10.6

84Logic Pro Effects
• Filter mode knob: Choose the type of filter used to process the incoming side chain
signal. Filtering the sidechain input signal can enhance the precision of trigger signals,
resulting in more surgical compression. The choices are LP (lowpass), BP (bandpass),
HP (highpass), ParEQ (parametric), and HS (high shelving).
• Frequency knob and field: Set the center frequency for the side chain filter.
• Q knob and field: Set the width of the frequency band affected by the side chain filter.
• Gain knob and field: Set the amount of gain applied to the side chain signal.
Use Logic Pro Compressor
This section explains how to effectively use the main Compressor parameters.
Tip: Click the Meter or Graph button to change the meter. This visual aid can help you
to achieve more precise compression.
Compressor Threshold and Ratio
The most important Compressor parameters are Threshold and Ratio. The Threshold
parameter sets the floor level in decibels. Signals that exceed this level are reduced by
the amount set as the Ratio.
The Ratio parameter is a percentage of the overall level; the more the signal exceeds the
threshold, the more it is reduced. A ratio of 4:1 means that increasing the input by 4 dB
results in an increase of the output by 1 dB, if above the threshold.
For example, with the Threshold set at −20 dB and the Ratio set to 4:1, a −16 dB peak in
the signal (4 dB louder than the threshold) is reduced by 3 dB, resulting in an output level
of −19 dB.
Compressor envelope times
The Attack and Release parameters shape the dynamic response of Compressor. The
Attack parameter determines the time it takes after the signal exceeds the threshold
level before Compressor starts reducing the signal.
Many sounds, including voices and musical instruments, rely on the initial attack phase
to define the core timbre and characteristic of the sound. When compressing these types
of sounds, set higher Attack values to make sure that the attack transients of the source
signal aren’t lost or altered.
When attempting to maximize the level of an overall mix, it is best to set the Attack
parameter to a lower value, because higher values often result in no, or minimal,
compression.
The Release parameter determines how quickly the signal is restored to its original
level after it falls below the threshold level. Set a higher Release value to smooth out
dynamic differences in the signal. Set lower Release values if you want to emphasize
dynamic differences.
Important: The results of your settings for the Attack and Release parameters depend not
only on the type of source material but on the compression ratio and threshold settings.