Installed Aftermarket radio in MKIV Jetta but has background noise

I'm fairly new to this forum but have used this site for tons of information for a my 2001 MKIV jetta. I was wondering if anyone had any ideas about a recent issue I have been having with a new head unit I installed.

I put in a single din JVC head unit a few weeks ago and everything hooked up just fine and sounds great but when I am on any channel, aux, usb, fm/am I have background static noise. It is always there and independent of the volume of the radio (even when on zero). The only time it goes away is when the unit is totally off.

Everything was stock originally and I had the Monsoon sound system. Stock speakers and amp are still installed, only the head unit was replaced. From what I have been reading it is most likely some sort of issue with the factory amp still being connected, or possibly some sort of ground issue, but not sure. Has anyone had this problem before or have a solution to how to fix it? Thanks!

I don't know specifics - just giving a general reply.
- All amps have background noise - as in no matter the volume level, the static in the background is a fixed value. You'll only notice it when it's quiet, engine not running, volume turned down. Some amps are very good (very little noise) others not so much.
- Feed this fixed noise into another amp, that other amp is going to amplify the fixed noise and add its own.

The JVC headunit could just have not so low 'fixed noise' and the factory amp is amplifying it so you're hearing it. Are you going from the speaker output of the JVC into the Monsoon amp? I don't know if it will work but pre-amp outs are quieter than going right from the speaker out into another amp.

Again, I don't know the exact specifics of what you're encountering, just giving you some ideas.

Thanks, I can take a look at that. Right now the speaker outputs from the JVC headunit are going into the factory harness, which i assume is through the Monsoon amp, because I didn't disconnect anything or rewire anything. Just spliced in the harnesses from the vehicle to the aftermarket harness and plugged it in.

I will look into the pre-amp outs as a possible solution. Is there a way to disconnect the monsoon amp and just use the amp that is included in the JVC headunit without doing a total rewire?

This is most likely a grounding issue.

You could jumper out the Monsoon amp, but I don't think you would want to. It's going to have more power than the amp built into the head unit.

You'd also have to put in some crossovers for the tweeters.

-J

Yeah I would like to leave the amp in if possible. Is it normal to have the background static/noise when installing an aftermarket HU with the monsoon stock system?

From what I have read on on this site and other forums it seems to be somewhat of a common problem. Do I need to be grounding anywhere else besides the ground from the aftermarket stereo to the factory harness?

When I put an aftermarket head in our 99.5 with monsoon, it got a very very slight buzz. I can only hear it with the engine and radio off.

Not sure what advice I can give on the ground loop :/

-J

Yeah its not that bad of a buzz, but I can still hear it even when engine on and music, podcast or anything playing. It only gets drowned out at higher volumes so it is slightly annoying especially when listening to talk radio or podcast/audiobook. Only time it disappears is when radio is off.

I'll keep messing with it and see if I can get it figured out.

Thanks for the help.

Does it increase with the speed of the RPM's?

No It doesn't, It increases slightly with volume. I think it's probably running through factory amp and being amplified then running into the headunit and the amp in the headunit and being amplified again. At least that's what a friend thought. Still haven't been able to figure out how to fix it other than doing a re wire.

Check all grounds first. Make sure your power wires don't run next to your signal cables.
If it changes with RPMs, it's likely alternator noise.

When the noise is present with the engine off,it is 99% sure it is a ground loop problem. The most simple way to fix the problem is to use the RCA's as your program source outputs.I realize you may not want to rewire your sound system, but at this point it seems to be the best solution.

Don't forget to send a thank you letter to the Chinese.

I used the special Crutchfield adapter when installing my aftermarket stereo in place of the monsoon head unit. Works great with no background noises.

Mike, which Crutchfield adapter did you get? Do you have a link? I used the crutchfield wire harness and antenna adapter but that was it. I will continue to double check the grounds. Thanks

Tony