Alternator Whine/Ground Loop, ready to give up!

Alright guys, I've tried every trick in the book.

I installed a 2ch Dual XPR52 behind my rear seats powering Kicker components in the front. Stock HU still powering rear speakers. Used high level inputs to tap into signal for the amp. The amp has it's own wiring harness that accepts speaker level inputs. All signal wires and remote wire are run through the driver's side kick panel and down the driver's side footwells, power is run to a fuse box behind the rear seats down the passenger's side footwells. Power/signal cables are not near eachother until they connect to the amp.

I have tried everything. Moving wires around, moving the amp around, nothing changes the constant hum (ground loop) and the alternator whine. Those sounds remain no matter what. I moved the ground to several different locations, get no change in sound. I've even moved the remote wire to different 12v locations (even tried jumping it all the way to the battery) and no change in noise.

I know most of the tricks for this stuff, but I've never had this difficult of a time diagnosing. Just wanted to know if anyone had this problem with this particular truck, and there is something truck-specific I should be looking for. I'm ready to give up and just call the amp shit and get a new one. It does only have a 75dba signal to noise ratio, but I've installed amps with that SNR before with no issue. IDK. Any thoughts/inputs are definitely appreciated.

 

Maybe
manethon can shed some light for you

 

Cheap amp is likely the culprit. I would try an outboard hi-low converter first, then try a ground loop isolator between it and the amp. You could also try running an extra ground wire from the amp ground to the stereo ground, but it really shouldn't need it.

 

I was thinking of a hi-low converter. I was also thinking of just throwing the Dual 2ch amp in the garbage.

I have a JL 250/1 mono powering the sub hooked up to the SAME high level inputs - no ground loop/alternator noise to the sub. That's gotta mean the 2ch amp is just shit.

 

While I agree about the amp, the test of the noise not going through the sub amp does not tell us much. The frequency is much higher than what the sub will produce with any authority, plus it has a low pass filter on it (as it should) that will kill the noise reguardless. It is reallly really difficult to get an alternator whine to come through a sub. I would go and get a jl jx400/4d and bridge it to your front speakers or power the rear speakers as well with the extra 2 channels.

 

Good point...

Gonna try a new amp with a higher SNR and see if that solves the issue. Will advise.

 

Is the noise a hum or a high-pitched whine?? If it's a hum, you can check this by disconnecting the audio inputs to the amp. If the hum disappears, there is a grounding problem between the stereo and the amp. Connecting them both to a common ground point will usually fix this. If it still hums with the audio inputs disconnected, then chances are the amp itself is defective. If you don't have any problems with your existing equipment then you can be pretty certain that the wiring is fine.
Good Luck.

- JAMES

 

With key to ON (engine off) the noise sounds like textbook ground loop (constant hum, doesn't change with volume but changes with gain). With engine running i still hear the hum, but also get alternator whine that varies with RPMs.

When I disconnect the high level inputs to the amp the noise goes away completely. Same thing if I disconnect the outputs (amp to speakers). I understand that this points to a problem with the high level input wiring, but I don't know how the hell else I could run these things. I ran them once, pulled them all out, and ran them again. No change. They are in the driver side footwells and kickpanel, the power wire is down the passenger side. I have good connections all the way around. I've tried 3 different grounding points (yes stripping the paint off each time).

This is why I'm wondering if the amp just doesn't have the ability to filter out the electrical system noise because it's a cheap-o amp. The installation is solid...

 

Installed a Kicker DX series 2ch amp that I got from a buddy and....drumroll please....all of my problems are SOLVED.

Dual makes CRAP

 

Glad you got it fixed. Enjoy.


- JAMES