Audio Research 100.2 Power Amplifier Review

[Sal1950]

For many of these people, the "supporting evidence" IS the subjective claim.
I know that might seem circular to you, but that's the way many of the subjectivist folks think about this.

This is ASR, subjective claims don't fly here as "supporting evidence".
When we say "be willing to learn" , that means come to the understanding that many outside factors will affect your ability to make accurate determinations. Things such as expectation bias will distort your perceptions and cause you to hear things other than what is the reality of the situation. Now if the listener is willing to take in the proven evidence of expectation bias and such, then you can move forward in the conversation. Otherwise he will be forever locked in the circular believe of magic dust and that "he can hear things that we can't measure" and its best that person just move on to the subjective sites where he will be happy.

 

[Deleted member 2944]

This is ASR, subjective claims don't fly here as "supporting evidence".
When we say "be willing to learn" , that means come to the understanding that many outside factors will affect your ability to make accurate determinations. Things such as expectation bias will distort your perceptions and cause you to hear things other than what is the reality of the situation. Now if the listener is willing to take in the proven evidence of expectation bias and such, then you can move forward in the conversation. Otherwise he will be forever locked in the circular believe of magic dust and that "he can hear things that we can't measure" and its best that person just move on to the subjective sites where he will be happy.

You're preaching to the choir. I understand the premise, the way it rolls here, and I don't need a lecture regarding it. I was just pointing out that some audiophiles don't believe in that concept. As you say, they should simply move on.

Regarding my contention that subjective evaluation is beyond discussion.......nobody has convinced me otherwise. 'Just some pathetic attempts to group me in with "Isotonic" and browbeat me with the local mantra.

Dave.

 

[SIY]

If you can’t accept the necessity of basic controls in an evaluation, then the issue is with your understanding of science. “Controls” is a sine qua non, and if you characterize it as a mantra, then trying to “convince” you is pointless.

 

[Deleted member 2944]

You already admitted that (at least some) subjective evaluations are not fact claims.
And you've mischaracterized my position by (apparently) claiming that I don't believe in controls for subjective evaluations. And I did not equate "controls" with mantra.

To use your own words....read carefully. I never said anything different.

Straw man arguments are pathetic.

Dave.

 

[SIY]

You already admitted that (at least some) subjective evaluations are not fact claims.
And you've mischaracterized my position by (apparently) claiming that I don't believe in controls for subjective evaluations. And I did not equate "controls" with mantra.

To use your own words....read carefully. I never said anything different.

Straw man arguments are pathetic.

Dave.

Jello. Nail. Wall.

 

[Deleted member 2944]

Jello. Nail. Wall.

Your moniker labels you "technical expert" and I've read a number of your articles. They're excellent. You should stick to that.

Dave.

 

[rmsanger]

This may be pissing in the face of many on this board but... With tubes what is the appropriate way of measuring performance? I thought in a subjective manner that people who want and enjoy tubes want the warmth and holographic nature of distortion that it adds to the sound quality. That by it's nature to minimize THD would be neutering the exact nature that people seek from tube amps? Don't they add 2nd & 3rd order harmonic distortion which many find pleasing?

 

[SIY]

This may be pissing in the face of many on this board but... With tubes what is the appropriate way of measuring performance? I thought in a subjective manner that people who want and enjoy tubes want the warmth and holographic nature of distortion that it adds to the sound quality. That by it's nature to minimize THD would be neutering the exact nature that people seek from tube amps? Don't they add 2nd & 3rd order harmonic distortion which many find pleasing?

There is much imagination in the “warmth and holographic” assertions. After all, Gordon Holt used to describe tube sound as bright and forward.

 

[sergeauckland]

This may be pissing in the face of many on this board but... With tubes what is the appropriate way of measuring performance? I thought in a subjective manner that people who want and enjoy tubes want the warmth and holographic nature of distortion that it adds to the sound quality. That by it's nature to minimize THD would be neutering the exact nature that people seek from tube amps? Don't they add 2nd & 3rd order harmonic distortion which many find pleasing?

Technically, there's no difference in measuring a tube amplifier or a SS amplifier. They all have the same four basic parameters, output power, distortion, frequency response and noise. Once the numbers get down to a certain level, the amplifier is audibly transparent, and it doesn't matter if it's tubes or transistors, a transparent amplifier will sound identical to any other transparent amplifier when evaluated blind and within its capabilities.

Having said that, it's much much easier and cheaper to achieve transparency with solid state, as tubes depend largely on the quality of the output transformer, and very good transformers are both large and expensive.

Commercially, there's no point in having a transparent tube amplifier, with the possibly important exception of looks, as it will sound the same as a far cheaper SS amplifier without the cost, weight, size and heat. Consequently, tube amplifiers are very commonly not transparent, and it's that which then can't correlate directly with measurements as the numbers won't tell you what you would like. Tube amplifiers of the SET variety are technically horrible things, and yet they have a following amongst those who actually like that sort of sound.

When I had tube amplifiers before SS amps became possible as a quality and reliability alternative, I evaluated them in exactly the same way , the four important parameters, as subsequently used for SS amps. In those days, it was a challenge to reduce distortions etc to try and achieve transparency, something increasingly easy by the late 1960s when silicon transistors became available.

S.

 

[pozz]

This may be pissing in the face of many on this board but... With tubes what is the appropriate way of measuring performance? I thought in a subjective manner that people who want and enjoy tubes want the warmth and holographic nature of distortion that it adds to the sound quality. That by it's nature to minimize THD would be neutering the exact nature that people seek from tube amps? Don't they add 2nd & 3rd order harmonic distortion which many find pleasing?

If you check the numbers for the distortion levels they are usually so low that they will be masked by the signal. Unless driven into clipping, in which case you get a spray of nonlinearity and H2/H3 are no longer dominant.

 

[Sal1950]

When I had tube amplifiers before SS amps became possible as a quality and reliability alternative, I evaluated them in exactly the same way , the four important parameters, as subsequently used for SS amps.

I guess I was a tube heretic. It was mainly the below review by John Atkinson that lead me to buy my VTL Compact Monoblocks back around 1990. David Manley's early designs were to make as good a measuring amp as he found possible and did not even include the Ultralinear-Triode switching that market pressure later forced him to add, etc, cause they didn't sound "tubey" enough. I loved these amps, they remained in my system for 20 years driving Klipsch La Scala's and supplemented by 2 huge HSU subwoofers powered by bridged NAD solid state amps.
I tried to "have it all" and came dang close.

"This is one hell of a transparent amplifier."
"On the test bench, you could have been forgiven at first for thinking that this VTL was a solid-state design, the small-signal frequency response (1V into 4 ohms) extending from 2.2Hz to 77kHz (–3dB). Noise levels, too, were impressively low, measuring –90dB, unweighted, with the input shorted, this improving by just over 6dB when an A-weighting network was switched in circuit ahead of the meter."
John Atkinson
https://www.stereophile.com/tubepoweramps/1188vtl/index.html

 

[sergeauckland]

I guess I was a tube heretic. It was mainly the below review by John Atkinson that lead me to buy my VTL Compact Monoblocks back around 1990. David Manley's early designs were to make as good a measuring amp as he found possible and did not even include the Ultralinear-Triode switching that market pressure later forced him to add, etc, cause they didn't sound "tubey" enough. I loved these amps, they remained in my system for 20 years driving Klipsch La Scala's and supplemented by 2 huge HSU subwoofers powered by bridged NAD solid state amps.
I tried to "have it all" and came dang close.

"This is one hell of a transparent amplifier."
"On the test bench, you could have been forgiven at first for thinking that this VTL was a solid-state design, the small-signal frequency response (1V into 4 ohms) extending from 2.2Hz to 77kHz (–3dB). Noise levels, too, were impressively low, measuring –90dB, unweighted, with the input shorted, this improving by just over 6dB when an A-weighting network was switched in circuit ahead of the meter."
John Atkinson
https://www.stereophile.com/tubepoweramps/1188vtl/index.html

Tubed power amps have never had particular problems with noise, -90dB S/N ratio was achievable in the 1950s. Similarly, a 20Hz-20kHz +-1dB frequency response at 1W output. Where tube amplifiers pretty much all had problems were in distortion. A very few managed <0.1% at mid frequencies, very very few could do that at 20Hz, or indeed at 20kHz. I don't know any that could do it at full power, as at low frequencies the output transformer would distort heavily, and at high frequencies, feedback would drop off due to poor open-loop gain at high frequencies.

VTL amps were one of the better amps, as was the old RCA Orthophonic amps. Probably the best of the bunch, certainly this side of the pond, were the Radford amps as Arthur Radford was a wizard at transformers, and his circuits also used an unusual arrangement of tubes to achieve a very wide bandwidth open-loop.

Tubed amplifiers undoubtedly can give satisfying results, and even half-decent measurements, but at a cost.

S.

 

[Sal1950]

Tubed amplifiers undoubtedly can give satisfying results, and even half-decent measurements, but at a cost.
S.

Yes, the cost to produce excellent transformers is the biggest obstacle to outstanding measurements and performance.
But today's tube market doesn't much care, they aren't interested in the numbers, they want that "tube sound", warm and lush.
Whatever, I grew up on tubes and miss the open glow, dancing gas colors, winking magic eyes, more.
I don't miss the heat generated, loss of transparency (distortions), somewhat narrowed bandwidth, marginal reliability, and all the rest.
Amps like the Benchmark AHB2 provide incredible performance only dreamed about in 1960. But such a boring little box they are.
I present for your appraisal, the VTL ICHIBAN'S Now here's some sweet pieces to stack in your audio shrine!

 

[rmsanger]