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User's Manual
Hum
Adding any component such as a sub-
woofer to an existing system will often
give rise to a hum which wasn’t there
before. Your rst thought may be that
the subwoofer has a problem, but this is
more than likely caused by a “ground-
loop” in your system.
Follow these steps to isolate the main
cause of the ground-loop hum (there
may even be more than one cause).
• Try to have all of your equipment on
the same electrical outlet or circuit, see
page 10 for more details.
• If your sub amp is a fair distance away
from your other equipment, you may
use a 15 amp extension cord as long as
it has a ground connection.
NOTE: Never remove the ground
pin from any power cords. This is
very dangerous.
• Turn off all components in your system,
including the subwoofer amplier,
ampliers and the preamplier, before
disconnecting or connecting cables.
• First remove every connection from the
sub amplier to the rest of your system.
Plug the subwoofer amplier's power
cord back in and check for the hum.
If it is still there, try plugging it into a
different outlet in case it is picking up
interference on the AC line.
• If you have followed the above guide-
lines for the power connections and a
hum is still present, then there is one
very common problem to consider: a
“ground-loop” introduced by connecting
a cable TV line to a VCR or TV, which is
then connected to the preamp. This can
be addressed as follows:
• Disconnect all cables which come from
outside the room, such as cable TV,
satellite TV, or roof top antennas. Make
sure that they are disconnected where
they rst enter the room, so they are
making no connection to your preampli-
er, TV, or any other component. If the
hum is caused by the cable TV line, then
you will need a “ground-loop isolator.”
This is an inexpensive device tted in
line with the coaxial cable feed.
• If the hum persists, disconnect all the
source components one at a time from
the back of the preamplier until you
identify the problem.
• Ground-loop isolators are available for
audio lines and video. Once you have
identied which components are causing
a problem, you can t the isolators be-
tween the component and the preampli-
er.
The subwoofer won’t turn off
• The subwoofer amplier should turn
itself off after approximately fteen min-
utes with no audio signal present. If not,
check there is no background hum. The
subwoofer may sense hum as a small
signal and stay on. See the above hints
to eliminate the hum.
The subwoofer won’t turn on
automatically
The subwoofer amplier should turn on
when an audio signal is applied, or
12 VDC is applied to the Trigger inputs,
or if the Start button is pressed. If it does
not turn on, check the following:
• The subwoofer amplier’s volume con-
trol may be turned down, or no signal is
received from your preamplier.
• Check the input connections.
• Check the mode switch or menu on sur-
round systems to be certain that a bass
signal is being sent to the subwoofer.
• Use the 12V Trigger for the most reliable
on/off operation.
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