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Speaker Hum on my Quad 12L Active's

I have a simple set up in my home office and up until recently things have been fine, but recently my Quad's have developed this hum. They hum when I'm not playing any music, plus I test them and they hum when the RCA cables are connected to the speakers, but not to anything else. Not sure what that means.

I usually play music from my computer wirelessly to my Airport Express and then go from there with RCA's to my active speakers. Any thoughts?

Also, I've checked around the forums for this topic and none of the previous questions seemed to fit my situation. Would appreciate any expertise here.
bdogsquad

Showing 1 response by shadorne

shadorne's avatar
shadorne
7,477 posts
 
It sounds like you have a ground loop because it happens when you connect the RCA cables.

One of the speakers may not be grounded properly at your power bar - when you connect the RCA you are connecting the grounds between the two speakers with your Y connector that goes to the Airport Express - a microamp current flow along the RCA ground wire (negative) can easily generate auidble hum.

Seriously you should look into getting XLR cables - I know the Airport does not support them but you could easily add a DAC/PRE with optical in and XLR out.
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