Subwoofer/amplifier gets LOUDER BY ITSELF??? wtf??

[supermario680]

So I recently installed a amplifier and subwoofer in my GF's rx8.

But for some reason it just gets louder and louder when were not touching anything..

I would adjust it to a decent level, nothing crazy, then get in the passenger seat to listen and then it would just super loud for some reason...

If you turn down the volume it would stop, but then do it again after the volume is up for a while.

And again, its just a modest setup, and were not pushing it that hard I don't think. Nothing crazy.

I turned down the gain and that seemed to help for a week or two but apparently it's doing it again.

And it's not just a little louder... its like Exponentially louder...

Any idea whats going on???? would a bad ground or something cause this???

(background)

its a rockford fosgate P2 12 inch sub

Its a PPI pc250 (precision power) amp (i think)

It's a 2 channel amp that im running single channel, not bridged (i don't think..)

the input signal comes from a splice off a speaker wire, right to the center of the RCA input.

I ran it like that on my other car for like a year without any issues....

the only difference I can think of is that the rx8 has premium sound so it has a factory amp for the speakers....

Could it have something to do with the "Q-bass" feature?

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[supermario680]

bump!

 

[mylows10 5,000+ posts]

maybe bad amp ,do you have an aftermarket deck or stock? if stock i would look at the hlc first

 

[BnGRacing 10+ year member]

Hmm...interesting.

Unplug the RCA's going into the amp and use one of those cheapie RCA-to-iPod adapters and use your MP3 player as a source. What we're doing is really isolating the amp from the HU. If the system stays at the same volume, the problem is upstream. If it still changes volume, check to make sure you removed enough paint from your ground source and are at least using a star washer. Hell, take a pic of where you grounded the amp and post it. There's a possibility that it's just a bad place and is causing your amps to go into fits.

I had a similar problem with a bad ground under the hood of my car causing the headlights/dashlights to glow really-really bright for a couple seconds and then go away. Your problem reminds me of that as both an alternator & PPI amp are regulated.

 

[supermario680]

that is a good idea. I never had a problem with it in my other car. Stock HU in both cars.

I do know the gound isn't the greatest. I was having a hard time finding a surface that wasn't covered in paint. It's grounded to a metal plate at the bottom of the truck, I tried to clean it with a dremel as best I could but I should probably find a better ground.

Thanks!