The LFE channel on the 7060B, 7070A and
7071A can be set to two frequency ranges:
19 to 85 Hz or 19 to 120 Hz by using the
"LFE BANDWIDTH" switch.
If the LFE signal
includes higher frequencies than 120 Hz,
they can be monitored by using the "Redirect"
function: Set "LFE BANDWIDTH" switch
to "85" and the "REDIRECT" switch to "ON".
Now the subwoofer reproduces LFE frequencies
up to 85 Hz and reroutes all higher LFE
content to the front center channel. This is
the most flexible setting for LFE signal management,
as it ensures that all LFE content
can be monitored in all situations and encoding
formats. Note that the "Redirect" function
is not enabled when the "LFE BANDWIDTH"
switch is set to 120 Hz.
Typical applications of different
LFE bandwidth settings
As stated above, using the 85 Hz LFE bandwidth
setting with "Redirect" function is the
most universal configuration for LFE monitoring.
However, there are situations when the
band-limited LFE settings serve a definite
purpose.
Limiting the LFE bandwidth to 85 Hz without
using the "Redirect" function can be used to
simulate the effect of some consumer decoders
that do not replay information above 80
Hz on the LFE channel when the bass management
is used. Checking the multichannel
mix with this setting on lets you know how it
translates in systems with this limitation.
The 120 Hz LFE bandwidth setting complies
with the replay systems of movie theaters
and cinemas. 35 mm movie soundtracks
use the LFE channel to reproduce a bandwidth
of 20 - 120 Hz through dedicated
subwoofers.In this case the LFE and main
channel bandwidths overlap between 85 and
120 Hz, which may create unwanted acoustical
summing if the same signal is present
in both channels. To avoid this, the LFE content
should be kept completely different (decorrelated)
from the low frequency content
of the main channels when mixing music
and sound effects for film release.
Using the LFE +10 dB function
In Dolby Digital and DTS encoding formats
the LFE channel has to be monitored with
+10 dB gain in relation to the main channels.
The object is to increase the recording headroom
of the LFE channel. Consumer and theatrical
decoders automatically add +10 dB of
LFE gain to restore the level balance.
The "LFE +10 dB" function on the 7060B,
7070A and 7071A subwoofers is designed to
add the +10 dB gain to the LFE channel in the
production stage, if it is not already done in
the output matrix of the mixing console. The
function is activated by switching the "LFE
+10 dB" dip switch on the subwoofer's first
switch group to "ON" or by using the remote
control. A yellow LED indicates that the function
has been activated.
The "LFE +10 dB" function should not be
used in following cases:
• If the +10 dB LFE gain is already
implemented by another device.
• When producing an audio format that
does not require the use of +10 dB
gain on the LFE channel, such as
DVD-Audio (MLP), SACD (DSD) etc.
• When monitoring a decoded Dolby
Digital or DTS soundtrack. The decoder
will automatically provide +10 dB
LFE gain.
Using multiple subwoofers
Genelec 7060B, 7070A and 7071A subwoofers
are equipped with a "SUM OUT" connector to
provide an easy way of coupling two or more
subwoofers together in high SPL applications.
Table 2 shows the recommended configurations
with different Genelec monitors. Connect
an XLR cable from the "SUM OUT" connector
of the "master" subwoofer to which the main
monitor channels are connected, to the "LFE
IN / SUM IN" connector of the other, "slave"
subwoofer and turn the "SUM IN MODE" dip
switch on the "slave" subwoofer to "ON".
When two subwoofers connected in this
way are positioned close to one another,
bass level increases by 6 dB. Three subwoofers
give an SPL increase of 9,5 dB and
four subwoofers 12 dB compared to a single
subwoofer. Adjust the sensitivity control of all
subwoofers in the group to match the SPL
level of the main monitor system.
Phase and Bass Roll-Off adjustments
should be done individually for each subwoofer
in the chain, especially if they are not
placed close together. To check the phase
alignment for the "master" subwoofer switch
off the "slave" subwoofer and follow the
instructions given in the previous sections.
To adjust the phase alignment of the
"slave" subwoofer, you need to switch off
the "master" subwoofer, connect a signal
cable from the "slave" subwoofer's "FRONT
CENTER OUT" connector to the center channel
monitor and switch the "SUM IN MODE"
switch to "OFF". This effectively changes
the "slave" to "master" mode and the phase
adjustment can be carried out. Return the
connections and "SUM IN MODE" setting on
the "slave" subwoofer back to the "SUM IN"
mode after completing the adjustment.
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