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HEAVY WOODEN WALL
ABSORBING
MATERIAL
VIBRATION
ISOLATORS
f ~ 2-8 Hz
Figure 4: Flush mounting the loudspeaker in
a wall constructed of wood
than one switch is set to 'ON' (within one
switch group) the attenuation value is no
longer accurate.
Vertical / horizontal mounting
Genelec HT320AC can be mounted ver-
tically or horizontally. If the loudspeaker's
orientation is changed, the DCW™ plate
must be rotated so that the treble and mid-
range drivers remain vertically aligned with
the mid driver at the bottom of the DCW™.
Remove the four corner screws of the
DCW™ (use a 4 mm Allen key) and pull
the plate carefully out without stressing the
wires and the gasket. Rotate the plate 90
degrees in the appropriate direction and
remount the screws.
Flush mounting
The HT320AC can be used flush
mounted into the wall structure, which
offers some acoustical benefits. No cabi-
net edge diffraction will occur, resulting
in an improved response, especially at
midrange frequencies. Low frequency
reflections from the wall behind the loud-
speaker can be avoided, which improves
the low frequency response and efficiency
and allows the loudspeaker to work in
half space conditions. In terms of instal-
lation and orientation, the loudspeaker's
CONCRETE WALL
SAND
BAGS
VIBRATION
ISOLATORS
f ~ 2-8 Hz
Figure 5: Flush mounting the loudspeaker in
a wall constructed of concrete
acoustical axis (See figure 1) should point
directly to the listening position. The loud-
speaker should be vertically aimed so that
the acoustical axis of the loudspeakers
meet around ear height at the reference
listening position. In the horizontal plane
the loudspeakers should be positioned
according to the multichannel (ITU-R
BS.775-1) placement recommendation.
The ceiling, side walls and especially the
rear wall should be acoustically absorbent
at low frequencies. The wall in which the
loudspeakers are mounted should have a
high acoustical mass to properly implement
half space radiation at low frequencies and
be angled so that the loudspeakers are
correctly aimed. However, the loudspeak-
ers should not be mounted too high as this
increases the required vertical tilt of the
speaker (maximum tilt angle < 20 degrees)
and reduces the optimum listening area.
Great care should be taken over how the
loudspeaker is mounted into the wall. Note
the following:
A space 50 to 100 mm (2 to 4") wide
can be left around the loudspeaker. Cover
the space around the loudspeaker with a
facing panel that should be fixed to the wall.
Leave a gap of about 5 to 10 mm (¼ to ½")
between the loudspeaker and the panel. Fill
this gap with a soft rubber gasket to allow
MULTI-LAYERED WALL
(WOOD, CONCRETE, BRICKS)
CONCRETE
STRUCTURE
VIBRATION
ISOLATORS
f ~ 2-8 Hz
Figure 6: Flush mounting the loudspeaker
in a wall constructed of a combination of
materials.
SPEAKER
RUBBER GASKET
(5-10 mm / ¼-½")
FACING PANEL
FIXED TO THE WALL
(50-100 mm / 2-4")
WALL
Figure 7: Covering the gap between the
wall and the loudspeaker cabinet.
for possible movement (see figure 6).
Ensure that the loudspeaker cables can
reach the rear of the loudspeaker cabi-
nets.
Regardless of the type of front wall con-
struction the loudspeaker cabinet should
be mounted on vibration isolators, with a
resonant frequency of 2 to 8 Hz, to pre-
vent vibrations from being transmitted to
the wall and impairing the low frequency
performance.
If a heavy wooden front wall construc-
tion is used, the space around the cabi-
net should be filled with absorbent min-
eral wool or foam plastic. The wooden
wall structure must be heavily braced to
achieve sufficiently high mass and rigidity
(see figure 4).
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