I just installed 3 amps and 5 speakers in my Z. Still waiting for the subs. I was runnning 2 amps. One a 4 channel and 1 a 2-channel. This is a surround sound set up. I am getting noise in the system, even with the engine off. The sound does not change pitch with volume adjustment and goes away if I run the 4-channel amp with only 2 channels.

Anyone have any idea what could be causing the noise? I think I'll install the amp in my other car and see if the amp is not the problem. Otherwise, I think it may be the fact that I ran the RCA's along side the power cable. Could there be anything else causing this. I grounded all three amps to different places and added a jumper between the back 2 amps.

Thanks

 

What does the sound sound like?

It sounds like distortion from the 4 channel amplifier or the headend possibly.

If you just run the front pair is the noise there?

If you just runthe back pair is the noise there?

Swap the front and rear RCA cable inputs into the four channel amplifier and see if the noisy speakers switch. If so it's the headend or the RCA cables. If not then it's the amplifier or the speakers themselves.

Ideally you should ground all the amplifiers at the same location. Running a nice heavy gauge wire between the seperate ground points is a good second choice. On my system I ground the amplifers together with 4 gauge cable and then ran 12 gauge cables out to the headend, brain, and remote disc changer.

 

Problem solved

 

So what did it sound like!

 

Almost like alternator whine, but does not change pitch. It is a constant volume. I got another power wire and ran it from the battery to the dist block and sure enough, it fixed the problem. Now I have to figure out how to get it run again and away from the huge mess of wires...

 

whats the difference between a 2 gauge and 4 gauge blah, and where can i ground my amps JL 300/4 and 250/1 in the passenger compartment? thx

 

4 gauge is thick wire, as thick as battery cables. It will allow the flow of very high current. You can get down to 0 gauge, this is extremely thick stuff. For ormal stereos, 4 gauge is more than enough. Then you can run 8-10 gauge to the amps. These are thinner.

Gounding point is just a piece of bare metal on the body of the car. Really anywhere on the body is good as long as you sand down any coatings. You can ground anywhere in the passenger compartment when you take the glove box off.

 

From my "Ugly's" reference:

4 gauge copper cable will handle 70 Amps of constant draw with out causing the wire to heat to greater than 140 F in raceway or cable which is pretty close to the inside of a car. In free air that number would raise to 105 amps.

2 gauge is good for 95 amps under the same conditions.

In use amplifiers draw more and less as the music gets louder and softer. The more musical your music the more that is true. The newer your music the less true. Roy Orban (the engineer not the musician) is a bit of an expert in audio compression. He did a study where he looked at the way producers compressed music in the 50's to current music. The trend is to make music more and more loud - with all the portions of the sound envelope normalized to the saturation point of the media.

If you're into competition I would run the heavier cable if possible. More watts in means more watts out.