PreSonus GTX44 - Manual (Page 6)

2.1 FRONT PANEL BASIC LAYOUT
Notice that the front panel is divided into four identical sections. These are the four signal processing channels of the
GTX44. Each channel contains:
Gate/Expander
Lo/Hi Filter
SideChain Monitor
Link & Bypass Control
Duck Mode
2.2 GATE/EXPANDER CONTROLS
Lo/Hi Filter
There are many situations, especially with drums, when other instruments open up the gate instead of the instrument being
gated. For example, tom-tom mics are generally placed very close to the cymbals on a drum kit, creating the possibility of
the cymbals opening up the tom-tom gates. The Lo/Hi Filters allow the user to specify which frequencies are ‘eligible’ for
gating. Therefore the cymbals may be removed from ‘eligibility’ by using a high cut filter to filter out the high frequencies of
the cymbals. The gate will no longer open up during cymbal crashes, leaving the low frequencies of the tom-tom to properly
open the gates.
Threshold
The gate threshold sets the level at which the gate opens. Essentially, all signals above the threshold setting are passed
through unaffected, whereas signals below the threshold setting are reduced in level by the amount set by the ratio and/or
range control.
Ratio
The expansion ratio sets the amount of noise reduction applied to a signal once the signal has dropped below the expansion
threshold. For example, a 2:1 expansion ratio attenuates a signal 1dB for every 1dB it drops below the threshold. Ratio’s
4:1 and higher act like a noise gate. Note: The Range Control overrides the ratio control. For example: If the Expander calls
for 40dB of attenuation but the Range is set to 20 dB of attenuation, the signal will be attenuated by 20dB.
Range
The range is the amount of gain reduction that the processor closes down to. Therefore, if the range is set at 0dB, there will
be no change in the signal as it crosses the threshold. If the range is set to -60dB, the signal will be attenuated (reduced)
by 60dB, etc.
Attack
The gate attack time sets the rate at which the gate opens. A fast attack rate is crucial for percussive instruments, whereas
signals such as vocals and bass guitar require a slower attack.
Hold
Hold time is used to keep the gate open for a fixed period of time following the signal going below the gate threshold. This
can be really useful for effects such as ‘gated snare’ where the gate remains open after the snare hit for the duration of the
hold time then abruptly closes. Hold is only available when the ratio knob is set to GATE.