JBL PowerBass PB12, Service Manual

Page: 11 / 43

PB12
11
Phase Control
The Phase Control determines
whether the subwoofer’s
piston-like action moves in and
out in phase with the main
speakers or opposite the main
speakers. There is no correct
or incorrect setting. Proper
phase adjustment depends on
several variables such as
subwoofer placement and
listener position. Adjust the
phase switch to maximize bass output at the listening
position.
Remember, every system,
room and listener is different.
There are no right or wrong
settings; this switch offers the
added flexibility to adjust your
subwoofer for optimum
performance for your specific
listening conditions without
having to move your speakers.
If at some time in the future
you happen to rearrange your
listening room and move your
speakers, you should
experiment with the phase
switch in both positions, and
leave it in the position that
maximizes bass performance.
TROUBLESHOOTING
If you used the high-level
(speaker) inputs and there is
no sound from any of the
speakers:
•Check that receiver/amplifier
is on and source is playing.
•Check that powered
subwoofer is plugged into
and active electrical outlet
and is switched on.
•Check all wires and
connections between
receiver/amplifier and
speakers. Make sure all
wires are connected. Make
sure none of the speaker
wires are frayed, cut or
punctured.
•Review proper operation of
your receiver/amplifier.
If there is low (or no) bass
output:
•Make sure the connections to
the left and right “Speaker
Inputs” have the correct
polarity (+and-).
•Make sure that the subwoofer
is plugged into an active
electrical outlet and (PB12
only) switched on.
•Adjust the crossover point.
•Flip the Phase Control switch
to the opposite position.
•If you are using a Dolby
Digital/DTS receiver or
processor, make sure that the
subwoofer adjustments on
the receiver/processor are set
up correctly.
•Slowly turn the Level Control
clockwise until you begin to
hear the desired amount of
bass.
If you used the line-level
inputs and there is no sound
from the subwoofer:
•Check that receiver/amplifier
is on and a source is playing.
•Check that powered
subwoofer is plugged into an
active electrical outlet and is
switched on.
•Check all wires and
connections between
receiver/amplifier and
subwoofer. Make sure all
wires are connected. Make
sure none of the wires are
frayed, cut or punctured.
•Review proper operation of
your receiver/amplifier.
•Slowly turn the Level Control
clockwise until you begin to
hear the desired amount of
bass.
•Make sure that you have
configured your
receiver/processor so that the
subwoofer/LFE output is on.