Final Cut Pro X Logic Effects - Expander

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The Expander is similar in concept to a compressor, but increases, rather than reduces,
the dynamic range above the threshold level. You can use the Expander to add liveliness
and freshness to your audio signals.

Threshold slider and field: Sets the threshold level. Signals above this level are expanded.

Peak/RMS buttons: Determine whether the Peak or RMS method is used to analyze the


Attack knob and field: Determines the time it takes for the Expander to respond to

signals that exceed the threshold level.

Expansion display: Shows the expansion curve applied to the signal.

Release knob and field: Sets the time it takes for the Expander to stop processing the

signal after it falls below the threshold level.

Ratio slider and field: Sets the expansion ratio—the ratio of signal expansion when the

threshold is exceeded.

Note: As the Expander is a genuine upward expander—in contrast to a downward
expander, which increases the dynamic range below the threshold—the Ratio slider
features a value range of 1:1 to 0.5:1.

Knee slider and field: Determines the strength of expansion at levels close to the

threshold. Lower values result in more severe or immediate expansion—hard knee.
Higher values result in a gentler expansion—soft knee.

Gain slider and field: Sets the amount of output gain.

Auto Gain button: Compensates for the level increase caused by expansion. When

Auto Gain is active, the signal sounds softer, even when the peak level remains the

Note: If you dramatically change the dynamics of a signal (with extreme Threshold and
Ratio values), you may need to reduce the Gain slider level to avoid distortion. In most
cases, turning on Auto Gain will adjust the signal appropriately.


Chapter 4

Levels Effects