The
MOD
knob controls how much the brightness (filter cutoff frequency) follows the EXCITE audio signal.
Starting from the minimum setting, turning the knob clockwise will progressively increase the amount of
cutoff modulation - with the maximum amount reached when the knob is at noon. Then, turning the knob
will reduce the damping, but will compensate by adding an offset. Thus, at 7 o’clock, there is no
modulation and the filter is fully closed; and at 5 o’clock, there is no modulation and the filter is fully
opened.
This mode is crazy and we have plenty of tips!
Send the same signal to both the IN and
EXCITE
input to get a strange gating/expansion effect.
Play with the log/lin response knob or with the
LEVEL
knob (used as an offset) to get gating effects.
Set the
MOD
knob to its maximum setting, unplug the IN jack, and get an envelope follower signal on the
OUT
.
Now some technical details… The module does more than extracting the envelope of the EXCITE signal.
It splits it into 3 frequency bands (bass - 100 Hz, mids - 1kHz, and highs - 8kHz) and detects the envelope
in each band - with different attack and release times tailored for each band. These envelopes are then
recombined to produce a single envelope. This detection process makes the envelope more
representative of the events contained in the audio stream. For example, consider a signal with crisp
drums playing on top of a loud drone. A traditional envelope follower wouldn’t show much variation,
because the waveform is dominated by the drone. Band-wise processing makes the detection process
more sensitive to the drums.
The spectral centroid is approximated by weighting the signal RMS level in each of these 3 bands.
This mode operates as a dynamics compressor. It requires the channel VCA response curve to be set to
exponential (full counter-clockwise position) - otherwise the linear VCA won’t be able to create the
extreme gains required for compression; and the
LEVEL MOD
knob to be set to its minimal position
(unless you want weird things to happen!).
The
EXCITE
input works as a sidechain - when a signal is detected on the
EXCITE
input, its level
determines the amount of gain reduction applied to
IN
. Do not plug anything in the
EXCITE
input, and the
module will work like a normal compressor on the
IN
signal. Please note that it takes about ten seconds
for the module to detect that the
EXCITE
input has gone AWOL.
The attack and release times are 0.2ms and 150ms respectively.
The
MOD
knob does something quite interesting. At 12 o’clock, no compression is applied. From 12
o’clock, turning the knob counter-clockwise, will progressively increase the compression ratio, until a ratio
of 25:1 is reached. Since no make-up gain is applied, this has the effect of taming the loudest parts of the
signal. From 12 o’clock, tuning the knob clockwise, will progressively increase the compression ratio and
will apply a matching amount of make-up gain. This has the effect of pumping the quietest parts of the
signal, while leaving peaks untouched.
Mutable Instruments | Streams
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