engine noise coming through amplifier

So, I just put in a new Eclipse XA2000 amp, (3122 wasn't cutting it ) and for some reason I'm gettting a little engine noise through my tweeters. But, through some testing I figured out it only happens when the line input is plugged in for each specific channel. If the left input is plugged in, the left channel does it. Right input plugged in, right channel does it. The pins of the RCA connectors at the amp when unplugged both have resistance readings to ground in the kilo-ohm range (ie, not much of a path to ground). And the outer barrels of the connectors both have a couple of ohms of resistance to ground. Nothing seems inconsistent between the two indicating that one is shorted to the chassis or anything. I'm not really sure what the readings should be, but that's what I got. The wire is just a normal patch cable from radio shack, and I'm running it the length of the car from the HU to the amp in the trunk. Oddly, the negative lead of the speakers on the right channel has a lower resistance to ground than the left channel. I think the left channel was in the kilo-ohm range, and the right channel was about 11 ohms. This seems weird to me, but I still think my problem is coming from the line input wire because the noise goes away with the inputs unplugged. Could it be that I just need a better shielded line input wire? The noise also gets worse when electrical stuff is turned on in the car. From that it seems like the alternator is causing it. Car is a '96 Mazda Miata.'96 Mazda Miata

what kind of wiring do you use?i would advise if there cheapos replace them and do you have all your wires wired on the same side. i would advise change that also i would put the power on the side the battery is and the signal and speaker wires on the other or if you what to get techincal you could put your signal in the center of the car.  sometime when your pushing alot of power you will get engine noise or alternator humming in your stereo good luck1993 sdv

Alpine 4x6 6x9 5 1/4 swr-10d4

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12.5 VGA flip down

Nettop pc w/10" touch screen

78nova

5-re audio 5x7 ,10" sub &

Xtx-500.5

"Take the faceplate off get the jumperpack"

Heres a question that I was always asked when I posted about "noise"...... what kind of deck?

Ok, I think I figured it out. See, the car has headrest speakers which I'm still running off of the HU because they're only little 3.5"s, and don't need to be very loud right next to your head. In order to not have to fade the head unit forward so much, I had the gain on the amp (powering the front speakers) cranked. Now, it's important to note that this doesn't mean I was cranking both my gain and my HU volume, I know all about clipping. I just had it turned up to take the place of the fader. Well, only problem is, setting the gain super sensitive means it picks up ANY engine noise as well as the true signal. My old amp didn't have this issue, but this is a class D with Eclipse's ICE power technology, so who knows what's going on inside the amp. Either way, yeah, I backed off the gain, and now any noise is down to a non-audible level. Deck is an Alpine CDA-9811. Oh, and the routing of the power and signal wires is a non-issue. It's a Miata, the battery is in the trunk stock. The amp is hooked directly to the battery terminals (with an inline fuse on the positive wire) and the power wires are still only about a foot long. '96 Mazda Miata

Alright, so that wasn't it. It's still there. I don't get it. I did hook up an external source to the amp. It only does it when the HU source is hooked up, so it is being induced by the inputs from the HU, not the speaker wiring or anything.'96 Mazda Miata

Try a ground loop isolator.There is no such thing as free installation!

Ground loop isolator didn't do it. I don't even think it quieted it down at all. I would start tearing apart the car looking for the problem, but 'A' I'm not even sure what to look for, a cut in the signal wire insulation shorting it to ground? Close proximity to other electrical wires? And 'B' the signal wire has both left and right joined to each other basically the whole length of the car running under the carpeting, so if the left channel isn't doing it, how could there be a problem with how the wire is routed? Any other advice?'96 Mazda Miata

did you get this resolved?Mark "Hamzter" Cinense

1991 Infiniti G20 w/JDM SR20DE

Eclipse CD8445

MTX Thunder 684

Polk DB6750

Polk DB6500

Optima Red Top in the Trunk

Turn off the internal amp on the deck and see what that does.  Otherwise, grab another set of RCAs and try that.  Also, if you have any other type of audio device i.e a portable mp3 player or a tone generator, plug that directly into the amplifier one input at a time, and see if the problem persists.  Good luck! 2003 Dodge Neon R/T

Alpine CDA9813, RF T2000.1bd, RF T162S, RFT142C, RF T600.4, RF T215D4

140.7 @ 28Hz

audiomaninc wrote: Turn off the internal amp on the deck and see what that does. Otherwise, grab another set of RCAs and try that. Also, if you have any other type of audio device i.e a portable mp3 player or a tone generator, plug that directly into the amplifier one input at a time, and see if the problem persists. Good luck!

I am not sure my Eclipse CD8445 will let me turn off the internal amp.Mark "Hamzter" Cinense

1991 Infiniti G20 w/JDM SR20DE

Eclipse CD8445

MTX Thunder 684

Polk DB6750

Polk DB6500

Optima Red Top in the Trunk