Weird audio problem!

stanleymomo · #1 (**permalink**) 01-29-2002, 09:06 PM

Hi Guys,

Today I went to my local shop to install a center channel speaker. My Panasonic decoder has a dedicated amp for a center channel speaker so my installer told me to get an Alpine speaker for this purpose. The funny thing that happens is that whenever I accelerate my car, there would be a 'hiss' sound coming out from the center channel speaker. This only happens if I turn on the center channel speaker. The higher the RPM, the louder the 'hiss' sound. The speaker was installed under the climate controls and they created a custom trim piece for me. (BTW, I can put two gauges there! Solved my problem about the thrid gauge since I have oil temp. on the dashboard already) The speaker doesn't seem to have any insulation at the back. Just plain metal. Do you think that I can solve the problem if I put some cloth or Dynamat on the back? Or do you think this has to do with the wires? Thank you!

ChaseBmw · #2 (**permalink**) 01-29-2002, 10:08 PM

Is it more of a hissing or a whining sound? Is the rest of your system powered by the Panasonics internal amp or an outboard amp(s)?I may be able to help you if you can answer these questions

BoominBenz · #3 (**permalink**) 01-29-2002, 10:09 PM

1)That sounds like a ground problem. You're picking up the "alternator whine." This can be solved by grounding the headunit to a bare metal part. You may have to file or sand away some paint to ground it to bare metal. Pick a good solid point(ie dashboard mounting bolts, and others.) If that doesn't fix the problem, you might want to consider a ground loop isolator, which can be picked up at Radio Shack, or car audio/electronics stores.

2) What do you mean by insulation on the speaker? Do you mean the speaker basket (the main chassis of the speaker)? Generally the basket is just bare metal.

stanleymomo · #4 (**permalink**) 01-29-2002, 10:18 PM

Hi!

Thanks for all your replies!

ChaseBmw:
Yes, the sound is more of a whining sound and it's louder as the RPM is higher. I have two Phoenix Gold amps (powering front/rear speakers and subs) and using the pre-amp output on the Panasonic decoder. However, I didn't notice any problems with them.

BoominVolvo:
Should I ground the headunit or should I ground the decoder. The unit that I have is a Panasonic LCD screen and it has a seperate decoder.

Yes, I mean insulating the rear of the speaker where the magnet is located. I was wondering if I should put some cloth or Dynamat to insulate it from noises.

Thanks again everyone!

BoominBenz · #5 (**permalink**) 01-29-2002, 10:41 PM

What kind of decoder is it? Surround sound?
Anyway, you should run the ground of both of them to bare metal (least resistance possible.)

I don't think dynamating the speaker would stop the noise problem. To tell you the truth, I really have no idea what that would do

stanleymomo · #6 (**permalink**) 01-29-2002, 10:43 PM

Oh! I will try that tomorrow morning and keep you posted. You know what I just found out? I found out that the ground cable for the Panasonic (yes, its a 5.1 channel) decoder is still in the BOX! So it means that they didn't connect it. So I will try that tomorrow.

Before, I thought that the speaker is picking up additional noise from surrounding areas and playing them through the speaker!

Thanks again!

LUNI2NZ · #7 (**permalink**) 01-30-2002, 06:51 AM

Was the decoder being used prior to the installation of the center channel? If so, was it powering any speakers? Engine noise is caused by a difference in ground potential between components. If grounding the decoder doesn't help, you may want to do a source ground setup. To do this, disconnect the deck ground from the wire harness. Using an 18ga wire, connect the ground from the deck to each of the other grounded components (decoder, eq, etc.). Then tie this wire into the ground wire at one of the amps and be sure to loop it to all other amps. In other words, all components are tied into the amp ground, which goes to bare metal chassis. This makes the ground potential the same for all connected components.

Good luck.

Jay

stanleymomo · #8 (**permalink**) 01-30-2002, 04:09 PM

Hi Guys,

I tried to look at the setup today. I found out that the decoder and the headunit was grounded. The headunit was grounded to the factory wire harness.

Should I purchase a ground loop isolator and just ground the center channel?

Does anyone else have any suggestions?

Thanks again!

ZzRicezZ · #9 (**permalink**) 01-31-2002, 11:35 PM

i have the sampe problem.. u have your power wire too close to your rca cable.. try seperating them..