Hey guys,

I'm trying to finish up a pretty extensive audio install on my '04 TL, but I cannot get rid of this horrendous alternator whine. And trust me, I've scoured the interwebs, trying to find a solution to my particular problem (I know alt. whine is a rather common one), but nothing has worked. The noise was not present before I started upgrading the sound system.

Here's the rundown:

What's been installed / done?

-Image Dynamics CXS64 V.2
-JL 10w3v3-2 (in sealed, fiberglass enclosure)
-Alpine MRP-F300
-Alpine MRP-M500

For the front stage, I'm taking the FL and FR signals (full range) directly from the factory headunit. For the sub, I'm taking the factory SW signal from the HU. The factory amp has been completely removed. In its old location (passenger kick panel), I soldered RCA ends onto the speaker wires from the HU (using Kicker KISL RCA adapter and Rockford Fosgate RFIF2SW). From there, Stinger 4000 series and Stinger 8000 series RCAs are run all the way back to the trunk on the passenger side (away from power wire on the driver side).

Both amps are receiving power from the battery via distribution block. Both are grounded to the frame (sanded) via distribution block.

The front stage is using passive crossovers (installed behind glovebox), and is being powered by the F300 (4 channel, bridged), which accepts the balanced signal output from the headunit. The sub is powered by the M500.

All gains were set using test tones, Ohms law, and a DMM.

What are the symptoms?

When the engine is not running, there is no noise whatsoever. As soon as the car starts, the noise ensues. The noise is like a clicking buzz sound, and comes through every front stage speaker. It directly correlates to the engine RPMs. Here is a video clip that another member (CLtotheTL32) took inside his TL. The noise is identical to mine. His problem was solved by replacing the factory amp (which I no longer have!).
What troubleshooting steps have I taken?

I don't even know where to begin...

Things that DID NOT get rid of the noise:

-Regrounded amps to new bolt in trunk
-Regrounded factory headunit to amp ground location.
-Regrounded HU to battery negative terminal
-Soldered RCA adapters in passenger kick panel (originally used butt connectors)
-Ran RCAs outside of the vehicle from passenger kick panel to trunk
-Removed factory HU from dash
-Replaced factory HU
-Upgraded battery ground wire
-Upgraded battery to fusebox wire
-Added engine ground
-Added alternator ground
-Replaced battery (DieHard Platinum)
-Cleaned alternator positive wire
-Plugged RCAs from kickpanel into a separate stereo (to bypass amp altogether)
-Added PAC SNI-1 ground loop isolator at front and rear of vehicle (not at the same time)


Things that DID get rid of the noise:

-Unplugged speaker wires from amp
-Unplugged RCAs from amp (used muting plugs)
-Unplugged RCAs from RCA adapter in passenger kick panel
-Plugged iPhone into kick panel RCAs (to bypass headunit and all wire runs behind dash)

Summary:

Based on my troubleshooting steps, I'm confident that the problem lies behind the dash (within the wiring between the HU and my RCAs), or in the engine bay somewhere (spark plugs, wires, alternator?).

Any advice would be much appreciated. I'd be happy to answer any questions.

Thanks!

 

Perhaps a line driver to up the voltage and reject some noise? I am using a JL amp wirhout a driver but my amp is under the seat so a much shorter run.

 

Pioneer head units can exhibit the same symptoms when the pico fuse inside the unit goes out (effectively un-grounding the RCA's). A quick fix for them is to solder a wire from the chassis of the radio to the RCA ground.

I'm not positive on whether or not you could do this in your setups since your RCA's are actually the head unit speaker outputs. If I were you, I'd take a trip over to caraudioclassifieds and post this there. They will probably have a definite answer for you.

 

I should have mentioned that I originally had a Rockford Fosgate BLD line driver installed in the passenger kick panel because everyone said that you would get noise after taking the signal pre-amp, unless you boosted it a little bit. However, this noise was present even with the line driver installed. I saw no point in having it, so it has since been removed.

I do remember reading about that issue with the Pioneer HUs. I suppose it wouldn't hurt to try grounding the RCAs to my HU. I'll take your advice and post this on that site as well.

 

I may have just found the answer. How did I not see this thread before?!?! https://acurazine.com/forums/3g-tl-audio-bluetooth-electronics-navigation-94/factory-signals-audio-unit-stock-amp-differential-816968/

 

Audiocontrol Matrix Plus ordered. Fingers crossed!

 

I'd still have opted for the CL-RLCs like I suggested in my DIMA post. Hopefully the Matrix will solve it for you, but the CL-RLCs have the same balanced differential input as the JL amps and I'm almost certain that would solve it. Plus they will be cheaper.

 

Let's not forget, you recommended the Matrix also :wink:. Plus, I figured if it worked for that guy, why wouldn't it work for me? At this point, as long as the noise is gone, I don't care what the price tag is! It'll be here Wednesday.

 

so you think the problem is the Alpine amps cant take the balanced signal? I dont think that is the problem. but whatever works!

 

Yes, that is what I am thinking. Alpine claims that the MRP amps can accept balanced inputs, but I have heard differently from other people. The Matrix is also a line driver, so I'll be boosting the signal a bit before it gets to the amps (which you recommended).

I'm betting you have no issues because your JL amp actually accepts (and performs well with) balanced inputs. Hindsight, I probably shouldn't have purchased these (somewhat cheap) amps. Hopefully the Matrix will work out. We will see (or hear).

 

this guy has a few good ideas about trying to isolate the point of entry of any outside interference. I doubt you have RCA cables coming out of your radio, but you can tell how he is troubleshooting it. You can also disconnect the RCA plugs on your amp 1 at a time to see which channel it is coming from , if not the headunit or wires through inductance. He called it "radiating" but its called inductance. I have a factory headunit running to a Pioneer D7500 amp and there is no noise.

 

Well boys and girls, the noise is finally gone. And while this fix is not up to my original standards, I am content and done with this project.

Here's the story:

I knew the AudioControl Matrix was intended to be placed as close as possible to the HU, but there simply is not enough room to put it in the passenger kick panel, and I didn't feel like mounting it under the seat. So for testing purposes, I just put it in the trunk with the amps. I tried it on every setting possible, and the noise was not reduced at all (if anything, it was increased on certain settings).

So out of desperation, I removed the Matrix, and just started trying random things. I plugged my iPhone into the RCAs at the passenger kick panel, but ALSO connected it to the car charger. Under these conditions, the noise WAS present with the alternative source (not nearly as bad, but present nonetheless).

This led me to believe that there was, in fact, a ground loop occurring somewhere further down the signal path. For whatever reason, I decided to plug in the PAC SNI-1 ground loop isolator at the passenger kick panel. I tried this $10 device months ago and saw no positive results. But miraculously, it worked this time. I isolated both front channels, and the noise was 95% gone (literally had to put my ear up to the tweeter to hear it). At this time, the gains on my amp were still set for my iPhone. I checked with a DMM, and the amp was putting out 15 volts, while my speakers can take 22.3v. I decided to keep the gains where they were, because I assume that increasing them would make the noise apparent again. Using Ohm's law, my speakers are rated to receive 22.3 volts at 4 ohms (125 watts). Since the amp is only putting out 15 volts at 4 ohms now, the speakers are getting 56 watts.

I'm not thrilled that my speakers are not reaching their full potential in terms of volume, but they still sound incredible, and get VERY loud. And who knows, maybe the GLI would still keep the noise down even at 22.3 volts. I might try that later.

I'll keep this thread updated with any future findings. Thanks for all the advice!