Hello everyone,

I've been working on my 420SEL's sound system and I've run into two issues:

1) Loud Buzz/Whine in speakers
When I have the car running there is this loud buzz/whine in the speakers. I'm not sure what it is. I had alternator whine in my 190E and was able to solve it with some ground loop isolators. Those fix the problem in the 420SEL however I loose a considerable amount of signal doing so. When I plug in a standalone mp3 player to the RCA cable feeding the cable everything is alright. No noise, just clean audio. I am wondering if it could be related to non-resistor type spark plugs. I swapped headunits, nothing changed.

2) This ****ty amplifier (Power Acoustik PS4-300) that I bought only seems to want to actually do its job when voltage is above 13v. The moment I load down the system with head lamps, a/c..etc the damned thing dims out. The power LED on it is still on and everything. It doesnt work all when the key is just on and the engine is off. I'm probably going to return it and buy a better one. Stupid waste of time.

While I can fix #2 relatively easy, I'm not so sure about #1. I cleaned the battery ground. I ran 12v power right from the battery to my headunit. I'm not sure what else to do. I even switched out batteries with my 300SD. I could switch out head units and see if that makes a difference....

What do you think?

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