I am making amplifiers. And I am trying to make it so, that it changes signal (yes, music is also only signal, and nothing special..) so little as i can do, in all respect (linearity, time domain..),and for reasonable price, so i prefer simple solutions(if possible) and do not like "unobtainium". For sure this "sound" will not be "good enough" for all, but for significant "minority" as You call it, yes. I am not trying to "improve" this signal according someones personal taste, and for sure not acording all peoples, it is impossible. I want let it as is.
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Hmm. I need to read that article more in detail, but how can an amplifier turn a square wave into sines while having a flat amplitude response up to 70kHz??
jan didden
Well, I'm pretty sure I heard the difference in those tracks despite not being a golden ear and using a 5 way speaker system. When Prof. Hawksford provides the key, I'll at least know if it's something I need to worry about. I hope that he's amused by some of the weird paranoia that has been exhibited about a simple listening test...
The key word being 'differences'. The question is not: 'which track has zero phase shift' or 'which track has +180 degrees at some frequency'. The question is simply: 'which ones sound different from some others', something experienced listeners are supposed to excel at. And it is assumed that the experienced listeners use the same (or better) speakers and/or headphones as we all do.
Coming back to the numbers; if there are 10 discrete different groupings possible, does that mean that the chances of getting it right by guessing are just 10%. And that when you get it right, you have a 90% confidence that you did that based on actually hearing a difference?
Some have asked about my own score: I came as far as identifying two files that I thought were clearly different from one other file. At that point, after trying for several evenings, I received other people's scores so that shot my objectivity.
About the paranoia: Malcolm mentioned that "everyone can be disappointed that i did not attempt to trick them".
jan didden
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Hi,
Well, if the amplifier does not change the signal, then by definition it is "transparent".
If it does change the signal (which all known amplifiers do) and if you do not have access to extraordinary components (e.g. you need to use normal semiconductors or tubes etc.) you will have to make design choices that trade off performance in one area for a loss in another.
For example, I can make an amplifier that is unconditionally stable, has 120dB NFB at DC and very low measured THD at 1KHz. By having done this however there is a good chance that I have worsened some other performance parameters and elevated some forms of distortion normally well below the noisefloor to prominence, plus these distortions may resist measurements using traditional steady state signals.
The end result is that I may have an amplifier I can point to my instrumentation as "changing the as little as possible" while it actually does provide quite reliably "bad sound". Where does that leave me?
How would you suggest we weigh the different dimensions of quality, what do we emphasis, what do we de-emphasise?
Ciao T
Well, if the amplifier does not change the signal, then by definition it is "transparent".
If it does change the signal (which all known amplifiers do) and if you do not have access to extraordinary components (e.g. you need to use normal semiconductors or tubes etc.) you will have to make design choices that trade off performance in one area for a loss in another.
For example, I can make an amplifier that is unconditionally stable, has 120dB NFB at DC and very low measured THD at 1KHz. By having done this however there is a good chance that I have worsened some other performance parameters and elevated some forms of distortion normally well below the noisefloor to prominence, plus these distortions may resist measurements using traditional steady state signals.
The end result is that I may have an amplifier I can point to my instrumentation as "changing the as little as possible" while it actually does provide quite reliably "bad sound". Where does that leave me?
How would you suggest we weigh the different dimensions of quality, what do we emphasis, what do we de-emphasise?
Ciao T
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Yet there are those here, that will state out of hand that such an amplifier can't sound good.
Hi,
And those, who like myself will state that from the given specifications it is not possible to conclude anything about the subjective sound quality of the Amplifier.
Ciao T
And those, who like myself will state that from the given specifications it is not possible to conclude anything about the subjective sound quality of the Amplifier.
Ciao T
Peter Walker must have been terribly wrong then in the way he designed amplifiers.
I think a good set of measurements, HD (split in its components), FR and phase response, slew rate, damping factor, and noise floor - together with a brief session behind the scope feeding a number of square waves at different voltages and frequencies under a realistic load, looking at both channels, provides a dead clue as to the sonic qualities of an amp.
vac
I think a good set of measurements, HD (split in its components), FR and phase response, slew rate, damping factor, and noise floor - together with a brief session behind the scope feeding a number of square waves at different voltages and frequencies under a realistic load, looking at both channels, provides a dead clue as to the sonic qualities of an amp.
vac
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Hi,
Why? Did he design his amplifiers like this:
"120dB NFB at DC and very low measured THD at 1KHz."
It has already been demonstrated that there are other factors beyond those. So some work with asymmetric semi-random signals may be needed, multitone or noiseloading can help.
Ciao T
Why? Did he design his amplifiers like this:
"120dB NFB at DC and very low measured THD at 1KHz."
It has already been demonstrated that there are other factors beyond those. So some work with asymmetric semi-random signals may be needed, multitone or noiseloading can help.
Ciao T
No, but Peter Walker mentioned on several occasions that in development work, he only relied on measurements, and measurements only.
I doubt if he ever set a specific goal for NFB at DC, since I don't think any of the great amps he designed did DC. But he used feed back when he needed it. The QuadII has both local and a small amount of global NFB. Not as a goal in itself, but in order to get distortion down to < .1%. Spectacular for its time. The result of all this focus on measurement and the use of NFB when called for, was an amplifier that, almost 60 years after it first hit the market, still is capable of delivering high end sound (given the right set of speakers).
vac
I doubt if he ever set a specific goal for NFB at DC, since I don't think any of the great amps he designed did DC. But he used feed back when he needed it. The QuadII has both local and a small amount of global NFB. Not as a goal in itself, but in order to get distortion down to < .1%. Spectacular for its time. The result of all this focus on measurement and the use of NFB when called for, was an amplifier that, almost 60 years after it first hit the market, still is capable of delivering high end sound (given the right set of speakers).
vac
If that article is typical, John Campbell doesn't have a theory, just some woffle. He confuses bandwidth with information rate, and does not appear to understand Fourier. He never actually tells us what was wrong with the amplifier he built, and how he fixed it. Instead he makes some inaccurate statements about phase shift oscillators and their relationship with amplifiers.lvigone said:
That was more of a rhetorical comment. I don't see or hear the connection between feedback and detriment to sonics that certain crowds profess to.
Really? I saw till yet only claims and feelings, no facts that can be independent verified. Please show one measurement, objective fact that supports your words.
It will show nothing new, only bring difficulty with interpreting those measurements. Here are no magical, unmeasurable, but audible distortions. Set of conservative THD vs.freq at various levels and IMD (evtl. substraction test with realistic music signal) and few scope screens show ability of amp to transfer amplified momentary voltage unchanged to output, with resolution well beyond possibilities of our ears...This is main and only reason to refuse DBT.. But I admit, it do not support selling
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