Allen&Heath GL4000 USER GUIDE User Manual

Page 16

ATCHING

THE

IGNAL

EVELS

For best performance it is important that the connected source signals are
matched to the "normal operating level" of the console. Similarly the
console outputs should be correctly matched to the operating levels of the
connected amplifiers and destination equipment. If too high the signal
peaks will be clipped resulting in a harsh distorted sound, and if too low
the signal-to-noise ratio is reduced resulting in excessive background hiss
and noise.

For best results operate the console with the meters averaging around '0'
letting the louder passages peak into the 'yellow'. Reduce the gain if the
red peak indicators flash. The GL4000 produces a standard XLR output
level of +4dBu for a meter reading of 0VU. It is advisable to adjust the
power amplifier input gain or fit an attenuator pad if normal console
operation results in an output level too high for the connected amplifier.
Normal operation should result in fader levels around the '0' mark. Note
that when reversed with the auxes the matrix and LR2 output level trims
can be used to match the console to the amplifiers independent of the mix
levels. Similarly the group output trims can be switched in to match levels.

The GL4000 has an advanced PFL (pre-fade listen) / AFL (after-fader
listen) and channel metering system to let you listen to and check the level
of signals at different points in the signal path without affecting the main
outputs. Use the channel PFL switches to set up the input GAIN controls
to read an average '0'. Signal activity is always shown on the channel
meters regardless of fader position. The green 'SIG' LED lights at -20dBu
to indicate signal presence, the green '0' LED indicates normal level,
yellow '+6' indicates normal peaks, and the red 'PEAK' LED warns of
potential overload 5dB before clipping.

The mix meters above each output fader monitors the pre-fade mix level.
You can run the mix 'hot' but reduce the channel fader levels if the red
'PEAK' LEDs flash.

EVEL

IAGRAM