dbx 1066 - Manual (Page 16)

12
Applications
Frequency-Sensitive Gating
Frequency-sensitive gating lets you use the SIDECHAIN INPUT to tune the response of the gating action. For
example, if you’re gating a kick drum in a track with lots of leakage, you can tune in to the frequency of the
kick with an outboard EQ and the gate will respond only to that drum. Feed the kick drum signal both directly
into the gate and also through an equalizer which is connected to the SIDECHAIN INPUT. With the equalizer
adjusted so that only the desired signal is emphasized at the SIDECHAIN INPUT, the gate becomes even more
selective in opening.
Frequency-weighted compression
It is possible to separate certain vocals and instruments from a mix by frequency-weighted compression. With
an equalizer inserted ahead of the detector input (in the sidechain, not the audio path), the equalization set-
tings do not shift the timbre of frequency response of the audio signal. They merely alter the threshold response
of the compressor on a “frequency-weighted” basis. With this arrangement, raising certain frequencies on the
equalizer causes them to be suppressed in the audio signal. A relatively high threshold setting can allow nor-
mal sounds to be unaffected while solo and very loud sounds are held back. (Of course, when compression does
occur, the level of the entire program is affected.) Depending on the threshold setting, lower level fundamen-
tals or harmonics will 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 detector 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 or digital overload at high frequencies, 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 tolerated by the tape, it has less need
for compression. The equalization in the detector 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 can be used: dipping the equalizer bands causes any sound with domi-
nant energy in the affected register to pull the level up because the 1066 will detect a need for less compres-
sion.
Frequency-weighted compression for 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 oper-
ated at a lower sound-pressure level, or additional mid-range drivers must be added. But inserting an equalizer
in the detector path (sidechain) of the 1066, 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 dam-
aging signals are present.
Pre-emphasis for broadcast applications
By inserting a pre-emphasis filter network in the detector path of a 1066 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 1066’s sidechain input and sending the audio signal through a delay line
before the audio input, the unit can “anticipate” the need for a gain change. With some experimentation the
effect can be that of “zero,” attack time at any given frequency. Additional signal delays beyond this “zero”
time will then cause the compressor to finish reducing the gain before the leading edge of the loud passage