dbx Pro 266XL - Manual (Page 9)

266XL
Compressor / Gate
E
XPANDER
/G
ATE
S
ECTION
7
When an input is above the THRESHOLD setting reference level, the RATIO setting
determines the number of decibels by which the input signal must increase in level to
produce a 1dB increase in the signal level at the output of the 266XL. A setting of 2:1
indicates an input/output ratio wherein a 2dB increase in signal (above threshold) will
produce a 1dB increase in output signal. A setting of ∞:1 indicates that an infinite
increase in input level would be required to raise the output level by 1dB.
Compressor ATTACK and RELEASE Control
The ATTACK control sets the amount of time it takes the 266XL to begin compress-
ing a signal once the detector has sensed a signal above threshold. The ATTACK
range is from FAST (for a tighter and more noticeable compression effect with very
little overshoot) to SLOW (for more delayed, gradual compression). A very fast
ATTACK setting will cause the 266XL to act like a peak limiter even though RMS
detection circuitry is used. Slower ATTACK settings cause the 266XL to act like an
RMS or averaging detecting compressor/limiter.
The RELEASE control sets how fast the compression circuit returns the input to its
original level. The RELEASE rate is from FAST (where compression follows the
envelope of the program material very tightly) to SLOW (for very smooth compres-
sion).
There is no absolute right way to set the ATTACK and RELEASE controls. However,
in general, you will want them set slow enough to avoid pumping or breathing
sounds caused when background sounds are audibly modulated by the dominant sig-
nal energy, yet the release must be fast enough to avoid suppression of the desired
signal after a sudden transient or loud note has decayed. For low frequency tones
(e.g., bass guitar), set RELEASE and ATTACK to 2:00 or slower.
Note: ATTACK and RELEASE controls operate together and in conjunction with the RATIO control.
Changing one control may necessitate changing another setting.
Auto Switch
This switch overrides both the ATTACK and RELEASE controls and enables preset
program-dependent attack and release times. These times are derived from the input
signal and continuously change to match its dynamics. Enabling this AUTO Function
duplicates the “classic dbx sound” of the 266XL’s forerunners which have become
standards in the industry.
Note: The Expander/Gate is off when the Expander/Gate THRESHOLD is set to OFF.
Expander/Gate THRESHOLD Control and LEDs (BELOW/ABOVE)
Adjusting this control sets the level at which the gate will open and allow the signal
at the input to pass through to the output. Turning the knob fully counterclockwise (to
OFF) allows the gate to pass all signals unattenuated, effectively bypassing the gate.
Turning the knob fully clockwise causes the gate to attenuate input signals below
+15dBu. The depth of attenuation depends on the setting of the Expander/Gate
RATIO control.
The two Expander/Gate LEDs indicate the relationship of the input signal level to the
threshold setting. The red LED lights when the signal is BELOW threshold, the green
LED lights when the signal is ABOVE threshold.