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Do audio amps have a fixed output? Answered

I was wondering if audio amps put out a fixed amplifying power no matter what the input is. Like if the input was really low would it be quieter or bring the audio up to a certain point? Thx


Yes, they have a fixed amplification. Turning up the volume, changes the amplification.

An amplifier which is LOUDER for quiet sounds and quieter for loud ones, has what we call AGC or automatic gain control.


so its just louder when input is louder? not the same output no matter what input is? I dont think it has AGC, will check though

An amplifier's output does what its input does, only more so. So, yes, everything is louder or softer in proportion to whether the input is louder or softer. (Within the design limits of the amplifier and speakers, of course. Push it too hard, and the signal will "clip" obnoxiously -- which is how you get fuzz guitar effects.)

k. thanks. i was wondering about that. i would not think it would be very good if audio amps were AGC. :) Thanks!

There are times, when the volume isn't important, but signal integrity is, that AGC is very useful. Its sometimes used in PTT radios, and its always used in RADAR systems for examples. For audio, not so much ;-)


In fact, some pro audio amplifiers don't have volume controls at all, and rely on devices earlier in the signal chain to control the volume.

(FWIW, the pro-audio equivalent of AGC is known as "compression". There are appropriate uses for it when mastering, or when doing certain kinds of live sound reinforcement (helping a caller be heard over a dance band), and some radio stations use it when broadcasting pop music on the assumption that there will be other noise (eg from your car) that they need to try to punch through. But it's something that should be used as a special-purpose tool; overuse tends to make the sound boring.)