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.1 output channel of a 5.1-channel discrete
surround sound source.
Once all connections have been made, the
subwoofer and main loudspeakers are ready
to be powered up.
Positioning in the room
The placement of the subwoofer in the room
affects the overall frequency response and
sound level of the system dramatically, as at
low frequencies the effects of the room are
strong. Even a slight change in the subwoof-
er's location can make a marked difference in
the frequency balance and often patient and
methodical experimentation and testing is
needed to find the optimum placement. The
placement will affect the phase difference
between the main loudspeakers and the sub-
woofer and the bass roll-off rate.
First place the subwoofer slightly offset
from the center of the front wall. The rec-
ommended distance to the wall is less than
60 cm / 24" measured from the subwoofer's
driver. This position gives increased acoustic
loading (and SPL) due to the proximity of the
front wall and floor. Cancellations from the
front wall and floor are also avoided. Front
wall cancellation for the 85 Hz high pass fil-
tered main speakers can be eliminated by
placing them at least 110 cm / 43" away from
the front wall (see Figure 2).
If the frequency balance does not seem
right, try moving the subwoofer slightly to
the left or right so that different room modes
are excited at different levels. Positioning
the subwoofer close to a corner will boost
the bass level at lower frequencies and may
cause asymmetrical spatial imaging.
Although the 7050B is magnetically
shielded, it may cause colour distortion if
placed near to very sensitive video loudspeak-
ers or computer displays. Move the subwoofer
further away or try turning the driver side of
the subwoofer away from the screen
.
Minimum clearances to walls
or other objects
Do not cover the driver side of the subwoofer
or place the subwoofer so that there is less
than 10 cm (4") of free space in front of the
grille.
Make sure that the space underneath the
subwoofer is clear from obstructions. Thick
carpets may block the ventilation clearance
needed for cooling the electronics.
The reflex port side (opposite of the con-
nector panel side) should always have a
clearance of at least 7,5 centimeters (3") to
any objects to ensure proper functioning of
the reflex port.
Flush mounting the subwoofer
If the subwoofer is flush mounted into a wall
or a cabinet, it is important to ensure ampli-
fier cooling and unrestricted airflow from the
reflex port. This can be done by making the
recess 7,5 centimeters (3") wider than the
subwoofer. Place the subwoofer into the right
end of the recess with the driver side facing
the room. This leaves sufficient 7,5 centime-
ters (3") of free space on the reflex port side.
The height and depth of the recess should
not be any bigger than is needed to fit the
subwoofer flush with the wall surface.
Sensitivity adjustment
The subwoofer requires input sensitivity
alignment to the source to obtain a correctly
balanced system. The input sensitivity con-
trol is located on the connector panel of the
subwoofer. An input voltage of -6 dBu with a
-6 dBu input sensitivity setting will produce
100 dB SPL @ 1 m in free field.
Setting the phase control
Incorrect phase alignment between the
main loudspeakers and subwoofer causes
Figure 3. Recommended distances to
the front wall
Figure 1. 7050B's amplifier panel, connectors and controls.
Figure 2. XLR to RCA connector for
unbalanced operation.