10.6

97Logic Pro Effects
Use Logic Pro Noise Gate
Set the Reduction knob to the lowest possible value to make sure that sounds below the
Threshold value are completely suppressed. Set Reduction to a higher value to reduce low-
level sounds but still allow them to pass. You can also use Reduction/Ducking to boost the
signal by up to 20 dB, which is useful for ducking effects.
The Attack, Hold, and Release knobs modify the dynamic response of Noise Gate. If you
want the gate to open extremely quickly for percussive signals such as drums, set the
Attack knob to a lower value. For sounds with a slow attack phase, such as string pads,
set Attack to a higher value. Similarly, when working with signals that fade out gradually
or that have longer reverb tails, set a higher Release knob value that allows the signal to
fade out naturally.
The Hold knob determines the minimum amount of time that the gate stays open. You can
use the Hold knob to prevent abrupt level changes—known as chattering—caused by rapid
opening or closing of the gate.
The Hysteresis slider provides another option for preventing chattering, without needing
to define a minimum Hold time. Use it to set the range between the threshold values that
open and close the gate. This is useful when the signal level hovers around the Threshold
level, causing Noise Gate to switch on and off repeatedly, thus producing the undesirable
chattering effect. The Hysteresis slider essentially sets the gate to open at the Threshold
level and remain open until the level drops below another, lower, level. As long as the
difference between these two values is large enough to accommodate the fluctuating
level of the incoming signal, Noise Gate can function without creating chatter. This
value is always negative. Generally, −6 dB is a good place to start.
In some situations, the level of the signal you want to keep and the level of the noise signal
may be close, making it difficult to separate them. For example, when you are recording a
drum kit and using Noise Gate to isolate the sound of the snare drum, the hi-hat may also
open the gate in many cases. To remedy this, use the side chain controls to isolate the
desired trigger signal with the High Cut and Low Cut filters.
Important: The side chain signal is used only as a detector/trigger in this situation. The
filters are used to isolate particular trigger signals in the side chain source, but they have
no influence on the actual gated signal—the audio being routed through Noise Gate.
Use the side chain filters
1. In Logic Pro, click the Monitor button to hear how the High Cut and Low Cut filters
affect the incoming trigger signal.
2. Drag the High Cutoff slider to set the upper frequency.
Trigger signals above this are filtered.
3. Drag the Low Cutoff slider to set the lower frequency.
Trigger signals below this are filtered.
The filters allow only very high (loud) signal peaks to pass. In the drum kit example
above, you could remove the hi-hat signal, which is higher in frequency, with the
High Cut filter and allow the snare signal to pass. Turn off monitoring to set a
suitable Threshold level more easily.