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Posted by auujay on Dec-16-2004 22:54:

Subwoofer question

Not exactly a DJ question but I am thinking this is the forum that will be the most helpful.

The problem is that in my Dad's stereo setup he gets a 60Hz (I assume it is 60, it is constant non the less) hum when the florencent light in the next room is turned on. I know a 60 Hz hum sounds like a ground loop problem but I am not sure because it is only happens when the light is on. My current theory is that the speaker cable running from the amp to the sub is acting like an antenna.

His setup is a Creek Audio A50iR amp with Ascend Acoustic CBM-170 speakers (left/right) and a Hsu Research VTF-2 sub. The amp does not have a subwoofer out (which Polk's site says you should usually avoid anyway) so the wires (14 gauge I believe) run to the amp's high level inputs and from the speaker outs to each left and right speaker. I think the distance from the amp to the sub is probobly about 12 feet.

I know that GLIs are one solution for ground loops but I have heard they compromise the sound quality. Any thoughts?

Posted by tvmann on Dec-18-2004 00:31:

If any of the parts of the system (amplifier, CD player, satellite box etc) are plugged into AC with a grounded (3 pin) plug, that might set up a ground loop causing AC hum, especially if 2 or more separate AC receptacles are used, like in different rooms. If you can rig up an adapter to convert the 3 pin plug to 2 pins, it is worth testing.

That cured my problem perfectly (was lucky to have such a simple solution).

Posted by auujay on Dec-18-2004 06:17:

Ya I know for a lot of the early FinalScratch users that seemed to clear it up. I think I already tried doing something like that but I may have a go at it again. The thing that gets me is that the light that affects it is built into the ceiling (it is not just a lamp or something) and the hum only happens when it is on. I would think that if one of the components was causing a ground loop it would always be their.