a typical house has 208 single phase power. what this is is two 120 volt circuits that are out of phase with each other. if the sub woofer is pluged into the other circuit " different from your preamp/amp" it will cause a 60 cycle hum. try mooving your sub woofer next to your preamp/amp and using the same power plug ( wall outlet )to power the sub woofer. if the hum goes away, find a different outlet on the same circuit of the power panel or use a large # 14 or #12 guage extension cord and place your sub woofer where you had it.
new sub makes my surronds hum
just bought a new powered sub for my home theatre i am using a yamaha receiver, mirage speakers all around with the effect off no hum,surrond on i have a hum in the rear speakers only, i am using the monster sub woofer cables tried one of my tara labs same thing sent the sub back they said alls fine,this sub has a ground plug i have heard something about grounded plugs?????? help