New Stereo = RPM noise through speakers

[ajw45]

I just installed a new Nakamichi CD400 and everything sounded great until I started the car. With the car running I'm getting a buzzing through the speakers that changes with engine rpm. This was with the stereo connected to the brown ground wire. The brown and black wires that the stock stereo used don't seem to be suitable grounds (one was noise free but would shut down the stereo everytime I used the brakes while the other had some noise and intermittent grounding) and I even tried wiring to the large nut under the steering rack where there is a massize collection of ground (brown) wires but found the same rpm related buzzing there too.

Does anyone have a suggestion for fixing this issue? Are there any other ground points close to the stereo rather than running a wire all the way to the trunk where the battery is (M5)?

TIA!

[greg.epps]

Install your own relay to turn on 12v direct from battery when the ignition is on. This is what we did when I was in the Marines installing radios in the MP (POS) Chevy Lumina cruisers, worked every time.

[ajw45]

So the conscensus is that my problem is with a dirty power feed and not a ground issue?

[John]

sometimes these are an endless search. Check all the grounds, from the battery to the body and the ground pionts under the dash and engine area. Also, some stereos just pick noise and in some cars there is no eliminating it. I had a pioneer in my Scout that nothing would make it quiet. If you have high power ignitions that can make endless hassels. Is the power cord near the speaker wires? Are there pre amp or RCA cords close to power? Do you have any extra amps? If so you may need a ground loop isolator

[Badger]

usually alternator or rpm noise is from a BAD GROUND. 90% of the time. make sure you have the best ground possible. then if you still have the noise run direct power from batter for the fused power line on the back of the radio. the ignition power for the radio should not pick up any noise signals. try that and check back tomorrow to see if it worked or give you some more ideas.

badger

[Josh in BrewCity]

My stereo ground is connected directly to the battery to resolve this issue. You should also run a larger gauge wire from the fuse box for power to the head unit. The original BMW head unit did not have an amplifier and did not demand nearly the power your aftermarket will. You will see the stereo dim when bass hits if you don't do the separate power feed.