Hello
I've just read a very good article about amp musicality vs measurement and about low or no nfb amps. Here's the link:
A Future Without Feedback? | Stereophile.com
After reading it, tell me your thoughts about it.
Bye
Gaetan
I've just read a very good article about amp musicality vs measurement and about low or no nfb amps. Here's the link:
A Future Without Feedback? | Stereophile.com
After reading it, tell me your thoughts about it.
Bye
Gaetan
Meh. People prefer listening to "warm" sound with lots of 2nd harmonic distortion - no new news there. They also like bass boost - my NAD 3020 has some moderate bass boost with the controls at zero, and I attribute that to this amplifier's popularity.
But so what. I can add 2nd harmonic distortion to a clean amplifier. Bit harder to remove it from an amplifier that generates it by default.
Amplifiers shouldn't colour the sound - use other components to do that.
But so what. I can add 2nd harmonic distortion to a clean amplifier. Bit harder to remove it from an amplifier that generates it by default.
Amplifiers shouldn't colour the sound - use other components to do that.
The article merely trots out the usual 'true believer' stuff. He doesn't like feedback, yet is happy with degeneration (which is feedback) and triodes (which get their linearity from feedback).
He describes an amplifier as having "obvious competence" despite a highish output impedance and wobbly frequency response; two things which clearly show incompetence. At that point I stopped reading.
He describes an amplifier as having "obvious competence" despite a highish output impedance and wobbly frequency response; two things which clearly show incompetence. At that point I stopped reading.
Reference to a1975 blind test. This has no value. Who knows how it was achieved. Only a double blind test can prove something. This is what's done on medical drugs a test field where placebo effect is well known. Any other sort of test in audio is bogus. The OP is just another futile attack against negative feedback.
I don’t think the topic is about amps “coloring” the sound, it was about audible difference if any between zero global feedback vs little or no global feedback. Local feedback is always there and probably unavoidable.
Suppose you have two amps both with, say 10ppm THD (I know, I know, 10ppm is so pedestrian with zero distortionistas
), and one uses no global feedback, whilst other uses lots of it to achieve same 10ppm THD - what is the effect on our perception to the music produced, all else being equal?
Suppose you have two amps both with, say 10ppm THD (I know, I know, 10ppm is so pedestrian with zero distortionistas
), and one uses no global feedback, whilst other uses lots of it to achieve same 10ppm THD - what is the effect on our perception to the music produced, all else being equal?
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Do you mean all the other forms of distortion being equal?Suppose you have two amps both with, say 10ppm THD (I know, I know, 10ppm is so pedestrian with zero distortionistas
Well known 20 years old article . Interesting that the thread starter wants for us to discuss it now (again). Not only we have (IMO) much better articles on topic, but also there are much better circuit solutions known now that those 20 years ago, which were mostly "distortion creating effect boxes". Some like it distorted, I agree.
. Interesting that the thread starter wants for us to discuss it now (again). Not only we have (IMO) much better articles on topic, but also there are much better circuit solutions known now that those 20 years ago, which were mostly "distortion creating effect boxes". Some like it distorted, I agree.
IMO the biggest improvement in sound (speaking about good recordings) now, compared to situation 20 years ago, is because of huge improvement of digital sources. Now we can make a choice of very decent D/A converters and they, with a good 96/24 source program, are able to give us fantastic sound quality. There is no need for added colorization anymore and the most accurate components give the best sound, in case they are also well engineered regarding EMI immunity.
It would be necessary to dissect the amplifier circuits Mr Collom set up and get the data to know what lies behind his aural listening results. Many amplifiers of that era may have had distortion levels around 0.1%- just detectable. However, IMD is more important than THD IMHO as that seems to me to lead to signals that might be called unclear - generating distortion signals that were not originally present. With 0.1% or so THD, IMD could be higher.
With today's fast transistors and wide bandwidth amplifiers with THD around 0.001% IMD has almost vanished too. I doubt that the comparison would work with todays best circuits.
With today's fast transistors and wide bandwidth amplifiers with THD around 0.001% IMD has almost vanished too. I doubt that the comparison would work with todays best circuits.
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Feedback changes many things, there are so many variables that to correlate sound with feedback only gives us limited guidance. It's been pointed out that feedback affects the output impedance - but you can design a feedback network to give you a wide range of output impedances so no general conclusions would be safe.
Like all aspects of amplifier design, any tool used poorly gives poor results. Some feedback is inherent (e.g. Triodes, as mentioned already) and some is created (traditional loop feedback) - it's how you apply it that matters.
I think there have been significant changes affecting quality of sound reproduction from many different things: quality of components (capacitors are now superb c.f. 50 years ago), speakers (not only better drivers but better boxes), semiconductors (higher gm and lower parasitics), music storage.
If only the quality of recording was more consistent, but as always, it's an industry driven by $.
Like all aspects of amplifier design, any tool used poorly gives poor results. Some feedback is inherent (e.g. Triodes, as mentioned already) and some is created (traditional loop feedback) - it's how you apply it that matters.
I think there have been significant changes affecting quality of sound reproduction from many different things: quality of components (capacitors are now superb c.f. 50 years ago), speakers (not only better drivers but better boxes), semiconductors (higher gm and lower parasitics), music storage.
If only the quality of recording was more consistent, but as always, it's an industry driven by $.
Really don't get the point of this old thread coming up again. We have advanced quite a bit on our knowledge of feedback and can make amps with vanishing low levels now.
I know I have heard "very good" sounding amps that didn't use much if any feedback and those that used as much as possible. Do not see any reason at all do demonize either one. Build or buy what you like.
I know I have heard "very good" sounding amps that didn't use much if any feedback and those that used as much as possible. Do not see any reason at all do demonize either one. Build or buy what you like.
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