ground loop on high/speaker level input to amplifier

[darkblade382]

well i am new here(but i do have audio and car audio experience)

i am seeking help for a problem.

i have installed a amplifier for a subwoofer in my car,

but i get alternator whine when i increase the engines rpm

i experienced this before (see below) so i knew this was a ground loop

current situation

the factory head unit does not have rca connections so,

my amplifier is connected to the high level from the rear speakers car.

the speaker wires(running on the right side of the car, where as the power and remote run left.) go into the high level input connector on the amplifier.

i isolated the amplifier as the loop's source.

i tried moving the ground but this did not help.

what can i do to fix this?

(below)

other audio devices in the car are: a car kit connected via a ground loop isolator(it had a ground loop too but it was low level, so i added a isolator and this fixed the problem) to a aftermarket aux unit ,that is in turn connected to the head unit.

Click to read more...

 

[dubstepper1000]

I don't know a whole lot about alternators but it sounds like the alternator is either starting to go after lots of use, or the belt connecting it to the engine is off by a little bit, even .5 mm off can cause a screeching or whine noise. Does the whine stop when your amp and everything is disconnected? Start by disconnecting all your amps and power cords and rebuilding your system one by one, checking between each part for the whine your describing. If it still whines when everything is disconnected, I would go see a mechanic.

 

[bradl79 10+ year member]

check a different set of RCA's or make sure that ur speaker wire is not hitting any metal from ur door speakers and make sure they are secured properly and not loose, are u using quick disconnects?

 

[dubstepper1000]

check a different set of RCA's or make sure that ur speaker wire is not hitting any metal from ur door speakers and make sure they are secured properly and not loose, are u using quick disconnects?

He isn't using RCA's, He said he is using high level speaker wire.

 

[darkblade382]

I don't know a whole lot about alternators but it sounds like the alternator is either starting to go after lots of use, or the belt connecting it to the engine is off by a little bit, even .5 mm off can cause a screeching or whine noise. Does the whine stop when your amp and everything is disconnected? Start by disconnecting all your amps and power cords and rebuilding your system one by one, checking between each part for the whine your describing. If it still whines when everything is disconnected, I would go see a mechanic.

just to clear this up

the whine stops when i disconnect the amplifier

so it is not a mechanical problem

and i am not using rca cables

i am using speaker/high level

 

[The Camry]

How To - Car Stereo - In Pursuit of a Noise-Free System: The Ten Commandments of Noise Prevention

Noise suppression guide

 

[darkblade382]

i already did all these steps before posting here.

i determined the amplifier was the source of the loop

i changed ground points , this did not help.

i cant put a ground loop isolator between a high/speaker level cable , because they are only for low-level in my understanding.

 

[trumpet 5,000+ posts]

It's possible the amplifier is faulty. Test it outside the vehicle.

 

[dubstepper1000]

If you have another amp to test i would test it in the car and see what happens, could be a faulty amp like trumpet said. If you wanted to add a ground loop, you can use an LOC to get RCA from the high level input, idk if this will solve your problem though. If all else fails, you can try to bring it into an install shop and see if they can diagnose your problem, I do this from time to time and they usually don't charge much to identify the problem. Always good to get a second person to troubleshoot if you cant seem to pinpoint the problem.

 

[los33]

Upgrading the ground on the stock headunit at times can help.

What type of speaker wires are being used to connect the headunit to amp thru highs speaker level?

Are all stock eq's set flat?

Also lower the gain and see if engine whine is still there.

If it is not there anymore after lowering gains then you should get a cleansweep or loc

Sent from my Z970 using Tapatalk

 

[darkblade382]

when i connect my phone to the amp there is no whine (the amp is not faulty)

all the headunits eq are set to 0(bass and treble)

if i lower the gain it is still there but less

i use normal unshielded speaker wire ,

1 postive wire and a separate negative cable for each channel ( 4 wires in total)

 

[los33]

when i connect my phone to the amp there is no whine (the amp is not faulty)all the headunits eq are set to 0(bass and treble)

if i lower the gain it is still there but less

i use normal unshielded speaker wire ,

1 postive wire and a separate negative cable for each channel ( 4 wires in total)

You may consider using better wire as long distance 16+ gauge non shielded wire can cause noise.

It sounds to me that the headunit is causing the noise.

A loc or dsp or cleansweep will clear the problem.

Sent from my Z970 using Tapatalk

 

[darkblade382]

i might look into a loc, but wont he noise transfer or do i need to install a ground loop isolator after the loc

i prefer not to buy a cleansweep or dsp because they are a bit to pricey at the moment