Stereo guys...Ignition noise thru stereo cure?

Hey guys what do ya'all use the kill that buzzing noise in your car stereos that increases with RPM. I have an MSD box/coil triggered by a point type dist.

Do we run some sort of capacitor in the power wire to the head unit or do we run one in the amp power cable?

Any advice and where to wire it in and exactly what I need to buy?

Rat

 

I used to own a custom car audio shop, but it’s been about 10 years and I may be a little rusty on the troubleshooting, so anybody else can jump in and correct me if I’m wrong. I don’t think I ever ran into a system in a car that had an MSD box so I don’t know how noisy they are.

First off, if you are running bottom end stuff, good luck…you may never get rid of the noise. Like most things in life ‘ya get what you pay for.

Is the noise on radio and tape/cd or only radio? It sounds like you are running at least one amp, yes? The radio (head unit) you are using, is there speaker outputs on it? If so I would hook up test speaker to the radio and see if the noise is in it. (Pull the fuse from your amp so it stays off) If so then you know the noise is most likely coming up the power or ground of the head unit. (Or antenna if you only hear it on AM or FM)

If no noise from the radio, put the fuse back in the amp and unplug the RCA cables from the input of the amp. Fire it up and listen for your noise. If its there, its getting in the amp power or ground. Make sure you ran power wire of a large enough gauge to support your amp all the way to the Battery. (Don’t burn down your car, put a fuse right at the Battery end!!) Run the power wire to the amp on the opposite side of the car from the RCA cables. Don’t use the el-cheepo cables either. Make sure all connections including the ground are first rate. I always used to crimp and solder the power connections. Good grounds are essential; don’t just stick the ground wire under any old bolt. Find a place to drill a hole and scrape paint and nut and bolt it.

If the noise is not there with the RCA cables unplugged but shows up when you plug them in, you most likely have current flowing on the shield of the RCA cables (or a bad cable). You can get a “Ground loop isolator” at most car audio shops to go in line with the RCA’s and it will break that path. Don’t go too cheep, as they don’t seem to hold up. Some people claim to be able to hear a loss of the high frequency response of the system with these, but unless you have an ultra high-end system, you won’t notice.

Hope this is helpful!

 

http://www.msdignition.com/1troubleshoot.htm

They have a pdf file on troubleshooting ignition noises

 

Also, be sure to check your ground cable. Make sure it is definately less then a foot long, and where you attach it to your car,make sure the sheet metal is grounded down. I have always followed that rule, and I have never ever recieved any intereference from the cars I've installed systems in. That may be the problem, or not, but be sure to check it out.

 

Good answer Moordoor!

I have an MSD 6AL box in my car and had major radio noise. A good ground and thier noise filter got rid of most of it. With a 6AL, its hard to eliminate all of the noise.

I did bypass the box and ran a HEI dizzy and that eliminated my noise.