Needing an explanation of amplifier feedback

Adampeter, while all that Al mentions is true, negative feedback has a negative consequence- it increases odd-ordered harmonics in the range that the human ear uses as loudness cues. This is actually more important than frequency response- if you think about it, imagine you and a tiger in the forest- you would be far more interested in how loud the growl of the tiger is rather than getting all the bandwidth of that growl :)

So the enhancement of the loudness cues leads to brightness. Some loudspeaker designers recognize this and design their speakers for amps that have little or no feedback. Usually the amount of feedback is listed in the specs of the amp.

For more information see:

http://www.atma-sphere.com/papers/paradigm_paper2.html

Thank-you Almarg!

I wouldn't take that statement too seriously. Amplifiers that use feedback excessively tend to be cheap lo-fi products and some mid-fi products. A quality amplifier, especially one whose sound quality has generally received favorable commentary, will not be one that uses excessive feedback.

Feedback improves gain linearity, reduces output impedance if used in the output stage, and reduces measured total harmonic distortion. These will be good anyway in a quality design, without a lot of feedback. If used excessively, such as to make a low quality design measure well in terms of these parameters, that improvement comes at the expense of transient response, transient intermodulation distortion, and overall sound quality.

That said, if the manual or product literature on the amplifier does not talk about the amount of feedback that is used (and they usually don't), you would probably have to ask the manufacturer.

Regards,
-- Al