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Vintage (1970s) Japanese SS Integrated Amps

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greg788

pfm Member
I'm really close to buying a fully restored 1970s vintage Japanese amp. I'm trying to decide between several, actually (Kenwoods and Sansui's). I have no clue what these sound like. Am I crazy to believe I'll get equivalent or better sound quality to modern amps with, say, a Sansui AU717, AU9900, Kenwood KA-8100, etc.? Which models do you recommend that are still reasonably priced (I'm excluding Accuphase, Luxman, McIntosh, etc. for this reason)?
 
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Modern amps will generally sound better but there were many advances and changes in the 70's hence 78' 79 amps can be very similar in design to todays amps but 70 -73 etc usually quite different.
 
AU717 is a bit of a sweet spot - the AU919 is very nice. Have a look at the Pioneer A27- massive and capable - love mine.
 
One of my bucket list amps is the Trio/Kenwood model 600 Supreme.

If it didn't sound nice I'd be perfectly happy just looking at it.

Mmmmm
 
One thing I’d do whatever the shortlist would be to track down the service manual (HiFiEngine has huge numbers for free download), search AudioKarma and AudioAsylum to see what issues others have had, YouTube can have a wealth of information too. This should help you avoid stuff with known to fail and totally unobtainable parts (e.g. Sony V-FETs!). Some models are far easier to work on than other stuff, and I’d allow that to sway my decision somewhat. Also really learn your models, ranges, price-points etc as I often see quite budget stuff going for similar money to quite upmarket stuff. All the major brands (Pioneer, Marantz, Kenwood, Sansui, Sony etc) had some really beautiful no-compromise kit, and some low-end tat too, so research pays off.

PS Also don’t overlook your local auction house, occasionally nice stuff turns up…

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I landed this pair of 1972-4 Sonys for £35 the pair including fees about five years ago, lovely things, real battleship build quality and still working (I’d want to recap the amp before trusting it, but the tuner is absolutely fine!). I’ve had a SL-120/3009 and an Akai 4000DB for £30 a throw there too, plus a lot of other nice stuff.
 
Sansui AU 717 : when anyone sees one for sale should jump on it right away ! Can’t describe how good it is, it’s a masterpiece full of musicality and robust like a tank. Someone would have to put a LOT of cash on the table to better it IMO.
 
Gervais Cote said:
Sansui AU 717 : when anyone sees one for sale should jump on it right away ! Can’t describe how good it is, it’s a masterpiece full of musicality and robust like a tank. Someone would have to put a LOT of cash on the table to better it IMO.
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I have one that's been meticulously restored by a Sansui expert on my shortlist and just emailed him a question, in fact, along with these other professionally restored units: Sansui AU-9900, AU-4400 (the cap coupling intrigues me), and a Pioneer KA-6006, KA-8006, KA-8100 ...

To Tony's point, I've been doing my homework. These were mostly found by posting a "WTB" on Audiokarma, in fact.
 
I’ve had a few of the big Japanese amps over the years, just wonderful pieces of engineering . Big old Sony, Sansui and Pioneer units especially. Looking back they were pretty good value for money really when you see how much went into them.

I had an old Pioneer SA5500 in which the phono stage packed in. From memory it had an unobtainable AN.... ic in it for those duties, not the end of the world as you could add an external stage but it does bring home how easily your expensive investment becomes a paperweight!

Last one I had was an SA9800 but like that old Lancia HPE I had I always felt if this goes pop I’m stuffed! Kept it a few years then sold it. They have of course now doubled in value:( but I was never in It for the money (just as well!)
 
wow&flutter said:
I’ve had a few of the big Japanese amps over the years, just wonderful pieces of engineering . Big old Sony, Sansui and Pioneer units especially. Looking back they were pretty good value for money really when you see how much went into them.

I had an old Pioneer SA5500 in which the phono stage packed in. From memory it had an unobtainable AN.... ic in it for those duties, not the end of the world as you could add an external stage but it does bring home how easily your expensive investment becomes a paperweight!

Last one I had was an SA9800 but like that old Lancia HPE I had I always felt if this goes pop I’m stuffed! Kept it a few years then sold it. They have of course now doubled in value:( but I was never in It for the money (just as well!)
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That's why I'll only buy a full restored one. The electrolytic caps are all ticking time bombs on those, and the "power pack" IC amplifier circuits that some of them used were not reliable. There were other assorted resistors and solid state devices (small transistors, diodes, etc.) that were also unreliable. Experts know what to replace and what with. I don't mind paying top dollar for one that's fully "sorted" other than I'm taking a risk on something unheard. But what's new with audio, lol
 
Some of those big vintage amps rely on those STK modules which were relatively inexpensive to buy back in the day. They were generally a cost cutting exercise by the manufacturers and provided they were properly heat sinked were reliable but my guess is they were never intended to be running 40 years after their introduction.
If a 5v or 12v output from the ic goes down it’s not the end of the world but any of its more complex output stage functions go and you’re pretty well stuffed!
My guess is a new dollop (technical term :D) of heat sink compound to replace the old dried out stuff may go a long way to extending it life.
Interestingly I was also told this about my Meridian 105s output transistors but as yet I’ve never got round to getting it done!
 
Another of those things I wish I’d stashed a few during the ‘80s black box era when they could be had for peanuts! IIRC they are way over £1k in good condition now. Rob has a beautiful mint wood case 9800, or certainly did have some years ago.
 
Just avoid anything with an STK module! They were mainly used in budget to mid price (-) gear and proper discrete electronics used for the better models. Often unobtainium or likely fakes these days.
 
Tony L said:
Another of those things I wish I’d stashed a few during the ‘80s black box era when they could be had for peanuts! IIRC they are way over £1k in good condition now. Rob has a beautiful mint wood case 9800, or certainly did have some years ago.
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I can remember seeing TOTR Pioneer and Marantz amps going for £30.... In a hi fi dealers S/H area! Not in the classifieds of the local rag... who probably had them at £70 'cos they hadn't been told it was "crap" now (not)
 
The units with the STK modules were at the same end of the market that now uses IC outputs.
They fail regularly because most were not designed for shorts or modern 3 Ohm dc resistance loudspeakers

Checking for a manual is a good idea, its hard to repair without one and look out for exotic parts (Sony!)
 
davidsrsb said:
The units with the STK modules were at the same end of the market that now uses IC outputs.
They fail regularly because most were not designed for shorts or modern 3 Ohm dc resistance loudspeakers

Checking for a manual is a good idea, its hard to repair without one and look out for exotic parts (Sony!)
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Except the current power IC's (LM3886, LM3875, LM1875) can provide very good sound quality. Jeff Rowland was building amps for a while with paralleled LM3886 and there are more commercial amps than you'd think that use them. Now the 47 Labs Gaincard was EXTREMELY overpriced for what it was, granted, but the LM1875 gainclone I built was IMO better than the 300B SET I built (including with EML Meshplates).
 
The STK modules gave good sound quality. They are a bit fragile for high mains supply and abuse.
I have published a clone design over on Diyaudio for one of the popular driver modules
 
Personally I feel that some old Japanese stuff sounds fantastic.

First up, the Optonica sm7100 integrated. Yeah it does use STK modules, but it also has a big toroidal transformer, pre/power stage, and for the prices they go for (almost always less than £200) I think they represent a bargain. This is my backup amp.

The Sony VFET amps sound wonderful. No getting away from that- my TA-F7 mesmerised me from the first moments of plugging it in. Very big sound, majestic yet nicely detailed. Mind you, that one has had some major work done and components replaced.
 
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