FLX-E Operations Manual Rev F
Page 17
Table of Contents
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7.2.4.3
Compressor/Limiter Blocks
The Compression block allows configuration of the dynamic compressor/limiter.
Audio compression is a specialized function used to reduce dynamic range - the
span between the softest and loudest sounds. The use of compressors can make
recordings or live-sound mixes sound better musically by controlling maximum
levels and maintaining higher average loudness. The Limiter block is derived
from a compressor and uses a ratio of 100:1 to provide a fixed upper signal
level.
Threshold
is a decibel property that can be adjusted by dragging the yellow
marker tracking the equality line on the graph. Alternatively, it can be adjusted
using the numeric up-down control below the graph. The threshold is the level
of the incoming signal at which the compressor amplifier changes from a unity
gain amplifier into a gain reducing compressor. The compressor has no effect on
the signal below the threshold level setting. Once threshold is reached, the compressor starts reducing gain
based on the amount by which the signal exceeds the threshold and according to the ratio control setting.
Threshold level could be thought of as the "sensitivity" of the compressor and is expressed as a specific
level in dB.
Ratio
is property available only in a compressor (not limiter) that can be adjusted by dragging the right-
most yellow marker on the graph. Additionally, it can be adjusted using a similar up-down control as the
threshold. Ratio is a way to express the degree to which the compressor is reducing dynamic range. Ratio is
expressed as the change in output level for a change in input level above the threshold. A ratio of 10:1
specifies an increase of 10 dB above the threshold at the input results in a 1dB increase in the output level.
Ratio is a constant value which is independent of the degree of compression taking place; the ratio of the
input change to output change is constant.
Soft Knee
is an option selected using the checkbox to the left of the bypass button. The level at which the
compressor starts gain reduction is called the knee. A Hard Knee is a sudden change from uncompressed to
compressed signal once the threshold has been reached. A Soft Knee applies a gradual level of compression
and is a less obtrusive change from unity gain amplifier to compressor. Note that a soft knee will result in a
small amount of compression starting around 6dB below the threshold.
Attack
is a time property that is adjusted using the blue dial of the compressor configuration window, or by
entering the attack time (in seconds) in the box above the attack knob. Attack time refers to the time it
takes the compressor to start compressing after the threshold level has been reached. Attack time affects
the sound quality in terms of overall perceived brightness or high-frequency content. With very fast attack
time settings, the compressor will activate very quickly, reducing gain instantly at the waveform level.
Release
is a time property that is adjusted using the orange dial of the compressor configuration window,
or by entering the release time (in seconds) in the box above the release knob. Release time is the time the
compressor uses to return to unity gain after the input signal has fallen below threshold. It should be noted
that very fast attack or release times will distort low-frequency sounds, as the compressor is capable of gain
