Just a thought here:

My Eclipse AV-8132 head unit has 8 volt preouts. My Memphis amps, (MC500d and MC2004), have a range up to 5 volts. Would the correct setting of my gains be to the lowest point to match them or all the way counterclockwise? You turn the gains higher to match lower preout voltages, correct? I am doing some system tuning in my Honda Pilot and need to start here. Thanks.

 

Technically you should use a digital voltmeter and a sine-wave test disc to set the gains.

Short of that you should just turn them where they sound good.

Remember that turning them down means that the amp requires MORE input voltage to make rated power... so I would start with them all the way down. Then see what you need to turn up. If you can run any amp with the gains at minimum you're better off from a noise pov.

 

Thanks for the advice. Confirmed what I thought. I have had alot of hiss in the front tweets and it was really to an annoying point. I think the four channel amps gains were a bit high but the sub amp was set to max. Why my installer did that I do not know. I still have some tweaking to do but, I think I am already getting closer.

Do you think 50 watts is enough power for Diamond S600s up front. I know they will handle alot more and I was thinking about bridging the amp to get them at 150 watts. Would that be a noticable difference?

 

I thought your amp was 75x4?

What difference would you like to create? If it's a midbass diff, install might have a lot to do with it too... damping, spacer rings sealed with foam tape, etc. - but more power can help.

If it's a high--freq improvement you seek, I don't think more power will help.

You may want to lower your tweeter OP on the xover for the front too, especially if you have the metal dome tweets.

 

Another way to do it is to match the input voltage to the output voltage. You need a digital multimeter for this - the output voltage is measured be removing the (+) speaker lead from the amp and connecting your voltmeter in between that lead and the terminal you removed it off of and setting your voltmeter for DC.