# Hello Fellow AV Fans: Amp Hum



## Gary Hubbard (Feb 20, 2009)

I bring greetings from my noobish species. /Volumes/Untitled/DCIM/101MSDCF/DSC00322.JPG I am hoping by some form of divine intervention that I managed to get a photo of my AV kit onto this message. IOf not, my apologies, I will try again sometime. Meanwhile, I could use help. My aux. amp. (Hafler DH220- which lives only to power the subwoofer) has decided to burst forth in a glorious 60 cycle hum upon power-up. The signal sequence runs: HD cable box>Denon AV1603 (subwoofer out)>Hafler amp>equalizer>home-made subwoofer. I am fairly sure that the cable runs are right. General thoughts on the subject?:huh::huh:


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## hddummy (Mar 9, 2007)

Welcome! Is this a result of a change you made in the signal chain or it just started happening out of the blue? I could also occur because of changes elsewhere...particularly in the cable system.


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## mechman (Feb 8, 2007)

Gary,

You need 5 posts before you can attach a picture. You can pad four more posts here.

Welcome to the Shack!  :wave:


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## tonyvdb (Sep 5, 2007)

Hello Gary, Welcome to the Shack.

Regarding the Hum have you added or changed any electrical devices recently like a florescent light or a dimmer. These can cause the 60Hz hum.


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## drdoan (Aug 30, 2006)

Welcome, sounds like you might have a ground loop, you will have to do some sleuthing by disconnecting each link in the chain one at a time. Good luck. Have fun. 
Dennis


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## Gary Hubbard (Feb 20, 2009)

No, Nothing added unless it snuck in when I was not looking.


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## tonyvdb (Sep 5, 2007)

Like Dennis suggested, start by unplugging one thing at a time on your A/V system and see when it goes away.


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## Sonnie (Apr 11, 2006)

[No message]


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