so my friend just got this jl 4 channel amp to power his inf. kappa interiors and when he hooked it up, he gets a whining noise coming through all of the interiors and when he hits the gas, the noise gets louder! i talked to a few ppl but keep getting diff answers as to what it can be. someone said to get something (forgot what he called it) to plug your rca's into. he said its a small cube or something. another person told me its a bad ground! his amp with his sub is fine. no whining coming out of the sub. he also has a capacitor hooked up....dont know who did the install! would it be two seperate grounds for the sub and interiors? doesn't the ground and power come off of the capacitor? im really lost and could use some insight please! reps given and thanx in advance!

 

I am going to guess it is the headunit. Take a piece of raw wire and wrap it around the metal part of the RCAs (behind the HU) and then ground that wire to the frame of the car.

 

Its alternator whine man, and all of that stuff could be a possibility. Make sure the paint where you have it grounded is sanded down to bare metal. If possible take a multimeter and measure resistance between the location you're grounding and the negative battery terminal. make sure everything in your system is grounded at the same location...not 3 feet away from each other.

The box your friend was talking about is a ground loop isolater, they work like 50% of the time so you could try that but it will cost you a little money...usually like 10-15 bucks.

listen real close to the sub and flip it to all pass for a couple seconds, sometimes the LP crossover will filter out the whine so you wont hear it as predominately as the highs amp. You can also check if you have bad RCAs by just getting a set off of a friend and tossing them from behind the deck back to the amp, not having to run them under the carpet, because as said...theres so much stuff it could be...I've even seen bad spark plug wires cause the issue in a couple instances

 

thanx guys! repped!

 

No prob man...good luck! its deffinatly not the funnest thing to have happen...I remember we had some simple stuff solve it too (an amp was mounted in the side wall of a navigator, the power wire was going on the bottom side of the amp...we rerouted it over the top of the amp and it solved the issue)

 

I'm having the same issue does he have a poineer deck becaus thats what usally causes it on these head unit I am going to try the rca ground fix to see if it helps.

 

I don't know who started that ridiculous rumor that wrapping copper wire around the grounds will help anything.

The common ground for the radio is the ground wire that runs to ground from the harness.
If anything you should route the harness ground to the chassis at a sanded spot with a stainless steel screw.

Proper wiring in the first place > that ugly picture ^

 

yea it is a pioneer deck...i was supposed to help him troubleshoot today but i got called in to work and its pouring now! im goin to try some of what you say tomm!

 

Actually, I would agree with the wrapping of the RCA's to a ground. When you are doing a high volume of FM modulators (dealership headrest TV's, etc.), amp installs, etc, this is a great known "down n dirty" method to isolate the issues and quickly. I have seen many vehicles that had all brand new gear installed, good equipment with power and RCA's run opposite sides of the vehicle, still getting the whine. Even gone as far as running a temp. jumper for amp ground to the same factory radio wire ground on the vehicle still to get a whine. Sometimes it just cannot be contained even when completely and professionally wired. We try to only use ground loop isolators as a last resort because as aforementioned, they are only about 50% successful.

That being mentioned, ALWAYS start with the basics- good equipment, good wiring, sanded and tight amp grounds, RCA's run completely opposite side of vehicle from power cabling and kept completely seperated, etc. If all else fails, ground the RCA's (I would wrap the raw wire as in the pics but we have found that it is more successful sending the other end of the wire NOT to the radio chassis but to the factory ground wire going into the factory radio harness).

Do it for a living managing multiple installs per day (all done professionally and properly), and you are bound to run into this a few times! Ask any professional installer. The difference is the installers who can actually fix it. We probably get at least one of these jobs a week where someone has ripped their hair out going over wiring, installing isolators, etc just to find that this method ends up being the only one that works!

 

There is a diffrence between grounding the headunit and grounding the rcas This is a common problem on poineer headunits that is why I asked what it was.