Newbie Problem, Please Help Jonathan, Glass, Anybody


New member
Username: Chrise

Post Number: 1
Registered: Jan-05
I just had a new system installed in my jeep. Here are the items:

Pioneer Premire DEH 350 HU
Memphis Belle Amp, 50x4, 100x1, ok to 1 ohm
2 10W0 JL Audio Subs, 4 ohm, in parallel
Sub Box made by me, per JL specs exactly.
Memphis MC 5 1/4's in the sound bar
Infininity Kappa 6x4 plates in the dash

Here is my problem. After the system has been on for awhile, I start to hear a sound that all I can describe is "pitter-patter" in the subs when they hit. This happens even at low volumes, and it is very noticeable.

I am sure there is nothing wrong with my box; it is sealed tightly.

I am tending to think there is an issue with the amp because it does not seem to do it when cold. It does it after it has run awhile (15 minutes or so).

Is this "clipping"?

The HU has a parametric equalizer, and there are countless adjustments on this thing. Others have mentioned how complicated these HU's are, and that is no lie. It is almost ridiculous.

Could I have something going on with the way the equalizer is set that could be causing the amp to "clip", if that is what is happening, or cause this noise?

I was hoping I could bypass the equalizer in the HU to test this theory, but there is no way to do it.

Am I barking up the wrong tree here? Any suggestions would be appreciated. Sorry about the newbie questions, but I thought somebody could help me out here.


Silver Member
Username: Jeremyc

Kunsan AfbSouth Korea

Post Number: 433
Registered: Jun-04
Hay Chris, check your ground. If it is doing it at low volumes it might be loose. Actually man double check all your wire connections. It sounds like something is loose.


Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 7383
Registered: Dec-03
yup. what you're describing sounds like spark plug noise to me.
that usually means a bad ground point at the head unit or amplifier.
that or your power and RCA lines are run side by side in the car.

New member
Username: Chrise

Post Number: 2
Registered: Jan-05
Thanks for the replies.

The ground at the amp is good. For the head unit; I just used the existing harness and just spliced in the speaker wires from the amp. Are you saying I need to trace the ground from the existing harness?

After I posted this and from doing more reading, I had the boost set on the equalizer to +6 on the lows. Could this be causing the amp to clip? I pulled it back to +2 to see if that made a difference, and I didn't notice it this morning on the way to work. But, it was obviously not as loud so maybe I just couldn't tell. I need to crank it up halfway in the garage for awhile and then see.

What is confusing is this is happening after it plays awhile (things heat up). Could this point back to the equalizer boost setting?


Gold Member
Username: Carguy

Post Number: 1133
Registered: Nov-04
Hey Chris, if you want to find the problem faster, get a walkman and attach it to your amp's rca input. Then slowly turn up the volume. See if it does it. If you get clean sound, then the problem is not with your amp/sub. It's an easier way of isolating the problem.
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