BSS Audio OPAL Series DPR-422 Owner's Manual - Manual (Page 27)

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HF De-essing with
full Dynamic
control
Rotate the THRESHOLD control anticlockwise until the BELOW THRESHOLD
meter is fully illuminated and an appropriate amount of gain reduction is
indicated on the GAIN REDUCTION meter. The FREQ control and
THRESHOLD control can now be fine tuned to achieve the desired effect
whilst listening to the program. Gain compensation will not normally be
required when de-essing. Although fast attack and release times are most
appropriate, they should be adjusted to achieve the best results. The AUTO
switch should NOT be depressed.
To aid the correct setting of the FREQ control in relation to the audible
sibilance, the source program can be listened to by depressing the SIDE
CHAIN LISTEN switch. This replaces the normal signal at the output connector
with the output of the de-ess filter.
9.3 Peak Limiting
Apply a signal to the DPR-422 input that is at the maximum level required
without limiting. Rotate the THRESHOLD control anticlockwise until the peaks
of the normal program cause the gain reduction meter to indicate compressor
operation, then rotate the THRESHOLD control back slightly so that no
operation is indicated. Peaks in the program that exceed the norm will now be
hard limited as the RATIO control is set to infinite. The GAIN control should be
set so that the (limited) output of the DPR-422 matches that expected by
following equipment. Note that the setting of the ATTACK and RELEASE
controls represent a compromise between speed of limiting and audible side
effects. For effective limiting, the ATTACK should be set fast.
A very common requirement is to make the threshold of the compressor
frequency conscious by inserting a graphic or parametric equaliser into the
control side chain. The input of the external equipment should be connected to
one of the send outputs of the unit, and the output of the external equipment
connected to one of the return inputs, as required.
All of the external equipment should be capable of operating at the general
line levels set by the rear panel OPERATING LEVEL switch have unity gain, an
input impedance greater that 10k Ohms and an output impedance less that 1k
Ohms. In order to preserve the THRESHOLD control calibration, it is essential
that unwanted frequencies are attenuated rather than wanted frequencies
boosted by the external filter. For example, if compression is to be controlled
by a narrow mid-band of frequencies, then the low frequency and high
frequency sliders should be pulled down, and the mid-band sliders left at 0dB.
9.6 Side chain insert