Operating instructions

OPTIMOD-AM DIGITAL OPERATION
3-51
Note also that it is virtually impossible to achieve undetectable dynamic
noise reduction of program material that is extremely noisy to begin
with, because the program never masks the noise. It is probably wiser to
defeat the dynamic noise reduction with this sort of material (traffic re-
ports from helicopters and the like) to avoid objectionable side effects.
You must let your ears guide you.
B3>B4 CPL (“Band 3>4 Coupling”) control determines the extent to which the gains
of bands 4 (centered at 3.7 kHz) and 5 (above 3.0 kHz) are determined by and fol-
lows the gain of band 3 (centered at 1 kHz). Set towards 100% (fully coupled) this
control reduces the amount of dynamic upper midrange boost, preventing unnatu-
ral upper midrange boost in light pop and instrumental formats. The gain of band 5
is further affected by the B4>B5
CPL control.
B4>B5 CPL
(“Band 4>5 Coupling”) controls the extent to which the gain of band 5 is
determined by and follows the gain of band 4.
The B4>B5 CPL CONTROL determines the gain reduction in band 5. The
B4>B5
CPL control receives the independent left and right band 4 gain
control signals; this feed is unaffected by the band 4 M
AX DELTA G / R con-
trol. Range is 0 to 100% coupling.
In the AM analog chain, the B5 compressor is useful mainly as a de-esser.
Used with substantial amounts of B4>B5 coupling and a fast release time,
it can quickly add additional gain reduction as necessary to prevent clip-
ping distortion on “esses.” In the HD chain, the B5 compressor is useful
both as a de-esser and as a means to prevent excessive high frequency
energy from being applied to a low bit rate codec, minimizing HF codec
artifacts.
B3>B2 CPL and B2>B3 CPL controls determine the extent to which the gains of
bands 2 and 3 track each other.
When combined with the other coupling controls, these controls can adjust the mul-
tiband processing to be anything from fully independent operation to quasi-
wideband processing.
B2>B1 CPL
control determines the extent to which the gain of band 1 (below 100Hz
or 200Hz, depending on crossover setting) is determined by and follows the gain of
band 2 (centered at 400Hz). Set towards 100% (fully coupled) it reduces the amount
of dynamic bass boost, preventing unnatural bass boost in light pop and talk for-
mats. Set towards 0% (independent), it permits frequencies below 100Hz (the
“slam” region) to have maximum impact in modern rock, urban, dance, rap, and
other music where bass punch is crucial.
Bx Out
(“Band x Output Mix”) controls determine the relative balance of the bands
in the multiband compressor. Because these controls mix after the band compres-
sors, they do not affect the compressors’ gain reductions and can be used as a
graphic equalizer to fine-tune the spectral balance of the program material.
Their range has been purposely limited because the only gain control element after
these controls is the back-end clipping system (including the multiband clipper / dis-
tortion controller), which can produce considerable audible distortion if overdriven.
The thresholds of the individual compressors have been carefully tuned to prevent