sub woofer noise

[admin_exported]

i just bought an eltax thunder 8 subwoofer not the best i know but all i could afford at the time. when there is no signal to the subwoofer it sometimes starts to make a rumbling sound. Is there any way to remedy this or is it just because i've got a cheap subwoofer.

 

[d4v3pum4]

Is it a hum? Does it do it with nothing connected to it? It could be ground loop. Google for solutions.