Engine whine after a few minutes.

[jassing]

I have a system that just started a funky engine whine -- but it only happens after the car has been running a few minutes. Turn the engine on -- no whine, drive around, all fine, then it hits -- it's not a high pitched whine, but lower/deeper whine that is in step with engine revs.

Now here's the odd thing ( to me anyway ) -- it's only on the subwoofer out out of the EQ; The high/low out eq is fine. Grounding is fine (all power run directly to/from the battery) I have tried swapping out rca cables but that did not help.

I tried to use a ground loop isolator, but this did not help.

Thanks for any thoughts/ideas.

-j

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[West]

What head unit are you using?

And a description of your setup may help.

 

[Flex68 10+ year member]

You indicate that your grounds are "fine," but that is exactly what this sounds like.

Unfortunately, it may be internal grounding issues that show up only after things warm up....

I would suggest individually 'removing' any stand-alone EQ and/or amp to see if this resolves the issue you're hearing from ur sub(s)

 

[jassing]

I know it sounds like a bad ground -- that's why I checked it -- and rechecked it.

When connected to the battery, 0 resistance from ground lead to chassis. Disconnect ground lead from battery -- open circuit.

I just tried grounding the shield from crossover -> amp RCA cables, and that made it whine right off the bat not delayed. I tried grounding the rca from head to eq; no difference.

It's a JVC HD radio CD player head unit. I forget the model #.

RCA from the head feeds epicenter, epicenter feeds eq, eq feeds crossover, crossover feeds the amps amps feed the speakers.

I have tried skipping just about everything -- and the noise is the loudest when connected to the eq (Regardless of if it's in bypass or active mode). Skip the EQ and the noise remains, but at subdued levels, heck, even acceptable levels while driving; just not when stopped...

Have verified each device is properly powered (constant to power, open/closed appropriately for signal/power-on feed, and ground is correct -- and disappears if disconnected from the battery).

I have checked continuity of all rca cables and there are no shorts, and none are broken/open.

I'll try grounding the other rca cables as I can... the weird thing is that for months it's been fine...

thanks

-j

 

[jassing]

Just a follow up - I removed the sub amp and all noise went away. Add power and/or rca's back into system, and noise returns. it has good ground; but after isolating the offending unit; it turns out that the amp is overheating (or so it says) - it's off for repair now.