The hum of a
powered subwoofer can have various causes.
As a rule, a
so-called "ground loop", which is caused by ground potential
differences. Due to the potential differences between
two grounded points, a current flows on the connecting line between two
devices, a voltage drop has the result that is then amplified as a signal. There is a 50 Hz hum in the subwoofer result.
cables are typically coaxial cable as antenna cable, RCA audio cables, HDMI
cables, etc., have a shield which is connected to the device ground.
About these ground lines, the devices are now
unwittingly into a "loop", via which a current flows. BEWARE solving Ground loops may
cause insanity due to the fact they can be very hard to remove in some cases !!
To prevent this you have to loop through "galvanic
decoupling" Cut, without impairing the function of the joints.
This is done
Bypass filter in the antenna cable
Galvanic separation filter in the
Should not be
used, ref. is prohibited:
Bypass filter in the antenna line
of satellite equipment
Masking of the grounding of the
power plug with electrical tape