working one for £50 as it often the way. Interestingly Jay says "the bass was beautiful" on these Radiograms, clearly an old memory & way off even Retro Bass mentioned above. An uninsulated open box wth severely limited Retro Bass usually sounded truly awful & boxy, if the earlier Valve ones made of better quality sound far better in their rather crude non-Hifi way with limited real Treble & Bass. Bass must be very limited as speakers in the same case as a Turntable could get Feedback Howling & the springs help limit that. What they do to the unit won't please The Purist, if perhaps it's best when the innards are so rough. They get another Grundig radiogram, a nice condition late 1960s or even early 1970s one as it has Slider controls. Radiograms still were selling into the 1970s until Music Centres that sat on a Sideboard became popular. They fit the Turntable & Tuner-Amp part from the Donor unit into the owner's old case. So they got a complete & working one for £50 perhaps, if not getting quite the same one, it's an acceptable repair, plus they get two Speakers to fit in as well. Donor Gram gets a side panel used as the Turntable plinth part which makes a good job. They play it, a very dull soft sound here perhaps is post-production sound, these usually sounded brighter & louder. The owner delighted & won't remember how it exactly looked. Overall not a bad job to not deal with the low quality parts by getting a donor unit, if not replacing anything. Repairing lower end units is generally not worthwhile, go find a better one.

Comparing Sleeper Amps to Sleeper Koalas?
Being of an age, the Koala Bear (they're not Bears) was just a static image with it never on TV so it never really mattered. An Australian Icon if they're still not that well known or cared about it seems to the masses in the EU regions. Barely in UK-EU-US Zoos even. The Internet has got the delightful Koala noticed as it looks like a live Teddy Bear & can be a fascinating animal that is actually very interesting beyond it's 22 hour sleeps high up trees & eating rubbishy leaves. Two versions, the Northern light grey smaller one & the Southern larger darker grey more furry bigger one, as in Adult Koala sizes. "It has What?" is what reading about them will reveal, as do YouTube videos of one chasing a Truck & one being spoken kindly to in order to get it out of a Car plus more. The young ones (Joeys) are ultra cute as looking at the Irwin's Facebook pages show often, 'Salt' is a very handsome one. Plenty of Facebook Koala groups. Only noticed the Koala again in January from the 'Crikey! It's The Irwins' on Animal Planet that are also showing the Steve Irwin shows again. Not seen these, 20 years ago not into Animal shows & not liking the Attenborough or BBC ones, so to see them now after having it as the main background channel after years watching 'My Cat From Hell' which makes you not like selfish cats so much. Seeing Zoo Animals interacting with us Humans shows much happier animals in a way not even UK's Chester Zoo with "The Secret Life Of The Zoo" can do. All these lovely fascinating animals from Australia to discover from Crocodiles to Komodo Dragons & all the Furry Ones. The more traditional ones now shown having character adds to the interest. To find the Tasmanian Devil is real, not just a Bugs Bunny character. Koalas are Cute when small, entertaining & funny when grown & an animal that needs to be better known. The Adult wild Koalas are interesting & from seeing the Horror on the girl's face on S2 E1 of 'The Irwins' on mating to see this is no dozy animal in reality. Fascinating & Likeable too. It is like Discovering Sleeper Hifi which we certainly jumped deep into over the last Ten Years, much joy seeing a Koala & watching the same bits on TV to keep up the joy of seeing our furry buddies. The reality of the Koala is a sad one, it costs the Rescue Zoo on average AU$7000 to 'repair' a Koala over a year & Australia Zoo has helped many. Koalas have a lot of problems & now are 'endangered'. Seems they are much loved by those lucky enough to meet them, if still rarely on TV otherwise. Good Hifi is Endangered too, much will have been thrown out over the Decades, or it looks for one who'll spend properly to keep it alive, the amount to do some amps justice will scare off many sadly as Vintage Hifi is often too old to use if some still is, it still can be risky trusting it. Finding Koalas again certainly a joy, the much loved Meerkats are more like Stoats & Mink to appeal as wildly, the Koala really is an unique animal. If only it had a bigger brain, ate better food not to sleep 22 hours a day, but it's unique ways keep it alive. You can do 'Star Trek' Fingers, now try 'Koala Fingers'. For a wild animal that's only in one country, the Koala brings happiness unlike any other, beyond domestic Cats & Dogs. Save The Koala. Long Live The Koala.

April 2022 Blog

1970 Belgium 'Carad 2001' Tuner amplifier aka 'Thorens 1250'.
We heard of this 35w one in 2018 via a Belgian contact. To see inside Photos shows it's that typical EU type build, part PCB & part hardwired. Said to be good sounding, if with problems as the age would suggest. To hear it's also the Thorens 1250 as Google shows the same fascia is how UK & EU amps were by then, some sold under other brands if the same innards. The one who mentioned the Thorens is one of those who wants to be told, For Free as always, how to Upgrade it & Wanting help how to do it & train a newbie, oh boy. Not deserving a reply as you'd expect, are we not offering a Rebuild & Upgrade service here? To always get one who thinks this occasionally, freeloaders despite making it clear. The Carad looks like other EU amps like the Revox & also the UK Goodmans. They have a style that can look good, but lids off to get that EU style radiogram innards build. The thing is these are not the quality of Japanese & USA amplifiers as we've tried, to even recap Like-For-Like is going to bring problems & upgrading just won't do like the better amps. Many like EU amps, but it's the reality, quality lacks. To do Upgrades on Amps we know can take it, the Carad as with the last UK Ferrograph years ago & Goodmans we had, we'd not try these again to upgrade as UK & EU built amps are a very different beast, even to Budget Japanese amps. The more amps we see, the more that we'd not want to deal with is a sad reality. Imagine the TV Repair Guys of old dealing with 'difficult' amps, but they were just Repairing & to imagine how many were given back after it was too much. The Hacker GAR-550 needed repair in about 1990 & after a few weeks, it was back as 'Unrepairable', to see when we got one again in 2011 that it was very repairable, if perhaps too big a job or beyond their knowledge? Hifi Repairs are not teachable beyond a Specialist Course & most of what you do is beyond what they teach. Basically, if you need to ask beyond potentially risky Forum advice, you really shouldn't be messing with Hifi as you'll ruin it.

Wiring Build Quality On Some Amps Is Extremely Poor.
This relates to the internal Wiring, not the PCB or case work which is usually not a problem if in nice grade. An Amp should be designed to be Repair Friendly. Many liked their amp & wanted it fixed regardless of it being Top Range or a Spirited Low Model. The absolute worst thing in amp repairs is getting Loose Wires. The later designs with plug-in boards & connectors are made for easy Construction & help Repairs. The very complex 4-Channel amps by Trio-Kenwood are a masterwork in wiring, done in Factories usually by Women as they have calmer manners & better Patience. Kenwood amps are nice to work on as are others like Pioneer & Sansui. Sony are a little more fussy with the STR-6120 a real 'loosie' one if other Sony are later & better as complaints will have arrived. One Prestige brand, who we'll not name, as they are otherwise Great Sounding & Reliable, sadly suffer from 'designed by the thickest person' to put it calmly. Some boards so tight & inaccessible to bring out the juiciest of cuss words & "Who designed this Crap?". Just look at a wire almost & it comes loose, so tightly bound you can't do much else with it & to move it can get many 'loosies' over doing a rebuild. To be prepared for this, else have to trace 6 feet of lines on a Schematic & avoid insanity. Of course we are mannered with repairs, to get cross at it but not get angry. How many amps get smashed up by amateurs thinking this work was easy? If an amp gets too much, put it away for another day, if to continue we can do & get it working again not to go sleep on a problem amp as you'll think of The Amp. Hifi Dreams. Later amps use PCB track for most so the wiring is minimal which is user friendly, but to see the track can be so fine it's not really the quality of wired connections.

An Unusual PA Styled Receiver: The Trio-Kenwood KR-6170 Jumbo.
A large sized receiver from 1971 with the Reverb & Rhythm Composer stage. This been up for sale a while & gathering dust since, oh dear. To slightly reluctantly drag it out after playing 2 other Trio-Kenwood just to play it again. Takes a few minutes to wake it up & then to think 'What The Hell are we Selling this for?" Only fairly average grade if tidy enough for a Bachelor Pad or Man Cave & the whole thing works. Not sold is because it's not much known. Ferocious PA Sound when cranked up louder & just a little Soundcard EQ to balance it to Our Sound, ie -3dB on 125Hz as the Tone Stage isn't great, plus adding high Treble +1dB on 8kHz & +2db on 16kHz. More 'Exciting' than the other amps, just 33w but it's a very decent power amp following on from the 1969-70 designs, this a 1971 amp that must have got good use in Small PA settings as it has a Guitar Input also. Playing Music is often about "Excitement" & the KR-6170 as it sits as we type certainly has it. Just needs the EQ tweaks if that means Custom Redesign inside. It did sound good on the Tannoys if the Bass Tone control isn't as good as Trio usually did. But it's a PA amp & the thicker sound to suit a Dry Sounding Room. Hifi is often a Thin Sound with no real Bass or Richness, high Damping Factor kills that. The unique KR-6170 sound needs to be heard. It has a typical DF of 50, so it's Rich Sound is in the design which is more a PA design than a Hifi Amp like the KA-6000 etc. Just moved from Rock & Pop to Reggae of the same era, ie 1977-90-ish. The sound 'Uptown Top Ranking' has compared to the other amps is much fuller sounding. On TV when you see a Reggae Sound System playing with that tough bass, even on a standard Hifi playing TV sound, it sounds rich & not what you'll be used to, just like hearing a fancy Wurlitzer jukebox on the 1956 era Rock & Roll films, the Bass is the thing. Retro Bass has it's place, but the KR-6170 hasn't got this. It's a little too rich on Reggae, if -3dB on 250Hz balances the treble. (Actually Loudness was on, the Tone setting switch is very small...) Still sounds fierce on even crisply cut stereo reggae, Bunny Wailer 'Dreamland' a track we first got on the UK LP mid 1980s & played on the Hacker GAR 550 with it's Retro Bass. To want the Bassy sound but without the Fake Ringing Bass, Retro Bass is a funny one, we clearly knew & liked the sound in the 1980s if want Hifi & Real Bass with the Retro Bass tinge, which is why the TR-707A appeals. The design shows how the KR-6170 does this appealing sound, it's all in the PA Amp design. KR-6170 will have got Old-Fashioned by the Late 1970s for the 'quaint' Rhythm composer, which is the same sort of thing in Electric Organs as a backing 'Vamp'. To see old Films & TV we remember the KR-6170 sound sometimes. Playing 1960s Ska now, it really suits this amp, as does other 1960s music. Now to know it better & realise how Great the amp is. But are we being fed a created sound, rather than a real Hifi sound? Wonder what it'll sound like Tomorrow. Next day to play it on the same Soundcard EQ on Headphones reveals the Amp Compresses the Sound to make 33w sound like 100w as taming the Peaks not to damage Speakers played Loud on a Stage-Gig setting. It does sound impressive cranked up Loud, to hear it's not so punchy played lower volume means it's use isn't as broad as other amps. Fascinating amp for it's PA qualities, a sound you may prefer for the Compression that tames the Dynamic Peaks subtly. Update May 2022. On getting the Trio-Kenwood TK-140X early one part done, to compare Trios. To assume we had the Tiny Tone Selector to 'Loudness' matching the above opinion. Sounds very different now & need to keep it again. The Game of Amp comparing has always been tricky, to retry many combinations as Blogged before a few times. To keep it a while for more Upgrades, no other amp sounds like this one.

Blaupunkt "Blue Spot" Radiogram on 'The Repair Shop'.
Used to see these ones often in the late 1980s, one guy we knew who fitted shops out had several of these & kept buying more. One on the 'Repair Shop' S9 E16 shows these Early 1960s items that were still working around 1988, if their one is now very tired. Interesting that it was kept by the Owner, memories of last using it to play James Brown 'Man's World' long ago in 1978 & likely put in a garage until their house cleared out. Jamaicans in UK bought these often, see on C4's "Desmonds" a similar one plus on the 1979 film 'Quadrophenia'. They were kept nicely polished with a cloth Doily on top, still proudly owned by the original owners, used to see these in their houses still in the 1980s. This was a step up from the Dansette type record player. The idea of a Cocktail Cabinet on the left half is Kitsch for sure. Wouldn't the glass shelf & contents Rattle when played? You think it has Bass, not so. Didn't hear these played much as the sound wasn't all that, better ones to play like the Stereo Coffee Table version of the Pye Black Box. Here the cabinet isn't too bad, the Cloth cover on the speakers typically torn & the speaker cones with holes. To get new speakers or recone? Never seen inside one, valves for the age & two speakers as a Mono unit of no real Hifi quality. The tattered cloth looks really bad if not hard to replace, how will he do it? Jay gets some retro looking cloth, probably easier to find than us trying mid 1990s. Stripping the top varnish off keeps the colour which isn't typical, to re-gloss it should work out fine, again not the usual result. Jay in a way sounding unaware of the actual sound, says the speakers matter, but the lousy way the other guy patched the water damaged elliptical cone are way off a proper replacement or recone. It'll never sound even like it did even? Once done, much not shown & to see the TV repair grade guy didn't understand what the small speaker was, an early Treble tweeter one like the EAR record player has. Looked smart, they played it, was it real sound or post-production, a rough distorted midrange sound if too punchy says a later added music track. Owner very pleased, they'll use a few times then probably not play again. Would we take on Radiogram repairs? No chance, to restore innards & outer is a job that'd way outprice the dream. Rebuild a seized Turntable? Rebuild a noisy crackly cheap Radiogram innards? Too many issues & far too much work to do right. If you want one, or want to restore Gran's one, go buy another one in nice visual grade that still basically works. An amount of items 'The Repair Shop' work on would be better finding a better grade one rather than restoring poor grade ones.


May 2022 Blog

We'll Just Plug It In And Try It.
People have been doing this with Electrical gear for decades, regardless of how Old the item is. Seeing 'The Repair Shop' S9 with that green clock ship oddity, the guy said he was glad he didn't just plug it in on seeing bare Mains Cables as the Rubber Covering on the 1940s unit had perished. To consider he'd not just plug old stuff in, you'd hope. The Radiogram repair guy they used before the current one, just plugged something in & fused all the barn's lights. We'd not plug anything in without having a good look & only trust with a Circuit Breaker unit, the type you plug in the socket & plug the item into, not just relying on the House Fuse or Circuit Breaker, the nearness of the plug in one to save upsetting other mains items. Look on ebay, they say they plugged it in & it lights up, or it started smoking & blew the fuse, if rarely hear of Circuit Breakers. Often 'Untested' is a lie, how can you price it as Not Working when if it did even work to a degree it's worth more? Of course the seller plugs it in, as does a customer wanting a rebuild. They've taken the risk plugging it in, which is better for us as to risk a total unknown is difficult. To not know the Status on an electrical item is a pure gamble & the idea of "Plug It In And See What Burns" is an old TV Repair guy way that at least gives a result, but be aware they'll be on Isolated Mains to not risk danger, if just plugging it in with no protection & touching metal casework is dangerous.

We'll Try It On Speakers Next.
Assuming the amp of 20-50+ years age hasn't gone bang, electrocuted you, started burning or getting hot, to hear if it plays music is next. To reach this stage of Hifi is usually called "In Working Order", regardless of what noises, crackes & hum it makes next, it is basically Working, if "Useable" is the detail rarely told. For us to be glad it basically Works saves a lot of time, to buy a 1966 amp expecting it to play is unlikely, if our 1966 Pioneer SX-1000TA early one remarkably is useable, often a much less useful sound is heard. The thing here is people just plug Speakers in. We don't do this as why trash a speaker, the outputs may have 30v DC on the outputs from damage or aging. The capacitor coupled earlier amps you'd assume would block the DC as designed, but the capacitors can fail. Not many will bother read the DC offset, over 100mV to 30v+ is not ideal. Relays click off, or won't turn on, if over 1v DC offset, non Relay amps could fry the speakers, again to read with a multimeter. "It Works But Is Noisy" is a good way to fairly sell a Vintage Amp in aged condition. Often amps don't work on both channels as faulty in some way. To not mention it when selling & charge £300-£600 as we've found is insulting the buyer. One 1969 Pioneer amp worked but with obvious noises & crackles not mentioned if not expecting perfection. One 1973 JVC amp had no Audio on Speakers if was fine on Headphones. They'd never tried it on speakers & to repair it was an advanced one. Who would think no Speaker output sound if it was fine on Headphones?

Explaining "This Website Is Not Secure" Scary Browser Messages.
The old "Legacy Server" uses http: not the https: secure mode. To see this is just about the standard now means we need to contact our Server to see what to. You'd think they'd message us saying the Secure Server is much the same price, paying monthly, but we're left not knowing & see the Browser Message on most browsers now. It must scare off 80% of users. The reality is select45rpm is a Manual site, the Hifi pages typed on 'Dreamweaver' & the Record Listing pages we create on Excel & other coding programs. No Database or Shop Trolley. Only the email & order forms require input. No real need for 'Secure' beyond the growing trend first seen pre 2020. Why the Hell don't the Servers tell you? They're not doing their job are they, leaving a few stranded not knowing what to do. All we have to do is Email back saying we want this Hosting Package & it'll take a few Hours to move Servers. The useful Stats page showing Page Use isn't available now is the only minus, if we have much used it to tailor the site. Package is monthly & including free https: for 3 years, then it's £30 yearly which is fine. Looking at old bookmarks, a lot of the hifi info ones still showing http: or the version not showing any http: as ours used to with a killer "Not Secure" on Chrome & Padlock strike thru on Firefox. In earlier days we used to look at Source Code on one records site, 'View Source' they still have showing even today. They add Cookies which we don't bother with. They use the CSS type coding like <span...> that is a lot of work to do. We did one page with CSS that took ages to do, the List Of Amplifiers page, this gets a lot of hits, if not so much more than the non CSS Receivers page. Doing the page link shows our 'Base Href' & other needs updating http: to https:, just noticed that, as typical we weren't told this would need doing. "No need for you to do anything", well we'll see. The 'W3 Mark Up Validator' used to rewrite pages as CSS if the results were often a mess, not tried it in years & it still shows 2013 copyright date. What Next. The Server transfer is quick, then to see what the site looks like. No top Menu most obviously. The http: to https: needs updating, this can be many thousands of links to update, Dreamweaver search & replace deals with that. To check it all works & every html page is correct. Address box now shows "https://select45rpm.com/", padlock on Chrome & Firefox both add 'verfied' if you click on it, now looks far more professional. If the http: isn't updated you get silly messages about insecure images as the links are http: still despite being hosted on https:. To see most would give up, or buy an e-commerce site in desperation as one we see has, losing all their chatty pages. Doing a website, even without a shopping cart & cookies still isn't at all easy, unless you buy a package. The top Javascript menu is old now, still works on a computer if a Mobile we've not checked in a while.

"The Repair Shop" Has Never Had...
They cover most items, but never any Hifi like we do, they've had old Radios & Radiograms, but not the complex Amps & Receivers like we do. Probably as they're aren't many left able to Repair let alone Upgrade Hifi. The age of those who dealt with Hifi Repairs back in the 1970s & 1980s are now 50 & 40 years older, they were always middle aged guys so well past retirement. Sobering thought indeed. Another subject is Enamel Signs. You'd think the Ceramics or Paintings women might try these. You see these on TV Auction shows making good prices. The money is in the Pictoral ones, the Text based ones are still wanted, if Graphics always add visual interest & higher prices. We've been into Enamel Signs since getting a "Street Cries" one originally from Islington, London in 1992. Not much at a Boot Sale back then & recently sold it as not matching the other ones. Some of the Best signs are now into Four Figures & for the interest over the last 20 years, these will be tucked away in collections for decades still. Possible sometimes to buy a Rare Sign in Low Grade, but what do you do with it? Some damage is acceptable, the Best Ones are Late Victorian to Pre War which means 80-130 years old now. To find a "You Can Telephone From Here" sign as a hole filler in a shed tells we first got that about 1988 & it took ages to sell for £20 back then. Still in decent condition, ones used to fill outside holes are often rusted away on one edge or with Nail Holes as it was of no value. To glue them to MDF flattens out bendy creased rough ones & allows a solid base for filler on holes & then painting. It's fine to do on cheap ones if you'd have a job getting them off again, best left. Buyers do like to see the backs for the typical way they look as the buyer is often not experienced on Originals for the Repros around since the "Street Jewellery" book days of the late 1970s. The MDF takes a wall bracket so to fit to the wall looks tidy once restored. How good is the painter? How good are the paints? The last one we fully did was in 2008, by 2009 the paints had dried out & the DIY shop no longer stocked the Enamel paints, if the Train Set 'Humbrol' paints in those tiny tins are still buyable. Glass Enamel on metal will 'ping' off if you try to straighten it & loss is going to happen on sticking to MDF properly. Once settled they stay good if the losses amid this can be scary. But it's a low grade one you'll fill & paint so it can be dealt with.

June 2022 Blog

"We'll Get It Restored And Give To The Grand Kids!"
You hear this on 'The Repair Shop' often by well meaning Restoration Owners. Well how pleased the Kids will be... Not. For a Start you don't start looking at Things Of The Past with Fondness until you are Older, could be your 30s, could be your 70s. Ones younger unless it was Familiar to them from seeing it are unlikely to have any interest beyond Selling it. As we put on the Prewar Annuals page, those lovely books stayed hidden away so later Generations never saw them so the books will only interest a Whimsical Few who like the Artwork or Cartoon aspect as we did. There is No Declaration saying you must keep things you aren't interested in, although the show does have Offspring liking things, one boy supposedly wanting his Mum's ragged Rabbit is highly unlikely, it's her item & means little to him is a reality the Sentimentality forgets. "We Don't Like That Tatty Old Thing" if not to upset by ever saying that. Some things you Only Want The Memory of, to actually be given them years later unaware they were Kept is a tricky one. That's why even a smart set of Medals from WWI with Great Grand-Dad's name on are sold on, they are nice to own if you knew the person, but sadly holding onto what should matter isn't considered if there is no connection. Having a Piece of History with a clear family link isn't for everyone. Some 'Repair Shop' things they get Sentimental about, like a Vacuum Cleaner or Car Jack can be very surreal that Women want them restored, but they are after a link to a Happy Past & of their choice. Trying to force your items onto uninterested family is best not done, leave them with you & let others choose on clearing out after you've gone. On the other hand, to hear Family sold or binned that item you liked as a Kid, they never told you so you missed the chance to buy it can leave you a bit lost. Go look online, odds are you'll find another one of it & have "It" nearly back.

How Organised are You?
In Hifi utmost care is needed to keep Amp bits as you take things apart in boxes & bags to keep it all together. Until you can't find said container of bits & an amp just sold needs these screws to complete it. Can find bags of Luxman LX33 top lid screws from over six years ago. You can see how Steve the Clock guy does it on 'The Repair Shop', he uses Flowerpot saucers mainly. We use the small Poly bags & spare drawers from the parts stacked drawer units, adding the Amp Name on bag or box. Good until you forget you had them boxed & looked in that box twice already. "The Missing Screw" will always catch you out, if we have a big stash of parts over the years so can always be fine. To find old bags with amps marked long since gone gets you wondering why you didn't find the bag if to know the screws stash got used. Oddest one we had was the 1971 4ch Akai AS-8100S, it lacked two case screws which had no long case side screw and recessed washer part. Amp still here, if the box it arrived in recently got used for the Sony STR-6055 as much the same size. Box here for 2 years & a little rare bit of joy in finding the missing screws still in the packing. The odds of that happening very limited if it happens. The thing with boxes of spare small parts is remembering you have them & they are usually boxed up together by the time you got them which helps find but can frustrate as you haven't got 4 of the same thing. One amp needed a push button with a smaller square inside as the part needing replacing was larger size, but luckily some parts were used on other amps so had a few of those. Another on a Pioneer amp we have stood out a mile as one the seller replaced without saying, so to be fussy & buy a whole set of them.

Errors On Service Manuals & Circuit Diagrams.
The Data is supposed to be Reliable, wihout it, you can be at a Loss as no idea what the Circuit really should be. Sadly Errors of quite Major Importance are in the Schemarics aka Circuit Diagrams. Realised by wondering what's going on, a Trio-Kenwood KR-6170 error on the HT Voltage, as in where does it come from. It makes no sense & if this was Faulty you'd be left with a Dead Amp. Pin 35 is missing connection to a Regulator, if (*1) says voltage comes from there. The Diagram doesn't show it's connected to any voltage source. To look at the Service Manual & look at the Board Layout Track side tells. There should be another 'Join Dot' between R82 & R83 but they missed it, it's joined by a track on the board. Seen others missing circuit lines leaving sections baffling, wrong Transistor numbers including NPN-PNP mixup & even wrong resistor-capacitor values by a missing zero, imagine the chaos there. A simple error can be a big problem as you Trust the Circuit is right. Not always.

Sony Portable Radio on 'The Repair Shop' & Akai AA-7000 Compare.
This S10 E2 Episode with the Sony Radio & an Egg Chair with built in speakers. The Egg Chair connects to your Hifi with a DIN connector, if what's inside to be found. The Foam typically turned to Dust & a big job to redo. The Radio is a broken mess, if with a crazy story, so they want it working. Not sure what he'll do to the case, but the Insides show Loose wires which later fix to the Antenna Rod inside. If the manual doesn't show how it's wired, your only chance is by having another one to reference to. The 1966 Akai AA-7000 receiver we had two of, the early non-grille edge one & the mid run one with the grilles. Later ones cheekily called it the AA-7000S if there were no Germaniums in it, a similar 'con' to the AA-5000 (S) as on our reviews page. The sellers cheated on the grille one as Transistors rusted so the legs were broken plus some fool unsoldered the Multivoltage wires from the Transformer so it wasn't even useable. No way to ever know which wires went where & to trust to use it, but of course we had another so could copy which colour went where. A third AA-7000 we got from a Customer to rebuild some time later. Probably not many more out there. Our AA-7000 that we still have here never worked on FM as someone had misadjusted the settings on the Front End, putting it way off. No way to ever get it right unless you have FM quality test gear, but we copied the heights of the ferrite screws & our one then worked on FM which is insane. No AM working, if FM more useful. The Sony radio didn't need much to get going, a Sony was never a cheaper item & it lasted well electronically. The owner delighted, but to think to see another high grade one 'like it was new' would appeal, the case that rough & broken will lose appeal quickly, you'd not use it. The Egg Chair they changed to a 6.3mm socket & used a Phone for Music, probably by Bluetooth to the Amp they plugged in? Inside it had flat speakers, not conical ones. Not sure if it had an amp in the chair base, if they only plugged in one item. Search more would answer, modern versions do have an amp built in. She did a great job on the cloth, one of the hardest things to restore like the Dolls & Bears.

July 2022 Blog

1971 Trio-Kenwood KR-6170 Jumbo Receiver: A Deeper Look.
This amp starts a fresh look at the Hifi we have here. The Focussed Sound in this isn't in all amps. Got this a few years ago & we rebuilt it if not really tried it out recently. Finding we had it on 'Loudness' gave it a sound we don't like, but to hear the Trio-Kenwood TK-140X early one we're working on, to compare to another Trio. To play the YouTube music videos needing Treble Tone saw it was set wrongly, the Selector is small & really only by using it to set three notches from anticlockwise. The Design of this matches impedance very differently to give what is a light compression effect. Known this from certain Sansui amps that put Phono thru Aux, if the KR-6170 is a far more sophisticated design. It gives a far better Focus to Midrange that not even our Luxman LX33 valves can do. The Hifi Ad Dreamwording of "Hearing More Than You've Ever Heard In Detail" really is in here, making 1960s Vinyl sound more Cohesive than ever before, bringing that Focus. The amp itself we've wanted one for ages if never seen one. One in Ausralia for about $1500 unsold & now $1200, nobody will pay that much for an untouched 1971 amp. We got this for £200, it looks better in daylight than the harsh camera pics, if the fascia wear & side edge missing isn't bad looking. The Reverb Spring & 'Rhythm Composer' beatbox is a bit away from Hifi, our early opinion as on the 'Other Amps' page, if it can be turned off to not affect sound. Based on the 33w Trio-Kenwood KR-5150 that we last had in 2013, the 5150 didn't impress. The 6170 with our Upgrades & more since shows these are rather tamed in design, if can be very different upgraded. The KR-6170 is an amp like the 4ch Amps & Receivers, a huge amount to service, the 6170 was very rough, yet as typical 'Working Order' they said yet actually far from it. Played this a few times now on Headphones & finding 1960s Music sounding More Focussed is the Unique thing here. Whether it'll be liked later after comparing to more amps is the thing. We've been playing the 1966 Sansui TR-707A mostly the last two years on Speakers, it too has Unique Design. The KR-6170 has Bass power & richness, if not quite the Deepest Bass. Big Monster Receiver Size? Actually within 1cm of the 1978 Yamaha CR-2020 so it's not so huge. Not many amps have 2x Aux & this can run 4 Sets of speakers, not all at once, if how the buttons work. Manual says you can use 4 Sets of 8 ohm Speakers, the Power Limiter 'Full' is 150w Dynamic Power (into 4 ohms), 33w RMS. On 4 sets they work in Series needing button combinations. To use Speakers in different rooms the idea. Comparing With Other Amps. Played the 1979 Luxman LX33 valves for a few hours as a Reference sound, by Headphones. Then the same tracks with the KR-6170. The Midrange is better defined so better focussed & 'Smooth' if not lacking Dynamics. The LX33 is so similar, it's our Sound Design after all, but it lacks that ultimate Solid Midrange, probably too subtle a difference for most, but it's Our Game to keep pushing for a better sound. The Focus in the design takes a very slightly raggedy edge to offer it Smoothly. In this case, 'Smooth' is an evenly balanced sound without the Softness & lack of Punch the term can mean. The KR-6170 has what looks strange design, but it's perfectly matched for Impedance to give a pleasing sound. To compare more amps on headphones, the 1966 Sansui TR-707A has to be next. This amp an Unique design in different ways. Has the same Smooth Sound, to have heard it elsewhere to hear it again, if this the first TR707A-KR6170 compare. Dynamics seemed bigger on the TR707A, but played it a little louder so KR-6170 up half a notch. A UK 1971 Private Press EP by 'Inshallah' a white pop cabaret group probably uses the Rhythm Composer, if they were fitted in Organs also.

Is It Worth Upgrading An Amp Further To Try Sell It?
Thinking on the Yamaha CR-200 & the Marantz 1072 still for Sale as of typing, both sold now. Yamaha is only about 15w but it's based on a 1969 era design from an earlier Receiver that had a Turntable fitted on some. One model is the Yamaha MS3. We have the manual for the Yamaha AA-70 which has no Turntable if the case is big enough. Comparing AA-70 to CR-200 both are Capacitor Coupled & are quite similar, the AA-70 is about 30w RMS per channel, the ratings doubled to 60w if the Power Supply is 63v, the 15w RMS CR-200 is 45v. This means the centre voltage is 31.5v or 22.5v. The CR-200 is very modest in spec, to maybe get 20w RMS for good upgrades. But is it worth trying? To listen to it again to see what it sounds like 3 years later. It puts out 15v clean Sine at 15w, a 20w-25w amp can be 18v clean Sine. Before Listening, the idea isn't so good, to give Good Upgrades makes it still a 15w Rated amp so it has a Price Ceiling as the CR-200 is around to buy as Raw. To try the Marantz before packing up, reveals it plays a nice clean sound of good tonal balance on Headphones with less rowdy music. Louder music is a bit less tidy as it reveals limits, if based on speakers it'd see, it will be better than the usual amp it'd replace. Yamaha next, a lightweight more tinny cased visual effort than others in the range as the lowest model, if still looks smart as the fascia is still the same quality as are the controls. Again as already Recapped with Upgrades, really not that different on Headphones with 15w compared to the approx 36w of the Marantz. Both with nice quiet background. The Yamaha better on louder music than the Marantz which shows the modest design being based on a 1969 design. To hear the sound is lively with a decent bass if it can be heard flattened off for the 15w design but not poor sounding or muffly. The Yamaha is a real sleeper, we can play it & not wish it was another amp as it's focus is pretty decent, the Marantz not quite as precise. 1969 designs beat later ones for Musicality as we've found a lot. Playing Stereo Rock it's a bit too much on Treble so roll the tone to -4 on Treble & up the Bass to +2. The Yamaha is an unexpected listen, it shouldn't play "Start" with such 'weighty' confidence at just under 4 on the volume, but it does. To hear the limits but overall this is not what Yamaha usually sound like. Wide Stereo too. The Headphone circuit is different to other Yamaha so explains the louder sound, sounds like a 40w amp. On Speakers it sounded decent too if more like a 15w amp. Re-reading our review shows we saw how good it was in 2019 & to have it unsold as Recapped Upgraded & Serviced shows how unaware people are of certain amps that don't fit their needs, a CR-2020 sells fast, the CR-200 unsold in 3 years tells & ebay shows £100-£150 would buy a raw one. Worth Upgrading the Yamaha? To sell it more Upgraded knowing what needs doing to 'up it's game' is advanced work & design work. The buyer of it won't have speakers like our Tannoys & the change only really shows knowing what further upgrades bring. As in it has 80% of Upgrades doing fine already, to do more pleases our listening, if outclasses a 15w amp pricewise. But knowing how good it sounds, to try a 15w after how good the 20w Sansui 400 & Sansui 350A sounded, it's more for our interest. Which was what this Hifi Site was & still is about. In the end, the CR-200 put back for sale as it was before.

1975 Yamaha CR-200 & 1978 Marantz 1072 Comparing Build & Circuits.
Both these amps show a similar build type, as in all on One Board, the single PCB style that was common by 1979. An excuse to cost cut further as Budget & Midprice amps were rather sad in how they were built by then. 1974 for the 'Comet' effect in cutting prices way low & 1979 further that lasted into the early 1980s. Inputs are via Shielded Cables to a Selector as the CR-2020 has. Phono is an IC pair of TA7122 used a lot in Hifi, the Marantz 2385 biggie uses the TA7136 in it's preamp, so not a budget IC if grading turds is allowed. The Marantz has the updated selector that's like the Yamaha, if a ribbon to set it right by the inputs with PCB mounted Phono sockets but this means very thin PCB track instead of a proper piece of cable. Easier to construct if not the same quality, it's the standard build since then. The Yamaha puts the stages in a way that looks like modern amps, power supply on the left, pre-tone at the front & power amp in the middle with the tuner on the right. TO220 'proper' transistor outputs, the Marantz has similar as a larger TOP-3 that is much used in the 1980s onwards. Yamaha & Marantz power transistors soldered to the PCB, no wires. The design is much simplified from the 1965-1972 era, some amps & receivers are very packed with multiple boards & lots of wire. The Yamaha track side shows bigger track than recent amps, thicker again for voltage ones, all much a template for the 1980s onwards on the Marantz too. Both before the Horrors of Plug-In connectors & those poor long ribbon cables that aren't shielded on Audio. The one board on the Yamaha has two bars soldered on underneath that holds the PCB solid plus the Outputs are fixed to the small heatsink with a bar across that's part of the base to hold it solid. One later Yamaha was only supported by the Solder on the Outputs, built-in obsolescence is a cynical way of building, even by 1978. Circuits are where they differ, the Yamaha has a 1969 based preamp & power amp with output capacitors. The Marantz is a Differential one with a strange NFB-Filter on the Input giving a bit of a Retro Bass, a little more tamed too. The Yamaha shows it's 1969 age with a much better design & a surprising lack of resistors in the Signal Path after the input, the 1984 Sansui AU-G90X still has 3 resistors if it's a 15w amp with the Yamaha. Yamaha Tuner. The tuner assembly on the Yamaha is dated '1975' with heavy steel case sides & fascia areas like the 1973 models, the amp features in the 1977 & 1978 HFYB if was updated for the next range by 1980. The tuner has ICs with 2 Ceramic Filters, the CR-2020 has 3 as well as 3 ICs. No Tuner features beyond FM or AM. You'd expect it to be an average tuner, but again it's a sweet sounding crisp tuner ahead of many tuners that are muddy sounding. Sensitivity not so high the only limit, better Antenna would help, not even a Mono switch. When this amp has a clean Tuner sound, how are some like the Marantz 2385 one so lousy? Why Buy A More Powerful Amp? Beyond the obvious extra power, the reality on 95dB speakers unless you want it very loud, this has a sound that is way ahead of more complex designs. There are other low power amps that hide Quality like this does, very few though, there are also plenty of cheap low power amps that are lousy, especially UK & EU ones.

Clever Repairs on 'The Repair Shop'.
S10 E6 has some complicated ones. Monkey toy with a chewed face is solved by backing the hole & inserting a cloth layer & sewing it in. Great idea & it works well. They never look too perfect & still keep originality, instead of redoing the whole face which would lose the original character. A Suffragette's book with a mouse chewed corner he uses similar layering to fix the inside book section. Book techniques we made up as we went along to repair books to make them readable & to see them do similar is cool, for the Annuals page books years ago. The interesting one is the Cloth Cover to the book. She can't match the faded colour so wonderfully realises to print the scanned colour onto a modified cloth covered paper. Colour spot on & a great technique. Again reminds us of the 1930s large 'Rowntrees' enamel sign we have. Long size with 'Chocolates & Pastilles' on. There was a Royal insignia on 3 corners, one was good but the others damaged & impossible to repaint such fine detail. So about 2002 we scanned the good corner & after repairs printed 3 more out on self adhesive photo paper. After cutting to the circle as the border had made a 'perfect' repair that still holds today. Still have the original ebay sales photo & the seller cheated by hiding 2 bad corners by setting up the photo with the sign upright conveniently hiding the worst corners. Only £100 seemed cheap if damage more than expected. 'Rowntrees' familiar from 1970s Sweets & 'Kit Kat' used to have the name embossed on the bar fingers before the brand was later sold to others a few times. Nice sign with the fancy font & Google images shows the 'C & P' version as not so common. Restoration techniques seeing used by others is good, they probably make it up as the situation needs. Working on Vintage Hifi often needs these sort of ideas adapted.

The Problems of RF Noise.
Earth Loops create RF Noise if there is Distance between Hifi & Computers, even if the same Mains Plug Socket is used, usually via Extension Socket Leads. A Constant Crackly Noise that can include Computer Mouse noise. We've mentioned this a lot & long ago, the Solution is a 'Ground Loop Isolator' preferably a small Box version rather than the cheap Round one with Wires attached. This works as you'd want using the Computer 'Audio Out' to the Amp's Aux input, hardly any loss of signal. The Problem Starts when you want to Record from the Amp via Phono, you get that Annoying Noise again as you've reintroduced another Earth Loop. One set of Cables picked up No Noise, but after a pin broke, to go buy the same again, but this time & every Cable since, the noise is there. The problem of needing a 10m Cable is what picks up the RF, but in a Studio be sure cables are much longer. The 'Rec Out' stage of Amplifiers should really have a Buffer to stop impedance mismatching altering the Tonal Balance, but few do. To try an Isolator on the Output signal doesn't work as the Impedance is way mismatched, so to try to record the sound plays a heavily reduced volume with treble much down. Try to be clever & wire it up 'the other way round' using a cable & a connector doesn't work either, the level is barely audible. The amp itself without the 'Rec Out' connected is extra quiet so it's not an amp problem beyond it being not tamed down to avoid the noises. No point removing the 'Aux In' as it avoids the Earth Loop & don't try amateurish dangerous ideas like taking the Earth wire out of plugs etc, some Valve Amps have 'Earth Lift'. Computer Issue Therefore. But what to do? Made a cover for the Soundcard that was grounded, made no difference. The Power Supply in the Computer will just have one Ground connection. Ideas seen online are a 'DI Box' which is 'Direct Inject' box used for very long Studio cables, it alters the Impedance as does the Ground Loop Isolator. But as Google tells... "converts the unbalanced, high impedance signal output of an instrument to a balanced low impedance mic-level signal" which is the sort of level we got above. Not much use to us. You could configure the Computer Line in to a Mic one perhaps, but what it does for Noise & Sound Balance? The recording we did with it connected 'the other way' is of no use even made louder, brings up Hum & Bassy Distortion. We want Line Level. Reading 'DI Unit' on Wikipedia shows they've been around since the 1960s & use the Transformers the 'Ground Loop Isolator' does. Go Try The Mic Input With 'Other Way'. No good, noise & no real signal. Look on ebay, 'Hum Destroyer' one calls it, they have Guitar inputs & RCA outputs or XLR Balanced ones. Some have a 'Phantom' power unit adding to removing Earth Loops. Surely the answer for Us is more in Computer terms. Using the Motherboard Soundcard no better, actually noisier & even unplugging the Monitor from Mains makes no difference. A DI unit won't solve the problem & creates output level differences, for a Guitar input is unamplified like a Record Player Cartridge, Rec Out outputs are Line Level. Maybe a 240v Mains Isolator like TV Repair Shops use? That is just a 1:1 winding transformer, Earth isn't part of it. The only known solution is as with days of Cassette & CD-R, to use 1m cables to avoid noise. The 'Earth Lift' idea isn't so good as it relies on the Connecting Cables to take Earth from their other end. Removing Earth from the Audio Cables doesn't work either. One not Solved yet...

1971 Sony STR-6200F & Sony STR-6065 Receivers. How Alike Are They?
Two Quality Sony Receivers, one an Update of the STR-6120 & the other is still 'Under The Radar' as no-one's had a look at it properly yet. The 6200F came before the 6065. 6200F rated 70w if only 60w as 20Hz-20kHz. 6065 rated 80w if only 50w as 20Hz-20kHz. 6200F is the bigger STR-6120 size & the 6065 is crammed into the STR-6055 case. STR-6200F isn't so easy to find & especially in decent visual grade. STR-6065 is a EU model only, as no room to fit the extra fuses some STR-6055 have. The 6200F still has the 1968 Tuner design & the 6065 has a slightly better spec version of the STR-6055 tuner. This has the Newly Introduced Ceramic Filters & it's a very decent Tuner. The next Sony range STR-7055 has a cheaper tuner, so the 6055 & 6065 have the Best Sony tuner as does the separate Tuner ST-5150. We're looking at the 6065 circuits to Upgrade ours soon, so to look at the 6200F to see how they compare. Preamp-Tone. Interestingly the 6120 & 6200F preamp are much the same, the boards look the same & only really minor differences. The 6065 preamp has no Low Filter & is simplified with Pots for Tone not the Stepped switches that make no difference in sound quality. Power Amps. The 6120 power amp based on the TA-1120A. The 6200F & 6065 have a new design with a Differential & no Output Capacitors. Likely the TA-3200F power amp came first & these are later versions, if of the first 3200F. The 6200F has the 'Speaker EQ' Bass Boost switch as the STR-6120 does. Again, both 6200F & 6065 Power Amps are much the same. The 3200F Power Amp has a more advanced input stage & 100w if not unlike the 6200F & 6065. The Differing Power Ratings on 6200F & 6065 make little sense, both have the 'Speaker Protection Circuit'. There are Two Types of Protection in the 6200F, one for Output Transistors & the other for the Speaker. The 6065 apparently only has the Output Transistor one, if both have the 'SCR' if the 6065 circuit description doesn't mention the Speaker protection if has it on the Circuit. Whether any of this actually saves the amp or speakers is another thing, we got the 6065 with a burned out Power amp with the Protection Stages well burnt, to the point of too far gone if a spare parts amp board saved it. 6065 rated 80w yet the 2SD88A output transistors are only rated 80w. The 50w rated TA-1120(A) has doubled outputs on it's 1965 50w outputs, this claiming 80w from 80w transistors may fry your amp board. A Sleeper Amp. The Sony STR-6065 is a real Sleeper amp, working original one in USA (117v model) for only $300 in June 2022 plus a nice early wood case shows it's not currently rated more than the STR-6055 is, if it sold the next day. The STR-6065 is an updated resized version of the STR-6200F. Both are very similar beyond the updated Tuner.

Silly Season "The Repair Shop" A Badly Smashed Up Radio.
"My Dad Bought Me This Radio" says the guy on S10 E7. Camera points to a badly smashed up late 1950s style Valve Tabletop Radio. Couldn't he have bought him a better one? Why even keep it, front & lower case all very broken. In reality this is a parts Radio & you can probably buy a working & complete one online for not much. But them offering to Repair it is Ridiculous. It's been dropped heavily & way beyond any sensible repair. The old guy would be happy with another of the same model Radio, "the one Dad had" and "one in nice grade like Dad's" can soon blur into the same item. What he does with this will be interesting. In terms of Hifi repairs a tatty non working one can become a tatty working one you'd not use as it's too tatty & resell value isn't there. He certainly is fond of it, to hear he recently had it sent to him & The Courier smashed it up, his Mum had kept it for years safely but it wasn't packed properly is obvious. But to not just go find another & want the wreck repaired? See if they show the maker & model to look online for one. A Philips one with a Magic Eye tuning display valve. Some of these are nice lookers, his on Google is like a "Philips FM 108" that sold for €200 so may be a rarer one, non UK model in different colours, if like with Vintage Hifi, you can usually find one. The box it arrived is not big enough & why damaged, if it holds all the bits so a Repair can be attempted is the premise. Broken Tuner Glass to scan & do artwork to 'repair' & then get it printed out, if you can find anyone who can do that, we got the 1963 Trio WX-400U glass back broken so got it remade, story on the review. The case to assume they'll glue back all the bits & to fix the electronics. Hardly a small repair job, in reality would anyone even touch it & be able to offer it back tidy & working? Verdict. Don't believe this one is for real. His clumsy way of fibreglass joining dozens of pieces of Bakelite is highly unlikely to give such a good finish, even the Ceramics repairs are never perfect. Gaffer tape isn't the right sort of tape to use either. The Tuner Glass again we couldn't find anyone to do a small bit of glass, only Perspex & they weren't skilled. Why he was soldering resistors on the intro doesn't fit in either. The Sound was Post-Production added, too clean if you've heard these old radios they have a charm if a much different sound. The show is for Entertainment, too much sugary sentimentality, the Guy was delighted, but a Rare "Phony" repair here, they sourced another radio & made one good unit.

August 2022 Blog

1971 TV & Radio Yearbook
Colour TV back in this time was Hugely Expensive if what you got was presented in wood veneer cabinets usually with doors for the Housewife to pretend they didn't have such a 'Low Class' Gadget in their Home. Even in the 1990s to hear having a Portable TV Screen size of maybe 12" wasn't 'Common' like a 26" TV of that era. All laughable now with some screens mega huge. A 42" one suits us, why have a TV so big you can't take the full screen in without moving your head, same with Computer monitors. TV Screens need a TV stand, not on The Wall over Mantelpiece height unless you want a stiff neck from looking up always, modern unthinking. The 1971 TV was so expensive as the RGB guns circuitry was very complex. We got given a 'Posh' big early 1970s TV in a smart wood case as in the early 1990s people used to give Old TVs to Charity, or get them to take their rubbish away more like. 'You Can Have It' so being interested to see what was inside, to take it. Days before ICs in TV left loads of circuitry & 10w resistors that were designed to Unsolder tripping like a Crude Fuse. These Old TVs once aged were terrible for 'Bad Geometry' as in using a Test Card, one line at the corners could be in 3 colours making 3 lines that couldn't be adjusted into a single image. This one had a Remote Control, not a Wired One but an early InfraRed for Basic Controls. TV of no use to anyone as picture poor from the alignment issues so in the bin soon after. Did try two other early TVs, a 1950s Murphy Console one with bad corrosion on tube pins & rotary controls if the case was nice so sold it. Another with the Doors on probably 1950s, with an Armour Plate glass screen over the Tube, still have that glass as it fits on the Pye G/RG gram top. It worked to a degree, if to bin it as a Dangerous thing was considered. Live Chassis most probably. Whatever they used as Varnish was a dusty mess that Paint Stripper wouldn't remove. The rubbish we used to get just to have a look, fascinating. Today Old TVs are Props with a modern screen inside or just used 'Off' with an image added in Post Production. Some still look cool, but of little use today as only Analog though you can put a Video VCR in via the Aerial socket.

We Write These Blogs Then Edit, Delete or Add To Before Posting.
Some Blogs run out of Steam, seem to Repeat Earlier Blogs or don't really seem worthwhile. It's the Writer's Advantage to re-read & edit. Not to give too much away in Upgrading as we've found Amateurs take an idea & think it can Universally Improve Any Amp. To Warn of Problems to Keep Amps Alive. To Question the Overpricing of Raw Aged Amps that "Work" but aren't really useable as crackly & noisy etc. To not tell of 'Bad Amps' as some issues can be very hard to solve, if to warn they are unreliable if an amp gets broken for parts, beyond being too damaged or too messed with. To keep it Positive. To show The Joy in Hifi & get Technical if not into Theory & Equations as it doesn't interest us. Design by Maths or Costing is Boring Design. Why Hifi Upgrades. Some Blogs are amp work in progress with ideas once tried that just look like thinking aloud which doesn't read well.

Some Collector Scenes & Restoration Are Really Boring?
The dear old 'Repair Shop' on S10 E6 gets us yawning a bit on a Diorama restoration. It's a dull one but it means something to the owners as family made it & to get another to even repair it 20 years later shows they care. The guy doing the work tells of his younger years doing similar & you can see the joy they have doing it, to at least appreciate the work. Collector Scenes are on TV a lot, the "Bangers & Cash" UK Vintage Cars one firstly on 'Yesterday' channel is on Season 5 as it works great on TV & for us some of the cars are familiar if thinking why the 1980s & 1990s everyday cars have any interest. It has sellers, owners & buyers talking about their Car Passion & it's a great watch. Another one on Auctioning Toys leaves us cold, 'Star Wars' yet again on "Scouting For Toys" but it's just a dull show with no personality as is the "Yorkshire Auction House" one. But Boring To You may be another's life, caring about the minutae of things, they'll probably see Vinyl Records & Vintage Hifi as boring, they're wrong of course, but to have grown an interest in mundane matters such as 'Train Spotting' kept many out of the Pubs & Clubs which is another world many care for. Seeing Record Collectors care about 'Matrix Numbers' & tiny variants is so dull, it's not stamp collecting, but it is to some. That same episode has a rough warped kitchen table, a drop leaf one. To think they used it still in that state is a bit sad. To see how he flattens the warp as it's plain pine wood is great, you couldn't do that with Veneered wood. To use 'biscuits' of wood to fix the top parts together that had come unglued interests as well as it's things we've done similarly & to see newer techniques. With any Restoration, the satisfaction in bringing a great result is what the restorer needs, "I made that tatty rough thing that nice" is pleasurable & to give it back looking 'like new' is the thing. To restore one amp & find strange issues, to think to tell them, but it's too specialist & they'd not know what it meant is thinking How Boring you could be to them, so to not tell this one, if a previous odd issue didn't get much said. The Customer only wants it Reliable & our Harsh Testing picks up on issues.

What Got Damaged In The Sony STR-6065 Power Amp Board?
An amp we got, bad damage to this board was considered too much to repair, as several badly burnt resistors & already found bad output transistors. The rest, as time proved is fine & we trusted it to work on Speakers, to hear what it's like as original. The odds of finding a Working Power Amp as a spare does happen on ebay USA if why they break it could be for visual damage, or it could be the remains of an amp used for spares elsewhere, as asking sellers for certain parts, to hear that's all they got, so an industry in parting amps. We parted a Sony STR-6120 years ago & most sold quickly, if no interest in the glass or transformer. 6065 Damage. Visually Resistors are burnt on the right side of the board, which ones failed interests, so R737 1K, R740 5.6K, R736 10 ohm, R726 2.2K & the R776 on the left side plus R720 330 ohm. Others have smoke damage so maybe not so bad, but to have to test all Transistors, Diodes & Resistors is a bit much. You'd have to spend maybe hours if an ebay search found a board so easy option the wise choice. Trusting Bad Damage is another thing, we trusted the new board on speakers after hours use on Headphones. Resistors show the NPN Push-Pull driver took a hit from the outputs failing, if why all 4 outputs failed & the other board side not much damaged shows it burnt a while before the SCR triggered. The 5w 0.5 ohm resistors look fine & test right, if to test every item to trust it. The 2SC895 on the bad side is shorted if the others don't read right. Damaged Sony STR-6120. As blogged before, we got our Canada-bought 6120 back after the buyer damaged it with Volume at Max on turn on & then got an Amateur to 'repair' it causing a lot more damage, blown out Main Cap & Track blown off the Power Amp. Labour Of Love to keep it going, replace nearly all the resistors on that board as it wasn't trusted. Good to do for our interest & revive it, if for a Customer to have to do that Much Work would be a job not done as Too Expensive. That 6120 lives on if we saw it again as Speaker Cables shorted. Some amps are 'Forever Repairable', if Costs are the Limit.

Next To Try The 1966 Pioneer SX-1000TA Receiver.
Going through our pile of Amps, actually all Receivers beyond the Yamaha CA-1000. This Pioneer still works on original caps & not serviced yet. Did need a little work, fit a Loudness switch & Volume control, unfindable bits if the never-worked SX-1000TD-F supplied those. Surprisingly quiet even with Volume up after the track ended & silent with Volume to minimum. Old caps need to wake up as it sounds vague if does wake up within 10 mins. A crisp focussed sound with no roughness, if the Bass Filter holds Bass back, the sound betters the recent Pioneers SX-1000TD-F & SX-1500TD-F the 1967 versions. This 1966 one with the Tuner Valve & Nuvistors that still work. Amazing to think somebody used this & yet sold it on for not much, to assume the speakers didn't match as on Headphones the sound is as good as the Sony STR-6065. Barely warm on the heatsinks & a sound of some beauty indeed. Never heard a Pioneer sound this lively & clean. Bass even though filtered on Headphones sounds reasonable, if on our Speakers, like the SX-1500TDF it'll be a Bassy mess with no direction. The design on the circuits oddly isn't so unlike the 1967 ones, the stage after the Output transistors differs. Circuit quite different to the earlier Pioneer SX-600T with Transformer coupling, no valve if 4 Nuvistors, one on ebay for £250 seemed a bit high, if missed trying it. STR-6065 & SX-1000TA are top amps with a sound that will just get recapped with upgrades, no circuits need altering.

The 1966 Sanyo DC-60E Receiver.
Different quality to more recent Sanyo, they made decent receivers with the 1973 Sanyo DCX-8000K & they made a lot of Transistors if not much Hifi until the Budget stuff of today. This one still in the 1972 HFYB shows a 1966 amp wasn't selling. No UK dealer or Hifi News awareness & the brand as with the 1969 DC-66 seem better known in Poland & nearby EU countries. The 60 & 66 are great sounding amps, so no wonder these are liked abroad. Smart looks & nice veneered cases hide an inside that is not so easy to work on. The DC-66 we recapped if without any Service Manual the non Standard circuit remains a bit unknown sadly. Good to have found the DC-60E Manual as a paper one on ebay, chances of finding both at the same time. The Power Amp is interesting as a Transformer Coupled design if thankfully Fixed Bias like the 1966 Akai AA-7000 is, if the 1966-68 Sansui 3000(A) needs adjusting, the National Panasonic SA-65 similarly. Build Quality is wires all over the place, to try to look at the Resistors board we didn't go further with after 3 wires unsoldered, so we'll put them back to play again. The thing was built hard-wired so there has to be an easier way, or not, as the DC-66 was very tricky. But amid the aged noise, a sweet sound in here. Germaniums amp beyond the 2SD68C outputs 50w 5A TO3. The left side inside is nearly half power supply & power amp, the right side is Tuner Boards & the Preamp-Power Amp earlier stages. For all the circuitry it's only about 17x8cm with wires mostly on the left edge if more midway & underneath. To take it out the only way & what that brings. The thing is as it's 1966, how good will it be? Surprisingly with Volume at Zero, there is No Sound, not even noise, if turn it up, very noisy. Volume is after Input, which is Aux through Phono & after Tone. Onto the Power Amp stages that are quiet offers hope, as it is way noisy. Design is similar to the Akai AA-5000 with PNP Germaniums & as higher NFB it's not one to convert to Silicon as the 1966 Sansui TR-707A allows. Higher NFB in several places creates a smooth sound, if it's not really the sound we'd play, the TR-707A NFB is far more subtle, such a great design. The question is to ask is it worth doing? A blind buy hearing how nice the DC-66 was & liking the Power Amp if the Driver Transformers are smaller than Akai & Sansui used. The fact the FM Tuner board was broken as unsupported so it cracked & only the AM works leaves this in Limbo a bit. We sold the Akai AA-5000 & next day bought another back as it looked nice as an ornament sat on the Trio-Kenwood tuner. For the while, this will be put back together & try it to listen to decide what to do. It is a good looker with a tidy case. But it's going to be a tough one to work on. Another day, or maybe not. Three wires soldered back, but there's a loose one, wasn't it soldered to the TO3 pin, no trace of it, so how did it work? Very odd. Eventually get it working after some fiddling, it is unserviced still. The sound is still decent as it goes over the place audibly, when it arrives it does sound amid the hum one side & crackle the other, not as noisy as before. Heatsinks pretty warm, the Ropey sound settles after some use. For a Germaniums amp it sounds 'modern', unlike the slower sounding AA-5000. It is in the league of the STR-6065 & SX-1000TA when it's stable. We're using the 'Tape In' via the DIN socket to bypass the Aux into Phono. Much less noisy than before & that great sound, if the Pioneer SX-1000TA & Sony STR-6065 are similar quality. Rock plays well with a clean sound on Guitar that is solid sounding, no thin grainy sound here. 10kg 25w amp with a Top Sound. Bass as it plays is full if not the deepest bass. It's in the league of the STR-6065, SX-1000TA & CR-200 which makes it tough. The thing with amps like this is it has a Max Sell Price for whatever brand & power it is. This one would need work & parts costing at least twice what it'd sell for. This makes it one to sit for another day, it's a great looker in nice grade at least.

September 2022 Blog

Amps We've Been Trying To Sort.
This involved the 1973 JVC 4VN-880, JVC 4VN-990, 1966 Akai AA-7000 & 1966 Sansui 3000 1st version. Blogging as they were being tried doesn't make good reading once issues have been dealt with. Quality Amps here, problems to solve like the 4VN-990 meter bulbs, to fit in the LED Festoon bulbs is possible if not with the Voltage the old bulbs use. Dealing with annoying Hum was very difficult. Using different Music as in our 1970s Rock folder including Stereo so added in a few Hendrix tracks, these are great for tesing, esp 'Voodoo Chile' as it gets Fierce & the detail is hard to resolve. The Sansui 3000 is a difficult one, those coupling transformers are 'too wild' & using hifi new capacitors brings in Thermal Runaway, it can run at 50°C if can run to 80°C without the fan. As 'Repair Shop' viewers will know, some Repair work isn't too interesting to see or Blog on, so to not publish it as 'work in progress'. By August 2023, sorted Three of Them if the JVC couldnt be made reliable. Three Out Of Four is good.

1973 Yamaha CA-1000 Amplifier
This one we got as a Risky Non Worker knowing it lacked several front controls, the Bass control found broken & the main caps one had burst & leaked. Likely left on 'Class A' in a limited space. Took a while to find the parts & Sept 2022 actually got the correct Bass Control from a parted one, the only amp that uses this Dual Pot 30K ohm. The seller has more parts on ebay, they recknoed the Transformer was bad, which from knowing the CA-1000 is unlikely unless it smelt burnt. We didn't like the Filter Amp so dared to better it. It actually Never Matched the Tannoys as most Yamaha don't, but for our ideas it matches fine, showing Amp Matching is based more on Preamp design, if not always. The 1973 amps JVC & Yamaha are noisy on the Relay as it turns off, even te 4VN-880 that's not recapped. We're using this amp on the Speakers, if to use the Speakers switch to silence it before Power Switching. They can turn on the Relay & then off sometimes, which would make The Noise which is too loud to put up with. It relates to an Instability, if we've not worked hat one out yet. The CA-1000 is the First Yamaha we've regularly used on Speakers since getting a Yamaha CR-1000 in 2012. The first CA-1000 we got earlier in 2012 to then get the overbright Yamaha CA-1010 that made the CR-1000 sound less lively when it was actually Neutral. The CA-1000 sounds Great on Speakers so that can stay as a Daily User & to try more with it another time.

1977 Yamaha CR-2020 Receiver.
Not had one of these since 2018, if we've had several of them over the years, including getting the USA style case as on the Gallery pages, as we needed a nice lid, so go a bit further. The USA one is 110v only so not so useful in UK. This one from the Original Owner is a very nice one, the American Walnut isn't faded so has the deep golden colour & a satin finish unlike the usual duller finish. This being a heavy 18kg receiver gets marks from moving around, this one so nice & crisp. This one a Mix of the UK & EU version, 240v only, no DIN but has the '75 ohm unbal' aerial socket & with the grey 2-core mains. Rated 100w into 8 ohms 20Hz-20kHz & 110w at 1kHz. Damping Factor of 40 more more, Tone Bass ±15dB & Treble ±10dB. Tuner 0.9µV at best. Some of these got Well Partied as the Over-Hot regulators leave a black mark on the grille, this one only slightly. It'll need the Hot Resistor-Regulator upgrade as on the Review page. No sign the Power Amps or Power Supply ever touched, just LEDs put in to update the bulbs. Rare to see one so nice, had a crisp CR-1020 before, CR-2020 usually got much use. But it is a 1977 amp, it'll be tired & need Servicing, we only Recap these now & Servicing part of the deal. To hear one again after getting the CA-1000 going as blogged above. Have A Listen. Plug fitted, will put a 3-Core longer cable later, Circuit Breaker & switch on. LEDs a bit garish, light green & too bright, not subtle. Power Switch a bit scratchy. Relay turns on fast, Silent background on Headphones. Plays Music well, better than an aged one sounds. Rock sounds weighty, Midrange solid if the Treble a bit blurry & not as crisp. A clean sound overall, the Yamaha sound. As with most amps, the Deepest Bass is rolled off, a 110w amp still playing safe, the 185w Marantz 2385 even less Bassy. The Soundstage playing known Stereo tracks not as deep as the CA-1000, if ours recapped with redesign, Stereo size modest. Working on a CR-2020 needs a lot of care, tight wires mean limited working space & the usual issues from tight wires. We've Upgraded our CR-2020s before, they do vary in sound amid the production as does the CR-1000, plus the amount of use affects quality. Phono has a bit of a background noise, not a hiss or hum but a broader 'white noise', compared to Tuner this only shows played much louder. FM plays without any Aerial as a sensitive unit, a Bassy sound, Stereo plays even, the AM the usual lo-fi sound, why even bother with AM on a Hifi amp? A slight noise on Turn-Off. Play the CA-1000 next day & then the CR-2020 shows similarities, the CR-2020 is a lesser beast for a cardboardy bass & lacking treble focus & power, midrange is solid, the CA-1000 we did redesign the Filter Amp, so a hard compare. CR-2020 as raw is a listenable amp, more aged ones can sound much more blurry. What To Do. A Full rebuild means the big job of the fascia & front panel off, undo the Tuner cord too, unsolder the 5 mini boards & recap. Having done this, only a minimal change for the work, so in this case of it being a very lightly used one, to save the customer money & us from the job of it. Phono is at the back of the Tuner board & very tricky to get to, again a stage on a high grade amp that makes not much difference. Power Supply & Power Amp are required to be redone as they keep it reliable & the Power Amp improves the most. Owner wants 4mm sockets, not ideal only having spring connectors for thin wire, a 110w amp needs thicker cable. We've not done this on a Yamaha before, the 4mm sockets on wires is what we use, after all the wire in the amp to the speaker outputs is only a certain thickness, another few cm & then use 5m of proper speaker cable. To replace if damaged, if connectors are useable we can make some 4mm socket cables as on the Sales Page. To offer options, not all Techs are after the biggest job costing the most. To offer good value. Circuit Gazing. Have a look at the circuits again, comparing to the CA-1000. The Preamp with the five tiny PCBs soldered in are the sort of circuitry we wonder what the purpose is compared to late 1960s designs. All five boards have the 'Class B' style circuitry in ICs, first one as a pair L+R usually covered with one Class A transistor, here it 'needs' 5, it's the Tone stage. Second board is after Tone as further gain for the Tone stage, again 4 transistors per channel on a single board, some odd sound-shaping circuitry in here. Next two boards with the Filter stages in between, these from the second board. Yet again the Class B stage as a pair of NPN-PNP, these seem to be Buffer Stages. A total of 13 transistors is Overdesign, explains why recapping made little difference. The Class B stages lose the tight focus & differing gain in the NPN & PNP seems illogical, nothing can be bettered in the Preamp-Tone, we have tried before. The idea was to eliminate switch noise. They all pull from the same 25v HT, as does the Phono. The Power Supply is in Two Stages, the top board & the upright-lower board with the 2 Main Caps on. Unlikely these will need replacing unless damaged, 18000µf 71v, have replaced the CA-1000 ones as one bad, the other was still good inside. Hot Resistors on the upright board, to try another way causes big heat elsewhere, what's not designed right here? Confusing error on the lower board. The Phono Stage is on the back of the Tuner & tight on the wires. Design is an IC for the MC stage, the MM stage is all Transistors if that Class B design again. as on the Turntables page we found this recapped with upgrades makes no difference as the Class B design blurs the sound. Double Volume Control. This is a 4 ganged control like 4ch Amps use, plus 2 more for Balance, but it's purpose is less clear. It uses 2 stages of Volume control in one, to see one is before the Preamp-Tone & another one is after. The Marantz 2385 uses similar as does the CA-1010 & CR-3020. This loses any noise on the preamp, if why this idea used when amps haven't needed this before is a little murky, as in why can't it be designed not to be noisy? To consider far too many Transistors on the preamp isn't the case. The CA-1010 we noticed this with & the CA-1000 only has one volume & balance, if the circuitry in 1973 wasn't so desperately searching for pointless THD ratings. Looking at the hideous CR-2040, this is stuffed with ICs, needing three on the Preamp-Tone, if the Power Amp looks fine. What Is The Hifi Niche For The CR-2020? Play It Loud Party Amp is the market for this, judging by heavy use on other ones. 1977 amps sound different to 1973 amps, if a 1973 can still sound like a 1966-67 one. Still the 'Yamaha' sound in here, powerful 110w, but a more Domestic Sound. Not everyone wants the very Detailed Sound which is why they play aged amps as the Sound suits. Until they hear a fresher sounding amp. Yamaha power amps sound great, the preamps vary the sound. To wonder what a CR-2020 without the excess circuitry would sound like can be done by using a different Preamp on the Pre Out-Main in sockets, which we tried before. Strong sound on lower frequencies, but the treble & midrange is grainy lacking focus on Headphones, it'll sound softer on speakers for the detail, the power makes it a real Party Amp, where it's strength is. Redo the Power Amp & Power Supply to play it again. Top & Lower Power Supply Boards. The large 71v 18000µf are low in the case & away from heat. One of the lower ones is an error as + and - are printed the wrong way. To keep the Original ones unless damaged, if they are 45 years old, Nippon Chemicon are a quality Brand & having cut open many replaced N-C caps, they are often still good. For Panasonic not making our usual ones, the ones we use instead are fine & look tidy. Here are the Hot resistors, well worth doing these as they will fail & the amp won't work. The Top Board is a lot of Capacitors. We have worked this out, if the board layout isn't numbered on board or circuit which isn't helpful. The Hot Top Regulators can reach a crazy 110°C with the top lid on, again this needs our Custom Upgrades to not stop working. Top Board is Lamps, Relay, Tuner Power Supply & the Regulators. It's very modest in some areas, if Upgrading didn't really bring too much difference. One Capacitor is a '123' Film one, it's actually an error if you work out what it does. To try not to pull the wires out is your challenge. The Power Supply is very cramped, couldn't they have used more space? Power Supply Done so try it before doing the Power Amps. These had screws hard to undo to nearly impossible to undo as too much locking paint, so chewed ends as the steel fairly soft. Hammer tidy & re '+' the holes. Before it sounded blurry with Treble Focus not very good. Not had one of these Biggies in 6 years now prices are much higher. Pleased to hear the Sound hugely better & Focus is much better & will improve more with the Power Amps. The Power Supply really does age badly even if it's not too heavily used. It's got a Solid Sound, not the full Deep Bass yet, but you can certainly tell it's a 100w amp.

Roots Of "Wheeler Dealers", 2006 "Auto Trader" TV Show.
Mike & Edd with a pre-cursor to the popular "Wheeler Dealers" show. Both of them as perfect casting, based on all the other Car shows, to only watch WD & "Counting Cars" as well as "Chasing Classic Cars". Here the AT show has interesting sections about improving Cars to Sell plus showing 'Lemons' in Cars such as ones not quite what they seem. To remember the show long ago from their big Sofa & not watching the more interesting bits further in. The first section about rather dull folk buying rather dull new Cars isn't too interesting. The fact 'Wheeler Dealers" starts in 2007 after 15 episodes shows they saw the strengths with 2007 bringing the Restoring aspect of cars on a Budget in the early ones. A bit awkward in two parts, if that was how the TV company wanted it, the Hour episodes brought it together better. "Auto Trader" the name of a Cars Sales Magazine since 1975 as well as a website, Google shows different names that might have clashed to move on to 'WD'. Interesting seeing the Dodgy Cars offered as good ones, the cut & shuts, stolen & renumbered to an interesting very nice one that had spent 3 days in a Saltwater river. Car cleaned up nice, but it's a write off as too much will be affected by corrosion, as the brakes showed & all the electrics would be bad. Only good for parts as water damage kills a car as does many items. Buyer Beware. This is always the way in any buying online or face to face. Most of what you buy is fine, you'll find many bargains & good buys. As with any Gambling, you'll get a seller not being fair, some you return, some you see it needs more work but still worth having. But buying amps as Raw is usually under £1000, seeing Cars that are no good sold for £10,000+ is a worry, one nice car we had they hid the Battery had leaked & eaten the bodywork, yet laughably hid it with folded plastic. It's what got it scrapped as it'd never repair.

October 2022 Blog

A Good Listen Of The Yamaha CR-2020 Soon After Valve Amp Playing.
This one Ready so time to give it a good playing. A Sept 2022 blog tells more & the General Opinion of the CR-2020 was it was a Soft Sounding Amp, rich & more wallowy. But this one is Different, this does happen with Yamaha, they do vary amid the production run. This is a 240v only model, looking at ones we've had since 2013 this is the Standard UK model, the Big Wood Case one is USA 110v only, we got the USA case as on the Gallery one as a better lid was needed. On first try a dull sound, but after Recapping the Power Supply it brings a very different sound. This amp is Recapped on the Power Amps too with Upgrades, if the Preamp front stages & Phono on Tuner Board not done but are fine. These are a tough job to do with toght boards & many loose wires making it a bit much when it actually still sounds fine & the design is decent enough to not do these tricky stages. Amp background is very quiet, take out the Headphones to hear how quiet it is. No Hum or Hiss, after a couple recently that did Hum, to be listening out for Noise & the Yamaha is excellent. The CR-2020 specs show Aux is -100dB Noise Floor which means a silent background that doesn't hide fine detail. Valve Amps are more Bassy on the 1965-1966 ones, the CR-2020 isn't as Bassy if the Damping Factor of 40 is far more 'friendly' sounding than later gear. Bass aside, the Sound is Fast, Crisp & Punchy without any Gritty sound or Harshness. Onto Stereo, it plays a Wide Stereo, not as wide as some & neither is our Yamaha CR-1000. Onto the Hendrix LP Stereo tracks it plays them cleanly, not the weighty sound some amps have played these with if +2 Bass Tone gives more. A 110w at 8 ohms with 1kHz or 100w at 20Hz-20kHz if not stating dB levels. Trying a Sine Sweep it gets Bass adequately by 40Hz if 30Hz is restrained. The Preamp-Tone Stage we've Recapped with Upgrades before, the difference for the job on it & Phono isn't needed on this amp yet, the Power Supply & Power Amp give the Best Value. Do we really fancy doing those stages & the difficulty it brings again? If they really needed doing, then perhaps, but having done these twice before, these stages don't bring much improvement. Says we playing this CR-2020 as we type. It's just Strange how Yamaha vary over the Production run, the Serial Number isn't always the '524th one made' as an example, with one amp by another brand to find later parts on an early number & vice versa. Try Again after the usual run in & adjusting. Has a clean precise sound. Playing the LX33 valves earlier, the CR-2020 needs +2 on Bass to fill out, it does sound a little flat from the amount of Transistors in the Preamp, 13 is a lot compared to earlier amps using 1 or 2 plus a Buffer. The Class B design is precise on detail. Trying 70s Rock Stereo tracks the sound is smaller. Comparing to Valves & 1966-69 amps is a tough compare, it reveals what it is. For a 1977 amp with the design ideas of it's era, it's still one of the Best, does seem to be depending on what you get in the Amp's run. On Speakers. Yamaha never really match the 1968 Tannoy 15" Gold Lancasters, the first Yamaha we've played for days on ours is our CA-1000 which had the Filter Amp redesigned. Here the CR-2020 actually matches quite well, not quite enough Treble Tone gain leaving a slightly thick Lower Midrange-Upper Bass. Our 'Loudspeakers' page says the CR-2020 is a good match, this one is Crisper than usual CR-2020s. The overall sound is smooth & clean, Stereo Width & Depth isn't like the Earlier Amps 1966-69, it seems 'more Mono' & flatter compared to the early amps, if for 1977 it's stil High Quality for it's era. The addition of 4mm sockets a little contraversial perhaps, first time we've tried this & it's much easier to connect. Good to Hear a CR-2020 if it does show Yamaha do vary amid the run.

Are Hardwired Valve Amps & Receivers Too Complicated?
They can Blow Your Mind in what a Valve Receiver looks like underneath, notice ebay sellers rarely photo the underneath knowing how Extreme it looks. The Hardwired way is soldered Point to Point with parts all over the place & ones hidden under each other. This gives the shortest signal path, bettering long thin track on PCBs. Unfortunately the Manuals never show which is 'C66' or similar, it's all unmarked. Having first done the 1963 Trio WX-400U to understand which area is which circuit & calmy number a photo of the whole underneath. This is advanced stuff, if you'll find it much more logical than it looks. To redo a few valve receivers now & it's not so bad, but you must be well planned in advance. Don't know electronics enough? Leave it, you'll ruin it. It's a big job to do if these amps are reliable. With our 1966 Pioneer ER-420 to rebuild this after we did the 1966 Pioneer SX-800A still is a very different amp & to start the job like it's a different amp, if there are similarities. Some sections can be fitted very tightly to wonder why they didn't put that like that to not pull off & not work right in ages. Faults are often 'Stupid Faults' as when you find them, there are no clever faults, all that Fault Finding for that? All adds to the knowledge. One thing to be aware of is not to touch or move the hardwired components as they can touch causing more Stupid Problems. To avoid ones part worked on that 'don't work' as try find what they did.

Use Quality Parts, But Avoid The Exotic 'Perfection'.
To find this quote on a Pioneer SM-83 which is the Amp version of the ER-420... "The difference between professional and amateur amp builders is pros use as inexpensive parts as possible and develop unique (good) sounding amps. Amateurs pick too many expensive parts and end up with less attractive (flat) sounding amps.” – Mr Ohshima, former manager of High-End Department of Sansui. Too right, the Quality in Rebuilds can vary from cheap ebay-China sourced parts that we'd never use. You can spend a fortune on Exotic Capacitors rated at 630v that only see 5v, but thinking why isn't quite the deal here, taking bits of Forum advice here & there isn't doing it properly. Metal Oxide resistors are in many modern amps, we used them in the 1979 Luxman LX-33 as it used a lot already. The Tube Technology valve amps similarly are with Metal Oxides as it's what they originally had. We use High Quality Parts that are 'Everyday' parts. Ideas we first used over 20 years ago, still using the Panasonic FC capacitors as they are of high quality, why spend more? Others use similar types in other brands, no reason why these would be any different, but you like what you like & has proven good. The traditional Carbon resistors are only usually 350v rated, the Metal Oxides rate higher. The Pioneer ER-420 uses a mix of resistors from the 'Allen Bradley' carbon composition resistors that we don't like as they can break, but they sound good. The ER-420 uses tube resistors with a hole through the middle, these are very precise if other types can age & drift values. On reading the ER-420 ones, some are higher than the 10% tolerance if still the amp works & sounds great. To leave them for the while if have only replaced 3 that were too far off. Look online at Valve Amp rebuilds to see everyone has different ideas, from the awful 'Capacitor Stuffing' new small caps in the old cans and those using huge coupling caps of high voltage thinking it's better. To try ideas like redo an amp stage with closely matched resistors, reading them on a meter, made no difference beyond looking tidier. Interestingly redoing one amp that came back wrecked & not trusting it, to redo with new resistors without matching gave it back a confidence, so it depends on the amp, one with NFB stages won't show it so readily. You may think that everything must be matched, the reality is an amp can be 10% tolerance with one channel playing slightly lower & you'd not notice as your hearing isn't perfectly matched as aren't other things there are two of.

The Joy Of Stereo.
In testing Amps, Stereo is crucial to show How Wide an Amp can play Stereo. Since starting comparing amps in 2011, Stereo has mattered as often the Stereo width seems forgotten with the more Blurry Amps not really giving The Beauty of Stereo. Considering we started on Transistor Amps with the Sony STR-6120 then the Trio-Kenwood KA-4002 to have a bunch of Bang & Olufsen receivers that didn't please in the same way, the 3000, 3000A, 4000 & 4400 Beomasters improved as the range went on, but not matching the looks with Sound. Stereo we play is Recorded from Vinyl with Valves, on Transistor Amps the Phono stage often is way below the Aux input, see our Turntables page for much more. Stereo started about 1955 on Open Reel Tapes, with Vinyl going Stereo in mid 1958. These are interesting, if Stereo pre 1970 isn't for us as it's not Mixed Well, the lousy Voices-Instruments mix of 'Please Please Me' Beatles LP is unlistenable. Our Music organised into Folders, with Rock & Pop 1970-1976 being mostly Stereo. To find some Mono 45s have LP versions in Stereo like "I Hear You Knocking" by Dave Edmunds is a much nicer listen. Decca were still Mono only in 1972 making certain tracks not really playable. To go find the LPs just to record them could be possible, if we have enough tracks that are Stereo. To forget there are many great tracks of that era beyond the horrible Pop, as with the 1977-1994 folder. You can only play the same tracks so many times. Stereo on a great amp is very wide with Crisp Detail making the separation even better. On Headphones Stereo can be a very big Soundstage to lose the 'in the head' effect of Mono. Used to get LPs to borrow & record, never got Jimi Hendrix in Stereo early on, only the Mono, if "Voodoo Chile" is awesome in Stereo & it's a 1968 track, seems we recorded some of the '613' stereo versions too. Pre 1970 Stereo can be thin & unimpressive, as are Rechannelled Fake Stereo used in some Tamla Motown 45s & Decca LPs. The Elvis Boxset on 'Reader's Digest' had the Fake Stereo of 'Don't Be Cruel' & others, for it's gimmicky effect it's insane to hear, if prefer the Mono when it's rarely played. Stereo is usually recorded well, if well played 1970s vinyl can sound rough as it wears plus the crackle in Stereo is more obvious. Stereo on a Wide Amp with Speakers can throw sounds on a TV show soundtrack that make you wonder where it's coming from, is it outside, skip back to hear it's on the TV. Good Hifi can help make you lose your mind, it's true.

It's Unrepairable Or It's Beyond Economic Repair.
No doubt Car Owners will know this one from Insurance Write-Offs. The basic idea is based on the Value of the Car now, to Repair it Isn't Worth Doing as it is Too High. Damage like the Roof being Damaged by a ladder fall denting the Windscreen Edges & Breaking the Glass is an Instant Write-Off as to make bent metal in a crucial area safe again isn't worth bothering with. If it was a £1M Ferrari then to get a spare roof as it's worth repairing. In Hifi this is depending on The Skills of the Repair Tech. To get the Marantz 4070 with "Too Far Gone" on a 1990s Repair label from a Shop was actually right for the state it was in. But to us it was Repairable if more a 'Keep It Alive' idea. The 1973 JVC 4VN-880 we got to cover work done on it & another 4ch item wasn't such a great trade. Severely Bad to need a Huge Amount to Service it, as Original we finally trusted it to try on speakers to see what it was like to the 4VN-990 we have. Sound was very decent even as Original & will upgrade well. The trouble is both 990 & 880 have a 'Hum' that's Hissy too. The 990 revealed it for Upgrading so wary of the 880. Not going to just abandon it, if seeing how Hard It Is to redo the Hissy transistors, a more novice tech would call it 'Unrepairable'. The preamp board on the right is an early Double Sided effort. To have to pull out 12 transistors is hard enough here, if then how do you redo the Transistors for what removing leaves? It's as 'Unrepairable' as a Computer Motherboard or 1990s High End type that uses the same build. We know what to do from other Double Sided PCBs, if this will be a huge job knowing it's issues that you'd not expect. A 1988 Repair Label reveals the Hissy transistors (bar one) on the Plug-In PCBs were replaced, to assume the preamp ones hissed too but were left, as was the Amp soon after to be so Rough if visually decent, not rusty or damp. To assume that Tech tried but gave up. Some amps are not designed with Repair in mind, they are therefore 'Unrepairable'. The JVC 4VN-880 if it has Hissy Transistors will now be considered 'Unrepairable' to most. The Tech spending Hours doing what should be Not So Hard will have trouble justifying charging Extra once they've Quoted a Price. The More Tricky Amps you get, the better the Ability to Price a Job to not Underquote for the Real work, but that will likely put off a Customer, when you may be the Only Tech who can do it. Sadly the 4VN-880 on trying to recap that awful double sided board resulted in track tears & poor resoldering, it'd never be reliable. Perhaps best to have sold it as-is & useable, but to gamble for the Upgraded Cost. A rare fail.

Modern Intolerance Of Replacing Old Filament Bulbs.
Watching a 2014 'Wheeler Dealers' to see the Maserati having old style bulbs in the Binnacle Display section reminds how 'lucky' we are with LED bulbs. Bulbs in Hifi especially Tuner Receivers showed with the 1966 Akai AA-7000 that even bigger bayonet bulbs, the same size as the 6.3v 'Torch' Bulb, don't last long. They can fail half of them within 2 years. To take things apart to rebulb is not welcome. Small bulbs like Yamaha use 1973-77 are smaller & can fail sooner. Some bulbs like B&O ones are custom size, voltage & current. Any small non standard bulb is likely to be obsolete if German ebay sellers don't have them. As you'd imagine, a bulb can work fine & fail on next turn on, the Fuse type 'festoon' bulbs start to go black or mirrored showing they'd fail soon. The fact old bulbs are a dingy Orange colour is not not acceptable in certain situations as Bright White light is preferred. LEDs seem to have been first used around 1977, the Yamaha CR-2020 uses them on the fascia lights, if not the meter lights. Watching progress in LEDs shows that true White LEDs are a later arrival than Red, Yellow, Green or once rare Blue ones. In Hifi only a White LED looks right, it gives a blu-ish tinge & isn't too bright. Many amps using the Festoon bulbs fit them in easily, if 29mm ones better than 31mm ones & the 29mm ones are a newer size to us, only seeing 31mm sold by Car parts sellers on ebay. LEDs are a narrow beam light that doesn't always 'fill' the area a filament bulb could light. AC or DC. DC is best for LEDs as no Flicker. AC is still in many amps from the days of AC valve heaters at 6v or 12v. LEDs on AC on some amps is mindblowing like a strobe light, some fit under darkened tuner windows to look good if they can catch you out of the side of your eye to see it flicker a tiny bit. 50Hz flicker as the Mains is. To change AC to DC with a simple circuit is possible, tried that on the 1984 Sansui AU-G90X. the JVC 4VN-990 has annoying tube bulbs of a rating not buyable, if there is space to put a Festoon LED Bulb with some wiring. To try that, really can't be bothering with using the filament Bulbs unless a last resort, the JVC has no other sign of being on otherwise.

1971 Akai AS-8100-S 4ch Bridgeable Receiver: Sort You Out.
One of the earliest proper Bridgeable Receivers, based on the AS-8100 with extras. We've played this on Speakers & it has that Big Wide Sound as do the JVC. But it has issues, horrible noises on start-up which must be the crude Triac protection circuit, that turns on for no apparent reason if the Low Filter can trigger it, if why isn't clear. All this led to 4 of the 8 output transistors shorting, Front L+R if only one fuse blows. Well made amp with lots of wiring as Shielded cable, it has ICs, the same LD3130 as the Teac AS-100 uses. The Triac SCR 'transistor' must be the fault & no way to get one of these, on other amps they are no problem. "IRC5" is unfindable. The Tuner display is only lit with the Tuner, pity as it looks better lit up, if seeing it has 5mm bulbs it'll probably not do well with LEDs as the light area is too narrow. Get Into Fault Finding Mode. Why remove a piece with no real proof it's the fault? That's not a pro way. It still works on the Rear L+R so listen for Noise, it does it on turn on & can do intermittently, the problem that hides. Use the Oscilloscope to look for the Noise, it's not on the SCR output & trying it a few times to confirm. As if Fault Finding is easy, to just keep trying until the Noise is found, if you can get it to be noisy. The Amp is recapped & was otherwise working which narrows the fault down, but where is this awful noise? After some tries the lesser White Noise that can be heard isn't on the small PSU board with the SCR. The main HT tiny AC ripple wobbles when the lesser WN is heard, but not hearing the big noises. Try the Temparature gun to find certain bits warmer, today 26° to find bits over 35° which you'd not tell otherwise. To wiggle the Balance joystick, there's the noise & it's what gets a little warmer. The circuit shows R22-R25 from the Tone Board, ours doesn't have these. To have thought the Joystick bad before, it's running warm on the L-R control, if not when set off midway both F+R. A little taste of Fault Finding, it's a difficult one & how do you solve it? The Low Filter (Bass) makes a noise in use that can set off the Protection. Still sits here & makes the bad noises, too nice an amp to give up on, another day.

In Praise Of The Earlier More Basic ICs?
Not to be confused with those 14-transistor stages ICs, we mean the Double Transistor early ones like the LD3130 the Teac AS-100 uses a renumbered version '42708' that shows no info. But the 1972 Akai AA-8100-S uses the LD 3120 (later updated to LD 3130) in the Phono & Preamp-Tone & helpfully the Service Manual shows these are Simple ICs of Two Transistors, much like the ones in the 1967 JVC 5040 & probably the Dokorder 8060 ones of the same size. Some ICs are fine, the Double FET simple IC is perfectly matched to make a more exact Differential with. This means the Resistors inside & Transistor stages can be made to a more exact spec than getting single Components. The opinions of the Teac & Dokorder were very good, in fact the Teac AS-100 was the First Amp we had in our Hifi Transistor research that had a certain preciseness to it. The Preamp in an Amplifier gives more to the 'Tone' of an amplifier than any other stage. Don't want ICs in Power Amp Stages as is seen by the mid 1970s plus the fact these are Long Obsolete. We had a 1971 Photax Concertone 333 receiver recently, had the 'dreaded' STK amp blocks, but two of them as L+R using an early STK031. This amp wasn't expected to have STK outputs if to try it to hear it wasn't as bad as later amps with STKs but no manual to find the fault made it end there. An unfinished experiment, to dare to try another STK early amp needs to happen. The Akai AS-8100-S is a difficult amp to get playing right, if playing as we type marvelling at how Clean the Sound is playing Jimi Hendrix stereo tracks. The 4ch Bridged Amp one of the first, still using Output Capacitors. It's rather dumbed down if to hear how good it was on Speakers playing in Bridged Mode, now it's moved on to sound surprisingly precise. See on HFE it's only rated 0.1% THD shows again how useless THD when the amp itself is so lacking distortions. The Akai we knew had ICs if to see they were like the Teac ones on the board layouts & for how it sounded, try it. Very smooth focussed fast sound, all on 18w. Another early IC is the one in the 1972 Sony TA-1150 preamp. We found the preamp with a quality sound once updated, if the Power Amp wasn't liked & far from the TA-1140 one. The 14 pin 'CX-0461' is a two channel IC, the manual only shows what it does if not a transistor-resistor equivalent. As it uses + and - voltage on a 'bias circuit' assume it's a Class B effort with a lot of transistor stages. The fact the preamp sounded good on a less good power amp could easily be the power amp hiding the true sound. Looking at the Sony STR-7065A which confusingly is rated 65w for the USA model if only 45w for the UK one. It has the 'CO-0461' in Phono & Preamp-Tone as does the TA-1150. Smart looking receiver, the last of the 'Silver Face' classic range that started with the 1965 Sony TA-1120. Tight row of Screws for Speaker connecting. It's a single-level amp moving on from the layered STR-6055 & STR-6065, very tightly packed with lots of wires all on the top. The "A" version is usually a Kettle type mains socket version. Update: On improving the Akai AS-8100-S to get a sound we liked, the Pioneer Sx-2500 sounded very similar if a 72w version. Early ICs are certainly worth trying, the extra precision of an IC having parts all made together gives them extra treble detail, if it can be too much treble & need taming a bit. The fact with an IC is you don't know the Transistor spec or the Resistor Values used in it, an amp with a Direct Coupled Transistor pair as the basic ICs are doing shows it's workings. Also easy to replace hissy transistors, getting a batch of LD3120 on ebay as an older tech was clearing out is unlikely to be repeated, if ebay search shows non UK sellers have lots, but to know they are equivalents of LD3130 & the Teac 42708 is the thng.

1977 Marantz 2235B Receiver Revisited.
We had this last year to Recap & Upgrade. On seeing it had 'Retro Bass' in the Design, to ask the Customer what they wanted to do. Saying they Bought this Model as it had a Better Bass, just to leave the Retro Bass as assuming they liked it. To us Retro Bass is a bad idea for the better quality of Speakers these days, to not need the Artificial Boost around 50Hz as blogged about above. The Retro Bass they never liked for our Upgrades bringing Bass out well, the Marantz upgrade nicely, if even the 1971 Marantz 2270 70w Receiver has this, we got rid of it on the 2270 & it sounded very much better. So to get it back to alter it. The 2235B on first try sounded awful as it'd never had Full Bass before, took about 10 mins to waken up bringing Treble Crisp & a Rich Bassy Sound in a Natural way. The 2235B not a high power model if it has a very decent sound as a 1975 amp updated with the 1977 'B' version. Playing tracks as we type it just sounds right on Headphones & on Speakers sounds much better. 45 years without Real Bass & now sounds great. Not all the 1970s Marantz are so great, the 1122DC & 1152DC are problems, the Marantz Receivers are much better, the 2235B has proper TO3 output transistors. The only thing with Marantz receivers is the AC voltage makes the LEDs flicker & not quite enough to have LEDs bright enough. The 7 rather warm bulbs in the front do decay the plastic. Anything is possible with LEDs if the amount of work to redesign things.


November 2022 Blog

Hi-Fi May Have Had A Shady Past!
Some Hifi has had an easy life, not heavily used plus Good Design makes some amps the Ones You Want. The Reality in Buying is you really Don't Know. Sellers will Openly Lie about things to make the Amp seem worth buying. Some list them as 'Working' which means they power up & play sound, if rarely are they Reliable. Ones with Transistors with Rusted legs & the Transformer with the wires unsoldered was with a 1966 Akai AA-7000. It'd not be useable & be a Parts Amp as you can't use it on Mains which shows what Messing goes on. Luckily we had another of this Rare 1966 Amp so to see how the Wires should be soldered. It got Rebuilt & Sold on as it was Good & Reliable. Would anyone else have fixed that one, unlikely unless they had a 'spare' one. Buying Vintage Amps Online is a real Gamble, once they are past 20 years old they need Work to Service, to Recapping depending on various factors. Post 1980 Amps may suffer from Worn Out Controls, they were made as a weakness so you Threw It Out & Bought New as Good Little People often did. The Vintage Scene attracts a different Audience from those on a Tight Budget to those who want to taste the Best In Vintage, aware how aged it is now, as with Cars. Then the Seller lies what condition it's in. To buy ones sold as 'Working' removes a lot of Gambling, but it can Hide What Some Idiot Did To It. Old Items have been in 'The Wilderness' for Decades, in 2011 we bought a rough caseless Fisher 440T for £10 just to see what it was. Beyond us then if probably fixable now as Manuals are around that weren't until HFE & others arrived. That Fisher got Parted Out & made an earner on the £10. To 2022, another Fisher, the Auto-Tune 'Fisher 800T'. Customer buys this cheap probably, it's an impressive 60w & the original era Fisher are Quality if not without issues. Having had 'Mint' ones of the Fisher 440T & 600T to know how nice they can be. The 800T looks smart as Fisher do, vinyl wrap case unusually & the size of a Pioneer SX-1000TDF. Can't wait to get the lids off & then ends the joy. Not Leaking Capacitors as the Buyer was told, but Resistor Burns & Bad Repairs. There are other issues as made like the TV-grade Plastic Case capacitors like UK-EU amps use plus about 100 tag-pin push on connectors. The topside actually was untouched, the strange Output Fuses still there & no Burn Marks at all, if more of those Plastic Caps. This is a Parts Amp Grade to most & to think what to do as Money Spent getting it here with another, a lovely 1970 Sansui 350A in aged but good order. You could give up on it which is a waste, if it was a lesser amp call it quits, but this is a Decent Amp otherwise. No Tech would take this as a full Rebuild or even Repair as they couldn't Guarantee it'd work. Neither Can We, but after hearing they plugged it in to see the fascia light it takes it into Less Risky territory. Heavy Gambling here, but Money Paid to buy what is was supposed to be, not a wreck, plus the fact We Want To Hear It got it rebuilt to a level to try it. It actually worked if still pretty rough & not sounding very nice. To use it more to 'Waken It Up' actually got a decent sound eventually, an amp that is really only a One-Shot to rebuild but to gather up what it needs to keep reliable means more work is needed, plus the slightly insane way of changing US voltage to UK instead of an easy plug block.

The Most Difficult Thing In Hi-Fi: Earth Loops & Hum.
The Reason Why is that it's Pure Guesswork as why it's there or not there. There is No Way to Measure why an Amp Can Hum with Ground put one place but Not Hum when put elsewhere. The 1979 Luxman LX33 we Rewired the Earth as it was with Hum, now it's very quiet beyond the Soundcard Record loop mentioned above. This means Designers can't Work It Out Either & have to Dumb Down to hide the Noise. Earth Loops can mean Hum & a Mainsy high frequency noise that is Echoes of the 50Hz mains. Another amp with Hum is the 1966 Akai AA-7000. This is a large sized amp so has a large surface area of Metal Chassis. To see it's Grounded at several Points beyond the one by the Power Supply. The Ground Wires have to be arranged in a certain way to minimise Hum. The earlier Akai AA-5000 doesn't have Hum, it's a smaller Amplifier version. That Board needs to be Grounded there & that other one Grounded elsewhere. To try to minimise Hum on altering the AA-7000 as the Hum was annoying. It's not a totally Quiet amp as made, if the Signal-Noise levels were acceptable in 1966, by the 1967 ranges the levels were better. Akai didn't make New Amplifiers until the 1970 ranges. The Crazy Thing is take a Wire & put it to a Capacitor Ground then to different parts of the Case. There it reduces the Noise, move it 12" (30cm) away & the Noise is louder. This means the absolute tiniest Resistance in a Case can affect things, if using a longer piece of wire that is Direct & Isolated can solve what 12" of Steel Casing can't. The Dramatic Difference is even tighter we've found before, with Mains Earth Ground 2" can make it very noisy or quiet.

Those Darned Repair Restore Your Amp Kits.
The reason we started repairing & playing around with Hifi was you could buy a decent Vintage Amp for no more than £20 in the early 1990s. From the Classic Marantz receivers to B&O Beomasters to Luxman & Sony. They were just Old Hifi & at the time they were Out Of Date as the Black Fascia was In Vogue, despite them being less easy to read out of bright light. Moving Years on, to see Sellers especially in USA are offering Kits Of Parts to recap Amps & Receivers of all types. To find this Amusing to see a Very Complex Amp can be 'Easily Rebuilt' is nothing short of Snake Oil selling. It assumes you have Decades of Hifi Repair Technique, if you did, you'd Source Your Own Parts not just buy a Kit of Generic Parts. Money will always be the decider, if for $175 you too can update your tired amp. No point saying things like we are advertising for Jobs, but the Worry Here is that Good Amps will be Trashed for the Silly Idea that anyone can fix Hifi. Do you Fix your Car? Do you do Wallpapering? Do you do Plastering? Very few can Wire a Plug which is why Moulded Plugs became normal by the 1990s, in earlier years you got an item with No Plug & fitted your own Plug with a 13A fuse unaware it's of no use where a 3A fuse should be. Buyers being Buyers, they'll leave a Negative as they were proven out of their depth "It was the first time and probably the last Time I buy that kind of Kit!" because it made them feel stupid, which is never a good thing to do in Trading. They jumped in not knowing what to expect it more likely the story, to see it really wasn't so easy, getting frustrated & chucking it all in the Bin. You'll get Bad Buys & Ripped Off dealing in anything Vintage or Worth Money, Buyer Beware is the general rule. Most play safe & buy New on Amazon or do a Contract to get a Car, or even Rent things according to an unlikely News Story, paying a year's Rent on a TV you could buy for much less to try to make it seem everyone's doing it. It takes a certain Mind & Attitude to Repair & Restore things. These Sellers with their Kits are Selling A Dream that really Never will be Done. Probably 90% of those Kits don't get touched once the Instructions are read. As with any Trade, get a Pro in. The Cost will scare most off, to show it's not so Easy, our Gallery photos are deceptive, as are Car Restorations, the work in it doesn't always show. If you want to Learn Hifi Restoration, start on Cheap Amps that you Can Ruin & learn from your mistakes.

Tube Technology 'Genesis' 100w EL34 Valve Monoblocks.
These we got first about 1999 as Ex-Demo from a Hifi Shop. they couldn't sell them & had been around all the Branches, so to Buy The Lot including Two Preamps was possible at a reasonable price. Two Box Preamp & a Single one with a Phono, if not the Valves out the top one. Two Box was a Regulated mediocre design, One Box had no Tone stage. The Monoblocks we got tired of how Hot they were in the Summer so another Ex-Demo on the 2002 Musical Fidelity A308-CR Preamp & Power Amp got swiftly moved on as we didn't like the Unnatural Sound, the IC OP-Amp for Phono & Cheap all the way with Ceramic capacitors yet a very costly amp case. Got another pair of TT Monoblocks for about the same price & these are the ones we've had since 2002. Many Alterations, the TTs were a lazy design based on a 1950s Mullard design with the poor splitter design, the Luxman LX33 had this too. We Question all we see in Hifi & by 2004 the amp was getting alterations. One early change was finding the two big capacitors were actually floating 500v between them, terrible design, so the Can Case on one had 500v on it with just the plastic between it & the Amp Case that had very tight fitting holes. Told the TT guys about this, no response as they know it was 'A Bad'. Better Ideas aplenty including Pentode Mode, Mains Choke & Heater TX for the ECC81s. Didn't like the Delay Start idea & used the space for other ideas. But after a further 2008 & 2014 rebuild, taking proper Wires instead of PCB Track on 100w Valves, to find by 2017 the preamp we last worked on in 2008 was needing work, but seeing it wasn't built to be taken apart so easily, we started using Transistor Amps. The trouble with Valves is the Power Amps are fine, but try getting a Good Preamp. The only good one we found was the Luxman CL-32, to find ones possible, but not in Nice Grade, No Wood Case or way too expensive. To have got the 1979 Luxman LX33 by then so didn't look for one further. The amount of work to get the LX33 how we wanted. Valve Amps sat gathering dust where they'd gathered dust always, on top of the Tannoys. Left no ring marks as the Wood Casing had faded to a lighter tone already when we got them. 2021 to think to get them to sell, previous use with 'Ei' valves had been annoying as crackly in TT & the LX33, later to find Shuguang which have been great since. A year later the box of 8x EL34 unopened. The thing is a Highly Custom Amp may sound Way Better, but to Sell it, to have to consider endless Questions by a Buyer, if one was even there. To offer it on ebay under the 'Spares-Repairs' but tell it'd Revalve & Bias up fine, if to leave that to the Buyer, they get a Bargain as they need do Work to it & it's their effort to get it to Working, not ours. New Valves about £200. To be tired of an Amp, to realise it'll not get used & to move it on. They've got an Easy Amp overall, if for it being so Custom, to sell as 'Parts' is final. Still Insured it on Posting as 20 years with it to play Safe as it's a 30kg box. Got Valves as the LX33 & the 1966 Pioneer ER-420. Comparing to decide what to do over some time had the TTs played on a 1971 Sony TA-1140 we redesigned the Preamp on. TA-1140 into the 100w 1971 Sony TA-3200F power amp continued the Sound from 40w to 100w, leaving the 40w one to a level that 100w surpasses, as in Louder, more Full & Extended. So try the TT valves as a power amp. We'd tried these via the SoundCard that leaves a little background, using the Computer Volume & found the TTs as much rebuilt as we had sounding quite small despite being very precise. They were never really Bassy which is why using Transistor Amps for TV-Speakers sound has been the usual for several years. The 100w TT just weren't what the 100w TA-3200F could be & gradually lost interest to sell on. Buyer delighted with the TTs, if we've moved on with Valves now.

The Reality Of Ordering New Parts To Upgrade & Recap Hi-Fi.
Since Brexit & the 'Big Lie' getting the Parts for Hifi Work is not as Easy as it used to be. Always quite a job to find the right size pieces & navigate the Search Boxes on Farnell & RS. Now on ordering parts, to see some are Not In Stock when they were supposed to be & even the Arrival Date moved to June 2023 on some items. Panasonic we've been using since 2002 as a brand we liked, were of quality & reliable, but gradually they stopped making the larger power Supply type capacitors. Then the smaller Red Film Capacitors went soon after. Now the larger Panasonic FC Capacitors are apparently Discontinued which is Panasonic making out more will arrive, if they go no Big Orders they'll not make any. There are other good brands we use anyway if liked keping a 'Look' on our amps, seems it's going to have to change. Both sellers have other good brands on larger values, if to see the smaller Electrolytics are In Stock, if perhaps they are selling the end of a line, as has been seen noted often. Then to have found a great Driver Transistor NPN-PNP pair to find they are no longer made! That took a long time to find the Right Spec & what was once easily available at a good price, only one seller on ebay with them at an inflated 'obsolete' price. Another one we've used in the Round Can is still available on checking. Demand & Supply is always what gets items continued or discontinued.

December 2022 Blog

1970 Sansui 350A Receiver Revisited.
We had one of these in 2019-2020 & to hear it's a great amp, having the 'Sound' that took a lot to put into the 1967 Sansui 400. Both are 20w which on 95dB sensitivity Speakers is fine for TV Use if not really to Rock Out with in a Loud Way. Been playing the 1973 JVC 4VN 990 as Recapped & Upgraded plus the 4VN 880 as original if much serviced. Played this when it arrived to hear it was fine, now to play it As Original to Hear How Good It Is. Sansui always a Quality Brand on 1966-70 era Transistor Amps, the Bigger 4000 & 5000 receivers never sounded as good as the 350A as Original. Actually the Sound is much like the JVC 4VNs if they still have a slight background noise whatever we try. The Big Wide Stereo isn't in all amps, the 350A has it which is why we liked it. Our amp here sounds a bit ropey with Sound not too Stable, but reveals the Quality. Upgrades well bringing a fuller Bass than the current sound that doesn't have much deeper Bass if is rich sounding. Smaller size amp like the Pioneer SX-1000. A very different amp to the 1968 Sansui 350. On looking at the Schematic again, to see Aux into Phono as other Sansui do, if the earlier Sansui 400 didn't. After more play it gets Noisy as the Customer said it was, not Grainy so to assume it's had Hours Play recently to wake it up. Design shows it might not so good on Speakers but on Headphones it's nice. Noise is quite loud on the R channel, a Seashore-White Noise sound, so best to leave it until redone, not knowing where the noise is exactly. Modest Amp but this Sleeper shows it's Class. A second hissy one shows this will be how they are, rebuild needed. More in a later Blog.


You Again? 1971 Trio-Kenwood KR-6170 Jumbo Receiver.
Not played this since before 'rediscovering' the 1975 Yamaha CR-200. This blog written a while ago it seems... Have been playing 1970s Rock more as tiring of the 1977-82 era as played too much. Last looked at on the start of the July 2022 blog if that was a few months before in real time. Been playing the 1973 JVC 4VN-990 & 880. Both sound great if the background noise spoils it. Got another 1970 Sansui 350A as above & liked that. But to try something different & the KR-6170 not played in a while. Treble not as smooth as the others just mentioned (sorted now), but it Kicks Ass for sure, suiting the 70s Rock & giving it an 'Exciting Sound' as it is a Guitar & PA amp. A richer upper Bass-Lower Midrange. Not as 'clean' as the other two initially, if still the Treble Detail & Clarity. Brings a rare weight to Drums, as in Hendrix 'Gypsy Eyes'. Clearly this is a Real Sleeper & the extra Effects & Reverb put some off, only 33w too, we thought it was Crazy but Bought one. Ours Recapped & Upgraded, it really brings Guitar Rock alive. Imagine a Real Guitar played through it, a sound to suit a Guitar input after all. Just played Test Tones to see how Even it is, plays to 30Hz with a bit of 20Hz audible. Sounds Flat to 1kHz so nothing like the Retro Bass that heavily Boosts 50Hz range. A 'No Relay' amp so on turning off it briefly goes silent then the sound returns until fades away.The Power Amp is the same as the Trio-Kenwood KR-5150, both are 33w. The Preamp has Complex Impedance matching involving reducing gain, which usually is not wanted or liked, but here it's done so well to leave it as designed. The Gain Loss makes the Amp not as Loud as it should be, if having altered it to hear why they kept it a bit low in gain. Remarkable Rich Big Sound, not many amps give Drums & Rock Guitar the right Weight in playing, playing Bass Flat, here it's the Rock Guitar Sound as it's a guitar Amp. Nothing else like this in Hifi, PA & Guitar Amp with Hifi credentials. Who was This Beast aimed at? The KR-6170 Brochure calls it the 'Jumbo'. "This is the New Stereo geared to listening & playing pleasure. what more could you want in stereo?". Seems they leave it for you to decide, our initial opinion was it was Insane as 'Other amps' page tells. Reverb & Beat Box aka Rhythm Composer may suit a Group on Stage, the sort of Beat Box an Electronic Organ has, a sound that was probably very dated soon as things moved on. "It can make your party" they reckon. The Preamp gives a Passive Compression, different to Aux through a Big Resistor into Phono, this Reduces & Impedance Matches to make extra fast Record Click not too aggressive a Click, the Rise Time is slowed down. Input to Output to the Preamp is about half so needs a bit more gain. Whoever Designed it & Why is using PA Amp ideas. Jimi Hendrix used 100w Marshall amps 'Super Lead 1959' from 1965 as Googling tells. Very surprising circuit, input heavily limited, after the input with no capacitor it runs on limited bass like 1960s Valve Amps, the superior Pentode mode. Diodes in the Power Supply. This will Distort & give his Trademark sound. The 1988 version uses the best valves, the ECC83 & the EL34, avoiding thoe more expensive KT66 & KT88. NFB is minimal to get the Big Volume. Runs 4 valves in Push-Pull to get 100w, our Tube Technology Genesis rated 100w with 4 valves. The Luxman LX33 uses 2 Push-Pull to rate 30w. The problem with all Valve Amps is getting a Preamp as Good as the Power Amps. Our TT amps only delivered to the Buyer yesterday, do we miss them? No. They never sounded like they should have, which is why we tried so much.

Solved: Computer RF Noise.
This has been a nuisance for ages, since the pins broke on one set of Cables. we're purposely using the ones you see on ebay with the Blue Cable & Basic Metal Plugs. The ones with "Digital" on the Metal Plug parts, bit silly as it's an Analog Cable mainly. 10m OFC HQ, made in China, said to be 'Pro Signal' brand. These cables are Basic without the 'Filtering' of more expensive cables.Just before Xmas 2021 decided to just buy two sets In & Out to have a fresh go, as the Out set, In to Amp were damaged. As you'd expect in August for getting the new Monitor, remembered them as had to pull out the old Monitor wires. So label these as In & Out & put them in place. 10m is too long but 5m is too short, so an excess of cable. Try the Amp, there is now... No noise which is a relief as we can't think of any other idea. The reason why is unknown, but to think both sets of cables from the Same Batch. We'd used the same Out to Amp in ones for ages, so to get this horrible RF noise that picks up Mouse & Monitor noise. The fact a New Monitor on HDMI cables may be part of this huge improvement. Silent Background in lostening to the Luxman LX33 on Phono & on Aux. To see how it Records the Input to the Computer. Only a tiny bit of noise that doesn't show on the -60dB lowest on the Recording DC-Art program, on the Spectrum Analyser it's around -90dB with only under 150Hz reading towards -60dB. the Noise does seem to be Monitor related, a 1m cable had noise very low, a longer 2m one brings it up slightly, if not as much as the old bulky cables. The RF noise is in the Computer Monitor cable, be it HDMI or older bigger cables. For having the 2m HDMI cable it picks up a bit of RF noise still. Not tried more as of Dec 2022.

Old Potentiometers.
From Volume Controls, Tone Controls, Balance Controls to the Small Adjust Pots on the Power Amp. Look at our Gallery Photos, we often use the Original ones. If they Service up & Don't Crackle as well as Read Correct on the Bias & DC Offset, then why replace them? The silver plate may look tarnished, but it's only the outside. the Difficulty in getting ones to fit can be a problem, they are supposed to be solid to adjust, not loose with trying to fit modern ones. The old style metal ones you may find on ebay if it'll not be a continous supply, as with awkward bulbs it can depend on old stocks by techs of old selling up. The ones that work in the middle of the rotating range will be best, those tht use right to the end can suffer from Not Zero-ing so a 500 ohm pot may do no better than 136 ohm & read 836 ohm max which is well out, but how they are made. wise designer using the central area doesn't care if it's not accuate. Designs like the 1966-68 Sansui 3000(A) use a 200 ohm pot over a 15 ohm fixed resistor, it'll be useless beyond a small end area & if it goes out of spec it's useless. A Pot can work, if to try to service you add to the wear then an amp once correct is now wrong until you fit a New Pot. Volume Controls are where the amateur messes & fits an unsuitable one for no reason beyond it needing servicing. To get the 1966 Pioneer SX-1000-TA with some 1980s undersize one & not using Loudness could make it Unrepairable, unless you had a spare 1967 Pioneer SX-1000-TDF to take these Rare Parts from. One Sansui 3000A we had to replace the Volume as it wouldn't go to zero as in silent. To get one from another amp is what saved it, other ones of the same amp hadn't got that problem. As the Sony preamp just above shows, to better a strangely designed one was needed. To replace any Fixtures can be tricky, but Only Replace if the are faulty or broken, this can include 'unreliable' where a Pot jumps from 50 to 400 on reading Bias, the pot has likely burnt away part of the track to lose contact, there to replace is the only way. If it doesn't need it changing, don't change it. One amateur replaced the Power amp Transistors in a big Marantz amp. They said these are the ones that often need replacing, yes, but you need to Damage it first. Fuzzy thinking. If It Ain't Broke Don't Fix It is fair comment on Amp Controls & Switches.

FETs & The 1971 Sony TA-2000F Pre Amplifier.
We wrote quite a bit about this Preamp, FETs & the 1969 Pioneer SX2500 which has a FET on the Preamp-Tone. Reading it through later after trying much, it doesn't read well. So to rewrite it from a Dec 2022 viewpoint. FETs are different to Transistors, read much online. A FET has 2-3x the Gain of a typical Preamp Transistor. The Specs don't tell you this, but trying a Transistor in place of a FET reveals the gain difference. Below tells of more FET interest, to see the few amps that use them & what they sound like. We've not finished with the TA-2000F or SX-2500 yet.

FETs are Difficult.
The TA-2000F is so tamed in many ways, but a Great Sound is in there. Sony were very scared of this 100w TA-2000F/TA-3200F combo, if there is a top sound in here suggesting it was considered 'Too Good' to dumb it down so much. You don't hear of FETs in Hifi before 1969 as Tuners usually were the first to get these, the 1968 Sony STR-6120 has three in the Tuner early stages aka Front End plus the 1967 KLH 27 tuner & the 1969 updates of 1967 JVC receiver tuners. In Hifi as in Preamps & Power Amps the FET first seen with 1969 designs, we had a FET on a preamp the 1969 Sanyo DC-66 but had no manual or info to upgrade unknown circuits, probably for the best. The 1969 Pioneer SX-2500 has a FET in the preamp. Trying to remember another amp finds the 1971 KLH 52 having one in the Tone Stage. The 1978 Pioneer SX-980 has them in the Preamp as does the 1976 Pioneer SX-950 & SX-850. Clearly there are More with FETs, if not often seen. 1973 Yamaha CA-1000 & CR-1000 use them in less obvious places, with switching & Phono early stages. Looking further back the 1974 Pioneer SX-838 has them, if the SX-939 doesn't. The 1972 Pioneer SX-828 does. For Pioneer to be using these into 1976 shows they are Good if only to use One in a Preamp, not Six Per Channel as the 1971 Sony TA-2000F does. A strange idea in the TA-2000F is using what is 'Positive Feedback' in the design, only lightly else it'll oscillate & upset the voltages, without it the amp isn't nice.

FETs In Preamps For Gain Stages Are A Rare Idea.
The 1971 Sony TA-1130 has a Preamp with FETs much like the 1971 Sony TA-2000F in the Blog above. The TA-1130 was considered very clean with Testing showing it was totally flat 20Hz to 20kHz after upgrading it years ago. But it was a Tame Sound, it didn't Excite. The TA-2000F after some extreme upgrading, hides a very lively sound but was restrained & rather boring sounding despite being very clean & the TA-3200F power amp testing so well. Similar issues found with the 1969 Pioneer SX-2500, to blog more when that's tried. FETs work in early tuner stages as they are very limited by small 'picofarad' (pf) values which are part of a Tuner 'Front End' design anyway. FETs are treated too carefully, the reason why is they aren't full range & must be very tame in design. The TA-1130 circuit on looking after upgrading the TA-2000F shows the TA-1130 is a strange one in design plus odd requests for FET grading that no Manual tells of, as in 2SK23-37 & 2SK23-35 when the basic 2SK23 exists. The TA-1130 manual says this is an 'Idss' rank. What this means is obscure if Data Sheets show voltages D to G & D to S to not exceed. Not a HFE Gain code, they use a 'mu' gain rating. 30v to 50v is ones we saw, preamps usually in this voltage range. The TA-2000F uses 150v on the Phono stages, an unique idea, if this is on Silicon Transistors only. For how Great we got the TA-2000F to sound after Five Years, to wonder why the ideas weren't used more. Probably to design is the tough thing & sounds Too Good. Swap Sony TA-2000F FETs to Transistors? Not worth doing if we tried it & helps understand the FET better for it. The Positive Feedback makes a bad noise as it oscillates as a signal generator. The Gain is Poor as the 2SK43 FETs are High Gain, with 'mu' of 6 with the Buffer one 2SK23 a 'mu' of 3. How this compares to HFE isn't clear, much theory on Google searching. In effect the FET gain vs Transistor gain is about Double the Transistor volume. The 2SK FETs are still buyable online suggesting these & the 2SK30 are reliable & worthwhile ones.

Why Bother With A FET & What Does A FET Sound Like?
You can read much online, Wikipedia is perhaps the most concise source as imagine all the Tech Egos writing & correcting each other. High Impedance & Low Noise are characteristics, if what They Sound Like is never said. There is a sense of Greater Linearity that a Silicon Transistor can get with NFB, if past a certain level NFB spoils the sound. The Transistor can often sound Grainy needing a little help, if like a Valve or a Germanium, the FET doesn't need any on a preamp stage. The FET having Greater Gain can be useful where a Transistor leaves the sound less precise. The Beauty of the FET Sound is well hidden in the 1971 Sony TA-2000F preamp & the 1971 Sony TA-1130 has FETs in the preamp that give a precise flat sound if the design is an over complicated one. Wondering why the 1969 Pioneer SX-2500 had a FET, to try a regular Transistor showed less Gain & an unfocussed grainy sound if not to try it further. The Only One with FETs in the preamp is the 1969 Sanyo DC-66 which was surprisingly clean sounding but No Manuals leaves it 'assumed' to be FETs. We must have had an error circuit diagram for the 1977 NAD 300 receiver, it has No FETs in the Preamp, going to look what they used & not there. So we know of No Other FETs Preamp beyond those with One FET. Looking in vain on our Reviews for more FET preamps, they appear more by mid 1980s & then the MOSFET became the standard by the 1990s. But a FET preamp using 12 as 6 per channel with no regular Transistors, seems a Sony TA-2000F & Sony TA-1130 thing. The 1971 Sony STR-6200F oddly has no FETs beyond the 5 in the Tuner. 1971 Sony STR-6065 has 5 in the Tuner also if differently. The 100w Power Amp 1971 Sony TA-3200F has No FETs despite the tag. Having heard how Great the 1971 Sony TA-2000F can sound, we're left with no other amps to compare it with. The 1984 Sansui AU-G90X uses FET Differentials n a few stages if mostly Transistors. Search FET on HFE Website. 1973 Sansui 8 Deluxe FETs in the Tuner only. 1977 Yamaha B-2 FET Differentials on this Power amp. Really all there is on Vintage Hifi, some Modern amps post 1995 use FETs.

Further FET Listening.
FETs a 'New Find' to us just with the last few Blogs, so to listen to more & try Transistor Amps to compare. Playing on Headphones and on Speakers shows the FET is a more precise sound, hearing Transistor Amps again thought very clear, they sound a little Smeary when the FET is just 'there' with no Grain or what sounds a little artificial once hearing the FET, Germanium or Valve sound. On Speakers, the High Treble that BBC TV leaves on it's Outdoor Shows like Antiques Roadshow has this Treble correctly reproduced to a 'Clean Knife Edge' when other Amps can struggle with it, a part of The Speed of an amp, as in Rise Time. A FET pre needs a Fast Power Amp or you'd not notice the difference, always the way. FETs on a Phono Stage. By Chance, the Sony TA-2000F has this, Nine 'amplifying devices' means 6 FETs. one regular Transistor plus two unusual 150v Custom Sony ones 2SC926A, these aren't on ebay so consider Obsolete. Rated 210v, there are equivalents suggested. The MC Amp board has 3 FETs, 1 regular Transistor plus two of the 210v ones. Sad that Sony hid the Quality in this Preamp, to the point we were thinking to sell it on, if remembering how much work in it already. The TT Power Amps a ton of work in, but not being used & tired of them after 24 years so it can be too easy to sell when More Work brings what we're hearing as we type, can any Amp better this? Playing one track, the Elvis-Reggae Mashup of 'Crying In The Chapel' the meters show how fast it is & the Sibilant at the start of the vocal is fully realised, some amps refuse to play it, "You Sssaw" can be "You Fffaw" a much used Test Track. The TA-2000F is still work in progress, could do with a bit more gain after more use, if on Speakers, it's Fierce with Bass going as deep as the 1966 Sansui TR-707A. Be aware you can Annoy Neighbours with an Amp like this, you'll play it louder as it's so nice. One Reggae track has 2 very loud but fast clicks, another Test Track, the Sony plays it fully, the meters not quite as fast as on a Sibilant. Meters are a more General idea of Level, to have them Ultra Fast would be a bit much. The FETs do show up clipping from Recording 45s years ago, as in we recorded into the Red without realising. Detail Freaks would love the sound, but it's a Smooth Sound, not a sound that makes Face Expressions as it's harsh.

1975 Sony TA-5650 "V-FET" Amplifier.
The 50w 1975 Sony TA-5650 "V-FET" interestingly has 5 FETs on several preamp stages with 3 Transistors per channel, if only V-FET outputs on the Power Amp. The 85w Sony TA-8650 is the higher power version if mostly ICs in the Preamp. TA-5650 Phono has 1 transistor then 1 FET (per channel), odd the FET isn't used first for low noise. Flat Amp has 1 FET then 1 Transistor with high NFB. Tone Amp has 3 FETs with a Transistor amid, it looks like they are trying to hide the Precise Sound. Power Amp is All Transistors including the Differential, only the Doubled Outputs are FETs as N & P versions 2SK60 & 2SJ18. These are Long Obsolete unlike the Small Signal ones which makes them Scary to have on an amp as Direct Coupled to a Speaker. The amount of Service Bulletins on the 5650 are a bit of a worry, so to look through all three. First one shows by 1978 the V-FET was getting issues, with Sony supplying Matched Sets of All FETs used. Second one mentions the Ranks of FET matching. Third mentions how to test the FET suggests in 1977 these were Too Experimental for a Domestic Hifi Amp. Another in Non-English possibly Dutch covers these points again. Seeing the ones on ebay from China, dare you trust them not to be Fake or one with NOS ones for £800, you can see the worry. The TA-5650 probably is extremely good sounding, if the V-FET outputs could probably be altered to take MOSFETs. One Audiokarma post says they are quite different & they couldn't get it to work. Too Risky sadly to take in a Customer's Amp on a V-FET amp, we were asked, they assume you don't know these things & will naively try it. A Damaged TA-5650 can still be Used as a Preamp if the Damaged bits are 'Neutralised' to not cause bother, the Preamp seems an interesting one, the Power Amp seems more standard beyond the Outputs. Amusingly a German ebay seller will tell you how to 'Convert' the V-FET to MOSFETs for £3.82 no parts just an email. Only A Fool would trust that. The TA-5650 has a Damping Factor of 50, the bigger TA-8650 has a worrying Damping Factor as high as 200 suggesting a very tight sound like Boring 1990s Amps. The 1975 Sony TA-8650 is nowhere as good as it has ICs on the Preamp & to get 80w it needs Tripled Outputs suggesting the V-FETs aren't too powerful.

To Jan 2023 Blog...