Alternator whine with new amp! None with old.

[sonick]

So I recently replaced my Pioneer GM-4000f 4ch amp with an MTX TC4004.

With my JVC KD-R800 head unit, I am now getting alternator noise/whine from the new amp from the front MTX component speakers which the amp is powering. I previously did not have ANY noise at all.

RCA's are no-name "twisted pair" from CanadianTire. Power and ground wires for amp are 4ga.

The whine does not increase with volume. At "1", the noise is just as loud as if it were at "30" and also persists when it is on PAUSE. However, it goes away at "0" as I think the HU cuts output altogether at "0". It gets louder with the headlights on.

I have gone through the following, which resulted in noise:

• New dedicated ground point for HU (at the driver steering column)
• New shorter ground point for amp (10", to sheet metal under the rear deck)
• Shared ground point for HU and AMP under the rear deck
• Disconnected RCA's at HU
• Set of cheapie home RCA's directly from HU to AMP through the middle of the cabin
• Stinger Ground Loop Isolator at AMP or HU end of the RCA (this may be faulty as I noticed the labeling was backwards with the female RCA ends going "to amp" and male RCA's going "to source")
• New positive battery terminal, new negative battery ground cable.

I have gone through the following with NO noise:

• iPod directly to amp with 1/8" headphone to RCA cable
• Shorted RCA's at AMP (amp is not the culprit)
• Disconnected RCA's at AMP

It just occured to me to try and connect the iPod to the amp VIA the current RCA to test for sure whether it's the cable that is the culprit. Will have to try that at home.

Any other suggestions in the meantime would greatly help!

[StereoInstaller1]

First off, do you still have the Pioneer? If so, swap it back in. You may have popped a capacitor or three in the alternator swap episode (dead battery, jumpstarts, disconnect/reconnect battery, all that jazz) or possibly in the head unit.

Always keep in mind the lengths that todays manufacturer will go to to produce a shitty component!

[StereoInstaller1]

Oh yeah: that Singer GLI? believe it or not, you are supposed to shove that thing behind your head unit!
Oh yeah, you got 6 channels of RCAs? Shove THREE of those bastards behind your deck!

What, do they think we work on class A motorhomes only?

[sonick]

First off, do you still have the Pioneer? If so, swap it back in. You may have popped a capacitor or three in the alternator swap episode (dead battery, jumpstarts, disconnect/reconnect battery, all that jazz) or possibly in the head unit.

Good idea, will try that. Really hope it isn't, I just got the HU a few month's ago!

The power wires to HU are fused though, so hopefully it wasn't the case that I blew it up, but who knows...

[StereoInstaller1]

A quick pulse to the ground side can make short work of circuit board capacitors.

Hoping for the best!

[sonick]

Update! Old pioneer amp works fine, no alternator whine there, not the HU.

Hooked up iPod at HU side of the cable, no whine, so it's not the cable.

Shorted the RCA's at the HU side of the cable, no whine, so not the amp.

But when the two get together, WHINNNNEEEE!!! Arrrrgh.

[Sir Smirnoff]

it's noise from the cable surprisingly or the speaker wire itself. You need shielded cables. Remember that the impedance of an ipod is like 32 ohms and the head unit may be 8 ohms... So that has something to do with it. You can also get a noise reducer to deal with it.

[StereoInstaller1]

Grab 20' of 18ga black wire.

Connect it to the amplifiers ground point, then connect it to the back of the deck.

Post your results here

[sonick]

it's noise from the cable surprisingly or the speaker wire itself. You need shielded cables. Remember that the impedance of an ipod is like 32 ohms and the head unit may be 8 ohms... So that has something to do with it. You can also get a noise reducer to deal with it.

I get the same noise with any source, whether iPod, CD, Radio. Also it is hooked up via iPod dock connector not the headphone output. May try some better RCAs.

Grab 20' of 18ga black wire.

Connect it to the amplifiers ground point, then connect it to the back of the deck.

Post your results here

I tried this with 16ga with no improvement. But the wire was grey lol.

[StereoInstaller1]

Better RCAs won't help. You have a mismatch between deck and amp.

Have you tried a ground loop isolator?

I still say your deck is bad, the old amp just didn't care.

[sonick]

Better RCAs won't help. You have a mismatch between deck and amp.

Have you tried a ground loop isolator?

I still say your deck is bad, the old amp just didn't care.

Yeah I have, two different GLI's (stinger and radio shack, not together just one at a time), no luck.

The deck is still under warranty and purchased through an authorized dealer, would JVC replace it for such a specific circumstance? I guess I will email them.

For the time being I've turned the gain down a tiny bit and it has helped, but my soundstage is fucked and the noise is still there when I turn on the headlights.