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

[Wes]

I think this is a valuable comparison.

Suppose the end result is a set of amps that measure within the SQ range of many (or the best) ones now -- one could then compare on SQ factors not measured (soft clipping?) or aesthetics, or price.

 

[restorer-john]

How did you ended up having four of them??

Long story. It involved long term storing all my best HiFi to move to another city. Then opportunity arose to get hold of a former Sony executive's personal stash and I took it up because it was easier than unpacking an entire house's worth of stuff to get to the HiFi. I called it my "backup system plan" in case the house burnt down or something. That was my excuse and I'm sticking to it.

 

[MakeMineVinyl]

In the 50s through early 60s measuring equipment in was far, far from what it is today. Distortion analyzers would be hard pressed to measure much below .1% distortion. It got better in the 70s with Sound Technology instruments being the "Audio Precision" of the day.

 

[kevinh]

Measurement of the Threshold Amps would be interesting, had an S/200 was a nice Amp, I think this was before Nelson found it profitable to tune in some 2nd harmonic distortion.

 

[restorer-john]

I don't about that Sony TA-N77ES. It gets a bad review here.

Ken Rockwell's testing merely confirmed my findings of a decade or more earlier. He even quotes my old post from TVK. (link). The multivoltage version of the TAN-77es is far more powerful than the US 120V version due to rail switching to ensure FTC long term compliance. The multivoltage unit has fixed secondary taps and sits at a slightly higher voltage. Considering I measured well over 600w BTL into 8ohms and nearly 1KW into 4R BTL, it's a powerhouse. Ran two 77esDs in mono at one point just because.

As for the rest of his review, it's certainly not bad- quite the opposite if you ask me.

This one is out at the moment:
(SMSL toy amplifier for scale)

 

[LTig]

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

Can't help with these, and the Denon POA6600 I owned a few years have been sold to a music band, due to going active (the deal was against my recommendations since these are not amplifiers for professional usage, but nevertheless they survived and, as far as I know, are still working!):

 

[GeorgeWalk]

I'll bite. I would go with a Nikko Alpha III. I bought it in 1978 and I am still using it today. Ignore the equalizer on top. I am not using that at this time.

https://tmraudio.com/old-products/nikko-alpha-iii-stereo-power-amplifier-2-channel-amp/

 

[A800]

 

[SIY]

I guess it is contenders I/we/others have had hands on experience with, either on the bench, testing, or owning for decades where the important parameters are excellent or near modern SOTA offerings.

Could you define what you mean, specifically, by "important parameters"? I've seen a lot of stuff mentioned here that have mediocre distortion and power bandwidth performance. A lot of those are good enough to be audibly transparent, but if you're talking about SOTA in the year 2020, 0.01% THD (for example) isn't it.

 

[restorer-john]

I would go with a Nikko Alpha III. I bought it in 1978 and I am still using it today.

A classic amplifier that Nikko. Nikko had a thing for making hybrid driver "ICs" in their gear. Your amp has a little 4 transistor potted module that if it fails, has to be rebuilt on a bit of perf-board. Luckily, they provided the internal schematic to do just that. U701. Keep this image if you don't have a schematic.

 

[restorer-john]

Could you define what you mean, specifically, by "important parameters"? I've seen a lot of stuff mentioned here that have mediocre distortion and power bandwidth performance. A lot of those are good enough to be audibly transparent, but if you're talking about SOTA in the year 2020, 0.01% THD (for example) isn't it.

Every single parameter that makes a product excellent.

Some of the products people are throwing into the discussion specified their THD (+N in real terms) from 10mW to full rated power, and all others were a minimum of 250mW to rated power and the numbers were worst case. Who is specifying that now? They aren't, they are specifying best case at full or half rated power, just before the knee and certainly not back around 250mW or below where the noise dominates. Not apples to apples comparisons.

Power bandwidth. OK, let's decide how important it is and what is acceptable and what isn't. On the one hand you have Class D proponents saying nothing over 20KHz should be measured, talked about, or tested and yet we have vintage amplifiers that
a) emit nothing in the HF that needs filtering just to measure, and
b) have power bandwidths (-3dB) of 40KHz up to any number you can imagine. So is a -3dB at say 40Khz@8R acceptable?
Let's test all amplifiers for upper and lower -3dB (half rated power) PBW points and score them on a performance chart accordingly. We know the Class D aficionados will be up in arms and say it's not important. Can't have it both ways.

Test amplifiers single channel, both channels, into 8/4 and 2 ohms. Burst power into half rated load impedances. Cook them for an hour and see what happens. Blow some fuses and trip some relays. Test these things. They are built for it- or at least the vintage ones were. (no screwdrivers across the outputs- that just not fair)

Are they well built? Will they last more than the warranty period? We have 40+ year old loyal products being suggested in this thread- that is surely an indication of fitness for purpose. We know some of those early Hitachi MOSFET (K134/5 J149/50) designs (Perreaux/Hafler/Nikko etc) are virtually as good as it got for the time (1980s) and still stack up now. Is the product easy to use, enjoyable in operation? Do they make noises/cracks/thumps etc? Is there any audible buzz/hum or hiss either physically or electrically? Do they shut-down when they shouldn't? Can you get parts at a reasonable price and is the product good value to start with?

Or were they simply great in some areas (whatever the flavour of the month happened to be) and not so good in others? There has always been a fashion in HiFi, and right now, we are just in another fashion moment. This thread is about looking for worthy challengers to the current fashionable SOTA gear. We all know that on a level playing field, the measurable differences between some vintage gear and modern are going to be close and most likely utterly inaudible.

What suggestions of yore do you have for gear that has floated over your bench in the past and really impressed you? What gear did you make proclamations of "instrument quality waveforms" or "the best you've ever tested"?

That's what this thread is about. Not zooming in on a singular measurement, but looking at the big picture. Maybe uncovering possibly very special vintage products languishing in members' basements that Amir (or yourself) might test if the member or the item is close enough. I have a ton of gear, but I'm on the other side of the world (with no AP ) and I know there's members with some really good vintage gear.

 

[MerlinGS]

Three amps that come to mind from different periods are the APT, Crown and Gas.

The Apt Power Amplifier 1, a well designed and reliable amp; still good by today's standards. Very reliably by the looks of its availability in the used market after all these yrs.

The Crown Reference Studio. A beast of an amp that could drive anything. Still can be had in the used market for a reasonable price (especially considering what some vintage Japanese amps cost these days).

Gas Ampzilla 2000. This is a more current design, but it seems to be very well engineered, which is more than can be said for many "high-end" amplifiers.

For those looking for space heaters, I always had a special liking for the Classe DR3 VHC. A beast that could be bridged, drive a pair of Apogee Scintillas, and remain in class A operation the whole time. Not kidding about being space heaters (the only way to cool them down a little was to drive them hard, unlike class AB and D designs).

 

[tmtomh]

Every single parameter that makes a product excellent.

Some of the products people are throwing into the discussion specified their THD (+N in real terms) from 10mW to full rated power, and all others were a minimum of 250mW to rated power and the numbers were worst case. Who is specifying that now? They aren't, they are specifying best case at full or half rated power, just before the knee and certainly not back around 250mW or below where the noise dominates. Not apples to apples comparisons.

Power bandwidth. OK, let's decide how important it is and what is acceptable and what isn't. On the one hand you have Class D proponents saying nothing over 20KHz should be measured, talked about, or tested and yet we have vintage amplifiers that
a) emit nothing in the HF that needs filtering just to measure, and
b) have power bandwidths (-3dB) of 40KHz up to any number you can imagine. So is a -3dB at say 40Khz@8R acceptable?
Let's test all amplifiers for upper and lower -3dB (half rated power) PBW points and score them on a performance chart accordingly. We know the Class D aficionados will be up in arms and say it's not important. Can't have it both ways.

Test amplifiers single channel, both channels, into 8/4 and 2 ohms. Burst power into half rated load impedances. Cook them for an hour and see what happens. Blow some fuses and trip some relays. Test these things. They are built for it- or at least the vintage ones were. (no screwdrivers across the outputs- that just not fair)

Are they well built? Will they last more than the warranty period? We have 40+ year old loyal products being suggested in this thread- that is surely an indication of fitness for purpose. We know some of those early Hitachi MOSFET (K134/5 J149/50) designs (Perreaux/Hafler/Nikko etc) are virtually as good as it got for the time (1980s) and still stack up now. Is the product easy to use, enjoyable in operation? Do they make noises/cracks/thumps etc? Is there any audible buzz/hum or hiss either physically or electrically? Do they shut-down when they shouldn't? Can you get parts at a reasonable price and is the product good value to start with?

Or were they simply great in some areas (whatever the flavour of the month happened to be) and not so good in others? There has always been a fashion in HiFi, and right now, we are just in another fashion moment. This thread is about looking for worthy challengers to the current fashionable SOTA gear. We all know that on a level playing field, the measurable differences between some vintage gear and modern are going to be close and most likely utterly inaudible.

What suggestions of yore do you have for gear that has floated over your bench in the past and really impressed you? What gear did you make proclamations of of "instrument quality waveforms" or "the best you've ever tested"?

That's what this thread is about. Not zooming in on a singular measurement, but looking at the big picture. Maybe uncovering possibly very special vintage products languishing in members' basements that Amir (or yourself) might test if the member or the item is close enough. I have a ton of gear, but I'm on the other side of the world (with no AP ) and I know there's members with some really good vintage gear.

You can't say "every single parameter" and then say "not zooming in on a singular measurement, but looking at the big picture" - that's sophistry. It's saying you will discount whatever you don't like by pointing to a single parameter - regardless of whether it's actually relevant to performance - but then on the other hand you will hold up whatever you do like by "looking at the big picture" and not focusing on any particular measurement.

The fact that Class D is measured with an ultrasonic filter is well-known and the reason is well-understood, including by you, and you know full well it has nothing to do with poor design, poor engineering, or audible issues. It's a feature of the design topology. If you don't like it, that's your prerogative. But your unending beating of this very dead horse is silly on a forum like this one.

And you are straw-horsing Class D proponents by claiming they say no measurement above 20kHz matters when you know full well that is not true. The ultrasonic noise is up around 400kHz in most cases. Amir and most others here would no doubt raise an eyebrow at an amp that had major noise at 30 or 40kHz.

Similarly, you know full well that Class D amps have smaller power supplies and usually smaller and lighter-weight casing because of the nature of the topology: they use switching supplies and they don't need the same kind of heat-sinking. You might not like their "toy" appearance and weight, but it doesn't mean they're unreliable or poorly engineered. A Radio Shack amp from the 1980s that was small and inexpensive was indeed a very low-power device with limited bandwidth and relatively high distortion and noise, because it used (as far as I know) a traditional Class AB topology and such a topology is difficult to impossible to make high quality in such a cheap, small, and light package. (Not ragging on Radio Shack - it's just that when I was growing up in the '80s their catalogue was the main place I saw little 12" wide, 10wpc Class AB amps for $129 - and I remember the specs were not what one would call hi-fi). But a different topology can perform well and be robust in such a package.

Now, where you are no doubt correct is that Class D amps cannot and do not produce their rated wattage in a fashion that you, I, or most others here (at least those of us of a certain age ) would call honest or what we expect from hi-fi equipment. A "400 watt" Purifi or Hypex module is rated that way into 4 ohms, whereas most vintage hi-fi gear of the '70s and '80s was sold based on watts into 8 ohms. And as tested by Amir, the Purifi module produces "only" 257 watts into 4 ohms and 131 watts into 8 ohms - at 0.0002% distortion! (And something like 275 and 170 respectively if one uses 0.01% as the distortion limit.)

If I showed you a Class AB amp that produced more than 125wpc of continuous, ultra-clean signal into 8 ohms at 0.0002% THD, and fully doubled its output to more than 250wpc into 4 ohms with the same ultra-low distortion, you'd be thrilled and declare it a superb design.

Your analysis here is motivated by your bias against Class D as a topology. Your knowledge is impressive (to say the least!), but your arguments here are just a fancy version of, "no amp that weighs just a few pounds and produces noise at 400kHz can be any good."

Finally, let me be clear - I love a good vintage amp. Give me an Adcom GFA-555 or 5800 and I'm happy. But the entire point of the subject you've devoted this thread to should be to identify which vintage amps actually deliver(ed) the goods in terms of specs to compete with high-performing amps of today. You keep saying such amps exist - and I certainly believe you - but you keep saying "they're scattered around the world," "I'll have to post some measurements," "some are great but not good candidates for this list," "xyz amp is essentially perfect except for its high noise," etc.

If it's this hard to actually identify a vintage amp that measures sufficiently well in "all the important parameters," doesn't that suggest that there are few if any commonly available, or easily/affordably purchased older amps that can "challenge or approach current state of the art"?

 

[restorer-john]

Your analysis here is motivated by your bias against Class D as a topology.

The entire premise is not about one topology vs another. It's about a level playing field and what is important vs what isn't. That is totally open for debate.

You can't have one topology dismissing parameters that were hard fought and won and neither can vintage or modern gear claim it's better because of parameters or performance that are arguably irrelevant in the real world.

SIY brought up power bandwidth. I didn't. I would have been accused of stacking the comparison against Class D. I'm not.

But if we are looking for vintage gear that approaches modern gear, let's face it, that vintage gear is not going to be Class D is it? It wasn't even a mature technology until recently. Let's just have fun with the thread. It doesn't have to be a vintage HiFi porn thread, but everyone likes some good looking gear to drool over don't they?

 

[Icboschert]

As a millennial who didn't grow up around any vintage HiFi, this thread is a joy. Never knew what a Denon POA 1500 was until now and what a beauty it is. My Anthem receiver has broken down twice within a year with different problems and I am longing for some solid tanks that just work...

 

[Hiten]

@tmtomh
I understand what you are saying. I agree with you. And uncertainty is bound to happen as we would be comparing highest performance today vs maximum achieved in the past with audibility in question. And if we are also uncertain about how far and what we should test will also add to confusion. Naturally technically todays equipment would have reached highest level. But that will stop us from exploring high performing equip. of the past.....

1. A fun, partially anecdotal discussion about solidly built and decently performing vintage amps, and
2. A discussion more rigorously focused on vintage amps that can challenge the best new amps on performance.

..i would prefer (2) because I would love to see how vintage amps did it. (I am not buying anything, just to learn) That I suppose is main theme of the thread. You all are experienced and probably know about this already. But people like me are unaware. Also hope that friends are posting amps they had or liked which is not the aim of this thread.
Regards

 

[laudio]

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.

Perhaps I will. Mint condition not as important as unmodified condition to me. Anytime I see a mod performed (or even a recap advertised bringing something back to original glory) - nope. A-717 flies under the radar.

 

[laudio]

Can't help with these, and the Denon POA6600 I owned a few years have been sold to a music band, due to going active (the deal was against my recommendations since these are not amplifiers for professional usage, but nevertheless they survived and, as far as I know, are still working!):

What a nice little amp monoblock that was. Think it's little little sibling was the 4400, same/similar to NEC M-50s which are pretty decent too.

If you saw that it for sale new today - not sure AHB2 would be such the rave, measurements notwithstanding.

 

[oldsysop]

A vintage amp is made by the same company that bears their logo on the front.
Class D is a grouting of modules and a fancy name.

 

[restorer-john]

A vintage amp is made by the same company that bears their logo on the front.
Class D is a grouting of modules and a fancy name.

I understand what you mean, but we do have NAD and Marantz taking high performance Class D OEM modules and building everything else bespoke, so it's not really that a different concept to the old Sanyo thick film hybrids (STK-xxxx) of the 1970s/80s where most of the power amplifier was in a single, off the shelf module. Practically every Japanese manufacturer used them for voltage amplifier stages, power output stages or the entire 2ch power amplifier satge. They were certainly not as robust as discrete, but did offer low cost, good enough performance and sample to sample consistency. Never really used in the top tier gear however and for good reason.

Manufacturers have gone with off the shelf amplifier "solutions" before and there's no reason to not be doing it now. There is a compelling business case for it. It's just somewhat disappointing they no longer have the in-house engineering chops or the pride/desire to build SOTA amplification themselves. With PWM amps, Yamaha did it, Sony had a go as did Panasonic but nothing that set the world on fire.