Hum in sub (1 Viewer)

[Andrew Tompson]

I just moved my sub from behind the TV to behind the couch for space reasons. I ran wire up one wall, through the attic and down another wall.

Now the sub woofer humms when the amp is off. It's a sperately powered sub. It never used to hum when it was behind the TV and it doesn't hum when the amp is on.

I'm thinking that my sub speaker wire is laying across a power line in the attic and that's the source.

Any other possible causes?

Is there a way to sheild a section of the wire if I can't avoid the power lines?

The line for the sub went from less than five feet to a 50 foot line. Is this a problem?

Thanks.

 

[Patrick Sun]

Is the line (50 foot) a shielded 75 ohm rated cable with the standard RCA male plugs?

 

[Greg_R]

Alternatively you could just run some quad-shield RG6 and get F-RCA converters (a $2 plug at Radio Shack). The key here is LOTS of shielding (it sounds like the cable you used is picking up noise). Try to avoid long parallel runs next to power cables...

 

[scott>sau]

I seal my approval of RG6Q with Patrick and Greg. It has 2 layers of foil shielding and 2 layers of braided shielding. You may also try a "cheater" adapter if the sub amp has 3-prongs to bring it to the outlet at 2-prongs to break a possible ground loop. $2 Home Depot, or Lowes. It killed the noise in my QSC sub amp.