Amplifier Gain Control Setting Guide

[cichlid_baby 10+ year member]

Well.. I found this..

http://www.fullsizechevy.com/forums/general-discussion/audio-video-electronics/165526-amplifier-gain-setting-tutorial.html

Yeah or Nah... any experienced guys here can help out?

Click to read more...

 

[dB-r 10+ year member]

It's one of those things that only works in a perfect world. Impedance rise is real, and can be ALOT and if you don't set your gains using a scope you really don't know if it's clipping or not, and if you don't use a AC ampere clamp and voltmeter you really don't know what your impedance is like once the speaker starts moving and no way to judge power output by voltage alone, you need the amperes measurement also to make it all be accurate.

DMM set to AC volts

DMM w/ AC Ampere clamp installed and set properly to AC Amperes

Oscilloscope showing the output waveform on the screen

Those are the things you need to be accurate at all, and way I see it is why even bother with the method mentioned in that post because it's not accurate at all.

 

[tinmanchris217 10+ year member]

This method does have it's flaws, but it definitely has 4 conditions:

1) Setting power at less than the amp's maximum clean power output

2) Amp does rated (or true power is known)

3) Amp generally has a relatively linear power:impedance relationship

4) Electrical system doesn't have a major voltage drop

For me, this method works well, if you don't have an o-scope, and need a rough estimate. I always set a little lower than rated, and bump the gain up slowly, listening for the onset of distortion by ear. Then I back it off until I'm confident that the user can't blow the system without REALLY trying.

 

[dB-r 10+ year member]

Correct. The method is "close enough", but you know how us technical types are... I happen to have portable lcd o-scope, and some nice fluke meters, one with a clamp, so I know exactly what's going on. I hate guessing...

 

[cichlid_baby 10+ year member]

I just used the "by ear" method... sound's okay to me right now I suppose.