PRESONUS STUDIOLIVE 16.4.2 - V1.12 User Manual page 105

5 Tutorials
5.3 A Brief Tutorial on Dynamics Processing
Vocabulary of Dynamics Processors
5.3.3
• Auto. Places a compressor in automatic attack and release mode. The attack and release
knobs become inoperative and a preprogrammed attack and release curve is used.
• Makeup Gain. When compressing a signal, gain reduction usually results in an overall
reduction of level. The gain control allows you to restore the loss in level due to compression.
(Like readjusting the volume.)
• Compressor Sidechain. The sidechain jack interrupts the signal that the compressor is using
to determine the amount of gain reduction it should apply. When no connector is inserted
into this jack, the input signal goes directly to the compressor's control circuitry. When a
connector is inserted into this jack, the signal path is broken. The control signal can then
be processed by an equalizer, for example, to reduce sibilance (de-essing) in a vocal track.
The control signal is then returned to the unit via the connector. One common application for
a sidechain is when using a compressor to reduce the level of music or other background
sound whenever a narrator speaks or vocalist sings, allowing the voice to be clearly heard.
In this application, the vocal signal is routed to the sidechain input, while the music is routed
through the main compression circuitry. Now the compressor will automatically duck—that
is, reduce the level of—the music whenever the narrator speaks or the vocalist sings.
Expanders
• Downward Expansion. Downward expansion is the most common expansion used in pro
audio and recording. This type of expansion reduces the level of a signal when the signal falls
below a set threshold level. This is most common used for noise reduction.
• Ratio. The expansion ratio sets the amount of reduction applied to a signal once the signal
has dropped below the expansion threshold. For example, a 2:1 expansion ratio attenuates
a signal 2 dB for every 1 dB it drops below the threshold. Ratios of 4:1 and higher act much
like a noise gate but without the ability to tailor the attack, hold, and release times.
Noise Gates
• Threshold. The gate threshold sets the level at which the gate opens. Essentially, all signals
above the threshold setting are passed through unaffected, whereas signals below the
threshold setting are reduced in level by the amount set by the range control. If the threshold
is set fully counterclockwise, the gate is turned off (always open), allowing all signals to pass
through unaffected.
• Attack. The gate attack time sets the rate at which the gate opens. A fast attack rate is
crucial for percussive instruments, whereas signals such as vocals and bass guitar require
a slower attack. Too fast of an attack can, on these slow-rising signals, cause an artifact in
the signal producing an audible click. All gates have the ability to click when opening but a
properly set gate will never click.
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