BSS Audio DPR-402 Owner's Manual - Manual (Page 9)

9
3.0 De-essing and Peak Limiting
A common problem encountered when amplifying the human voice is the
large amount of High Frequency energy, heard as the sibilant 'sss' sound.
These high frequency or sibilant sounds can reach levels considerably greater
than the normal voice level, and will result in signal break-up or distortion. It
is possible to control these sounds independently of the normal program by
making the normal compressor sensitive only to these high frequencies.
Selective high frequency compression is generally called de-essing, as it
removes the 'sss' content from the program.
Referring to section 2.2, attack time was defined as the time taken for the
compressor to respond to program levels which have exceeded its threshold
level. It is also found that for relatively low frequencies a longer attack time
is required than for high frequencies, to avoid any unpleasant dynamic
distortions. When compressing a program mix that includes a wide range of
frequencies, some compromise must be made to the setting of the attack time,
and this will inevitably result in a setting that suits the lowest frequency
components present. For general dynamic range controlling using a
compression mode, this is of no serious consequence. However, in a limiting
mode, where the peaks of the signal are being restricted to a maximum
operating level to avoid distortions in following equipment, it is essential to
have the attack times as fast as possible for all frequency components.
Operating the compressor in a limiting mode, with a high ratio, high threshold
and dynamic settings to suit the low frequency components, will result in very
fast high frequency signal transients passing through without causing gain
reduction. These transients can then cause distortions in following equipment,
such as tape recorders and radio transmitters.
It should be remembered that the DPR-402 is a peak limiter, designed to be
used in conjunction with the main compressor section. If it is used exclusively
on its own, then dynamic distortions will generally result on program signals
having anything other than high frequency content.
De-essing and Peak Limiter
The DPR-402
4.0 The BSS DPR-402
The BSS DPR-402 compressor, de-esser and peak limiter has been designed in
response to the demand for a versatile, compact stereo unit which provides
the three most commonly used dynamic functions in a single 1 unit rack
space. The internal architecture, including two independent insert accessible
side chains per channel, allows unprecedented flexibility and scope for the
creative operator. In its normal mode, however, this complexity remains
totally invisible for the user who required a conventional system with
operational simplicity.
The dedicated de-esser control and associated variable filter allow wide band
sibilance control simultaneously with compression and peak limiting. For
highly critical de-essing application, the compressor section can be switched
to operate at high frequencies only, i.e: as a dynamically controlled tunable
HF filter.