5.6 How do I set the gains on my amp? [JSC]
The best way to do this is with a test tone and an oscilloscope (See section 5.18 How can I use an oscilloscope to set the gains in my system? [AO].) Since most people have neither item, the following will work approximately as well.
- Disconnect all signal inputs to the amp
- Turn all sensitivity adjustments as low as possible
- Turn head unit on to around 90% volume (not 100% or else you'll have head unit distortion in there - unless you've got a good head unit) with some music with which you're familiar, and with EQ controls set to normal listening positions
- Plug in one channel's input to the amp
- Slowly turn that channel's gain up until you just start to notice distortion on the output
- Turn it down just a wee little bit
- Disconnect current input
- Repeat steps 4-7 with each input on your amp
- Turn off head unit
- Plug in all amp inputs, and you're done
If by some chance you do have an oscilloscope (and preferably a test disc), you do essentially the same thing as above, except that you stop turning the gains up when you see clipping on the outputs of the amplifier.
Note that if you are paralleling multiple speakers on a single amp output, you need to set the gains with all of the speakers in place, since they will be affecting the power and distortion characteristics of the channel as a whole.