Allen&Heath GL4800 USER GUIDE - Manual (Page 19)

GL4800 User Guide 19
Matching the Signal Levels
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 GL4800 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 GL4800 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.
Dynamic Range