Traditionally the accepted notion is that adding negative feedback will decrease voltage gain in an amplifier and also decrease the output impedance.
However it is interesting to note that the addition of negative feedback will not alter how much power the amplifier is capable of into a given load. When you think about it, the reason is obvious. The power generated by the amplifier for a given load comes from the output devices and power supply in the amp, and not from how much signal is returned to its input.
Negative feedback will change how the amplifier reacts to the load, having the effect in some cases of reducing the amplifier's power into certain impedances, and increasing it into other impedances, so long as this power increase is within the limits of the amplifier in the first place.
Unfortunately, negative feedback also increases odd-ordered harmonics in the range of the 9th, 11th and beyond- a place where the human ear is very sensitive. The result is that amplifiers with negative feedback will exhibit an unnatural sheen and/or harshness in the high frequencies.
In the world of high end audio, this effect is audible enough that many companies have eschewed negative feedback for other means to the same end. We live in an interesting time.
However it is interesting to note that the addition of negative feedback will not alter how much power the amplifier is capable of into a given load. When you think about it, the reason is obvious. The power generated by the amplifier for a given load comes from the output devices and power supply in the amp, and not from how much signal is returned to its input.
Negative feedback will change how the amplifier reacts to the load, having the effect in some cases of reducing the amplifier's power into certain impedances, and increasing it into other impedances, so long as this power increase is within the limits of the amplifier in the first place.
Unfortunately, negative feedback also increases odd-ordered harmonics in the range of the 9th, 11th and beyond- a place where the human ear is very sensitive. The result is that amplifiers with negative feedback will exhibit an unnatural sheen and/or harshness in the high frequencies.
In the world of high end audio, this effect is audible enough that many companies have eschewed negative feedback for other means to the same end. We live in an interesting time.