cies, where there is less headroom. However, gentle tapping of a drumstick or brushing of the cymbal
will not be held back. Assuming the tom-tom is a lower frequency instrument and can be better toler-
ated by the tape, it has less need for compression. The equalization in the sidechain circuit means that
the compressor is not triggered as readily by a loud tom-tom beat as by an equally loud cymbal crash.
The converse of the above EQ technique may be used: dipping the equalizer bands causes any sound
with dominant energy in the affected register to pull the level up because the 160S will detect a need
for less compression.
De-Essing
To apply de-essing to vocals (i.e., a reduction of sibilance), use a parametric equalizer in the sidechain
circuit and set it for high frequency boost in the specific frequency range where the vocal
hiss
or lisp
occurs (generally in the 4-6kHz region). This pre-emphasizes the already
hissy
vocal input to the detec-
tor. Used in conjunction with a moderate to high threshold and compression ratio, this arrangement
greatly attenuates the
essing
without affecting the basic sound quality or balance of the voice. While it
is true that all frequencies are lowered in level when the compressor is triggered, generally the
sss
sound
occurs alone, before or after the dominant tone in the voice.
Increasing sustain
To increase the sustain of a musical instrument (e.g., a guitar or bass), use an equalizer in the sidechain
circuit and boost the EQ in the dominant frequency range of the instrument, along with a fairly low
threshold and a moderate compression ratio.
Using a Filter in the Level Detector Circuit
The results of inserting a filter in the level detector circuit are basically the same as obtained with an
equalizer, as previously described. Those frequencies passed by the filter are subject to compression (or
at least they are subject to considerably more compression than those frequencies outside the passband).
Because a passive filter can have insertion loss, it may be necessary to lower the 160S's threshold set-
ting to maintain a given amount of gain reduction within the filter passband; this can be determined by
monitoring the 160S's threshold indicator LEDs.
Multi-way speaker systems
If a single compressor is to be used with a multi-way speaker system (i.e., before the crossover, after
EQ), the system operator is faced with the problem of keeping levels below the point of destruction of
the most sensitive part of the system. If, for example, mid-range drivers are frequently damaged, the
whole system must be operated at a lower sound-pressure level, or additional mid-range drivers must
be added. By inserting an equalizer in the detector path of the 160S, it can be made more sensitive to
frequencies in the range handled by the sensitive drivers. The system can then be run at higher levels
and will only be dropped back when damaging, mid-range signals are present.
Pre-emphasis for broadcast applications
By inserting a pre-emphasis filter network in the sidechain circuit of a 160S processing pre-emphasized
audio, higher levels can be run within the headroom limitations of the broadcast chain.
Anticipated Compression
By feeding the program directly to the 160S's sidechain return and sending the audio signal through a
delay line before the audio input, the unit can anticipate the need for a gain change. See diagram on
the following page. With some experimentation, the effect can be that of zero attack time at a given fre-
24
160S
notes
Operating
