Negative feedback, voltage and output impedance

No rule without exception. "The result is that amplifiers with negative feedback will exhibit an unnatural sheen and/or harshness in the high frequencies", Atmasphere says. But McIntosh, to give but one example, uses a large amount of negative feedback in its amps, and still they sound natural and sweet in the highs.

The difference between Atmasphere and McIntosh is that Atmasphere wants to make its product more marketable spreading a gossip that less feedback is always better.

Zero negative feedback on my amp also sounded the best, hands down. Increasing the feedback seemed to constrict the sound, decrease it's palpable quality.

All,

Thanks for the replies.

If I understand this correctly, if I want to buy a high power (voltage for ESLs) tube amp with low output impedance and low or no negative feedback, then I need to look at OTLs, correct?

Thanks.

Mike

The term "negative" is unfortunate. It really should be called "corrective" feedback. It corrects various forms of distortion and frequency response deficiencies, but if used to excess can introduce its own problems.

The amount of feedback is always user adjustable, if the user has a soldering iron. I went through a stage of feedback tweeking, but eventually decided that the designer always got it about right. Why would he do otherwise?

Among tubophiles there is a tendancy to conveniently forget the significant feedback provided by the ultralinear windings of the output transformer which are applied directly to output tube auxillary grids.