MSD Digital 6 and Sterio Hissing?

[Kevin Hebert]

With the engine running I have very annoying hissing from the sterio ,, only wish I could spell it! Whole car rebuild, all new parts, old sterio! Ignition / filters?
TIA Kevin

[project hotrod]

From the MSD site... It can also be used on 6 series ignitions but is "recommended" on 7 and 8 series.
Part number 8830


"If you experience radio noise after installing the MSD Ignition, you may need to install an MSD Noise Filter. Electro Magnetic Interference (EMI) is occasionally generated from the MSD power cables and can be easily eliminated by installing the Noise Filter on the heavy power supply wires coming from the MSD. When the MSD draws current, it will draw through the Noise Filter instead of directly from the battery, so all other accessories that operate off 12 volts, like the radio, fuel pump, or the engine computer, will be unaffected by the MSD.The Noise Filter will also prevent damage to the MSD during jump-starts and will keep a vehicle’s 12-volt line “clean” by removing any voltage and current surges that could interfere with the operation of some MSD accessories such as the Soft Touch Rev Control or the Two Step Module Selector. It is recommended that the Noise Filter be used on installations with the MSD 7 and 8 Series Igni*tions to prevent this interference."

[Magntik]

I had the same problem, bought the noise filter from Summit for $50, and it didn't help.

I stopped by a local stereo shop and they help me "fix" the stereo system in my car.

We ran a larger power wire to the amps, ran a ground from the negative post on the battery to the firewall where a engine ground strap was. And Ran a larger ground wire from clean metal in the trunk to a distribution block and grounded both amps to the distribution block.
Problem solved.

Stereo guy said somthing about good continutity in the chasis ground front to rear. And running the ground wire from the battery to the firewall helped make sure the "tub" of the car was a good ground.

Not sure how correct he was, but that noise is gone.
The heavier wires for the power and ground are 4 guage.

Hope it works for you.

[Kevin Hebert]

Thanks Guy's , looking forward to having music again! :git:

[MiDiablo]

In all my experiences a "radio hiss" is usually caused by a faulty ground. Sometimes something as small as not having removed (wire wheel) all the paint from the metal before securing the ground strap, and other times it can be because the wires aren't up to "snuff" as mentioned a few posts above me.

Also, I always use 0 gauge power wires, and between 0-4 gauge ground wires in my installs.

Hope you got'er fixed!!

[MCOR Automotive LLC]

Sometimes the filters help, but they are usually just covering up the real problem. If a system (both the cars' basic electrical and the audio/video system) are both wired correctly, there should be absolutely no need for any filters, ground loop isolators, etc. We don't even stock them-that is the easy way out.

What the stereo shop did was absolutely correct. It is IMPERITIVE that the factory electrical system is of the proper guage and proper ground points. All too many times people just put in a large system, maybe even run all large 0 to 4 guage wiring just to find that their factory (or retrofitted in the case of the older cars) wiring is 10 guage and only the engine block is grounded.

In the audio world, there is a process known as the "Big Three Upgrade". It is an essential part of building a correct system. It involves running at least 2 guage wiring from the battery positive fuse box, from the battery positive to the alternator, and from the negative battery post to the body (well sanded point of contact) and to the engine block.

We have had tons of instances where customers even realized louder and crisper tones from their stereos after doing this relatively simple upgrade.

And for you classic big block guys, this is a must (you need this power just to crank over the starter and that high compression).

If you are handy, parts and wiring can run as little as about $40 and labor is usually only about three hours or less.