class d and fm reception
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=106729
Printed Date: July 09, 2025 at 7:49 PM
Topic: class d and fm reception
Posted By: smoothdesignz
Subject: class d and fm reception
Date Posted: August 12, 2008 at 3:53 PM
We've been having some trouble with an 05 Honda Pilot, after installing a Phoenix Gold 4-channel and a JL Audio Slash 500/1. I've read through a few topics of bad radio reception due to missing a wire or a faulty antenna, and also a few speculations of a Class D amplifier hindering reception. It seems that the JL is causing the radio to lose reception. A few things we have tried is to move the amp, actually taking the amp to the front of the vehicle and just connecting power and ground directly to the battery. We grabbed a JL G series amp to only run into the same issue. The truly odd issue is that we connected a class a/b A series JL Audio and the issue ceased.
So, after waiting for hours on hold for a JL Audio Tech, it was confirmed that glass mounted antennas are subject to interference when using a Class D amplifier. Figured that I would pass this along.
Andreas
Columbus Car Audio of Newark
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95 Mazda 626
Pioneer DEH-P960MP
DEI Stilleto
Boston Acoustic SL60 Front
Boston Acoustic S85 Rear
Alpine V12 MRV-F407
Alpine V12 MRV-T757
2 Rockford Fosgate P2D412
Python 990 Alarm/RemStart
Replies:
Posted By: DYohn
Date Posted: August 12, 2008 at 5:17 PM
If the switching power supply in a Class D is interfering with radio reception, I'd suspect a faulty Rf shield inside the amp - or just a poor design. I have never seen such interference, but that does not mean it can't happen since Class D amps do operate at radio frequencies. ------------- Support the12volt.com
Posted By: smoothdesignz
Date Posted: August 12, 2008 at 8:29 PM
It would have to be a bad design since both Class D JL Audio amps we tried did exactly the same thing. But yea, you echoed what the JL Tech said about the switching supply emits the same frequencies as FM. It was interesting listening to the amp power down, it sounded like a chopper getting ready to take off. With all the installers in our little company, not a single one had heard anything like it before. But I can promise you, it is completely possible!
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95 Mazda 626
Pioneer DEH-P960MP
DEI Stilleto
Boston Acoustic SL60 Front
Boston Acoustic S85 Rear
Alpine V12 MRV-F407
Alpine V12 MRV-T757
2 Rockford Fosgate P2D412
Python 990 Alarm/RemStart
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