stupid stereo

quick question about my stereo. So i wired a new head unit and an amp and a sub, all that stuff works great, I tried replacing the 6.5"s on the back gate with a 3-way 6.5" and everything works great, i ran it off channel three of my amp and when the truck isnt RUNNING it's got great sound, but when the truck is running, theres a pretty loud whine coming from just that one speaker.
What could cause switched interference like that?
Just to try and answer any setup questions that may come first, im running 20ft rca's from the back of the head unit (preamp rear) into the amp, theres no L/R on the amp, only one input for each channel, so the rca's are plugged into channel 3 and 4's inputs. From the back of the amp, im running reg speaker wire over to the 3-way on the door. Im not bridging or anything. do you think i have a bad connection at the head unit? Idk what would cause the interference only when the truck is on.

Best

Turf

You need a better ground.

Ground for what? the whole stereo? then how come everything else works just fine? i was thinking it had something to do with the rca cables i used. the speaker ground runs from the speaker to the amp, and the amp is grounded real well. IDK, spike suggested trying to take the alternator out and seeing if that fixes it. if it does, it would mean that the cables aren't shielded well enough. idk. stupid stereo

Are you running threw the factory amp or did you bypass it? The factory headunit ground is like 16-18 guage and I would use at least 14 for any aftermarket head units. You can try taking the belt off and see if that helps also.

bypassed the factory amp. but thats a good point about the gauge of the factory ground. i'll go out there and fiddle with it (the radio) in a little bit.

heres what i know now, ive shown the same ground to both connections at the same time. Gone so far as running a jumper cable from the battery terminal, to the stereo ground and the amp ground at the same time. Still get the interference, swapped the RCAs for the sub for the ones for the speaker, same interference. The sub i bridged channel 1-2, the preamps for the speaker run to channel 3-4 of the amp, but im only running speaker wire off channel 3. The interference starts when i plug the second rca (from stereo preamp (rear)) into channel 4, even though the channel im running speaker wire from is 3. It's very confusing, I wish i had another speaker to test it with. When i touch the speaker ground (from the back of the 3 way speaker) to the amp ground, it pops and the whining gets louder. Next im going to figure out how to take the fan belt off so i can check the alternator, but i dont even know what that would tell me.
Frustrated.

ummm

maybe this will be easier

http://www.newlaunches.com/archives/lasonic_ghetto_blaster_boombox_with_ipod_dock.php

Schuler, fix this

New rca's didnt help, went back to the original, here's my new ground, brought straight from the back of the head unit harness, joined to solid wire and fixed to the firewall


Here's what i learned today. The noise IS affected by engine RPM, i.e. throttle up-->whine up.
the noise DOESNT matter what channels are plugged in, when i run the 6.5 off of channel 3 it whines, when i run it off channel 4 it whines.
When i only plug in one RCA to the back of the amp for channels 3&4 (for the channel running the speaker) i get no sound, when i plug in the one that doesn't have the speaker run off of it, i get noise.
Is there anything else diagnostic wise i can do to this thing? I'm pretty well stumped. I'll re-check the amp ground tomorrow, but it's done similarly to the head unit ground.
Is this something i could take to an indy shop and pay them to fix? Or would i waste all my money on them trying to find the problem?

If the whine is changing with engine rpms its the alternater. Get one of those inline noise filters and see if that helps.

Hilltoppersx wrote:

ummm

maybe this will be easier

http://www.newlaunches.com/archives/lasonic_ghetto_blaster_boombox_with_ipod_dock.php

Wow thats a whole lot of bling in a little package.