Allen&Heath ML4000 USER GUIDE - Manual (Page 27)

ML4000 User Guide 27
SAFE / EDIT. This green LED has a different
function according to console operating mode:
Normal The LED lights when the channel has
been made safe from the snapshot and MIDI
automation.
Edit Safes Continues to indicate which channels
are automation safe while they are edited.
Edit Groups The LED lights to indicate that the
channel is assigned to the VCA or MUTE group.
Edit MIDI Channel Number The LED flashes to
indicate which MIDI channel has been selected for
the console. This affects only CH1 to 16.
PAFL. Press this switch to listen to the channel
signal in the headphones or engineers monitor
without affecting the main outputs.
Either PFL or stereo in-place AFL. Either PFL
(pre-fade listen) or AFL (after-fade listen) is
selected according to the master section INPUT
PAFL switch. PFL is mono. AFL is stereo ‘in-place’
as it provides a stereo mix of L and R with C mixed
into both. This lets you listen to the image of the
signal in the 3 output main mix using the console
stereo headphones and monitor.
Latching or momentary action. The switch
provides latching or momentary action depending
on how long it is held down. Press and hold for
longer than 1 second for momentary action.
PAFL override monitor. Pressing any input PAFL
automatically overrides any currently selected
output AFL or monitor source. Releasing PAFL
restores that selection.
Auto cancel or Add mode. The master section
ADD MODE switch determines if pressing a
channel PAFL cancels or adds to any previous
selection.
Clear all. Pressing the master section CLEAR ALL
switch turns off any PAFL / AFL switches selected
and restores the monitor source.
INPUT SIGNAL METER. The 5 LED bar meter
displays the pre-fade signal level. SIG lights to
display signal presence at –26dB, -6, 0 and +6
display normal signal level, and PK (peak) lights
when the signal is within 5dB of clipping. PK
senses the signal at 4 critical stages in the signal
path, pre-insert, pre-EQ, pre-fader and post-fader,
to warn of potential overload. PK can flash, for
example, if the preamp is clipping while signal reads
low due to attenuation through an inserted
processor.
VCA GROUP Indicators. These LEDs light to
show which VCA groups the channel is assigned to.
The channel can be assigned to more than one
group. The channel is assigned or removed from a
group using the EDIT GROUPS function in the VCA
master section. The LEDs always show VCA group
assignment.
FADER. A 100mm smooth travel ALPS K-fader is
fitted providing +10dB gain above the nominal 0dB
operating position. Audio is not passed through the
fader. Instead, its position is read by the console
computer which produces a DC voltage to control
the level of the channel VCA (voltage controlled
amplifier).
Removing the Fader
The vertical, offset shaft design of the fader reduces
the risk of damage through dust and liquid spillage.
The fader should provide long life subject to the
usual wear and tear and not normally require
servicing or replacement. If necessary, access to
the faders is by removal of the fader module from
the top of the console. First unclip and lift away the
plastic ident strip. Undo the fader panel crosshead
screws and lift the module up being careful not to
damage the circuit assemblies and cables. The
fader can be unscrewed, its harness unplugged,
and then removed by sliding it out of the assembly.
Checking the Channel Signal Level
When plugging in a new source start with the
channel muted or fader and sends turned down.
This prevents any unexpected signal in the
loudspeakers. Adjust the channel GAIN control for
an average channel meter reading of ‘0’ with loud
moments lighting ‘+6’. Select PAD if the signal is
still too high with gain turned down. Reduce the
gain if the signal meter red PK LED lights. It may
be necessary to re-adjust the gain if changes are
made to the equaliser or inserted signal processing.
If the PK LED lights with channel meter reading low
then check the channel for correct gain structure, in
particular the equaliser and inserted equipment
settings.
Set the master INPUT PAFL switch for PFL and
select channel PAFL to check the signal quality in
the headphones while the fader is off. The signal is
also displayed on the main VU and LED bar meters
providing finer resolution and dynamic display.