Facilities And Controls; Stereo Expander; Stereo Spectral Compressor - Focusrite MixMaster Mode D'emploi

FACILITIES AND CONTROLS

The following pages describe the facilities on the MixMaster. Each section of the unit may be
bypassed individually, or all sections may be switched together using the EFFECT BYPASS
switch to allow easy global A/B comparison of the processed or unprocessed signal.
All variable controls are detented types to allow settings to be reset accurately.
POWER - turns the unit on. We recommend that the unit is turned on before connecting or
powering up any equipment that it is feeding to avoid clicks or thumps which may harm output
devices.

STEREO EXPANDER

The stereo expander would typically be
used to clean up background noise at low
signal levels. The expander is like a soft
gate, but instead of cutting off any signal
below the threshold (see below), it
proportionately decreases it as shown in
the diagram. This gives a more natural
sound than a gate when recording non-
percussive sources. The Expander in the
MixMaster has unusually low threshold
settings to allow it to work right down to
the noise floor. Using the Expander, background noise which may appear relatively loud in
very quiet sections at the beginning or end of a track can be made inaudible.
THRESHOLD - determines the level below
which gain reduction starts, and is variable
between -30 and -60dB. The higher the
threshold, the more the low-level noise is
reduced and the more extreme the effect.
- is displayed on the
GAIN REDUCTION
8-segment LED bargraph in the expander
section, monitoring the effect of the Threshold
control.
RELEASE - sets the Release time, the rate at which the expander gain reduction decreases and
is variable between 0.5s and 6 seconds. The release period begins immediately after the signal has
dropped below the set Threshold level. On transient signals a fast release may be appropriate
(control anticlockwise), but with other material a slower release (control clockwise) may give a
more natural sound. Ideally the release needs to be slightly slower than the natural decay rate of
the signal to avoid audibly cutting it short.
-20 Threshold
-60 Threshold
- switches the Expander in and out of the signal path to allow easy A/B comparison of the
IN
processed and unprocessed signals. The switch illuminates when pressed to show that the
Expander is active.

STEREO SPECTRAL COMPRESSOR

The spectral multi-band compressor is an optocoupler design, optimised for stereo mix
compression of three independent frequency bands. By splitting the compression across three
bands you avoid the unwanted effect of, for instance, a massive kick drum triggering
compression across the whole stereo signal. The compressor on the MixMaster allows a kick
drum to only affect the LF band, a vocal to compress only mid frequencies, and a hi hat to
compress only the HF band.
THRESHOLD - globally determines the overall level at which compression begins. The
lower the Threshold, the more the signal is compressed. Setting a higher Threshold allows
quieter passages in the music or speech to remain unaffected, and only passages that exceed the
Threshold will be compressed.
LF/HF TRIM - allow up to 20dB relative variation in threshold between bands, allowing
some very creative use of the compressor. However, note that the audible effect of the Trim
controls is also dependent on the settings of Ratio and Threshold. At high Ratio and lower
Threshold more relative variation will be achieved. If a more gentle effect is required the
LF/HF Trims should be bypassed by pushing the Lock switch (see below).
- sums the thresholds of the three bands when pressed to give even compression across
LOCK
the full frequency range. This might be used to preserve the tonal character of signals which
have an unusual spectral balance making it difficult to get equal compression in each band.
Alternatively it may be used when you deliberately want a very "compressed" sound, or when
you want the more gentle feel of a classic compressor.
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