Amp Volume Fluctuations

**Gewehrschuss** · 06-17-2005, 01:16 PM

I have my Carputer running directly through an amp powering the speakers (no head unit) and when I drive, the volume decreases when I step on the gas or brake pedals.

I tried disconnecting the computer and using a standalone MP3 player as a sound source for the amp and it still did the same thing, so it shouldn't have anything to do with the computer. I also regroudned it, but it didn't help.

The amp is 60 W x 4 and the alternator is 90 amps. The carputer has a 90W AC power supply fed by a 150 W RMS inverter.

I'm out of ideas and I'd be very appreciative of some suggestions!

**scott_fx** · 06-17-2005, 01:23 PM

when you are driving you are probably around 14.4v when you are idling it'll drop between 12-13v so thats why the volume is going down. how new is your battery?

one option is to get a louder exhaust, that way it'll sound louder at idle

**Gewehrschuss** · 06-17-2005, 01:35 PM

my battery is a couple of years old. I hooked a voltmeter up to the power leads to the amp and the voltage does fluctuate when idling if I turn on the headlights or AC, could that be the cause? If so, how can I fix that... other than muffling it out with a loud exhaust?

**Moondog51** · 06-17-2005, 02:04 PM

Originally Posted by Gewehrschuss

my battery is a couple of years old. I hooked a voltmeter up to the power leads to the amp and the voltage does fluctuate when idling if I turn on the headlights or AC, could that be the cause? If so, how can I fix that... other than muffling it out with a loud exhaust?

I believe the traditional fix for this is to add a stiffening capacitor for the amp.
Ive never used one myself though.

**scott_fx** · 06-17-2005, 02:08 PM

A cap wont solve that, they don't have the staying power, they are only used for quick bursts like a bass hit. I'm not sure exactly how to solve it, maybe an optima yellow top? what gauge wire are you using? do your headlights dim when the bass hits?

**Gewehrschuss** · 06-17-2005, 02:30 PM

I'm using 10-gauge wire

**Gewehrschuss** · 06-17-2005, 02:31 PM

no, my headlights don't dim at all

**scott_fx** · 06-17-2005, 02:36 PM

the wire may be too thin, it may be adding too much resistance into the system. maybe you could try a quick test by running some 4 gauge instead. a quick test may be to just get some 8 gauge wire and wire it in parrallel (doesn't have to be hidden, just run it on the outside for this test) to the 10 gauge that you have. keep your revs high and listen to the radio then let it idle and see if the volume goes down.

**Gewehrschuss** · 06-17-2005, 02:40 PM

I'll give it a try, thanks for the suggestion

**scott_fx** · 06-17-2005, 02:47 PM

keep us posted if it doesnt work, we'll get down to the bottom of this. there are a few pro installers on this forum that may chime in with some other advice