Vintage amps (70s)

[Mikado463]

Or Carver, Phase Linear, Fosgate, Peavey, etc?

Ahhhh Jim Fosgate, never had one of his amps but I still enjoy to this day his fine phono-pre in my main rig....

 

[TLS Guy]

Quad amps for sure. They were easily the best amps of that era, and most of the production still in regular use.

 

[lovinthehd]

Quad amps for sure. They were easily the best amps of that era, and most of the production still in regular use.

So the Chinese owners have been reasonable owners of the brand?

 

[TLS Guy]

So the Chinese owners have been reasonable owners of the brand?

No, I am referencing amps designed and produced when Peter Walker owned the company. This is a vintage thread as I understand it. So we are talking 2004 and prior. I have 10 Quad 909s in daily use and three Quad 4052s.

 

[lovinthehd]

No, I am referencing amps designed and produced when Peter Walker owned the company. This is a vintage thread as I understand it. So we are talking 2004 and prior. I have 10 Quad 909s in daily use and three Quad 4052s.

Thanks, didn't think so. Wasn't sure if you meant the previous design/current production or what meant by still in regular use particularly....

 

[dlaloum]

what , no Krell or Threshold ? how bout 'Ampzilla' ?

I don't recall any Krell's, Threshold or Ampzilla's among local (Melbourne) stores...- but at the time there were plenty of high end alternatives (Nakamichi was around, so was Tandberg - my list wasn't exhaustive... might remember a few more if I pause and think about it!)

 

[dlaloum]

Or Carver, Phase Linear, Fosgate, Peavey, etc?

I remember Carver being around in Oz, and we sold Fosgate in our store...

 

[Mikado463]

I don't recall any Krell's, Threshold or Ampzilla's among local (Melbourne) stores...- but at the time there were plenty of high end alternatives (Nakamichi was around, so was Tandberg - my list wasn't exhaustive... might remember a few more if I pause and think about it!)

If memory serves me correctly Nakamichi got license rights from Threshold to produce amps that utilized Nelson Pass's Stasis technology ?

 

[dlaloum]

If memory serves me correctly Nakamichi got license rights from Threshold to produce amps that utilized Nelson Pass's Stasis technology ?

Yes, and the stasis tech was a close relative to Quad's Current Dumping circuits too..

 

[TLS Guy]

Yes, and the stasis tech was a close relative to Quad's Current Dumping circuits too..

That is true. There is no doubt that he infringed Peter's patents. But Peter was a gentleman and never pursued legal action. To tell you the truth, he thought that might widen the adoption of his technology. It surprised him and others, including myself, that this topology did not command wide acceptance. It think it is because it is counter intuitive. But it works, and works very well, and above all has long legs. I think there are two good reasons for this. 1). The part count is very low and so reduces the risk of component failure. 2). The amps, are highly efficient and run very cool. Low signal performance is the same as high signal, as there is zero low signal crossover distortion. You get class A performance without extreme inefficiency.

I will never understand why there has never been widespread adoption. Very good amps good be made now with major cost savings, and deliver performance the equal of digital amps and better than AB amps. Receivers for a start would benefit enormously from this amp topology.

 

[m. zillch]

Do vintage amps from 1970s sound different than one another?

The short answer is "no", not the good ones.
The long answer is that all good amps, in good working order, kept within their output limitations, played at exactly the same volume (determined by precise, external instrumentation, not "I winged it") in double blind testing, analyzed and showing results with adequate statistical significance, tend to all sound exactly the same: neutral/transparent. There are many caveats, however.

Not all amps qualify as "good" (although, surprisingly, many quite affordable ones do, even some receivers).
Not all amps have adequately low noise for all listening conditions.
Not all amps have a frequency response that is adequately flat regardless of load.
Not all amps from the 70's have components working just like when they were brand new. (e.g., the caps)
Not all have the same power. Some will clip on the musical peaks sooner than others.
Not all have the same features or reliability.
Not all have the same capability of driving difficult loads.
Not all have the facilities to set their output levels precisely to a tenth of a dB so external means have to be undertaken for careful listening tests and then there's a risk that device itself is not transparent [so be sure to use it on both amps being compared so it's at least a fair fight].

It baffles my mind that some people can be (in my view) bamboozled by marketers into thinking having an amp that instead of just amplifying the signal it also in some way "desirably changes" the sound and this is supposedly, um, "a good thing", but they exist. It certainly isn't desirable for those of us seeking to hear the signal accurately and unblemished, not the music after it has been mangled altered by less than fully transparent wiring/DACs/amps.

 

[dlaloum]

The short answer is "no", not the good ones.
The long answer is that all good amps, in good working order, kept within their output limitations, played at exactly the same volume (determined by precise, external instrumentation, not "I winged it") in double blind testing, analyzed and showing results with adequate statistical significance, tend to all sound exactly the same: neutral/transparent. There are many caveats, however.

Not all amps qualify as "good" (although, surprisingly, many quite affordable ones do, even some receivers).
Not all amps have adequately low noise for all listening conditions.
Not all amps have a frequency response that is adequately flat regardless of load.
Not all amps from the 70's have components working just like when they were brand new. (e.g., the caps)
Not all have the same power. Some will clip on the musical peaks sooner than others.
Not all have the same features or reliability.
Not all have the same capability of driving difficult loads.
Not all have the facilities to set their output levels precisely to a tenth of a dB so external means have to be undertaken for careful listening tests and then there's a risk that device itself is not transparent [so be sure to use it on both amps being compared so it's at least a fair fight].

It baffles my mind that some people can be (in my view) bamboozled by marketers into thinking having an amp that instead of just amplifying the signal it also in some way "desirably changes" the sound and this is supposedly, um, "a good thing", but they exist. It certainly isn't desirable for those of us seeking to hear the signal accurately and unblemished, not the music after it has been mangled altered by less than fully transparent wiring/DACs/amps.

My short version is: All well engineered amps sound identival when operated within their specified performance envelope. (ie: within their power and current output capacity, into the loads they were designed for)

If you want to hear amps sounding "different" - use a very difficult, reactive load, and get a bunch of amps for which that load is outside their operating envelope - each amp will misbehave differently, causing a different mix of distortions, and resulting in different "sounds".

When you stick to the design operating envelope, they all act like a straight wire with gain.

Some people have lived their entire audio life with easy to drive, 8ohm non reactive load speakers, and therefore all amps have always sounded the same.... Others have had the experience of living with "difficult" speakers (as I have) - and as a result have heard amps sounding "different".

The people with the latter experience tend to choose amps with high stability into reactive loads, capabilities into low impedances (1ohm is good!) and high current output.... cos then you can update your speakers and have a high degree of confidence that whatever speaker you choose the amp will handle them just fine!

 

[m. zillch]

Others have had the experience of living with "difficult" speakers (as I have) . . .
, , The people with the latter experience tend to choose amps with high stability into reactive loads, capabilities into low impedances (1ohm is good!) and high current output.... cos then you can update your speakers and have a high degree of confidence that whatever speaker you choose the amp will handle them just fine!

Please name an example of any speaker we discuss sometimes in this forum, currently made, that fits the bill as being a torturous/problematic load for the lesser amps, making them audibly stand out against other, more capable amps (but with the same wattage rating into 8-ohms as the lesser amp). Thanks.

Back in the 80/90s the go-to "dangerous load" speaker people used to like to cite was the Apogee Scintilla but I have no idea what they cite these days, so I thought I'd ask..

 

[Speedskater]

The Stereophile magazine loudspeaker reviews sometimes in the test section, calls the speaker a demanding amplifier load.

 

[Verdinut]

Please name an example of any speaker we discuss sometimes in this forum, currently made, that fits the bill as being a torturous/problematic load for the lesser amps, making them audibly stand out against other, more capable amps (but with the same wattage rating into 8-ohms as the lesser amp). Thanks.

Back in the 80/90s the go-to "dangerous load" speaker people used to like to cite was the Apogee Scintilla but I have no idea what they cite these days, so I thought I'd ask..

See the Stereophile magazine measurements of Bowers & Wilkins 804D D4 loudspeaker, with impedance reaching down to below 3 ohms and a phase angle of -70 degrees. That's a really incompetent design by a big manufacturer:

Bowers & Wilkins Diamond Series 804 D4 loudspeaker Measurements | Stereophile.com

Sidebar 3: Measurements I used DRA Labs' MLSSA system, a calibrated DPA 4006 microphone, and an Earthworks microphone preamplifier to measure the Bowers & Wilkins 804 D4's frequency response in the farfield. My primary axis for the measurements was level with the tweeter, but I also performed a...

www.stereophile.com

 

[lovinthehd]

See the Stereophile magazine measurements of Bowers & Wilkins 804D D4 loudspeaker, with impedance reaching down to below 3 ohms and a phase angle of -70 degrees. That's a really incompetent design by a big manufacturer:

Bowers & Wilkins Diamond Series 804 D4 loudspeaker Measurements | Stereophile.com

Sidebar 3: Measurements I used DRA Labs' MLSSA system, a calibrated DPA 4006 microphone, and an Earthworks microphone preamplifier to measure the Bowers & Wilkins 804 D4's frequency response in the farfield. My primary axis for the measurements was level with the tweeter, but I also performed a...

www.stereophile.com

Ir's that glorious english audio bullshit @TLSGuy

 

[m. zillch]

I already use speakers with a "difficult load" yet a cheapo, mid level AVR not rated for 4 ohm with no problem in my use, despite Stereophile's specific warning not to:

"Sidebar 3: Measurements

The Polk LSi7 is of slightly above-average voltage sensitivity, at an estimated 88dB/2.83V/m. The impedance is specified as 4 ohms, but as the plot of impedance magnitude and phase against frequency shows (fig.1), the load remains above 6 ohms for much of the audioband, with a minimum value of 4.2 ohms at 212Hz. However, the electrical phase angle is quite severe in the upper bass, which will add to the drive difficulty. A good amplifier or receiver rated into 4 ohms will work best with the speaker.

What I think is lost on many magazine reviewers is often an amp isn't rated for lower impedances not because it can't do it, at all, but mostly because they don't want to invest in the expensive additional cooling fan which would be necessary to easily pass UL/CSA long term temperature testing.

 

[m. zillch]

I once attended a technical training seminar on Yamaha amps/receivers [what I now use actually] and the guest lecturer was describing all the internal parts they use to us, one by one and in great detail. At the end of the talk he asked the crowd: "OK, now that you understand what everything does and why it is important, who here can guess which part is the most costly for us to produce/procure?". There were all sorts of guesses by us attendees:

"It's those massive, heavy transformers.". . .
"Nope". . . .
"How about those beefy storage capacitors?". . .
"Nope". . .

When we gave up guessing he told us: "Not counting the entire outer chassis (box) itself, it's the metal cooling fins used o dissipate heat".
We were all a bit surprised.

 

[dlaloum]

Please name an example of any speaker we discuss sometimes in this forum, currently made, that fits the bill as being a torturous/problematic load for the lesser amps, making them audibly stand out against other, more capable amps (but with the same wattage rating into 8-ohms as the lesser amp). Thanks.

Back in the 80/90s the go-to "dangerous load" speaker people used to like to cite was the Apogee Scintilla but I have no idea what they cite these days, so I thought I'd ask..

Anthony Gallo Reference 3.2 which I have, drops down to 1.63ohm, and has a capacitive tweeter - causes trouble with many amp designs!

This model was discontinued a few years back, but Gallo still make the "bookshelf" version (Strada2) - which has the same midrange and tweeter drivers, and is designed to be matched with the Gallo sub (which uses the same driver as the now discontinued full range reference series).

But you can do a search for speakers with very low EPDR, or low Impedance - EPDR is more meaningful but also less frequently used.

The Kef LS50 Meta (passive), Reference 1, and LSX II, Magico S5, GoldenEar Brx, are all reputed to have difficult EPDR...

People do tend to focus on the woofer crossover (which in many designs drops down to circa 3ohm or a bit less) - but the difficulty is sometimes in the tweeter design and crossover, where massive power & current is less of an issue, but stability into a reactive load can be MORE of an issue (and more audible!)

 

[PENG]

Ir's that glorious english audio bullshit @TLSGuy

That's actually one thing (among only a few Lol..) I agreed with TLSGuy, designs that resulted in such impedance behavior is not a "good" design, though in the case of the B&W diamonds, it might be fair to say that could be considered acceptable but imo as long as the manufacturer stated clearly in their specifications how/what their "recommended amplifier power (or variations of such..)" mean and how that would affect performance. I only say this because I assume their design likely put much more emphasis on sound quality related issues than amplifier requirements related to costs of such amplifiers.