8

Chapter 4 Dynamics 51
The Hysteresis slider provides another option for avoiding chattering, without needing
to define a minimum Hold time. You use it to set the range between the threshold
values that open and close the Noise Gate. This is useful when the signal level jitters
around the Threshold, fluctuating slightly but rapidly around it. This causes the Noise
Gate to switch on and off repeatedly, producing an undesirable chattering effect. Using
the Hysteresis slider, you can set the Noise 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 contain the fluctuating level of the
incoming signal, the Noise Gate can function without creating chatter. This value is
always negative. Generally, –6 dB is a good place to start.
In some situations, you may find that the levels of the signal you want to keep and the
levels of the noise are close enough to be difficult to separate. For example, if you are
recording a drum kit, and using the Noise Gate to isolate the sound of the snare drum,
the hi-hat may also open the gate in many cases. To remedy this sort of situation, you
can use the Sidechain controls to isolate the desired signal using Hi and Low Cut filters.
To use the Sidechain filters, click the Monitor button to turn on monitoring. This lets
you hear how the Hi and Low Cut filters will affect the incoming signal. Now you can
drag the High Cut slider to set the frequency above which the signal is filtered out, and
drag the Low Cut slider to set the frequency below which the signal is filtered. These
filters only allow very high (loud) signal peaks in their range to pass. In our example,
you could remove the hi-hat’s signal, which is higher in frequency, using the Hi Cut
filter, and allow the snare signal to pass. You can turn monitoring off to set a suitable
Threshold level more easily.