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Vintage amplifiers that could challenge or approach current state of the art amplifiers

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restorer-john

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Kenwood L07M and/or L07M MKII monoblocks

The Kenwood power amps were very good, but had aggressive current limiting below 4 ohms and the Mk2 power amps are prone to going up in smoke due to stability issues. At one point, I had 7 of them. They are all sold and gone now. This is my pic from 2007. I kept the left hand pair up until a few years ago

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The Onkyo M-508 is a lovely power amplifier for sure. I don't own one of those, and I've only ever worked on one. All it needed was meter illumination repairs.
 
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restorer-john

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Hewlett Packard made a hifi amplifier!

Yes, one of the most collectible amplifiers on the planet. One of you guys can send me one for my collection anytime thanks. It's just beautiful.

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Hiten

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So what suggestions do you guys have for vintage challengers?
I have been reading your posts. You are the best judge. I would definitely like your recommendation and why they were special. Specially technical bits (Though I understand little). And probably layouts, Components used, clever engineering ?
Thanks.
 

tmtomh

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This is a very cool topic - thanks for starting it @restorer-john ! And I look forward to seeing some measurements of older/vintage amps that "could challenge or approach current state of the art amplifiers."

However, so far I don't see many, if any, such amplifiers in this thread. There are many that John has ruled out for a variety of reasons - "just budget," "dreadful on the bench," "stripped down to fool audiophiles," "would be contenders, except for their residual noise," and so on.

By contrast, most of the amps John feels are good so far, he has described as "lovely." Hardly a standard that tells us anything.

So thus far, this is basically an AudioKarma.org-style amplifier-porn thread. If the actual idea here is simply to talk about cool older amps, that's fine. I know I enjoy seeing photos and descriptions of great gear.

But if the intent is truly to identify older amps "that could challenge or approach current state of the art amplifiers," then maybe dispense with the broken-record, a priori claim that modern Class D amps are "fragile" and start naming some older amps whose available measurements do in fact "challenge or approach" current state of the art in terms of flat frequency response in the audible range: low mechanical and electrical noise; low distortion; high current capacity; ample power reserves; and if it's thought to be desirable or meaningful, good damping factor and/or slew rate.

I don't know what realistic benchmarks should be for all of those figures, but I'd say that audible hum is deal-breaker and SINAD worse than, say -95 or -100 would be a deal-breaker. So too would frequency response deviation of more than, say, 0.2dB from 20-10kHz be unacceptable, and no more than 0.5dB at 20kHz. And I cannot stress enough how little I care about ultrasonic frequency response. Sure, no crazy spikes in the 20-30kHz range is sensible to ensure the amp doesn't stress or damage tweeters, but beyond that we don't need ultrasonic performance as an indirect measure of quality when we have plenty of direct measures of quality we can look at instead. Finally, for power, how about 100wpc continuous into 8 ohms, 20Hz-20kHz - that seems like a decent number to ensure sufficient power in the majority of home environments with the majority of speakers.

My understanding is that quite a lot of excellent older amps can nail the frequency response and provide plenty of sustained wattage over the full audible spectrum. Distortion and noise, by contrast, are generally tougher nuts to crack for older amps. So that would likely be a way to weed out the best from the rest.
 
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restorer-john

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I have been reading your posts. You are the best judge.

I am just one judge. One guy on the internet. There are plenty of others who have had experience with equipment I have never owned, repaired or studied, particularly US made amplification gear which we rarely saw here in Australia. The Australian 240V market was too small for much US made stuff.

What I like is the gear that was state of the art when it came out, was not obscenely priced, was beautifully constructed, ultra reliable and still to this day performs and looks as new. Not a tough ask.
 

tmtomh

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I am just one judge. One guy on the internet. There are plenty of others who have had experience with equipment I have never owned, repaired or studied, particularly US made amplification gear which we rarely saw here in Australia. The Australian 240V market was too small for much US made stuff.

What I like is the gear that was state of the art when it came out, was not obscenely priced, was beautifully constructed, ultra reliable and still to this day performs and looks as new. Not a tough ask.

That seems like a description of a solidly built amplifier whose components do not degrade as they age. But if the amp's "as new" performance did not "challenge or approach current state of the art amplifiers," then it wouldn't be germane to the purpose of this thread, yes?
 
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restorer-john

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By contrast, most of the amps John feels are good so far, he has described as "lovely." Hardly a standard that tells us anything.

Realistically, the amplifiers are spread across the world and 99.9% of them are in normal audiophile's homes. By normal, I mean they don't own an AP or suitable test gear to quantify them. I can only go on my experience with the products I have found that are close to flawless, and many of them are either stored or have been disposed of.

I probably own a hundred amplifiers now, and there's at least half a dozen big amplifiers right here that would fit the criteria, but are they the best for this list? No.
 
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restorer-john

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That seems like a description of a solidly built amplifier whose components do not degrade as they age. But if the amp's "as new" performance did not "challenge or approach current state of the art amplifiers," then it wouldn't be germane to the purpose of this thread, yes?

Yes.

The Pioneer A-717 and A-91D (both circa 1989) pulled out of storage tested as new. They both have THD below what I can reliably test. I have four Sony TAE-77es/esD preamplifiers here and they all test identically and they are all 100% original, made in 1990. I have three TAN77es (1989/90) power amplifiers here, all original, all beyond my test gear's resolution at high powers (<.002% for 30V and up).

Recently, I put a 45 year old integrated amplifier (untouched) to the same tests done (most of them) by HiFi choice in the UK (I had the original 1970s review) and came up with identical performance. Al those figures were way better than the specifications.

Also, much vintage gear was grossly under-rated in various parameters. Power output, distortion etc was worst case sample, line in the sand type stuff.
 

Hiten

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That seems like a description of a solidly built amplifier whose components do not degrade as they age. But if the amp's "as new" performance did not "challenge or approach current state of the art amplifiers," then it wouldn't be germane to the purpose of this thread, yes?
I would see it as this way. Probably sufficiently good performance was achieved long back. Modern high performance components are just a notch or two above. But some modern components don't even reach levels that were achieved in the past. So thread title is appropriate as challenging modern amps instead of better than modern amp. I suppose everyone likes to take a peek inside and measure and discuss a very well made electronic product/s regardless of time.
Best Regards
 

McFly

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Some of big vintage Perreauxes I've owned would be contenders, except for their residual noise. In all other parameters, they were/are pretty much unbeatable.
Which models?

Would yamaha have any contenders? I have a beat up MX-1 here with a lot of A.C. voltage on the chassis which I've been meaning to look into. They claim 125db SNR

IMO integrated amplifiers should be included with power amplifiers, as most can be used as such if desired.
 
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restorer-john

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Which models?

2150B, 3150. Both Hitachi MOSFET application note designs. Residual noise from the gigantic transformer and it's proximity to the front end made for low level, but audible hum/buzz. Otherwise, flawless. But you can't really fix the problem. Later models tried with shielding, but it didn't really work.

The only thing that fails is the power switches in the older Perreaux amps from the massive turn-on arc (no slow/surge turn on).

Would yamaha have any contenders?

Yes. The MX-600/800/1000 power amplifiers were pretty amazing, although the APS (switching rail) made them a little unreliable in the 1000. I'd say they would be more than competitive in the noise, THD and power output stakes with modern amps. I only have an MX-600 and MX-630 here I could do limited tests on. They have pretty obscenely high short term dynamic power as well.

The M-80/85 were damn fine amplifiers too, but suffered from bond-glue issues.

I never saw an MX-10000 Centennial (1987) power amplifier in the flesh. I don't know if it was ever properly reviewed, but it should be right up there for sure.

The one I'd like to get my hands on is a 1980 Denon POA-3000 or 3000z.

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1kVA transformer, 100,000uF filtering. FTC continuous rated 180+180W@8R, 122dB S/N etc.

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https://audio-database.com/DENON-COLUMBIA/amp/poa-3000-e.html
 

Vini darko

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I'm gonna throw a curve ball. Got a soft spot for aiwa stuff growing up with their tape players. This is the best amp they ever made, last time one came up on ebay I got out bid in the last couple of seconds. Not sota but I still want one.
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restorer-john

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I'm gonna throw a curve ball. Got a soft spot for aiwa stuff growing up with their tape players. This is the best amp they ever made, last time one came up on ebay I got out bid in the last couple of seconds. Not sota but I still want one.

I've actually got the matching FM (only) tuner AT-9700! It's an absolute beast. Ugly some might say. Weighs more than many amplifiers.

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Pretty sure it was born out of the transition of Heitaro Nakajima from head of Sony's audio and loudspeakers when he was overseeing Aiwa. It was around 1979/80. He went over to be the president of Aiwa in 1982. I think they shared much from Sony's audio division.
 

Vini darko

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I've actually got the matching FM (only) tuner AT-9700! It's an absolute beast. Ugly some might say. Weighs more than many amplifiers.

View attachment 70135

Pretty sure it was born out of the transition of Heitaro Nakajima from head of Sony's audio and loudspeakers when he was overseeing Aiwa. It was around 1979/80. He went over to be the president of Aiwa in 1982. I think they shared much from Sony's audio division.
Yeah might be one of the most overkill fm radios out there :D. I like the formidable design on it.
 

laudio

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I have a few favorites in the basement.

Pioneer c91/m91 are great. Nakamichi pa 7 what a beast. Luxman m117 tho - better than r117 although r117 imo was best receiver ever made and have it too.

Nec a10 integrated from mid 80s was no slouch and measured better than most amps to this day if you go back and find the old reviews. Denon made great integrateds too. Pma 777 for example. I could go on and on. Yes - many great vintage amps out there built to last and built right.

That said I like what my teac AP 505 hypex based amp does better for different reasons and it sounds every bit as good as any of them. It's called progress in a small form factor that uses far less power.

This thread will get countless recommendations on what was best. Should be enjoyable if it stays on track and somebody calls out something that is actually better than what I mentioned. The a91d has been been on my watch list as maybe the best integrated but having a lot of gear never pulled the trigger on it.
 
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restorer-john

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The a91d has been been on my watch list as maybe the best integrated but having a lot of gear never pulled the trigger on it.

Just do it, but wait for the right one. As long as you get a carefully looked after unit you will love it. You don't want one that has been touched, "upgraded" or messed with, in any way shape or form. Then you know where you stand and what, if anything, needs to be done. The trouble is, 30 years on, a 65lb amplifier is likely to have picked up a few marks from being moved a few times, finding a mint one will be very hard.
 
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