matt11601

I read the FAQ on engine whine, but it seems like they're talking about the engine whine coming through all speakers in the car. My engine whine only comes through one speaker. The FAQ recommends all sorts of things like better grounding, re-routing wires, etc, but would those suggestions apply to me? Or is something else going on?

Thanks for any help you can offer.

-Matt

PS I was thinking the RCA wire that feeds that particular speaker might be cut or nicked somewhere? I don't know, just a thought.

pancit175

If it happens to be a problem with the RCA wire a couple of ways to test that out is to simply switch the RCAs from the noisy one to one that is not as noisy. This should be done at the amp leads or the leads at the HU. There is a possibility that the problem may occur at the amp itself or the deck. In one particular situation I've seen the amp seemed to create noise in one speaker. Upon further investigation it happened to be a bad channel on the amplifier. So starting off by switching the RCA leads will help to determine that.

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matt11601

If I understand you correctly, you're saying test the channels on the actual amp by switching RCA cables to see if the noise persists? And if the noise comes through the newly switched cable on the very same speaker then I know the problem is with that particular amp channel?

DarquePervert

If you switch the left & right channels going into the amp and the noise switches sides as well, then the problem is the cable itself or possibly your audio source (although not likely).
If you switch the left & right channels going into the amp and the noise stays on the same side, then the problem could be the amp channel or the speaker wiring or possibly the speaker itself (although not likely).

I'm faced w/ scenario #1 thanks to some cheap RCA cables I purchased.

Also, there's a whole FAQ about troubleshooting engine noise that will likely be helpful in your plight: http://www.mp3car.com/vbulletin/advf...iew&advfaqid=8

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matt11601

Got it. Thank you.

So let's say it turns out to be the amp. Is my next step to buy a ground-loop isolator?

pancit175

I've seen in some situations that the noise could not be helped by a GLI. In the instance I began to mention above, the noise was more prevelant when the engine was on. Although, upon inspection, I realized that the noise was still present when the engine was off, but at a lower level. In that specific case, the grounds at the amps RCA terminals were harboring a resistance or a floating ground, but only on specific channels. So I recommended to the customer to get a new amp and that fixed everything.

In your specific case, I would venture to guess that it may be a similar situation. If it happened to be altenator whine, then more often it would be present on multiple chanels/speakers as opposed to just one single chanel. As I mentioned earlier, by switching the RCAs, at the amp and the source unit, you can determine if its a problem with either the amp, cable, or headunit. You can attempt to use a GLI and if it works, then it works. But realize that a GLI is only a bandaid for larger problems, such as bad amp, cable, or HU. So it just takes a little trial and error.

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durwood

It could also be a speaker wire barely touching the chassis. Some amps go into protect while others continue to play but you get nasty engine noise.

I'd switch your left and right RCA cables as suggested first to see if the problems follows though.


It could also be that your power wire is run too close to your passive crossovers inducing EMI into one of the coils. If you don't have separate components or passive crossovers then you could neglect this possibility.

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pancit175

Also if it comes down to it, if when you do switch the RCAs and there is no change to the static on the one speaker, one way to see if its the speaker line and not the amp is to switch the speaker line.

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matt11601

Very interesting information.

I did a quick test this morning in the freezing cold. I pulled out the RCA lead from the computer side and the noise was absolutely gone. I plugged it back in and the noise re-appeared. I took the same lead out and the noise was gone again. So it seems like the problem is with the RCA cables and not the amp correct?

pancit175

Not really. By switching the RCA cables, and not just pulling it out, you can gather that type of information. But by just disconnecting the leads, the amp does not detect any type of input and does not have a referance to amplify the signal and effectively does not output anything. In theory, if the cable was defective and picking up ambient noise/EMF unplugging the source would still allow the noise from the cable to be picked up and sent to the amplifier.

There is another test with an RCA end and a resistor, to see if your amp is the cause, but I forget how to do it.

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matt11601

Ahhh I understand now. Thank you for the explanation. I'll post back.