Hi

So I installed two amps and an after market HU in my coupe and now there is a noise coming out of the speakers.
The noise sounds like the noise you hear when your radio couldn't receive any signal while your listening to FM radio.

I hear the noise when I power on the head unit.But the noise goes away when I turn the "source" button off(the HU is still on but there is no audio source). The noise also goes away when I turn the HU's volume to zero.

I grounded my HU behind the in dash clock where the metal harness of the HU and Navi screws on and the first amp behind the back seat(I sanded a spot down to the metal on the body of the car). The second amp is grounded in the trunk next to the factory bose amp.(there is a screw next to the bose amp that was used by Inifiniti as a grounding point)

Now, am I having this noise problem because I grounded the HU "behind the clock"(which might not be connected to the body of the car) and the two amps in diff. points?

Please help me.

 

how close is the main power wire for the amps to the remote wire?

 

I ran the RCA signal cables and the remote wire together on the driver side and the main power wire over to the passenger side.

The only time they are next to each other is when they get to the amps.

 

If the noise goes up and down with volume, it's not a ground problem, as those will be audible whenever the amp is on, regardless of what the headunit is doing, and they don't increase with volume either.

This sounds to me like the amps have a poor signal-to-noise ratio, high noise floor or the headunit itself is generating the noise.

What kind of amps/headunit?

 

Yes, the volume of the noise goes up and down with the volume of the HU.

HU-- Pioneer avh-p4200
Amp #1-- soundstream ref 4.920
Amp #2-- pioneer gx??(it's old I don't remember the exact model)

Do you think this is caused by the old amp?

 

Is whatever the Pioneer is hooked up to the only noisy thing? Are your amps set with a pass-through or each running from their own RCAs?

 

Yes. All the amps have their own RCA coming from the HU.
I was messing with the gains this morning and I saw that I had set the gains down to 0.2v on the Soundstream amp and about 0.4v on the Pioneer amp.
So I changed the settings to about 7v on both amps and now the volume of the noise is lower. I could say that its almost unnoticeable. But the over all volume is now lower because the gains are lower? For example, the 5 volume on the HU is not as loud as the same 5 volume with the gains set to about ~7v.

Do you think this was the cause of the problem?