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JBL powered subwoofer has a hum https://mail.karaokescenemagazine.net/forums/viewtopic.php?f=1&t=9974	Page 1 of 1

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Author:	micbob [ Wed Jun 06, 2007 7:51 pm ]
Post subject:	JBL powered subwoofer has a hum
I have a JBL JRX SP118 Powered sub and it has a terrible hum. At first I thought it was a ground issue with one of the cords but I have disconnect everthing I could think of and the hum is still there.  Has anyone ever experienced this if so what could it be? I was thinking it might have something to do with the built in crossover.  :thinkin:   Thanks

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Author:	timberlea [ Thu Jun 07, 2007 3:07 am ]
Post subject:	Re: JBL powered subwoofer has a hum
It's most likely your power cord is too close or touching your sound cord from either your mixer or crossover.  Try separating them.

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Author:	micbob [ Thu Jun 07, 2007 4:07 am ]
Post subject:	Re: JBL powered subwoofer has a hum
Thanks Timerlea, I have disconnect and moved everything I could imagine. This hum has been there the past two nights and at seperate venues.  :shock:

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Author:	karyoker [ Thu Jun 07, 2007 7:04 am ]
Post subject:	Re: JBL powered subwoofer has a hum
Is the hum there with the input disconnected? Try plugging in the power with a ground eliminator adapter. If it is a 60 or 120 hertz hum then the filters in the power supply are bad.

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Author:	karyoker [ Thu Jun 07, 2007 8:17 am ]
Post subject:	Re: JBL powered subwoofer has a hum
In fact I'm working on a jbl eon amp right now The 2 large round black filters on the left are in the 38 volt supply the 4 smaller blue ones are in the +&- 70 volt supply. Jbl schematics are availible on the net schems and they have very good tech support. amp

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Author:	micbob [ Fri Jun 08, 2007 11:29 am ]
Post subject:	Re: JBL powered subwoofer has a hum
Thanks

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