the output rise by 1 dB implying 9 dB of compression, 2:1 will cause the output
to increase 5 of those initial 10 dB suggesting 5 dB of reduction. Some engineers
relate ratios of 20:1 and higher with limiting, however technically traditional
limiting also requires very fast attack times to respond to transients and prevent
signals from actually going above a certain level.
COMP IN
Engages the compressor, and is indicated by a green button. Other than simply
engaging the compressor, engineers often toggle this button to aid adjusting
the make-up gain for similar average levels. The comp in button is also used to
compare the untreated signal to the compressed signal to verify a positive change is
being made.
THRESHOLD
Sets the level where the compressor begins to react and respond to signals above
the set threshold. With the knob set clockwise, only extremely loud signals might
cause any gain reduction. With the knob set counter-clockwise, even relatively
quiet sounds can cause compression.
GR METER
Indicates how many dB’s of gain reduction are happening at a given time. This
particularly aids in choosing threshold and ratio settings. While the GR meter is
great to confirm what we think we are hearing, usually our listening skills provide
a more direct path to choosing compressor settings than meters. The meter will
generally indicate very brief gain reductions but will tend to exaggerate the
duration so that the eye can see transient compression.
LEVEL METER
Displays the final peak output level of the 5051 regardless of whether the unit is
set for EQ PRE or POST. This meter assists adjusting the compressor gain, and helps
prevent equipment that the 5051 may be feeding from clipping or overloading.
In the case of A to D converters, one should primarily depend on the converters
own meters due to possible converter calibration variables. The 5051 level meter
is calibrated for dBu, and the red LEDs may not necessarily match up with the
destination device. It is often advisable to maintain levels 10 to 20 dB below the
destination’s maximum input for ease of later processing.
S/C INSERT SND
A 1/4” unbalanced phone jack used to send the signal to an external device,
primarily EQ, to create a key signal (it can be any old EQ or device since the
audio isn’t effected). For example, you may EQ the signal, cutting all the lows and
boosting somewhere between 5 kHz and 8 kHz to cause the compressor to respond
to frequencies associated with sibilance, and become a de-esser. An engineer
can also gently reduce lows and increase mid highs so that the compressor may
respond similarly to how our ears may perceive apparent loudness.
S/C INSERT RET
A 1/4” phone unbalanced input jack that is receives the signal from the external
