noise noise noise

[mexicanzero]

sorry if this has already been asked but i did a search and did not find what i was looking for.
so i have a Rockford Fosgate p200.2 amp (bridged) and a cheap 10" thump sub.
my car is old but works really well and has relatively low mileage, its a 1992 Subaru legacy but the alternator is almost brand new and the battery is probably about 3 years old.
i have a pioneer deh-p5800mp
i have the rca wires (far from top of the line but not the cheapest possible) on the right side of the car and the power wire (8 gauge) is on the left side.
the amp is grounded with 8 gauge wire to bare metal on the floor of the trunk is this a bad spot since the metal isn't that thick?

i had an amazingly awful whining sound that went up with rpm's which is what convinced me to change the rca's to the opposite side on the car. it seemed to be gone... but wasn't

lately when i pause my cd i wont hear anything then i'll go over a bump and my sub will thump as if it was getting signal and then the whining which increases with engine rpm will come back then i will hit another bump and the whining will go away again.

this happens intermittently almost as if it just feels like doing it.
my head unit is grounded using the wiring harness, some people have told me to ground it to the same spot as the amp. should i bother?

i have not checked the alternator wires since they are hidden and would require removing a lot of components to get to. the battery grounds looked dirty so i loosened them and moved them around just in case they weren't contacting properly.

i have troubleshooted it a lot: when i unplug the antenna nothing changes when i unplug the rca cords from the amp its gone and if i unplug them from the head unit the noise is also gone. this led me to think it was coming from the power wires of the head unit so i installed a couple of noise filters, they didn't change a thing.

i have spent way too much time on this without success so please tell me what to do!
thanks a lot
-Alex

[subba]

The ground loop in your deck it self is maybe shorted.

http://www.sl-i.net/FORUM/viewtopic.php?t=5346

[mexicanzero]

i tried grounding the receiver to the same spot the amp is grounded to and it didn't do anything
also now even if the engine isn't on the whine is there all the time the key just has to be on and its loud enough that i have to unhook the rca's from the amp because i can't stand it and it can't be good for the sub/amp

[subba]

http://www.sl-i.net/FORUM/viewtopic.php?t=5346

^^^^ Click It And Try :grin:

[mexicanzero]

well i want to use the pre amp outs because then i can control the sub volume and x-over from the head unit.
doesn't that convert the regular speaker outputs to pre amp? because then i can't control it from my deck. and i have all 4 outputs going to speakers anyways... so how am i supposed to use it?
thanks for the recomendation though
-Alex

[Shep2112]

I know this is older, but it didn't get a response.

You'll still have control over the levels to the amps and stuff, because you have control over the speaker output volume. The downside is you get only 4 channels, and the amp will derive the sub level from those signals, and you'd need 2 of them for 4 channels, so no separate sub level control.

Those adapters will lower the quality and are only really useful if your preamp outs fail, or you never had any in the first place. :) The problem is, your boosting the signal inside the head unit via the amplifier, and adding the noise and all that's inside the amp on a chip inside the head unit. Then using the impedance transformer, you're knocking the signal way down so your line input devices (amplififiers) can then boost the signal back up upon output, and boost the extra noise they picked up in the first place, from the speaker level signal.

It can't be alternator whine if it's doing it with the engine off. Sounds like a deck problem. Subba's right about a short inside your deck somewhere. Could be ground, could be something else. I'm not surprised the filters didn't help/ I don't think that would fix this, since I imagine the incoming power is good.

If you don't hear the noise in the speaker outputs, something is really screwy in your deck. It'd be best to figure out what's wrong, rather than trying to 'fix' the problem by installing little hacks like these. One day, the deck may decide to output pure DC (full signal strength, full volume, completely clipped, resulting in a square wave). That could kill your electronics downstream from it potentially, and most likely damage your speakers.

If you haven't yet, I would get the device repaired by the factory or a local technician. You could end up being very sorry.

I once shorted out the speaker outs on a Kenwood head unit and I heard something sizzle inside and then smoke came out of the unit. I opened it up and a little orange component had heated up and oozed out its mojo onto the circuit board. I went to a repair place, ordered a new part for 7 bucks, desoldered the old one (2 conductors), soldered in the new one, and it worked fine after that. Your problem may be something similar, though it's easier to find the culprit when it melts and is easy to spot. :twisted:

Hope this helps someone. :razz:
Eric

[mexicanzero]

my final assumption was that it was the deck. once i have enough money i will upgrade but for now its not as bad as it was a while ago.

thanks a lot for the reply though i appreciate it i recently fixed a blown amp that had gone dc so i will most likely attempt to fix the head unit

the reason i havent gone to the line drivers is i really like the separate sub controls for fine tuning the system and its not like that would fix the deck so i might as well just fix it or replace it instead of buying line drivers

thanks
-Alex

[Shep2112]

So you know all about DC and audio and how much fun it can be, eh? Ugg

I agree, just getting a new unit might be better, especially if it's still a mystery what's going on with it.

Eric

[mexicanzero]

o yes when my amp went dc it blew my sub up, it was a 5 channel amp too but luckily only the sub channel went dc so my speakers were untouched

[Shep2112]

Ouch, well it could've been worse then. I need to figure out what's wrong with the rear left channel on my 5 channel HiFonics Zeus amp. Something internal, there's no sound at all from it. When I get time I guess. :)