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take exception of the simplistic FB statement made by chip.

OK How about

"The use of global negative feedback does several things: it flattens and extends the frequency response, it reduces distortion generated in the stages encompassed by the feedback loop, and it reduces the effective output impedance of the amplifier, which increases the damping factor. All of these things affect the tone in some manner.
The flattened, extended frequency response obviously changes the tonal character by removing "humps" in the output stage response and producing more high and low end frequencies.

The distortion reduction makes the amp sound cleaner and more "hi-fi", up to the point of clipping, with less output-stage generated noise.

Perhaps the main difference for the "feel" in a negative feedback amplifier, as opposed to a non-negative feedback amplifier, is the increased damping factor produced by the negative feedback loop. The decreased effective output impedance causes the amp to react less to the speakers. A speaker impedance curve is far from flat; it rises very high at the resonant frequency, then falls to the nominal impedance around 1kHz, and again rises as the frequency increases. This changing "reactive" load causes the amp output level to change with frequency and changes in speaker impedance (a dynamic thing that changes as the speakers are driven harder). Global negative feedback generally reduces this greatly. This can be good or bad, depending upon what you are looking for. Negative feedback makes the amp sound "tighter", particularly in the low end, where the speaker resonant hump has the most effect on amplifier output."

http://www.aikenamps.com/index.php/what-is-negative-feedback


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  • take exception of the simplistic FB statement made by chip. - Chip647 16:58:20 01/15/17 (0)

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