Hey:

I've recently purchased a complete system and had it profesionally installed in my 2003 300M Special (all this stuff was recommended by the salemen, I'm not sure if thats a good thing or not):

Factory HU
Peripheral SVEN4 High Level to RCA Converter
MTX TC 4004 4-ch Amp
Infinity Reference 6020cs Component Speakers (Front)
Infinity Reference 9622i 2way 6 x 9's (Rear)
Stinger Cabling

There is a pile of white noise coming from all the speakers. On top of that there is alternator whine. The noise is even present when the stereo is turned off.
It also appears that the amp is overheating and going into thermal protection; I'm not pushing it too hard, the gain levels are set around 1/3 of full scale. However, it does take about a half hour of continuous moderate use to cause it.


If this helps I have noticed a few things while trying to figure this out on my own:

The installer shunted all my HU outputs into the high level convertor leaving all the original wiring (probably going to the factory amp) active. I thought that was odd, why leave that stuff running?

When the amp goes into thermal protection, the centre front speaker (which up to that point I didn't know existed) continues to work

When I unplug the jacks connected to the HU the noise continues

When I unplug the RCA's on the output side of the high level converter the noise continues

When I unplug the RCA's at the amp input the noise stops

I verified that the amp power and RCA's where run on opposite sides of the car (but the HU ACC wire which is used as the remote wire to the amp was run with the RCA's). Further, as an experiment I connected a set of RCA's (cheap ones unfortunately) directly from the high level converter output to the amp input. The noise persisted

Does anyone have any suggestions? I was thinking it was noise induced into the RCA's, but then why didn't my experiment work? Maybe I'm on the wrong track, I'm definately lost. Does anyone have an oppinion on these signal processors, in particular the MTX Re-Q5, would it help the noise level?

Thanks, any help will be much appreciated.

 

Oh yeah, a quick note regarding that shunting of the head unit wires:

I tried unpluging the the factory amp and there was no change.

 

it kinda sounds like the gains are too high on the amp. I myself wouldn't have used the sven 4 I would have used the RE-Q instead it costs more but does a much better job. We've had problems before with the sven 4 cause they don't seem to deal with amplified systems well. it's seems it has to do with not being able to cut the high input enough which causes the aftermarket amps(mtx 4004 ) to over heat. The amp trigger running with the rca's is just a trigger not enough to cause noise in the system. As for the alternator noise I would still do a complete check of the grounds to the amp as well as the factory deck itself. Chrysler has had problems with grounds for a while now.

 

I have a suggestion (without being smartass) take it back and tell them to do it PROPERLY!!

I work hard for my money and you probably do as well. If I paid for a professional, then I expect a professional job.

Dont tell me the installer couldnt hear the same things YOU are hearing from your audio system.

Or is this the full story?

What I mean is, have you added or changed anything since the install that could be causing this?

BTW, I have the same 4 channel amp as you and they are pretty powerful. I was stupid enough to bridge it and cook a pair of fronts. That amp is probably putting out 25% more power than its rated for.

Cheers

John

 

^^^ I agree!
There are a number of things that sound just plain messed up - you noticed a few of them . . .
MTX amps typically have no problems pushing 2 ohm loads, so really there is no reason why the amp should go into protection - unless the installer bridged something - then it is the installers fault.

If grounding is the issue (and it looks like it could be) the installer should find a better ground.

One other thing (that is still the installer's responsibility) is the location of the crossovers. In my Subaru, I installed my cross-overs behind the Head-unit. My speakers where getting noise even when I disconnected amp. It turns out that the rat's nest of wires behind my HU were inducing noise to the cross-overs (I think that's called inducted noise but I'm not sure). I moved my cross-overs so they were 8 inches away from any electrical wiring and my noise was gone.

Yup, there are a lot of things wrong with your install . . . the first problem is likely the installer. Even if the equipment is faulty, any good installer would note that from his first test run.

 

U need to take it back and get it done right. Tell them to call u when that works properly.

 

Hello Everyone:

Before I get into it, I again want to thank everyone for all your feedback.

I would also like to be absolutely clear. I recieved the system from the installers with all the problems I've mentioned. The work I'm doing is in attempt to fix these problems.

I also do feel like I've been blown off by the installers, I've pretty much given up on them. He told me the noise was caused by the poor quality signal delivered from my factory HU and I would have to buy an aftermarket one to fix the problem. I didn't believe him but couldn't prove otherwise. Moreover, I live in Fox Creek Alberta (boondocks) and the closest store (to remain nameless: I don't want to point fingers, I just want to fix this thing) is a couple hours away in Grande Prairie. I don't mind doin the work myself anyway, it's a bit of a learning experience. I just didn't want to route wires, thats a major pain in the butt.

That being said I bought a Re-Q5 as Godzilla suggested and installed it. In hooking it up I noticed a few things:

The ground wire on the output side of the SVEN4 was not terminated

After installing and testing the Re-Q I noticed the noise was not present when I turned the ignition key backward. However, with the key forward but without the car running the noise was present.

This got me thinking about pulling fuses to determine the cause. It turns out the "Heater Moter / AC" circuit was causing the noise. That is, with the key forward (car not running) noise was present. On pulling the fuse the noise was gone.

My question is: What can do about this?

 

Is there a reason you want to keep the factory head unit? If it was replaced your noise would be gone and it would sound ALOT better. If there is a reason for keeping it try grounding the outer portion of the RCA cables to the chassis of the head unit, and make sure the ground strap from the factory is there. I would also go back to the installer and DEMAND my money back for such a crappy job in the first place.

 

Yeah, I want to keep the factory Head Unit so I can maintain my steering wheel controls and CD Changer. It's also personal preference: I prefer an "unassuming" appearance. I generally dislike the "flashyness" of aftermarket units.

Could you please expand a little on this grounding stuff. Is there supposed to be some sort of "grounding Lug" attached to the chasis of the HU? and do you mean ground the shield of the RCA's? How do you do that?

 

There is supposed to be a Ground Strap or wire from the factory grounded to the back of the head unit metal chassis, and yes ground the Sheild from the rca wires just srip a bit of insulation wrap and solder a wire onto that and ground to head unit. But first make sure the FACTORY GROUND IS THERE.