not cause compression, and the program is not subject to the phase shift normally caused by program equalization.
During the recording of cymbals and tom-toms, a compressor with an equalizer in the sidechain path can help prevent tape saturation. The equalizer can be adjusted for boost with a peak of about 5kHz, causing the cymbal to be compressed on a very loud crash, stopping tape saturation at high frequen- 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 162SL 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 162SL's threshold set- ting to maintain a given amount of gain reduction within the filter passband; this can be determined by monitoring the 162SL'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 162SL, 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 162SL processing pre-emphasized audio, higher levels can be run within the headroom limitations of the broadcast chain.
