Need Amp advise asap

[tsenfw 10+ year member]

Just bought a used Hifonics 1605d from someone here on CA. Directly replaced my current amp with this new one to test it.

With the volume on the HU down to 0 and no matter where the gain is, I'm getting this hissing, whining, and white noise coming from the sub. Very low volume but enough to hear when the volume is really low on the headunit.

Is this a ground loop or alternator whine? Or is it something wrong with the amp?

My old amp that was just installed the exact same way did not make this noise.

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[azbass 5,000+ posts]

check if the noise increases with stepping on the gas.

 

[tsenfw 10+ year member]

seemed to be about the same but it's hard to tell with my exhaust being noisy.

Also, is running an amp at 8ohm is perfectly fine right?

 

[Rashaddd 5,000+ posts]

Turn your LPF on? Sounds like alternator whine, check and see if possibly a ground came loose or somethin

 

[tsenfw 10+ year member]

LPF is on at the HU (9887) and on the amp it's a dial. Turned it all the way down no difference in noise. Will check my ground right now, good idea.

 

[Rashaddd 5,000+ posts]

LPF is on at the HU (9887) and on the amp it's a dial. Turned it all the way down no difference in noise. Will check my ground right now, good idea.

All the way down as in all the way to like 50hz or however low it goes on your amp? As in its doing the most it can be? You shouldn't hear anything at all above double that frequency coming out of that amp, so unless you've got a very low frequency 'hiss' it should stop it

 

[tsenfw 10+ year member]

Ahhh it hiss/whines with the car off, so that rules out alternator whine.

LPF all the way down it still will make a high pitched whine every once in a while. I'll go double check that ground now.

IDk i think i got screwed on the amp. ****it, why can't anyone be honest on CA anymore!?

 

[kovemaster559 5,000+ posts]

Ahhh it hiss/whines with the car off, so that rules out alternator whine.
LPF all the way down it still will make a high pitched whine every once in a while. I'll go double check that ground now.

IDk i think i got screwed on the amp. ****it, why can't anyone be honest on CA anymore!?

because !

just check all the grounds. if not i think its the hu

 

[Rashaddd 5,000+ posts]

Ahhh it hiss/whines with the car off, so that rules out alternator whine.
LPF all the way down it still will make a high pitched whine every once in a while. I'll go double check that ground now.

QUOTE]

Are you sure its coming from your sub? I may be wrong but...with LPF all the way down you shouldn't hear it at all unless its very low.

 

[tsenfw 10+ year member]

Completely redid the ground, same noise.

Definitely coming from the sub. Even with the LPF down, car off, it still whines. Even with headunit on pause or volume all the way down, still the same white noise and whine. Sort of sounds like on an army radio when no one is responding and all you get is that faint whine and white noise.

I really don't think it's my headunit as my old amp was not making that noise all of 2 hours ago.

I was very careful uninstalling/installing the amps too. Was sure to take out the fuse on the power line. Was also sure to unhook the rca's before the disconnecting the ground, and hook the rca's back up AFTER reconnecting the ground so the amps wouldn't ground out through the rca's.

EDIT: oh it also makes the noise to the sub without the rca's plugged in. I mean, definately has to be the amp at that point right?

 

[tsenfw 10+ year member]

Put the old amp back in, very very slight white noise, barely audible. No whine or squeal.

Is this an amp grounding issue or obvious problem with the new amp, I don't get it.