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Pro Logic) should not be connected to the
"LFE IN" input. See section "Subwoofer in
analogue matrix sound systems".
SUM OUT: Use this output connector when
you want to link another subwoofer to your
system. "SUM OUT" carries an unfi ltered
sum of signals combined from all input chan-
nels. See section "Using multiple subwoof-
ers".
Middle row
FRONT L, C, R CHANNELS IN/OUT: Use
these connectors for the Front Left, Center
and Right channels of a surround sound
system or the Left and Right channels of
a Stereo system. Connect line level signal
cables from your signal source to their respec-
tive "LEFT IN", "CENTER IN" and "RIGHT IN"
connectors. Then connect the subwoofer to
your main monitors with XLR cables from the
"LEFT OUT", "CENTER OUT" and "RIGHT
OUT" connectors. All "L, C and R OUT" chan-
nels are high pass fi ltered with the fi ltering
frquency fi xed at 85 Hz (12 dB/octave).
Bottom row
REAR L, C, R CHANNELS IN/OUT: Use
these connectors for the Rear Left, Center
and Right channels of a surround sound
system. The connection is made in the same
way as with the Front channels. Also these
channels are high pass fi ltered at 85 Hz.
Once all connections have been made, the
subwoofer and main monitors 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 fi nd the optimum placement.
The placement will affect the phase
difference between the main monitors and
the subwoofer, and also the bass roll-off rate.
These effects can be compensated by the
use of the controls in the amplifi er unit;
but we recommend that at fi rst you leave
the switches untouched and concentrate on
fi nding the position where the subwoofer
gives the smoothest response, and only then
use the controls to fi ne-tune the balance and
phase alignment between the subwoofer and
the main monitors.
To begin with, place the subwoofer slightly
offset from the center of the front wall.
The recommended distance to the wall is
less than 60 cm / 24" measured from the
subwoofer's driver (See Fig. 3). This position
gives increased acoustic loading (and SPL)
due to the proximity of the front wall and fl oor.
Cancellations from the front wall and fl oor are
also avoided. Front wall cancellation for the
85 Hz high pass fi ltered main speakers
can be eliminated by placing them at least
110 cm / 43" away from the front wall. In
a multichannel system the main monitors
should ideally be positioned symmetrically
and at an equal distance from the listening
position.
If the frequency balance is not 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. If you
are using two subwoofers, try placing them
asymmetrically relative to the side walls.
Sometimes moving the subwoofers apart
into the front corners helps with problematic
rear wall refl ections and the loss of mutual
coupling is compensated by the bass boost
caused by corner positioning.
Figure 3. Recommended distances to
the front wall
Figure 1. 7070A's amplifier panel, connectors and controls.
Figure 2. XLR to RCA connector for
unbalanced operation.
Gen 7060A+7070A+7071A 22.5.2002, 11:043
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