raigen18

Just recently I noticed that whenever the car is running that I am getting a buzzing and whining noise that changes according to engine rpm. I have tried almost everything including:

1. upgrading big 3 with 4 AWG wiring
2. swapping out the amp with a brand new one (same model) JBL GTO 100.4
3. tried rerunning the rca cables (had them run through the cabin)
4. used brand new rca cables
5. swapped out the head unit with a brand new one
6. tried grounding head unit directly to chassis and battery
7. 4 awg wiring for both power and ground cables for amps
8. rca cables run on separate side of the car
9. used 2 ground loop isolators (haven't tried using one for all 3 pre outs yet)

The buzzing noise seems to change when I take out the head unit from the dash or if I play around with the rca cables. The buzzing noise seems to vary from very little to really loud depending on where the rca cables are placed behind the dash. I have also tried grounding the rca outer shields to the deck chassis but the buzzing is still there. Both amps are grounded to the same chassis point which has been sanded down to bare metal.


Here's the equipment i'm running:

Amps: JBL GTO 100.4 + Alpine MRP-m500
Sub: alpine type r swr-1242d
speakers: 2x jbl gto 938 + 2x jbl p660C
head unit: pioneer deh-p4200ub

Any help is greatly appreciated as this issue has been bugging me like crazy...

lpchouinard

if you unplug the RCA at the amp the noise still there?

raigen18

I haven't tried unplugging the rca's at the amp but I have from the head unit (should be the same?) and the noise is gone when they are disconnected.

lpchouinard

ok then, even if you tried to ground the RCA on the HU i think you have the pico fuse issue... have another deck to test by any chance? if you feel like driving i have a 6100bt to try

raigen18

the thing is that I tried a brand new alpine deck before and I still got the exact buzzing + alternator whine noise so I think the problem isn't with the deck. It seems like the rcas are picking up noise around the dash cavity but i'm not sure.

lpchouinard

possible, but when you unplugged the RCA at the deck the noise stopped so it's really when the deck is in the circuit that you get the noise... Have you tried another ground for the amp?

raigen18

I have not but currently I am using the seatbelt bolt as my main ground for both amps. I will see if relocating the ground elsewhere helps.

Also I forgot to mention that the buzzing noise seems to go away if I only have the rcas for the rear and sub channel plugged in. As soon as all 3 channels are plugged in, the noise comes back.

lpchouinard

def try another ground! seatbelt bolt for ground is not the best

raigen18

update: okay so I moved the ground for both amps to the rear strut mounting bolt as well as added an extra ground wire to the chassis of the deck. I also re-adjusted the gain on the 4 channel amp and now I can't hear the any buzzing or alternator whine even with the volume at 0. I guess the gain was set too high (1/2) before and now it's just a little pass 1/4.

For people with pioneer decks, what is your normal listening volume? The max seems to be 62 and with the re-adjusted gains, I need to crank the volume up to at least 20-25 and that's with no bass boost, no loudness, flat eq, and SLA at +3.