Electronics > Beginners
What audio amp gain setting does?
fonograph:
There is attenuator at the output of amplifier,the "pot" like Alps RK27.It makes no sense to me to attenuate the input before amplifing it back,thats like intentionaly stabbing yourself in the leg with dirty knife and then spending two hours meticulously desinfecting and stitching yourself.
boB:
Audio power amplifiers don't normally have their "gain" adjusted.... They sit at a preset gain, usually somewhere in the 20dB to 30dB area and the input signal level is adjusted by a volume control which is just a voltage divider. The output is what it is and like EEVblog's KRK video would like to show, the output noise is hopefully low enough not to hear unless you stick your ear right up to the speaker. The best way to change the gain using feedback would be with a switch rather than a pot so that when the pot gets dirty or has DC passing through it, there is no crackling or "opening" of the feedback loop which could be very bad. Reducing the gain in this way could also reduce the residual amplifier output noise if wanted too.
The only places I have seen an output attenuator or "pad" is where their are multiple small speakers and you want to individually vary the zone volume.
Changing supply rail voltage won't do much except to make the audio clip earlier. Not to be confused with the amplifier topology that switches in different output transistors dynamically to reduce heat. Is that Class H ?
boB
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