Understanding Gain adjustments...

[pokefan]

Ok, I come from car audio so help me get all of this right. I've been extremely confused around here listening to others help people setting up their subs correctly.

Gain control...

Most people here interchange gain for level. In a car amp this is incorrect. The gain is to match the proper output voltage of the source (your receiver) to the input voltage of the output stage (the sub). If it's set to high you get clipping (distortion) but set to low and you'll never get full power from your amp.

So is this incorrect in Home audio? I assume it's not since all amps are basically the same. I just want to shed some light on the subject.

To properly set you amp gain it's best to use a voltage meter and a calibration CD. The easy way to do this though is to play a bass heavy track at around 75% of the volume with the gain turned all the way down. Slowly raise the Gain until you start to hear distortion and quickly back it down to just below this point. This is actually quite accurate but obviously not 100%. Your new max volume though would be this 75% mark, but if done at reference levels I'd assume none of you would ever play anything near this level any way.

Gain/Phase:
I seem to see this interchanged ofter here too. These are completely different. The phase is the signal coming into your speakers. Really nothing more then switching the red and black wires on a speaker just done with a switch instead. Some phase adjustments are more detailed then this but 180° phase adjustment would be the same as switching the red/black.

I mainly wanted to bring this up because all to often here I see someone post "if you want a little more bass just turn up the gain". If this is indeed the same as a car amp you are essentially shortening the life of your sub/speakers if you do this.