Here's my question. I'm something of a newbie, so bear with me. I have a 1700 watt peak, 800 watt RMS Kenwood amp attached to a pair of audiobahn 10" subs, 600 watts RMS. my car is an old school mercedes 190-e. I just had to replace the alternator because i think they burned it out. however i also had the gain turned all the way up on the amp. so i turned the gain down to about 25% which is still fine sounding. my question is: since i turned the gain down, does this also lower the RMS of my amp and therefore put less strain on my alternator? I want to do eveyrthing I can to avoid damaging the brand new alternator i just put in. thanks!
no. the "gain" is actually not a true gain. it's an input sensitivity adjustment that allows you to balance a wide array of head unit line voltages to match the input stage of the amplifier. if you have a 4 volt line voltage from the head unit for example, you'd want the "gain" of the amp set to 4 volt input. If the gain is set too high (too sensitive for the input voltage used, for example amp is set for 2 volts, and you have a 4 volt head) you'll over-drive the input stage of the amp and cause the amp to clip, causing distortion and speaker damage by sending DC voltage to the speakers. If the gain is set too low, you amplify a weak signal and get more noise and a lower S/N ratio etc.. basically you're amplifying a poor signal so it won't sound as good.
if you fried the alternator, you may want to consider going to a larger high output alternator, and using a second battery in the car.
power (watts) = current (amperes) x voltage (volts)
volts are a fixed quantity so the current has to come from somewhere.. and that's the alternator and batteries.
solutions are upgrade the charging system, or get a smaller amplifier, or turn down the volume so you use less power. that's about it. use less power or get the means to feed more juice to the amps.