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dbx 166xs
In OverEasy mode (OVEREASY button depressed), signals begin to gradually activate the 166xs
gain change circuitry as they approach the THRESHOLD reference level and they do not get
fully processed in the manner defined by the RATIO control until they have passed somewhat
above the THRESHOLD reference level. In OverEasy mode there is no distinct point at which
processing begins, and the THRESHOLD setting corresponds to a point on the input/output
transfer curve midway between the onset of processing and that point at which the transfer
curve corresponds to the setting of the RATIO control. Figure 2 shows the OverEasy
compression curves and how they correlate with the THRESHOLD LEDs.
OVEREASY Button and LED
Depress this button to select the OverEasy® compression characteristic. The yellow THRESHOLD
LED turns On when the signal is in the OverEasy region. When this button is in the Out
position, the 166xs operates as a hard knee compressor/limiter. (Yellow OverEasy LED is active
only in OverEasy Mode.) In Hard Knee mode, the threshold of compression is defined as that
point above which the output level no longer changes on a 1:1 basis with changes in the input
level. See Figure 1. In OverEasy mode, the threshold of compression is defined as the middle of
the OverEasy threshold region, that is, "half-way" into compression, as shown in Figure 2.
Compressor RATIO Control:
Rotate this control clockwise to increase the amount of compression from 1:1 (no compression)
up to ∞:1 (no increase in output level, regardless of input level increases above threshold.)
+20
+15
+10
+5
0
-5
-10
GREEN
-15
Below Threshold
-15 -10
-5
INPUT LEVEL (dB)
Figure 1: Hard Knee Compression Curve and
Threshold LEDS
When an input signal is above the THRESHOLD reference level, the setting of this control
determines the number of decibels (dB) by which the input signal must change in level to
produce a 1dB increase in the signal level at the output of the 166xs. 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. In other words, the output
level stays constant when the input signal rises above threshold.
Compressor ATTACK and RELEASE Control:
The ATTACK control sets the amount of time it takes the 166xs to begin compressing 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 166xs to act like a
peak limiter even though RMS detection circuitry is used. Slower ATTACK settings cause the
166xs 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
1:1 Unity
RED
Above Threshold
2:1
4:1
20:1
:1
Rotation Point Threshold
0
+5
+10
+15 +20
Getting Started
1:1
+20
+15
2:1
+10
4:1
+5
:1
0
RED
−5
Above Threshold
OverEasy Range
−10
−15
Below Threshold
−15 −10 −5
0
+5
+10
+15 +20
INPUT LEVEL (dB)
Figure 2: Over Easy Compression Curve and
Threshold LEDS
Section 2
7
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