10
Operator’s Guide –
How Sound Gating Works
The
VGM-804
’s microcontroller measures all input levels continuously, 2500 times per
second. It “learns” the ambient sound at each mic to ignore background noise such as from
air conditioning. Any mic whose level is 6dB louder than the others, gates ON. Once live, a
mic remains ON as long as at least one of the following three conditions are met:
•
Its level remains higher than the threshold described above
•
Less than 0.2 seconds “hang time” has elapsed since being above threshold
•
It is the last (and only) input still gated ON
Microphone inputs gate OFF when all conditions become false, remaining so until active
again. Gating works best for orderly discussions where generally, one person speaks at a
time. The two Auxiliary inputs are not gated, thus can operate along with mics.
Operator’s Guide –
Optimizing the Sound Gating
Follow these instructions if you need to adjust your mixer’s sound gating:
First,
be sure that your sound system’s audio levels are set up properly. When your
mixer is working near its design level, its microprocessor receives detailed information on
mic usage, thus can make better gating decisions. Use your level display to verify this:
•
Have an assistant speak or read into a mic while you slowly advance its control.
•
As you turn up the mic, listen to the sound in your auditorium while observing the
bargraph. The display should reach 1 - 2 yellow LEDs when your sound has found its
comfortable, customary level (if compression is enabled on that mic, you’ll also see the
COMPRESS
LED illuminate) . If not, repeat the adjustment procedure on page 5.
Next,
observe the sound gating performance using two or more microphones
alternately. Note if the gating is operating to your satisfaction. If not, you can fine-tune the
microcontroller’s decision process by turning the
Gating Threshold
control (bottom panel) in
the direction recommended below (use a fine slot screwdriver) :
•
If your mics seem to gate ON too easily, set
the
Gating Threshold
control clockwise
approximately one-quarter turn.
•
If your mics hesitate to gate ON – especially
if you have increased the gating threshold –
reduce it by turning the
Gating Threshold
control counter-clockwise.
•
This control affects gating results especially
when room sound is relatively quiet.
Gating
Threshold
Compression
