Amp Squeal

[SpudRacer]

I spent way too much to repair my factory AM/8-track radio in my 69 Charger R/T SE.  They said the transisters had burned out.  I decided to install a small amp under the passenger seat that takes speaker outputs as the input signal.  I have the power coming directly from the battery, and ground to the dash.  I figured this would ease the strain on the factory radio allowing the amp to do most of the work allowing the transisters to run cooler and last longer.  The problem is that I get a horrendous squeal through the speakers with the engine running.  It sounds fine with the engine off.  THe engine is the factory 440 with an updated electronic Pertronix ignition.  I assume this is either a dirty ground, or dirty power wire.  I've been told to use a "ground-loop isolator" from Radio Shack, but my local radio shack doesn't have a clue what that is.

Can anybody help me?  As my car stands now, I leave the radio off while driving, and can only listen to it when parked.

Thanks so much,

Tom
Bryson City, NC

[2Gunz]

The guys at Radio Shack are clueless.

Here is what you are talking about....

http://www.radioshack.com/product/index.jsp?parentPage=search&summary=summary&cp=&productId=2062214&accessories=accessories&kw=ground+loop&techSpecs=techSpecs&currentTab=summary&custRatings=custRatings&sr=1&features=features&origkw=ground+loop&support=support&tab=summary
Doesnt help you though since it is RCA Level and not speaker level.

Moving on..................



Firstly reground everything. Make sure your alternator has a good ground.

If that doesnt help I would add another ground wire from the chassis of the Radio, amp and alternator to the chassis of the car.

"engine" noise is really created by the alternator. Make sure it really is that, you should hear it change as you increase the engine

RPM slightly.


Other things to do.....

Get the speaker wires that feed the amp away from any power cables.

I have an amp in the trunk and power goes down the Drivers side of the car and signal on the other.

When power and signal must come close make it as short as a time as possible.

If that doesnt fix it I would convert the speaker level wires to RCA.

Connect this

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=269-050

to the back of your radio then run RCA's to the amp.

If that fails....

You could try adding a power isolator to the Amp, radio or both.

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=265-042


Anyway I suspect your problem is when you installed the amp, you ran the

speaker wires and power wires right next to or on top of each other.

Get them apart and check your grounds.

Let me know how it goes.

[2Gunz]

Oh and I forgot a thing or 2.

There is also Ignition noise... which is more of a pop and hum sound.

And it is possible your alt is working but has a bad diode which is causing the noise.