Harman JBL SUB 550P, Service Manual, Page: 8 / 43

TURNING THE SUBWOOFER ON AND OFF
Set the subwoofer’s Power Switch to the “On” position. The subwoofer will
automatically turn itself on when it receives an audio signal, and it will go
into Standby mode after it has received no audio signal for approximately
10 minutes. The subwoofer’s LED will glow green when the subwoofer is
on and will glow red when the subwoofer is in Standby.
If you will not be using the subwoofer for an extended period – for
instance, if you’re going on vacation – set the Power Switch to the “Off”
position.
SUBWOOFER ADJUSTMENTS: CROSSOVER CONTROL
NOTE: The Crossover control functions only
when the Input Mode switch is in the “Normal”
position.
The Crossover control adjusts the subwoofer’s
built-in low-pass filter crossover between 50Hz
and 200Hz. The higher you set the Crossover
control, the higher in frequency the subwoofer
will operate and the more its bass will “overlap” that of the satellite speak-
ers. This adjustment helps achieve a smooth transition of bass frequencies
between the subwoofer and the satellites for a variety of different rooms
and subwoofer locations.
To set the Crossover control, listen for the smoothness of the bass. If the
bass seems too strong at certain frequencies, try a lower Crossover con-
trol setting. If the bass seems too weak at certain frequencies, try a higher
Crossover control setting.
SUBWOOFER ADJUSTMENTS: VOLUME
Use the Level control to set the subwoofer’s
volume. Turn the knob clockwise to increase the
subwoofer’s volume; turn the knob counterclock-
wise to decrease the volume. Once you have
balanced the subwoofer’s volume with that of
the other speakers in your system, you shouldn’t
have to change the Level control setting.
Notes on Setting Subwoofer Volume:
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for films, while the ideal setting for films is too quiet for music. When
setting the subwoofer volume, listen to both music and films with
strong bass content and find a “middle ground” volume level that
works for both.
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to place it in a different location. Placing the subwoofer in a corner will
tend to increase its bass output, while placing it away from any walls
or corners will tend to lessen its bass output.
SUBWOOFER ADJUSTMENTS: PHASE
The Phase switch determines whether the subwoofer
driver’s piston-like action moves in and out in phase
with the satellite speakers. If the subwoofer were to
play out of phase with the satellite speakers, the sound
waves from the satellites could partially cancel out the
waves from the subwoofer, reducing bass performance
and sonic impact. This phenomenon depends in part on the placement of
all the speakers relative to each other in the room.
Although in most cases you should leave the Phase switch in the “Normal”
position, there is no absolutely correct setting for the Phase switch. When
the subwoofer is properly in phase with the satellite speakers, the sound
will be clearer and have maximum impact, and percussive sounds like
drums, piano and plucked strings will sound more lifelike. The best way
to set the Phase switch is to listen to music that you know well and to set
the switch in the position that gives drums and other percussive sounds
maximum impact.
OPERATING THE SUBWOOFER
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