audio interference after recent rewire, help

[ragingxtc]

i'm experiencing some interference with the new system i've installed... mainly an alternator whine thats completely independent of the volume. i also get some interfere (louder than the whine) when i adjust my mirrors, and a slight noise when i lock and unlock the doors.

first off, i'll give you some background on my install. about two weeks ago, i finished a month long, interior out install. i replaced all four speakers... infinity kappa components (2 ohm) up front, and some older mtx coaxials in the rear deck. all four speakers are powered by an alpine mrp-f240 4 channel amp (gains set to minimum). i figured that it would be a good idea to replace the stock speaker wiring with 16 awg and to isolate the rca's, speaker wires, and power and remote lines running through the cabin. so i ran the power and remotes down the left side, the front speaker wires down the middle, and the rca's down the right. i then ran the speaker wires under the dash, through the drilled out molex connectors in the doors, and finally to the crossovers mounted in the doors.

the stock headunit is still in use, but i've done the 4 channel rca pre-out mod as well as the loudness mod. i'm running a phoenix gold sld-44 line driver to boost the signal strength (full gain on the front channels, probably half on rears). for input, im running the auxmod aux input with my ipod. i'm running tsunami v10 rca's.

i also installed a 2 farad cap. previously installed was the 4 awg kit, kicker mono block and two infinity reference tens.

it sounds f---ing awesome... crisp highs, punchy lows, excellent vocals... and most importantly, superb staging. i absolutely love it except for the interference (it's driving me insane).

ive checked all of my grounds and they are all solid. any ideas? should i shield the speaker wires under the dash and through the doors?

sorry about the novel... thanks in advance.
-kiel

 

[chuyler1]

Sounds like a great setup. Sometimes stuff like this could be a simple as a bad RCA wire or as complex as an exposed speaker wire. You basically have to isolate and test everything. Here are some tips:

1) Fade front/back left/right to see if you can isolate the issue to a particular speaker or channel.
2) Try disconnecting RCA cables one at a time to see if the sound goes away.
3) Try swapping RCA cables to see if the sound switches location.
4) Try removing components from the signal path (ie your line driver) to see if you can isolate the issue to a particular component.
5) Try disconnecting speaker cables from the amp to see if the sound goes away
6) Try swapping speaker cables to see if the sound moves around.

One more thing, you generally don't set your amplifier gains to the lowest setting. I usually have mine at about 1/2 way. Try doing that and lowering the gain on the line driver. That may help reduce the noise.

Anyway, that should get you started on things to try.

 

[ragingxtc]

so i spent sometime last night trying to isolate the problem and finally figured out that it was the power lines going into the line driver cross-talking with the rca lines going from the line driver to the amp. i put some shielding on the power lines and most of the alternator whine went away. i still have the interference from the power mirrors and a very very slight whine, but i can live with that.

i also tried turning the line driver down and the amp up, but that just seemed to raise the noise table.