•
If the +10 dB LFE gain is already
implemented by another device, for
example, a surround sound processor or
the output matrix of a mixing console.
•
When producing an audio format that
does not require the use of +10 dB gain
on the LFE channel.
Additional Information
Positioning the Subwoofer in a Room
The location of the subwoofer can affect
the frequency response and sound level
dramatically particularly when the room
acoustic effects are strong. Even small
changes in a subwoofer's location can
make a marked difference in the frequency
response. To begin, place the subwoofer
near the front wall slightly offset from
the room center line. Often systematic
experimentation is needed to find the
location giving the flattest frequency
response at the listening location. Usually
the subwoofer is placed close to a wall as
this creates the highest output. Positioning
the subwoofer close to a corner will boost
the bass level at lower frequencies and may
also cause asymmetrical spatial imaging.
Measured from the subwoofer's driver the
recommended distance to a wall is less than
0.6 m (24 in). This avoids a loss of audio
level at low frequencies created by the audio
reflecting off the wall and cancelling certain
frequencies radiated by the subwoofer.
Operating Environment
This subwoofer is designed for indoor use
only. The permissible ambient temperature
is 15-35 degrees Celsius (50-95°F)
and relative humidity 20 – 80% (non-
condensing). When the product has been
stored or transported in a cool environment
and is taken into a warm room, wait about
one hour before opening packing to prevent
condensation of humidity before connecting
to mains power.
Minimum Clearances
Do not cover the grille or place the subwoofer
so that there is less than 0.1 m (4 in) of free
space in front of the grille. The space must
be ventilated or sufficiently large to dissipate
heat so that the ambient temperature
does not rise above 35 degrees Celsius
(95°F). Make sure that the space under the
subwoofer allows air flow. Thick carpets
may block ventilation needed for cooling the
electronics. The reflex port opening should
have a clearance of at least 7.5 cm (3 in) to
ensure functioning of the reflex port.
Figure 5. The curves above show the
main channel's frequency response
with 85 Hz lowpass filtering, the fre-
quency response of the LFE channel
and the effect of the Bass Roll-Off
adjustment to the response of the
7380A.
Flush Mounting
When the subwoofer is flush mounted in a
wall or cabinet, ensure unrestricted airflow
in the reflex port and amplifier cooling.
Make the recess 7.5 cm (3 in) wider than the
subwoofer. Place the subwoofer to the right
side of the recess if the driver is facing the
room. This leaves sufficient free space at the
reflex port side. The height and depth of the
recess should not be much bigger than what
is needed for ventilation as this may cause
unwanted acoustic effects.
Using Multiple Subwoofers
Multiple Genelec 7380A subwoofers can be
coupled together in high SPL applications.
The necessary cabling is different for digital
and analog signals. When subwoofers
are close to each other, the sound level
increases typically by 6 dB for each
doubling of the number of subwoofers.
When subwoofers are far from each other,
the total increase in the sound level can
be less. It is safe to assume the increase
is 3 dB for each doubling of the number of
subwoofers. Accurate understanding of the
increase in sound level requires acoustic
measurements.
Digital Cabling
Run a signal cable from the AES/EBU
OUT connector of the first subwoofer in
the chain to the AES/EBU IN connector of
the next subwoofer. Check that the Digital
LFE and LFE Channel A/B control switches
have the same settings in all subwoofers in
the chain.
Analog Cabling
When daisy-chaining multiple subwoofers
with analog signals, run a cable from the Link
Out connector to the next subwoofer’s Link
In connector. When using the LFE signal,
also run a cable from the LFE Out to the next
subwoofer’s LFE In.
Control Switch Settings When Using
Multiple Subwoofers
We recommend using the GLM software
and its AutoCal function for subwoofer
calibration. Then, no manual adjustments on
the subwoofer are necessary.
1. If the GLM is not available, manual
adjustments can be done as follows:
Calibrate subwoofers one by one. Turn on
only one subwoofer at the time.
2. Calibrate the subwoofer level to match
Figure 4. Flush mounting the
subwoofer. Note the clearance needed
on the reflex port side.
Figure 6. The curves above show the
harmonic distortion analysis of the
7380A in free field. In half space the
SPL will be 6 dB higher.
+0
+20
+40
+60
+80
+100
10
200
20 30
50
100
Hz
Level vs Freq (Hz)
7380A 11.5.17
LFE channel
Main channels
Bass
Roll-Off
-4, -8 and
-12 dB
dB
SPL
+0
+20
+40
+60
+80
+100
10
200
20 30
50
100
Hz
Level vs Freq (Hz)
7380A 11.5.17
dB
SPL
3rd harmonic
2nd harmonic