Ok,
I am at a loss for how to eliminate the engine noise from my current setup, I have posted on this before but yesterday I got more aggressive and took my car apart again. I have come to the conclusion that the issue resides in the proximity of the back of my alpine deck RCA connections to the ABS ECU which is about 2 inches from the back of the deck. I am wondering if I could maybe mount some sort of barrier between the ecu and my deck and if that would make a difference.

Basic Layout:
Alpine HU mounted right above the "Not an Ashtray" coin jar.
Dedicated ground wire runs from the deck to the battery, I have tried grounding it to the chassis with no luck.
Dedicated power wire that runs to the Battery.
RCA's run down the center of the car to my Amp in the trunk, I have since upgraded the RCA's from cheap ass streewires to Monster Cable 401xln's.
Amp has a dedicated 2 gauge power wire running down the drivers side to a distribution block in the trunk, where it feeds the amp.
The amp power wire does not cross the RCA's
Speaker wires run in parallel with the RCA's and I used a high quality 12 gauge wire to the front of the car where the signals are split by passive diamond crossovers.
I have tried moving the crossovers several times and I am now to the point where I only here noise out of the drivers tweeter only.
I have tried running the drivers speaker wire to run under the center of the drivers seat rather than down the center of the car but that did not make a difference. What I can see is that when the car is turned off the whine continues until a relay next to the ECU pops and turns off, the noise than stops.


Ideas?

 

Does it happen with the deck/amp OFF?

Do ou have any kind of ground loop isolator? Where is it located?

Where are the xovers?

If you moved the xovers and now only get it out of the driver's tweeter, I wonder if they are under the glovebox on the passenger side? I had mine there and if they were too far to the center, one xover would pick up noise from the ECU.

 

no noise when everthign is off, only when the car is on, once you kill the motor, the whine continues for about 15 seconds untill a relay pops.
I do not have an isolator, is this a good product or do you have another that you would recomend: http://www.cardomain.com/item/STISGLI.
Is it better to plug iit in between the deck and amp, nearest the deck or back by the amp?

I have moved the drivers cross over from behind the deck so it is now under the steering wheel which seemed to have a small impact.

 

Thanks... not totally clear from the message if there is noise when the Ignition is on, but the HU and AMP are off ("everything" is a lot

I am not recommending an isolator at this time... just wanted to know if you had one. The isolators have transformer coils in them, so the non-shielded ones (and they are ALL non-shilded except for the Iso-Max, which lists for $200! will pick up ECU noise and make it worse!

As a test, if you only have noise on the driver's tweeter, is to get three 6-foot pieces of crap speaker wire, a Sharpie, and a roll of electrical tape. Extend the xover input, tweeter ouput, and woofer output wires using these three pieces of speaker wire and wrapping tape around them. Use the Sharpie to mark each wire so you don't get them confused!

Then attach the passive xover to this extension wire set and hand it out the door sill on the ground outside the car.

Retest.

This is totally what we would do in my shop.

If that doesn't work, it's NOT the passive xover.

At that point we would take the radio out of the dash and see if taking it out of the dash and away from the ECU as far as possible (have a towel in there to keep the dash from being scratched) gets rid of the noise. If moving the deck closer to the ECU makes the noise worse, then the deck is picking it up internally. I don't think this is the first thing to test, otherwise, you would have not had good results frommoving the xovers.

We rarely try to hide xovers anymore due to this kind of speaker xover noise problem. Funny, the first time I ever ran into it, in 1988, it was an Accord

 

Since it's only the driver's side, why not put the xover right next to the passenger's side xover - assuming you haven't tried that already.

From your description it sounds like the wiring for the left and right channels runs together until the crossover, it's likely the crossover picking-up noise or an equipment problem. Switch the RCA cables left to right, right to left, noise still on the drivers side? It's not the equipment then (baring something odd). Have you tried putting the xovers in the passenger's foot area, against the firewall (as I believe elduderino mentioned)? When I had crossovers, I had them there, and there didn't seem to be a problem.

Although, in one of many of my systems incarnations, I did experience a sound you describe, can't say it's the same obviously, but it did sound like something was discharging energy and the speakers would play it for a few seconds after the car was turned off.

 

Ok, I have a few items to try, I will get back to you all later this afternoon

 

Took my car apart, I think this issue is related to the gains on the amp, I had them up all the way. I turned them down to about 75% and I can no longer hear the noise when I drive, but it is still there when the car is off and the radio on

 

huh.... that sounds odd!

 

Noise can often be caused bygains that are high and reduced by turning them down.

But not on only one channel...

 

Still not clear on this...

 

adjusting the gain did not nessarly fix the problem, it just lessend it. I tried hooking the tweater dirctly up to hte amp and its deffianly a problem related to the RCA's, I am fairly confident it is an issue with the proximity of the rca plugs to the ecu as I pulled my deck out and the whinning stopped. Now I have to think about how to build a shield of some sort as that 200 dollar filter is a bit steep... Thanks for the help though.

 

The $200 filter won't fix it if it's being picked up that way. That only blocks ground loop currents. If the noise changes when you move the deck, you don't have a ground loop current problem, because that problem wouldn't change with deck location.

If you are using 401XLN RCAs, it's almost IMPOSSIBLE for those cables to pick up noise out of the air in the audio spectrum It's a physics thing having to do with the wavelengths we hear and the tightness of the twist and the antenna characteristics of the conducotr with that shape (I would say this about many twisted pair cables, it's not that I'm all hot about those).

My concern is that the circuit board of the HU is picking up the noise prior to the RCA cables, and I don't see a great way to prevent that. TRY attaching a ground wire to the HU chassis directly.

If that doesn't work, I seriously would borrow a friends HU (different model!) to see if it has the same problem...

 

hmm, good advice, I will try the ground wire first and go from there... Maybe this is my excuse for a new deck

 

That sucks, but maybe it is the deck, because I have a deck mounted in the same location and I don't have a noise issue. Hummm...build a Faraday cage?