Can't Figure It Out...

I have an aftermarket Pioneer HU. Recently I replaced my 4 channel Sony Amp with a 4 Chanel Pioneer Amp due to my front passenger channel going out. After the install, I noticed two issue that I can't seem to remedy. First, when the HU turns on, a buzzing noise (sounds like interference) is heard but then fades away within 30 seconds. This noise is very quiet, can't really hear it honestly. Second, if I switch over to my radio tuner, a louder buzz noise (again like interference) is heard, but I can drown it out with music. Odd thing is that on any other input (satelite, ipod, etc.) the buzzing goes away. I have tried everything it seems. Gounding RCA's/HU, replace RCA's, etc. nothing makes a difference. This noise does NOT change with engine RPM, so I am not sure if it is a grounding issue. As added insurance to make sure it was the HU, I disconnected it from the amp and plugged my ipod directly into the amp. Clean sound, no problem. The fact that this only happens when on the radio input makes me believe it has something to do with the HU. Is the tuner bad/going bad? Let me know what you think. Thanks!

i would still try to re-ground the amp. was this new amp new or used? if new i would return it.

This would be a brand new amp. Like I said above I isolated just the amp and the speakers and the sound went away, and only appears when on the radio tuner input, all others are fine. Wouldn't that rule out the amp? Thanks!

Class D amps generally interfere with radio reception. Some have built in chips that kill this effect but not many.

Is your power wire running next to your RCA's ?

It is not...

So if you pull the amp totally out of the equation, the noises go away?

Etroze86 said:

Class D amps generally interfere with radio reception. Some have built in chips that kill this effect but not many.

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We've had class d sub and full range amps for some time, no issues here.

If I read this correctly im leaning a little more tward the head unit, If the sound is only happening with the tuner it may be ground related with the installation of the radio or the antenna ground. That is where I would spend my time troubleshooting

Graygoose said:

We've had class d sub and full range amps for some time, no issues here.

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True mind is still stuck in time when Class D amps originally came out in the mass market.

Etroze86 said:

True mind is still stuck in time when Class D amps originally came out in the mass market.

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Yea, new class d full range are very common. Seems like each month technology changes

Graygoose said:

So if you pull the amp totally out of the equation, the noises go away?

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No if I pull the head unit out of the equation, the noise goes away. I plugged my ipod directly in using the current RCA's that the head unit is using and I get clean sound.

Bkhsvt said:

If I read this correctly im leaning a little more tward the head unit, If the sound is only happening with the tuner it may be ground related with the installation of the radio or the antenna ground. That is where I would spend my time troubleshooting

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Correct this is only happening on the radio tuner. If I switch to Sirius, ipod, bluetooth, etc, the sound goes away. The antenna adapter that I am using actually has a wire that connects to the remote wire.



If I disconnect the antenna from the back of the radio, I loose signal, but the noise is still there. What is weird is this just started happening, it has been fine for about a year. You mention the grounding of the radio. What are some things I can try to better ground it?

You can look for metal back there, usually there's a large metal bar going across the dash. I'm betting if you put a new radio in there it will go away. Sounds like an internal radio issue to me

Thanks for the help everyone, I am leaning towards it being the HU as well...