Stock HU and Speaker + Amp problems!
 

Hi,

I am using the stock HU with a Jensen amp which has high level inputs on the amp itself. There is one harness for front and one for rear. Each harness consists of 5 wires, Left pos/neg, Right pos/neg and ground.

I have wired the power to the amp direct from the battery via 8ga wire. I have the amp grounded to the body (under the passenger side seat) using 8ga wire. The remote power is spliced into the accessory wire from the stock wiring harness.

I have cut the speaker leads on the stock HU wiring harness. From there I am running speaker wire back to the high level inputs on the amp. And then running speaker wire from the amp back to the 'speaker side' of the wiring harness. I have grounded the high level input on the amp to the same ground as the amp.

Sound good so far?

Here is the problem. Everything sounds fine when the car is not running. When the car is running I get a faint whine from the alternator. If I switch the park lights on that sound is about 10X worse. It seems only like the park lights are causing the problem. I don't get the serious noise when the daytime running lights are on, and the noise doesn't change when I go from just park lights to full head lights. This leads me to believe that the park lights are the culprit.

If I remove BOTH the ground from the high level inputs the noise goes away, but the sound quality is HORRIBLE, and the balance/fade does not work properly.

If I shut off the HU I get no noise at all. If I remove the high level inputs and crank up the gain on the amp, no noise. I assume from this that the amp by itself isn't introducing the noise.

I can get the noise to all but dissapear if I turn the gain on the amp way down, but this defeats the purpose of the amp. :)

Any ideas?

I've done a lot of reading, but wanted some advice from people who have similar set ups or have experience with a set up like this.

Thanks!

Jay

Try a different ground for the deck.

Well the 8 leads for the speakers are already cut. When the time comes that I get rid of the car I will just splice everything back together and remove the additional equipment. No too big a deal to me.

Which wires are you talking about exactly? The speaker wires? I'm kind of at the mercy of location on that one. Under the passenger seat is probably the closest location to the HU. The ground wire is all of about 4" long.

Wouldn't adding a reverse harness be adding length and complexity to things anyway? More wire and additional mechanical connections.

Thanks for the advice.

Jay

go to radio shack and get one of those noise eliminators

Well thanks to Dave Cameron I found the source of the problem.

I originally spliced the remote power lead for the amp from the stock wiring harness. As a test I moved it over to the main power for the amp....90% of the noise was gone. Now the lights have no effect at all on the sound. I'm happy.

BUT, I think that I will be returning the AMP and buying a new HU. I think that I will be better served by this in the future.

Thanks for your help Dave you rock!

Jay

Hey Jay,

Glad you were able to resolve that issue. That was a good call on Dave's part. I totally didn't think of doing that because I had zero issues with mine. I have had issues with where I have taken amp main power from in other vehicles, but never problems with the turn on lead. Go figure.

Dale.

my best bet..you used a "ground" not intended for the inputs..

some system have isolated input and output ..meaning they have floating grounds and they should not be connected to your car amps "body" ground..and you said you used the same amp ground for the "HI" input ground.. :)

the way i understand your "HI" input wiring..you have your amp inbetween the head unit and the car speakers..try this..re-connect the HU original wirings..and just "tap" your amp's "HI" input to your car's rear speaker leads (amp "HI" input parallel connected to speaker).. this will save you from "noise" that could be injected thru your wires.. :)

make a straight forward connection..connect you amp ground to car body ground..and you amp's HI input ground ..only to your HU output ground..or speaker ground since you have a "HI" input config.. ;)

general rule...dont mix grounds even though they spell the same..inputs and outputs with supply ground.. :)