alternator whine with different amps

[qwerty778 10+ year member]

A few months back, I was running my comps and subs off of an old school sony four channel amp with no problems. I eventually switched it out for two mtx 2 channel amps and now I have alternator whine. I'm using the exact same wires I was using before except for an extra power and ground wire for the new amp. I cannot figure out how this whine has developed.

Is there any way that a different amp could cause this problem?

My amp grounds are both very good, but my hu is using the stock ground. I still don't see how this is a problem though because before I had no whine whatsoever.

Can anyone make any sense of this?

I plan on regrounding my hu soon, but I doubt that will help.

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[indosia 10+ year member]

Are both amps grounded to a single point? Is everything mounted in isolation of chassis ground?

 

[qwerty778 10+ year member]

Are both amps grounded to a single point? Is everything mounted in isolation of chassis ground?

The strange thing is the whine became apparent when I switched from one amp to another w/o changing anything else. Originally I had my comps bridged off a four channel amp running no subs and I had no audible whine. I then switched out the four channel amp for an mtx 282 and suddenly I had whine. I have since regrounded the hu and installed a second mtx 282 for my subs. So the whine is unrelated to the second amp.
I am wondering if its possible that one ground would suffice for one amp, but isn't solid enough for another one. It seems to be the only logical conclusion.

Can anyone else shine light on this problem?

 

[indosia 10+ year member]

Alternater whine is ussually the result of a voltage differential created by more than one ground path or a poor ground path. This can happin if your head unit, amp, eq, or crossover ect. are not mounted in isolation of chassis ground. For example. One time I had alt whine. I found that the back of my head unit was touching a piece of metal under the dash. Another possibility is that you have a component mismatch. Try adjusting the gain on the amp. Also try grounding your head unit at the same point as your amplifier.

 

[HelloImBob 10+ year member]

ground out your RCAs off the back of your head unit TO the head unit...

read the sticky...

it works wonders and you will never have to put up with that whine again

 

[indosia 10+ year member]

Hey Bob, did you have alt whine to? You both have mtx amps.