OT: Stereo System noise

[DodgeGuy]

This probably isn't Mopar specific, but with the wealth of knowledge and experience on this board I'd thought I'd ask.

So, a week ago I (finally) installed my new Kenwood stereo into my '74 Challenger.  I didn't wire up the factory speakers in the dashboard as I'm sure they would sound terrible.

I did hook up the 6x9's that are in the rear deck, they are aftermarket speakers (Pioneers IIRC, but that's really irrelevant).  In any event, the system works fine, but was a bit "toneish/plain" for my taste with only two 6x9 speakers. 

So I bought a used Kicker Amp and a Subwoofer from a friend next door, who also is into classic cars (although he's a Chevy guy, we won't hold that against him, lol).

I wired it up, using a kit I purchased off Crutchfield that  included a 4 gauge power cable (I ran it directly from the starter relay, through the firewall, along the edge of the driver's side, under the backseat and into the trunk.  I also ran two RCA cables from the stereo to the amp (running side by side with the power cable, and I know after doing some research that this could be an issue for the noise).

I grounded the amp with a 4 gauge wire, I bared some metal on a spot in the trunk on the left where the rail for the trunk lid mounts on and connected the ground wire.

With the car off, the stereo sounds AMAZING with the amp and subwoofer, however, when you start the car and turn the stereo on, you hear "noise" coming from the speakers, that continues when playing a song.

I've been doing some research on the subject this morning, and it seems like there are a multitude of things that can cause this, from poor grounding of the amp, to running the RCA cables to close to the power wire of the amp, etc.

It has to be an issue with the amp, and not the stereo, since without the amp there was no type of extraneous noise.

Any suggestions?

[Cuda Cody]

This is why the T/A's and AAR's had the antenna moved to the rear.  With a Fiberglas hood the radio picked up a lot of engine noise.

They made suppressors that will help.  But it's most likely the engine electronics being picked up by the radio.  Does it happen with a CD, iPod and radio station?

[DodgeGuy]

This is why the T/A's and AAR's had the antenna moved to the rear.  With a Fiberglas hood the radio picked up a lot of engine noise.

They made suppressors that will help.  But it's most likely the engine electronics being picked up by the radio.  Does it happen with a CD, iPod and radio station?

The only 1 of the three I have used so far has been the iPod.  I'll start it up and try a CD and the radio here in a bit and see if I get the same noise with them.

[Cuda Cody]

Also, what are you running for ignition?  Points or electronic?

[DodgeGuy]

Also, what are you running for ignition?  Points or electronic?

Electronic

[1 Wild R/T]

Is it a whining noise?  A ticking or popping noise?   If it's a whine it's likely the alternator, try unplugging one of the small wires going to the alternator & see it it goes away...

[DodgeGuy]

Is it a whining noise?  A ticking or popping noise?   If it's a whine it's likely the alternator, try unplugging one of the small wires going to the alternator & see it it goes away...

Of those 3 choices, I'd most closely compare it to a "whining" noise.

Definitely NOT a ticking or popping....it pretty much is a steady sound. It doesn't seem to be affected at all by the RPM's of the engine as far as changing how the noise sounds, how loud it is, etc.  It's just a "steady" noise for lack of a better word.  If the stereo is powered down, you hear nothing, but as soon as you turn the stereo on, and the car is running, the noise comes immediately.

I will try your suggestion with the alternator.  My buddy is coming over here in a bit.

[1 Wild R/T]

Alternator noise typically follows engine RPM... Was the heater fan running?   Electric motors create a steady whine since the RPMs don't vary much.... 

[DodgeGuy]

Alternator noise typically follows engine RPM... Was the heater fan running?   Electric motors create a steady whine since the RPMs don't vary much....

No accessories were running at all.

So I just tried some things:

1. The noise is there whether it's the iPod, the radio, or a CD.

2. I disconnected one of the small wires from the alternator, and the noise is still there.

3. I disconnected the power line for the amp from the starter relay and connected it directly to the battery, thinking that MAYBE since the MSD Ignition Box and the alternator bypass wire were connected there too it might be causing the noise.  However, that did nothing, as the noise is still there.

4. I'm not sure what this means, but on the back of the stereo deck itself, I have 2 sets of the RCA cables connected.  One set connects to the amp, and then which from there wires to the 6x9 speakers.

The othe RCA set connects to to the amp, which then goes to the subwoofer.

When I leave the RCA cable connected that feeds the 6x9's, but disconnect the RCA cable that feeds the subwoofer, the noise seems to disappear.  If I disconnect the RCA cable for the 6x9's, but leave the one connected for the subwoofer, the noise is still there.

I know the subwoofer works correctly, because when the car is not running, it sounds great, all of it, speakers and sub, through the amplifier. No extra "noise" whatsoever.

[DodgeGuy]

Just an update in case somebody has a similar problem in the future and does a topic search.


I ended up finding the problem, which was having the RCA cables running in such close proximity to the main power wire for the amp (as I mentioned in my original post, I should have listened to myself when doing the original install  ).

In any event, I left the power feed on the driver's side, and ran  the two RCA cables down the passenger side, got everything all tucked away again, and it sounds awesome, with no "buzzing" noise anymore with the car running.

[1 Wild R/T]

Yup, IO should have remembered/mentioned that possibility...  Glad you got it fixed...