Remember that class most of us slept through (or played Doom on the laptop) in engineering school? Given enough open loop gain ANY feedback stabilized system will take on the transfer characteristics of the feedback network. Granted most SS amps have far more OLG than the typical tube amp, but enough OLG and they all sound the same.
I did not mean FB, I meant "no sound whatsoever". Lifeless, artificial sound of some non-linear amps linearized by NFB, or low-bandwidth amps in which frequency response was improved by NFB, does not mean absence of coloration. It means specific colorations that sound nasty, but can't be measured by irrelevant to sound quality measurements like THD.
Lower THD does not mean less of sound distortions. Higher THD does not mean higher sound distortions. If some patients in a clinic had been killed the average temperature may be normal, but it does not mean that all patients are healthy.
Yes tubelab,
Av = G / (1 + G/H)
the loop gain equation.
When G >> H,
Av = G / (G/H) = H
This is true regardless of distortion or frequency response. Distortion means a change in G with respect to amplitude, while frequency response changes the gain and phase. As long as G is much bigger than H under all those conditions, the approximation remains true.
Wavebourn: you seem to think immesurable quantities are discernable. Testing has shown that fractional THD figures, and whatever other measurements are in vogue (frequency response, phase shift, IMD, TIM, whatever), are inaudible below a threshold. To ascribe a series of vague adjectives to a given set of parameters when those parameters are certainly indistinguishable is, at the very least, psychosomatic.
What I'm surprised at is how little acceptance there is of psychosomatics in audio. It's clear to an outside observer that this is the reason; why not accept it? Go ahead and make an amp with low distortion, just don't call it anything it's not. Or build an amp with gobs of distortion, and just groove to it. Who can tell you you're wrong for enjoying distortion? Just don't fool yourself by thinking it's something else, most of all something immesurable.
Tim
Av = G / (1 + G/H)
the loop gain equation.
When G >> H,
Av = G / (G/H) = H
This is true regardless of distortion or frequency response. Distortion means a change in G with respect to amplitude, while frequency response changes the gain and phase. As long as G is much bigger than H under all those conditions, the approximation remains true.
Wavebourn: you seem to think immesurable quantities are discernable. Testing has shown that fractional THD figures, and whatever other measurements are in vogue (frequency response, phase shift, IMD, TIM, whatever), are inaudible below a threshold. To ascribe a series of vague adjectives to a given set of parameters when those parameters are certainly indistinguishable is, at the very least, psychosomatic.
What I'm surprised at is how little acceptance there is of psychosomatics in audio. It's clear to an outside observer that this is the reason; why not accept it? Go ahead and make an amp with low distortion, just don't call it anything it's not. Or build an amp with gobs of distortion, and just groove to it. Who can tell you you're wrong for enjoying distortion? Just don't fool yourself by thinking it's something else, most of all something immesurable.
Tim
What are you talking about?
When people sit comfortably and judge which system sounds better, it is not the real test. Threshold of conscious recognition may be tested such a way, but not a threshold of perception. When you tell that "Systems sound" that exactly means that systems Sounds, that means errors are above the threshold of recognition of artificial reproduction.
My tests demonstrate that when I design and build systems according to my understanding listeners tend to hear as if they hear something outside of the system, like piano playing in the house, frogs singing on backyard, and so on. My best indicator is subconscious reactions, like people scared by a roaring beast recorded on the track, people looking into the window on the sky when I play record of a helicopter, or when I myself jumped turning around when suddenly heard falling water sound (on CD!).
This is the real test. Can equipment hide itself fooling an imagination, or not. If it can't, it is out of field of our review.
Cause chip amps don't glow......at least not for long!
Whatever the "real test" is does not matter to a manufacturer. The only "real test" is the marketplace, which is driven my the masses, and how well the masses are controlled by the media and marketing departments.
I vividly remember auditioning a tube amp to several "30 somethings" at a friends house. There were several engineers in the crowd. All the people that were present had been exposed to iPOD's and big box HT systems for most of their listening lives. Most were unimpressed by the tube amp and many said that it sounded bad because it didn't shake the whole house. The oddest thing happened when an action movie was played. When things on the TV screen started blowing up both cats in the room ran and hid. They got the realism but none of the humans did. The homeowner remarked that he had played that movie scene dozens of times and the cats never got scared before.
Nobody present at that demo was the slightest bit impressed by a tube amp. Many wonder why a well respected engineer would make such things. However the cats understood. Since the cats don't make purchasing decisions, the tube amp failed in that market. That seems to be the case with the gigawatt HT crowd. To me their HT system sound bad. Lots of boom, but absolutely lifeless with any music. Obviously some listener expectations are involved here. Much of that crowd has no clue even what to listen for. Or maybe they have never even heard live music.
So, what type of test equipment do I need, and to what specs do I measure to impress cats?
"It reproduces frequencies that only dogs can hear" Maybe it sells Acuras, but it doesn't sell tube amps! The amp was a 300B based Tubelab SE. The frequency response doesn't go much past 25KHz.
Hold on, George! Let's believe together that a holiday will come on our street some day!
I've had some sadly similar experiences in the past, and now just play with/to people who "get it." At my most recent party with 25 people present only 3 were interested in hearing my stereo system, one was an engineer/audiophile like myself, and the other two were just naturally curious..
There does seem to be increasing interest in tube amps, and vinyl in my neck of the woods. And I no longer get as many odd looks when I mention vinyl, as often as not I hear something to effect that vinyl sounds really good, often better than CD, and this from a kid wearing a pair of iPod headphones...
So that was one of your amps? Cool.. Maybe you can market it as "The amp Acura thought cool enough to impune on national TV."
In a sense it might actually serve to raise awareness that new tube amps are actually out there. I still find a lot of people don't realize that hifi tube amps are being made in significant quantities now.As a former Acura owner (bought a new Legacy 2.5GT Limited this year) I was a little disappointed that a manufacturer of somewhat overpriced cars for the more privileged would disparage something that plays to a similarly exclusive market that probably even constitutes a significant number of their customers... (I know several tubies who still own Acuras..)
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No, the amp in the commercial is a Jolida which by many accounts is not high end.
I just make fun of the commercial every chance I get. The fact that someone mentions dog hearing may be a coincidence. There is another commercial that is played far less often where the same guy mumbles a bunch of disconnected words expressing his cluelessness.
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