Noise in Rear Channels
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=11005
Printed Date: July 27, 2025 at 1:58 AM
Topic: Noise in Rear Channels
Posted By: pilot_chris
Subject: Noise in Rear Channels
Date Posted: March 16, 2003 at 10:54 PM
Ok I'm getting some annoying noise in the rear channels of my car and am not sure what's up. Here's what I'm working with:
95 Cavalier 2.2L
185/85 High Output Alternator (custom built and amperage confirmed)
MTX 4244 4 channel amp powering 2 polk two way front door speakers and 2 Pioneer 3 way rear deck 6 X 9's.
JL Audio 500/1 amp powering 2 X Rockford Punch HX2 12" DVC subs
Ok here's the question, why am I only getting noise from the engine in the rear channels running off the MTX amp and not any other speakers. I can understand why no noise is hear through the subs since the JL amp is filtering out all high frequency sound but the interference is not coming through the front Polk speakers which are set to pass high range. Suggestions?
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95 Cavalier 2.2L
High Output Alternator
Rockford 1 Farad Punch Capacitor
JL 500/1 for RF Punch HX2 500 watt RMS subs
MTX 4244 4 channel for Polk & Pioneer door and rear deck speakers
Replies:
Posted By: dragonrage
Date Posted: March 17, 2003 at 8:16 AM
First of all, try switching the front/rear channels on the MTX amp. Does it switch to the front speakers or does it stay how it is now?
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2009 Pontiac G8 in planning stage
HU: ?
Speakers: ?
Amps: ?
Posted By: esmith69
Date Posted: March 17, 2003 at 8:35 AM
Are you using the stock head unit or is it an aftermarket one? Double check all your grounds, especially for the amps. Also, make sure you don't have the gain turned up too high on the 4-channel amp. If it's a stock head unit, did you use a LOC?
Posted By: pilot_chris
Date Posted: March 17, 2003 at 8:54 AM
The head unit is a Kenwood KDC-MP8017 CD/MP3 unit (very nice) with pre-amp outputs which are being used. All the grounds are good and the gain is up just short of half way and makes no difference in how loud the engine noise is. I'll try switching the speakers to different channels soon - I don't have time at the moment. Also, I have a remote turn on wired into the ignition harness serving as my power on 12V source to activate the REM line on the amps (to turn them on). I wonder if this could be part of the problem?
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95 Cavalier 2.2L
High Output Alternator
Rockford 1 Farad Punch Capacitor
JL 500/1 for RF Punch HX2 500 watt RMS subs
MTX 4244 4 channel for Polk & Pioneer door and rear deck speakers
Posted By: esmith69
Date Posted: March 17, 2003 at 8:56 AM
Very doubtful that the +12v switched is causing the noise. Though just to make sure, you ran the RCAs and the power/remote wires down opposite sides of the vehicle, right?
Posted By: pilot_chris
Date Posted: March 17, 2003 at 1:48 PM
The power and signal cables had to be run alongside each other on the left side of the vehicle since there are obstructions on the right side that prevent the signal cable from going there. I'm using a premium Monster audio cable from the head unit back to the amps in the trunk that is very heavily shielded and have not had any interference before so I wouldn't think that is it.
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95 Cavalier 2.2L
High Output Alternator
Rockford 1 Farad Punch Capacitor
JL 500/1 for RF Punch HX2 500 watt RMS subs
MTX 4244 4 channel for Polk & Pioneer door and rear deck speakers
Posted By: dragonrage
Date Posted: March 17, 2003 at 3:09 PM
DC current doesn't really even cause much interference anyway.
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2009 Pontiac G8 in planning stage
HU: ?
Speakers: ?
Amps: ?
Posted By: esmith69
Date Posted: March 17, 2003 at 9:29 PM
Running signal wires for a sub amp alongside the power wire is one thing, but when you've got a 4-channel amp powering full-range speakers, I highly recommend against running the power next to the signal. DC current under 1 amp (the maximum amount that might go through a remote wire) does not cause much interference, but 40-80 amps of DC current going through the main power cable DOES cause interference!!! Maybe you meant voltage? Sometimes you have no other choice but to run them together as was the case in your situation. But that doesn't mean it has to sound like poo.... I'd write out a whole bunch of instructions on how to properly troubleshoot the system, but you might wanna check out this page instead--it's got solid, accurate advice and has some nifty pictures too
Posted By: pilot_chris
Date Posted: March 17, 2003 at 9:52 PM
Thanks for the advice, some of the stuff in your link may be helpful. Thanks again.
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95 Cavalier 2.2L
High Output Alternator
Rockford 1 Farad Punch Capacitor
JL 500/1 for RF Punch HX2 500 watt RMS subs
MTX 4244 4 channel for Polk & Pioneer door and rear deck speakers
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