SSInnovations

iTrader: (8)

I'm completely lost here and would appreciate some help if any of you guys have had this issue before. I just competed installation of a new stereo in my 98SS - I eliminated the Monsoon system and replaced it with a new head unit, 5 channel amp, and component speakers. I tuned the system with a DD1 to make sure the gains are perfectly matched.

Issue:
The moment the car is turned on there is high pitch static in the front speakers (only the fronts). The noise is present at all times, even when the head unit is on mute. As I turn the volume up it will overpower the noise but I can still head an underlying high pitched hum. Almost like a tea kettle sound.

RCA cables are not the issue
There is no issue with the individual channels (1,2,3,4) - I connected a single lead from the RCA's to each channel, it is dead quiet
Channels 3&4 do not have the issue
I confirmed it's not the amp, I can play music from iPad + RCA through all channels without any noise

Now the weird part, when I plug only one RCA into Channel 1, it's fine. The moment I plug the second RCA cable into Channel 2 the noise starts. Any idea what's going on here? All components are new and relatively high end.

B52bombardier1

Something in the wiring of your new stereo is acting as an antenna to pick up electrical system noise. You say this problem only occurs when the "car is turned on".

Turned on to run but no engine running?

Turned on with the engine running?

If with engine running, does the noise change when you blip the throttle?

This should be manageable to fix using standard noise reduction techniques for car stereos. I'm thinking RFI filter kit or perhaps Type 43 or Type 75 split toroids (completely passive) on the offending wire that is acting as the antenna. The engineering discussion on how these work is below:

https://palomar-engineers.com/ferrit...-mix-selection

Mouser Elecgtronics or Digi-Key should also stock these. With the loss of Radio Shack, we must turn to the Internet to find items like these. I really miss Radio Shack . . . . I spent so much allowance money there when I was a kid.

Rick

LLLosingit

iTrader: (4)

Sounds like an back feed problem, Try adding a ground to the amp or isolating components. In other words either pull the front speakers so they are not grounded to the chassis and see if the noise goes away or swap front and rear outputs and see if the noise follows to the rear speakers. or try another set of speakers that aren't mounted.
Also check that wires are running close to other electronics like fans and such. It may take a little work but you should be able to narrow down the problem thru process of elimination.

LLLosingit

iTrader: (4)

I was thinking the same thing but usually the noise comes out of all speakers not just front or rear and newer cars don't seem to have the issue like the old ignition systems used to.

SSInnovations

iTrader: (8)

Thanks Rick!

Some more details:

It is there when turned on to run with no engine running, and the same when the engine is running. There is no change when I blip the throttle. One weird thing I have noticed, the sound changes when I turn the interior light dimmer up and down. Does not go away, just makes a weird feedback sound.

I think you're right about just using a noise filter, but I was really hoping to find the actual problem. What has been throwing me off is that channel 3&4 are fine. And Channel 1 and 2 are independently okay but not okay when both are plugged in. If this was a wiring noise issue wouldn't it affect all channels?

SSInnovations

iTrader: (8)

I haven't tried pulling any speakers yet but the noise definitely seems to be an issue up at the head unit. I tried plugging an iPad directly into the amp and the front channels play perfectly fine. Also each channel independently plays fine, it only starts when channel 1&2 are both connected. Do you think it could be a head unit ground problem (instead of amp problem)?