Electrical 1966 289 Audio Interference, Noise, Whine

Discussion in 'Classic Mustang Specific Tech' started by Rakobernik, Oct 1, 2012.

  1. Hello there, I am new to the forum but have gained a ton of great information from this community before.

    I recently wired in a cord that both connects my iPhone to my speakers through RCA cables and also charges the phone through the 12V system. Now the speakers pick up and amplify every little bit of electrical interference the car puts out. Most notable is alternator whine but I also hear turn signals and even some crackling when the car is off. The problem is much worse when the phone is plugged in, but the noise is always there if the speakers are on.

    I have traced the problem down to the black (gnd) charging wire. There is very little noise with the RCAs and the red charging wire hooked up. But as soon as I ground the black wire all hell breaks loose. It doesn't seem to matter where I ground the wire, I get the same result. It is so sensitive that if I merely hold the wire in my hand and touch anything metal on the car, the speakers amplify it.

    I currently have the red wire attached to the lighter post and the black grounded to a screw behind the ashtray. Driving this system is a little amplifier that is wired into a spare port coming form the accessory fuse and grounded to the same ashtray screw. Another helpful detail may be that when I have the phone hooked up from the headphone port, there is no noise...but then the battery drains quickly, hence the new cord.

    Any ideas on what may be causing this or how to eliminate it would be really helpful. Thank you so much.

  2. I know there used to be a popular filter that you wired inline with the alternator, but I'm not sure that will help your situation. I have the same problem, my monster cable and IPOD have a very annoying high pitched whine...
  3. This may not even be it, but I would make sure the engine is grounded properly, there should be a block to chassis ground cable that gets lost over the years on these cars. Good luck and please update if you solve it with this or another method.
  4. im not sure which brand of iPod cable you have, but i know with our PAC cable, we had that issue. All you could do was replace it.
  5. Replace it with a different brand? What did you use that worked? What is PAC?
  6. ^^ ground loop On of your grounds isn't hooked up right. The same thing can happen on guitar pups and amps if i forgot to tie in one of my grounds.. :grin: