okay, need some help and it almost has me stumped

[pwnt by pat 10+ year member]

Alright, so I'm working on a buddys car, a 94 Acura Legend. I sold him an amp a while ago, Eclipse 3242, and installed a RE35.1 in it temporarily. The 35.1 replaced a Kicker KX120.2. A Panasonic head unit controlled everything. It sucks //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif. Anyway.

The system was noise free. Both amps grounded to the same spot and sanded to the metal, nothing done under the hood. The main power wire was 4 gauge to a distro then 8 to the amps.

So, I did a direct swap out. The re35.1 was set so that at maximum unclipped volume, it was only outputting ~600w. I used a piece of 8 gauge power wire about 6" long from the distro.

Hook everything up and bam, whine - but only on the rear speakers and sub. It's not alt whine, just engine whine. It increases in frequency when the break pedal is hooked up.

The system was inherently noisy when installing everything the first time, and I didn't have time to troubleshoot it at the time, so I sent him to Radioshack for a ground loop isolator - and solved the problem.

Here's the schematics for the RCA's:

The head unit has four channels of output, front and rears, no sub. Fronts go directly to the fronts on the Eclipse.

Rears goes to the sub amp, then output on the sub amp to the main channel amp. It has to be this way 'cause his RCA's aren't long enough to go the other way around. The noise isolator is on the rear channels, I do believe (after you remove the seats, it's a cluster-fudge. He plays with it when I'm not there to supervise).

Anyway... Steps taken:

1) Reground amps to same location. 35.1 ground was different 'cause we didn't want to remove the seats last night, which is a half hour job. so resanded the ground and grounded to the same spot. still noise.

2) Did a bat - to chassie ground up front using 1/0. Ground sanded and wire is about 8" long. Still noise.

3) Unplug RCA's from subamp, still noise

4) unplug RCA's from everything, still noise

5) unplug 35.1, still noise

6) unplug the remote for 3242, no noise.

7) turn gain down on the 3242, noise, but it's lower - and on the rear channels only, again

8) play with crossovers and reset the gain on the 3242. I switch the rear speakers from "stereo" to " L + R", no noise - at all

9) hook up the 35.1, no noise, even with the engine on.

10) get all packed up. He turns the car on to leave and BAM noise is back and louder than ever.

Now, this would lead me to belive the 3242 is somehow bad, at least on the rear channels. It's odd, though, how the noise coinsided with installing the 35.1. I will be playing with it more tomorrow, including regrounding the head unit to the back with the amps, eliminating the ground loop isolator, and some other things.

So, any input would be helpful.

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[phantom240 5,000+ posts]

... I know exactly whats wrong. its a legend. lol. dont get me wrong, i loved my legend (90 coupe), but that thing had the weirdest electrical gremlins. Maybe try switching the RCA's at the head unit between the amps. Also slap him and tell him to get a better HU. That may be a cause too. Some hu's just dont like some amps.

 

[pwnt by pat 10+ year member]

Well, as per #4, the noise persists when the RCA's are completely disconnected.

I'll be swapping amps tomorrow, as well. I'll also be doing a new engine-chassie ground as the stock looks to be 10 gauge.

 

[phantom240 5,000+ posts]

Also, i noticed the wires are really small for those 2 amps together. Try upgrading to thicker wires all around

 

[pwnt by pat 10+ year member]

for the cumulative 1000w, 4 gauge main wire should be just fine.

According to this:

http://www.caraudio.com/forum/showthread.php?t=166038

the 8 gauge should be just fine. We're getting a better distro to run 4 gauge tomrrow, too.