Added an aftermarket amp where the stock amp was along with a new head unit in the dash. I'm getting a slight whining sound on acceleration which I believe is from the amp picking up noise from the alternator or fuel pump. I've tried a noise isolator on the cables as well as several different grounding points for the amp.

Is there another location to fish these wires other than the stock passthrough which would be further away from the fuel pump? Will better shielded RCA cables fix the problem? Any help is appreciated.

 

Usually with the whining noise, it's b/c of a bad ground or that you're running the power cables right along side the speaker cable. I had it on my M3 and I hated driving that car b.c of it.

Edwin

 

I had this problem in my old Supra where I tried using a ground loop isolator to fix it, but it didn't really help much. I ended up rewiring all the grounds to a single point to reduce the whine.

 

I had that sound when I first installed my stereo. I was told to make sure the speaker wires were not close to the power wires. I was careful to isolate the amp main power line from the speaker wires, but found that I had the amp remote power "on-off" switch wire running along with the speaker output wire from the head unit and through the fire wall. I separated this power lead from the speaker output wires at the head unit and ran them through the firewall at two different grommet points and the noise went completely away.

 

it is called alternator whine. not sure why it does it. it happened back to me in my teen years. i think the fix was to go with some huge 4 or 6 gauge power cable to the amp, make sure it is a fusable link.

 

Run power directly from the battery & you'll avoid all the noises. As the previous poster recommended, make sure you fuse the wiring right next to the battery.

 

It is caused by interference being picked up in the RCA or speaker lines OR the grounds are seeing different impedance from the amp compared to the headunit. The units should be both grounded and powered up at the same points, all speak lines and RCA lines should be clear of any power line, for the stereo or not. The last thing would be a ground loop issue which would be component incompatibility, but this doesn't happen much anymore with the newer units. You can also buy group loop isolators. they plug directly into the RCAs to kill the noise. Most of the time some is still there but 95% of it is gone

 

Can you tell me what second gromet point you used for the remote amp wire?

I have so far only seen the one empty grommet behind the battery.
Thanks

 

All the way over to the edge on the drivers side there is a rubber wire harness that plugs in a hole to allow a batch of wires to go through the fire wall. The top and bottom of the rubber piece can be drilled to pass additional wires through - just be careful to stay away from the main part of the harness with the drill bit. The top offers more room to drill a hole, than the bottom. I believe these are the OEM stereo and speaker wires, but I am not certain. I had the "whine" after my install, but when I utilized this second passageway to separate the wires, it cleared right up. The whine definitely had to do with power running along with sound wires. I used some foam like from a small round, hollow flotation noodle and put all the speaker wires in it, as they left the head unit and kept the power lines out of the noodle. This kept the speaker wires separated from the power wires by a few inches in the console area behing the head unit and then I kept them apart from there on, as I routed them up front.

 

Did everyone run their head units and amp power lines direcxtly to the batery?
Right now I have the head unit sourcing power from the factory harness and the amp direct to the battery. I have also done some work seperating the power, ground and remote amp wires from the head unit from being near the RCAs.

 

I did the amp directly from the battery and the head unit from the OEM wiring and was able to eliminate the whine by separating the power wires from the speaker wires.

 

Many are using ground isolators, filters and careful wiring.

I've been going directly to the battery (via a fusible link) since my first aftermarket "stereo", every car since with no issues.
(Good old days story alert!) This was 1981; a radio/cassette head unit to a "20 W" booster/equalizer. It was the family car (some godforsaken British Leyland model ), I created a new "deck" out of the rear parcel shelf and added two 8" domestic woofer/tweeter units. I had the only car with booming bass in the neighborhood. (Not sure when it became more common)