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Re: Hummmmmmmmmmmmm.

You are the one who is trying to patch a non-linear circuit with a crutch that above about 1Khz simply stops working. If YOU understood linearity you would also realize that the transfer function of a triode tube is closer to linear than either a bipolar or mosfet transistor.

However; it is clear that 1)global feedback simply doesn't work well up to 20Khz. This can be seen readily in damping factor vs. frequency and THD vs. Frequency plots. Most high feedback amps show a decreasing damping factor above 1KHz and an increasing THD starting about the same frequency. 2) It appears to increase the ratio of high order harmonics (this can be shown mathematically and in practice) and signal correlated "noise" floor. Granted it is not the only culprit in this as noise and power supply hum can add IM products and muck up the sound as well as underbiasing the transistors/tubes. 3) Feedback can make the compatibility with speakers worse due to back EMF from the speaker being reinjected into the amp and reamplified. This was shown by Otalla et al in the late 70s early 80s.

So from my listening experience and based on technical analyses I have seen and measurements I conclude that in general feedback does more harm to sonics than the good it does "linearizing" the circuit. This argument of "its more linear so it must be better" is so shallow and so easy to expose when one looks behind the THD curtain. Give it a rest, we are not oscilloscopes who don't give a shit about harmonics. We are more sensitive in a lot of ways than the oscilloscope and especially to the harmonic content of distortion.

You and I both know that it is not the absolute amount of THD that is important but the harmonic and IM content of the distortion under DYNAMIC conditions. So, absolute linearity is not necessarily a requirement or the issue because an amp can be less linear in an absolute sense (say 2% THD vs. 0.1% THD) than another and yet have less AUDIBLE distortion (the 2% amp could be all 2nd and 3rd harmonics while the other has harmonics right up to 20Khz for a 1Khz sine wave). Audible linearity is the issue, Dan so stop with this linearity according to the oscilloscope is everything. I know you don't even believe that yourself or you wouldn't bang the drum that your amp makes "only" 2nd order harmonic distortion (yeah sure it does).

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