Crown Audio IQ-USM 810 - Manual (Page 20)

Page 20
IQ-USM 810 IQ Digital Processor / Digital Mixer
IQ-USM 810 Reference Manual
• • • • • Soft Knee Width: sets a range in dB around the
actual threshold through which the compressor
gain is gradually modified from unity to the final
compressed gain. Control range is from 0 dB to
+20 dB in
1 /
2
-dB steps.
4.3.6 Automixing
Automatic mixers allow “hands-free” mixing that mini-
mizes many of the undesirable effects of using multiple
microphones. Applications such as conference rooms,
training rooms and boardrooms typically implement
many microphones for individual speakers. Simulta-
neously mixing all microphones with acceptable gain
before feedback many times is not possible. The IQ-
USM 810 implements three auto-mixing functions to
address this situation: Priority Ducking, NOM Attenua-
tion and Adaptive Gating.
Each of the sixteen A/B Processing Sections can be
grouped into one of four Auto-Mix Groups. This allows
up to four separate Auto Mixers (A, B, C, D) to be
implemented within the same chassis. In addition to
the Group assignment, each A/B section includes a
separate Enable control. This controls whether the re-
spective channel participates in the assigned group
AutoMixing functions. Automixing’s affect on input gain
is metered by the Input Dynamic Cut/Boost Meter (See
section 4.2.2).
Priority Ducking enforces a "priority order" of open
microphones such that high-priority inputs "duck" (at-
tenuate) lower-priority inputs. Additionally, a maximum
number of equal-priority open microphones may be
specified. Keeping the number of open microphones
to a minimum reduces background noise while allow-
ing a higher gain before feedback for improved intelli-
gibility. Gates must be ON to use Priority Ducking.
Gates must be ON to use Priority Ducking. Gates must be ON to use Priority Ducking. Gates must be ON to use Priority Ducking. Gates must be ON to use Priority Ducking.
Note the six controls and two firmware indicators:
• Master Priority Ducking Enable: turns ducking
priority on and off within an automix group.
• Duck Priority Level: assigns a relative priority to
each channel. Control range is 1 to 8 where 1 is
the highest priority and 8 is the lowest priority.
• Depth: sets the “ducked” mic gain. Control range
is from –100 to 0 in 1 /
2
-dB steps.
• Attack Time: sets the time required for Priority
Ducking to attenuate the mic gain by 20-dB. Con-
trol range is from 10-milliseconds to 10-seconds
in 10-millisecond steps.
• Release Time: sets the time required for Priority
Ducking to increase the mic gain by 20-dB. Con-
trol range is from 10-milliseconds to 10-seconds in
10 millisecond steps.
• Max Number of Open Mics: sets the max number
of open mics within the automix group. A last-in,
first-out algorithm is used to determine which mics
are ducked. When Max Number of Open Mics is
equal to one.
• Highest Open Mic Priority Indicator: shows the
highest priority level for all open mics within the
automix group.
• Total Number of Open Mics Indicator: indicates
the total number of presently open mics within the
automix group.
NOM attenuation reduces overall system gain as the
number of open mics increases beyond one for im-
proved gain before feedback. There are three controls
for this feature:
• Master NOM Attenuation Enable: turns NOM
Attenuation on and off within an automix group.
• NOM (Number of Open Mics) Attenuation
Mode: sets the attenuation algorithm to linear or
logarithmic. In linear mode, each open mic be-
yond one will cause all inputs in the auto-mix
group to be attenuated by an amount equal to the
Attenuation Step Size, defined below. In logarith-
mic mode the attenuation per open mic will de-
crease as more mics open. Linear mode may allow
each individual mic to use a higher nominal gain by
more aggressively attenuating as more mics open.
Logarithmic mode with Attenuation Step Size of 3-
dB emulates “classic” NOM attenuation schemes.
• Attenuation Step Size: with NOM Attenuation
mode, determines the attenuation as a function of
the number of open mics in the auto-mix group. In
linear mode, each open mic beyond one in-
creases the attenuation by this amount. Control
range is from 0.5 to 3-dB in
1 /
2
-dB steps.
Adaptive Gating dynamically modifies the gate
thresholds in the auto-mix group as a function of the
ambient level in the room. The ambient level is com-
puted as the weighted average of the closed mic input
levels. The weighted average makes it possible to
compensate for mic locations with different ambient
levels. There are four controls and one meter for this
feature:
• Master Adaptive Gating Enable: turns Adaptive
Gating on and off within an automix group.
• Ambient Weighting: the weighting factor used
in the ambient level calculation. This control
should be set to 1 with the following two excep-
tions: to exclude the mic from the ambient level