Allen & Heath Sigma 24 Service manual

CONCEPT

In a dream world every console would have unlimited
inputs, unlimited faders, unlimited aux sends, infinite equalisers,
reset itself every session and come complete with a mind reading
computer interface and be small enough to sit on your lap.

While we are working in that one we offer the Sigma Series

the low budget recording console runs out of muscle. Mixing and
recording techniques are now well established, however the
demands of special effects mixing, digital recording and electronic
music have increased the demands on the console's capacity,
versatility and performance.

as a practical solution to real sound control challenges available
now at attractive prices. Look at the module summaries for details
of the controls available. There are more module types available
than it is necessary to install in any one Sigma console. Each
console is the response to a particular sound control task. Your
task may call for more inputs and fewer outputs, or sophisticated
monitors or many simple monitors, in-line type controls or split
"inputs left" "outputs right" controls or any combination.

The Sigma Series is AHB's response to the demand for
increasingly sophisticated multitrack and live mixing consoles at
increasingly attractive prices. Sigma consoles take over where

consoles is transparent for all practical purposes. What you will
hear in the mix is your client's performance plus a little bit of noise,
distortion and hum from your mics, instruments, multitrack and
effects units. If you have been used to low budget consoles with
clicking mutes, inconsistent pot laws and noisy inputs you will
breathe a sigh of relief using Sigma. The designers of Sigma have
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consoles are not big low cost products. Sigma consoles are for
clients who want good sound consistently from reliable income —
earning hardware.

MIXING/RECORDING TECHNIQUES WITH SIGMA MODULE SYSTEMS

Each module has an individual data sheet, here are

summaries of the benefits of each standard console system.

choice of source during recording and mixing does not involve
replugging. With this system track bouncing is done via the M420

M410 and M430 modules:

Split module system with inputs on the left, outputs on the

modules. SSR automutes operate on the input faders and monitor

faders but not on the group outputs.
right. The M430 is a high density module which compressed two
outputs and monitor sections into a single module width, leaving
more space for M410 inputs in a standard frame. Two large faders
with each M430 provide the group outputs. Two monitor sections

from inputs and monitors and ergonomic efficiency. All faders in

the M410/420 system can be non automated, VCA or automation

types as an option.
each have three sources; outputs, tape or (echo) return line inputs.
One equaliser is shared between both monitors. Fader reverse

M470 in-line module system:
allows mixing the monitor sources on large faders. Due to space
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mitations these faders are not automation capable.

This is the choice when space is at a premium and inputs

more important than track monitors.

M410 inputs provide mic line and tape inputs so that the
choice of source during recording and mixing does not involve
replugging. With this system track bouncing is done via the input
modules. SSR Automutes operate on the input fader and monitor
level controls but not on the group outputs.

Each module provides three inputs and one output (to tape). The
inputs are mic and line on the small fader (normally). The monitor
input selects between output and tape input and uses the large
fader (normally). For recording and bouncing operations the
module works as a single entity to provide controls for record
input to tape plus monitor input from tape to the monitor/remix
output. Equalisation and aux send are shared between the input
and monitor. Both inputs have the standard Sigma PFL/AFL,
SOLO MUTE, MUTE AND AUTOMUTE. There is no fader for record

M410 and M420 modules:

output. Trim of record level is provided by a rotary control.

Split module system with inputs left and outputs right. M420
modules are called line I/O types since one module provides
output to tape and input from tape to the stereo mix

AND

group
output. Of course, there is also the additional (echo) return line
input source provided so that the module provides two functions:

1. mix and output, 2. monitor of output, tape input or return
input.

A full set of input controls occupies most of the M420 panel.

Group output controls are located above the large fader. The rest

fader is to mix the track with EQ and echo. The small fader can be
used as a second input to the mix with echo send or as an
additional echo send itself via assignment. Echo returns use spare
modules and inputs. Analogue subgroups to the mix are available
on modules 17-24 (16 track systems) and 25-32 (24 track
systems) on small or large fader. Within a small frame M470 in line
systems give the maximum facilities for highly efficient multitrack

operations.
of the module is monitor input controls. These include assign to
groups, EQ, aux send, mute and a small fader which may be
reversed with the large fader below. Choose the way you want to
work — output on large fader or monitor on large fader. Either way
when it comes to bouncing tracks you simply select the new
output. The valuable EQ and echo settings do not have to be

from many sources simultaneously, electronic music sessions for

example, then the M470 system gives two line inputs to the mix

simultaneously with EQ and echo send shared. Input reverse

allows the choice of large or small fader preference to be given to

the three source programmes at will.
copied across to an input module. This not only saves time it
reduces the risk of an operator error.

VCA or automation types as an option. SSR Automutes operate on

all small and large faders.

Take for granted that the sonic performance of Sigma

stened to the complaints about low cost products. Sigma

M410 inputs provide mic line and tape inputs so that the

Choose this combination when you want high performance

All that is required for multitrack record overdub and remix.

For mixing operations the primary function of the large

When the situation demands high priority for live inputs

All large faders in the M470 system can be non automated.

SSR AUTOMUTE SYSTEM

The SSR MIDI remote controller is a powerful micro
computer enabling the automatic control of channel and monitor
mutes as well as up to 16 effects devices under MIDI control. Pre
programmed mute patterns and MIDI patch changes can be
synchronised to a MIDI sequencer, driven from the SSR's internal
sequencer or MIDI clock generated from SMPTE to MIDI
converter, and the SSR recognises MIDI song pointer information.

The SSR can control a complete Sigma automute system of

up to 64 inputs, up to 16 different MIDI controlled effects devices,
enables MIDI keyboards and sequencers to have precise control
over muting and effects, or the SSR can operate as a conventional
music sequencer or computer recorder. In the sequencer mode it
enables switching from one SSR MIDI programme plus one MUTE
PATCH combination to another, under manual or automatic timing
control.

There are 8 alternative clock options for operation in the

sequencer mode allowing for different synchronisation methods.
CLOCK MODE 0

Manual footswitch stepping of MIDI and mute data, useful

for work with pre-recorded material with no sync-track.

CLOCK MODE 1

As above but steps automatically to next song, enables

more than 100 steps to be used under manual control.

CLOCK MODE 2

SSR runs the sequencer from its internal clock, from 29 to
320 BPM. The MIDI and MUTE data will be changed when the
internal clock time and event times coincide.

CLOCK MODE 3

SSR driven from external clock 24 (sync 24) pulse code,
with stop/start control, also providing SYNC 24 to MIDI converter.

CLOCK MODE 4

SSR controlled by MIDI timing data, START, STOP, CLOCK,
CONTINUE START and SONG POSITION. Also providing MIDI to
SYNC 24 converter.

CLOCK MODE 5

Data entry in real time with the internal clock. Each
depression of a footswitch enters current song time into event

ming data. Error correction via INSERT and DELETE facilities.

ti
CLOCK MODE 6

Data entry in real time with timing data from SYNC 24 pulse

code, with full error correction and editing facilities.
CLOCK MODE 7

This enables real time recording in synchronisation with

MIDI clock, with full error correction and editing facilities.

The control unit is illustrated below approximately half real

size and is a mobile panel connected to the console through a data

cable.

All program data is stored in the KMM memory cartridge and

braries of data can be created to accompany synth discs and

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RAM packs for example.

SSR mute commands operate the console audio mutes in
co-operation with manual local pushbutton mute commands. An
un-muted channel (or monitor) responds to SSR mute and de-mute
commands. A channel (or monitor) which is manually muted does
not respond to SSR commands.

SSR is a unique innovative system which exploits MIDI for the
benefit of the electronic music artist in particular. In applications

which do not call for this benefit, the system may be operated

without the SSR control unit, alternatively simply select a mute
patch where all mutes are cleared.

MODULE M410: MONO MIC/LINE INPUT.
Phantom power on switch

Mic input phase reverse switch
20dB mic input pad switch
Mic input gain control

Input source selections: either mic or line or tape source is available.

Tape and line input GAIN control with gain indications.

EQUALISER section: pre fader, post insertion point. Dual concentric controls.

HF shelving ± 12dB.
MF peak/dip ± 12dB.
MF peak/dip ± 12dB.

4k Hz to 12 kHz range.

1.1 to 11 kHz sweep range, Q =1

0.35 to 3.5 kHz sweep range, Q =1

80Hz fixed frequency low-cut filter. 12dB/oct.

LF shelving ± 12dB.

30Hz to 400Hz range.

EQ BYPASS operates on the four variable sections simultaneously.

AUXILIARY SENDS: four controls with six outputs.
Aux 1 and 2 are switchable, pre or post fader. The pre fader selection is preset internally either
pre equaliser or pre fader (ex works standard).
Aux 3/5 and 4/6 are preset internally either pre equaliser, pre fader (post equaliser) or post

fader (ex works standard).

GROUP ASSIGN selectors for group outputs 1 to 24 from input fader: six pushbuttons select

twelve outputs in pairs.

SHIFT selects either outputs 1 to 12 or 13 to 24.

L-R assigns fader output to the main stereo output.
PAN operates with the assign selectors.
PEAK responds to pre fader, post eq signal level.

SOLO MUTE: with ENABLE (see M450) retains this input and operates the MUTE on all other

inputs not selected SOLO.
PFL/AFL: operates control room loudspeaker and L/R meter changeover to receive either the

PFL or AFL mix. PFL is pre fader listen. AFL is After Fader Listen. AFL responds to input pan
and mute.
MUTE: press to mute the input post fader. Cuts post fader aux, assign and AFL. Also responds
to SSR Automute and solo.

Fader: choice of 100mm analogue or Fader Automation.

AHB SF 1/7

MODULE M420: LINE INPUT/OUTPUT,
MONITOR section controls:

Input source selectors, choice of group output, tape input or return input.
Input GAIN for the selected source. Normal position central.

EQUALISER ASSIGN switch to either group output or monitor section.
EQUALISER section: pre fader, post insertion point. Dual concentric controls.
HF shelving ± 12dB.

MF peak/dip ± 12dB.
MF peak/dip ± 12dB.

4 kHz to 12 kHz range.

1.1 to 11

kHz sweep range, Q =1

.

0.35 to 3.5 kHz sweep range, Q =1

80Hz fix frequency low cut filter.

LF shelving ±12dB.

30Hz to 400Hz range.

12dB/oct.

EQ BYPASS operates on the four variable sections simultaneously.

AUXILIARY SENDS: four controls with six outputs.
Aux 1 and 2 are switchable pre or post monitor fader.
The pre fader selection is preset internally either: pre equaliser or pre fader (ex works standard)

Aux 3/5 and 4/6 are preset internally to be either: pre equaliser, pre fader or post fader (ex
works standard).

SMALL FADER: normally the monitor input fader to the group assign and post fader sends. See
FADER REVERSE.

GROUP ASSIGN: selectors for group outputs 1 to 24 from the monitor input fader. Six

pushbuttons select twelve outputs in pairs. SHIFT selects 1-2 or 13-24. L-R assigns to stereo

output.

SOLO MUTE: with ENABLE (see M450) retains this input and operates the MUTE on all other
inputs not selected SOLO.

PFL/AFL: operates control room loudspeaker and L/R meter changeover to receive either the
PFL or AFL mix. PFL is Pre Fader Listen. AFL is After Fader Listen. AFL responds to input pan
and mute.

MUTE: press to mute the input post fader. Cuts aux, assign and AFL. Also responds to SSR

Automute and Solo.
FADER REVERSE: interchanges small and large faders. Pre and post sends not affected.

GROUP OUTPUT section controls: PAN ON connects the group fader output to the main stereo

mix.

PFL/AFL operates in the same fashion as monitor PFL/AFL above.
MUTE: press to mute the GROUP OUTPUT post fader. Cuts output, pan and AFL. This mute is

manual only and does not respond to Automute or solo system.

LARGE FADER: choice of 100mm analogue or Fader Automation.

AHB SF 1/9

MODULE M430: DUAL OUTPUT/MONITOR
MONITOR section for ODD numbered output and inputs:
Input selector switches with three sources; group output, tape input, return input.

AUXILIARY SENDS: four dual concentric controls with six outputs.

Aux 1 and 2 are switchable pre or post the monitor level control.
The pre fader selection is preset internally either: pre equaliser or pre fader (ex works
standard).
Aux 3/5 and 4/6 are preset internally to be either: pre equaliser, pre fader or post fader (ex
works standard).

Monitor LEVEL and PAN are concentric controls. The inner 'level' adjusts output to the console
stereo mix. The outer 'pan' adjusts image position.
SOLO MUTE with ENABLE (see M450) retains this input and operates the mute on all other

inputs not selected SOLO.

PFL/AFL operates the control room loudspeaker and L/R meter changeover to receive either
the PFL or AFL mix. PLF is pre monitor level. AFL is after monitor level and pan.

MUTE press to mute the input after the level control. Cuts aux, AFL and stereo outputs.

Responds to Automute and SOLO commands.

EQUALISER section: pre monitor level controls. Dual concentric controls.

HF shelving ± 12dB.
MF peak/dip ± 12dB.
MF peak/dip ± 12dB.

80Hz fix frequency low cut filter.

4 kHz to 12 kHz range.

1.1 to 11 kHz sweep range, Q =1

0.35 to 3.5 kHz sweep range, Q =1
12dB/oct.

LF shelving ±12dB. 30Hz to 400Hz range.
EQ BYPASS operates on the four variable sections simultaneously.

EQ ASSIGN: places entire equaliser either in ODD or EVEN monitor.

MONITOR section for EVEN numbered output and inputs.
Facilities identical to ODD section above.

GROUP OUTPUT section controls for two outputs, one odd one even.

FADER REVERSE interchanges the large fader and the monitor level control. Pre and post fader

sends are unaffected.

PFL/AFL operates the control room loudspeaker and L/R meter changeover to receive either

the PFL or AFL mix. Group AFL is central mono.

MUTE press to mute the GROUP OUTPUT post fader. Cuts output and AFL. This mute is manual
only and does not respond to Automute or SOLO system.

LARGE FADER: 100mm analogue fader. Part of 16 or 24 way panel.

AHB SF 1/11

MODULE M440: STEREO MASTER, 76mm WIDTH
Two sets of identical controls provide console master output facilities and
return input sections.

RETURN input section controls:

LEVEL control and selector switches for return to Aux 1 and 2.
GROUP ASSIGN selectors for return to group outputs 1-24 from the level
control below. Six pushbuttons select twelve outputs in pairs. SHIFT selects
either outputs 1 to 12 or 13 to 24.

L-R assigns return to the main stereo output.

LEVEL adjusts return to group assign and AFL.

Note that RETURN to AUX is preset pre LEVEL control.
PAN operates with the assign selectors.
PFL/AFL operates control room loudspeaker and L/R meter changeover to
receive either the PFL or AFL mix. PFL is Pre Fader Listen. AFL is After Fader
Listen. AFL responds to input Pan and Mute.
MUTE cuts off outputs post-level control. Not affected by console SOLO or
Automute commands.

AUX MASTER output section controls. Six identical sections, eight on in-line
console systems.
Output master level control numbered and calibrated.

PFL/AFL operates control room loudspeaker and L/R meter changeover to
receive either the PFL or AFL mix. PFL is Pre Fader Listen. AFL is After Fader
Listen. AFL is central mono and responds to MUTE.
MUTE: press to mute the output after the level control.
Cuts output and AFL. Not part of Automute or SOLO system.

CUE OUTPUT section controls. Two identical sections.

Three source selectors for the stereo cue output, Aux 1, Aux 2 and L-R can be
operated singly or combined. Aux 1 feeds left cue output. Aux 2 feeds right cue
output. Mono combines left and right cue outputs.
Cue 1 and 2 output master level controls are calibrated for normal position.

MUTE: press to mute the cue output.

CUE 1 and 2 receive talkback from the monitor master module.
Talkback operation dims the CUE source and superimposes TB speech.

STEREO OUTPUTS Left and Right. Two identical sections.
Peak responds to L and R pre fader mix level.
MUTE: press to mute the main stereo output L or R.

FADERS: 100mm analogue output faders.

AHB SF 1/13

The Sigma I/O design offers space saving, value for
money, in-line consoles. The three standard formats
are:-

32/24 in small frame
44/24 in large frame
56/24 extended large frame

(1.55m — 61in)

(2m — 79in)

(2.65m — 104in)

Each frame can be part filled allowing for easy future
expansion. I/O modules can be loaded into frames
with the master modules in any sequence required.
The standard master module set is supplied including
the M441 8 auxiliary send version. Other Sigma

module types can be included if required.

The M470 in-line module is a complete record/
overdub/remix system for three sources and one

record output.

A great deal of design effort has been applied to make
the M470 ergonomically efficient, with the most used
controls being grouped nearest the fader, ie. mute,
solo, pan and equalisation. The signal path switching
is designed for minimum effort transfer from record/
overdub/bounce and remix modes. An example of
this is that when all the pushbuttons are released the
module is in the correct mode to record a mic source
on to tape with simultaneous monitoring on the large
fader, therefore you are already rehearsing your final
mix, with only two button presses track bouncing can
take place. Each module is controlled for status
locally there are no master controls or overrides,
module status reminder indicators are included for
source, eq and assignment functions.

The Sigma in-line system has generous and versatile
facilities necessary for modern recording techniques.

Five band eq switchable between the large and small
fader, eight mixes for cue and effects sends. There
are separate faders for input and monitor, each with
a dedicated pan and gain trim control, solo mute, PFL
and AFL checking and access to the auxiliary sends.

Large fader SOLO has the benefit of SOLO SAFE
which prevents SOLO MUTE occuring, necessary
when echo returns are wanted in a solo section. The

MIC/LINE source section is a true dual input. Line

input is dedicated for use by instruments and echo

returns. The output from the multitrack occupies the

module tape input connection leaving MIC or LINE
sources available as required.

Both faders can access the output assignment
section; in the 'normal' mode priority is given to the
pre-recorded source via the large fader to the mix,
with the small fader being the 'live' input fader to the
bus output. In 'reverse' mode 'live' inputs are
controlled on the large fader section and small fader
is the monitor to the mix.

The M470 in-line module has unique features that are

a bonus in high performance remix operations.

The small fader can be switched to receive the large
fader output, so that when all the auxiliaries are used

up the small fader is used as an echo send fader, with

mute, and assigned to a bus output, which is then

patched to the echo device. Each fader has a path

to the mix via its own pan pot so when necessary each

module is a twin input device.

During remix when the first 24 faders are used for
tracks some group faders may be needed. On non­automated consoles the system allows two solutions.
Bus outputs can be patched to any spare fader and
reassigned or added to the mix. Also the small fader
can be configured to receive the bus output mix,
performing as a group or subgroup fader and
reassigned or added to the mix. This variation re­allocates the 'follow large' pushbutton as a `normal'/
'bus' source selector. Of course, maximum creative
freedom is achieved when fader automation is
installed and takes over group functions.

The design of the M470 module affords excellent
sonic quality with transformerless balanced audio
interfaces, low noise and distortion design, a
generous 22dB of internal signal path headroom, with

100dB dynamic range. Mute switching is carried out
by highly reliable solid state switches. The I/O module
mic preamp is an improved version of the standard
preamp having lower distortion; the bus output has
an increased overload margin; the standard equaliser
has been improved with the addition of switched
bandwidth (Q) for the two midrange sections,
switched bell or shelf characteristics for the HF and
LF sections and a variable cut off frequency for the
high-pass filter. The musical responses have been
chosen with the benefit of listening tests and the
improvement is achieved without degradation of
noise or distortion performance.

The advent of mute sequence memory, pioneered

by AHB on the Sigma Automute system gives MIDI
sync of input and monitor mutes. Sigma in-line

consoles not only benefit from improved ergonomic

design of the control surface and operating systems

but also all mute operations on small and large faders
are recognised by the mute processor and stored in

memory, thereby eliminating separate key entry of

mute data. The console mute status at any time can

be stored as a 'snap-shot' with memory identity for

recall. There are 32 patch memories available for
storing mute patterns, plus the 'in-progress' scratch

pad memory. Real time access is now also possible
from a MIDI sequencer to module mutes. This is the

basis of the Sigma MIDI automation system which
stores, recalls and up-dates the mute data in sync.

The in-line format of Sigma offers a great deal at

present. The combination of sonic excellence,
versatile and efficient control systems, and a compact

layout that reduces operator fatigue adds up to a high

performance console. It can be as straight forward
or sophisticated as you chose with or without fader
automation, with or without patchbay, part filled or
fully filled frames.

The Sigma console concept allows you to plan for
future needs with the ability to extend frames on-site,
fader automation achieved on-site and module

addition achieved on-site.

Finally, with AHB's on-going design programme new
module types will become available, all compatible
with existing frames, making Sigma the console for
today's as well as tomorrow's studio.

AHB SF 1/20

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M470 CONNECTIONS: PATCHBAY INTERFACE OPTIONAL
1, 2, 3, 4, 5, 6, 1/4" JACK SOCKETS. 0dBv is 0.775v RMS. Minimum loads: balanced outputs 600 ohms, unbalanced
2K ohms.

max.

1.

Bus out, unbalanced, -2dBv. 22 ohm source impedance, +21d

2.

Bus in, unbalanced, -2dBv
Bus in/out are patched to create subgroups on large faders 25 upwards as required.
Large fader insert, breakpoint post EQ prefader. Unbalanced 0dBv, tip send, ring return. 22 ohm/5K ohm

3.
+21d

max.

Bv

Small fader insert, breakpoint post EQ prefader. Unbalanced 0dBv, tip send, ring return. 22 ohm/5K ohm

4.

5.

6.

7.

8.

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MODULE M470 I/O SYSTEM

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30 Select aux 5 and 6 to follow small or large fader

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max.

+ 21dBv
Tape in, input to large fader section, balanced, nominal +4dBv
Line in, input to small fader section, balanced, nominal 0dBv, tip +, ring-, 15K ohm impedance.
Bus out, output to multitrack record input, balanced nominal +4dBv, pin 2+, pin 3-. XLR 3M. 50 ohm impedance

+26dBv max.
Mic in, input to small fader section, balanced pin 2+, pin 3-. XLR 3F. Switched +48v phantom power is included.
2K ohm impedance.
Tape in (low): -10dBV (300mV) input to large fader section. Passes through the high level Tape in jack switch contacts.
50K ohm impedance.

Internal meter connection. Nominal +4dBv

Internal meter trim adjustment.

Mic/line source select.

48v phantom power on switch.

15dB mic input pad switch.
Source reverse connects mic/line to large fader, bus/tape to small. Normally mic/line is small fader, bus/tape is
large fader.
Separate mic and line gain controls. Mic range +70 to + 30dB; line range +20 to -6dB.
Group assign: select 24 outputs in pairs. Connected to pan pot output of small or large fader, see 19.
Shift selects outputs 1 to 12 or 13 to 24.
Assign is normally connected to the small fader output. Select lge to switch the assign section onto the large fader.
Status LED (55) turns on.

Bus trim, trim pot adjusts bus output level to tape + 5dB, -10dB.

Bus trim enable switch.
Aux 1 and 2 send level controls.

Aux 1 and 2 switchable between small and large fader, normally in large fader signal path.

Select aux 1 and 2 pre or postfader.

Aux 3 and 4 send level controls.

Select aux 3 and 4 pre or postfader.

Select aux 3 and 4 to follow small or large fader.

Aux 5 and 6 send level controls.

Select aux 5 and 6 pre or postfader.

Level and pan for auxes 1/2 or 7/8.

Select auxes 1/2 or 7/8.

Select aux 1/2 or 7/8 pre or postfader.

HF equaliser: shelving or bell characteristics between 2kHz and 16kHz with 12dB infinitely variable cut and boost on

the inner control, frequency selection on the outer control.

Select HF shelf or bell characteristics. Normally shelving curve, when pressed gives a peak/dip (bell) curve

characteristics to HF equaliser. Bell Q = 0.7.

Places EQ section in the large fader signal path. Controls 39 and 40 also are switched with the equaliser to the large

fader.

MF equaliser peak/dip (bell) curve equaliser operating between 1KHz to 10kHz with 12dB infinitely variable cut and

boost on the inner control and frequency selection on the outer control.
MF Q is normally 0.6 and can be sharpened to 2.5 with the pushbutton.
EQ phase reversal select. Phase reverse switch, inverts signal phase of the programme being equalised.
Peak indicator responds to EQ output level and lights when 3dB headroom remains.
MF equaliser, peak/dip (bell) curve equaliser operating between 100Hz to 2kHz with 12dB infinitely variable cut and
boost on the inner control and frequency selection on the outer control.
MF Q is normally 0.6 and can be sharpened to 2.5 with the pushbutton.
Press to select rumble filter, 12dB/octave slope. Cut off frequency is adjustable with control 45.
LE equaliser; dual concentric inner control gives 12dB continuously variable cut or boost with shelving or bell
characteristic at 90Hz frequency.
Dual concentric outer section adjusts rumble filter cut off frequency between 20Hz and 400Hz.
Select bell or shelf characteristic for the LF equaliser. Bell Q = 1.6.
EQ switch, press for equalisation. Phase reverse and rumble filter are independent from the EQ in/out selector.
Pan pot for small fader, affects output to the stereo mix and the assign section.
Follow large connects small fader to the output of the large fader. The small fader can then be assigned to bus outputs
and used as an additional echo send with level and mute. An internal link option changes this switch function so that
small fader can select the bus output to tape as its source. This provides a subgroup which can be re-assigned to
another output or added to the stereo mix.

Mix connects the small fader output to the stereo mix.
PFL-AFL for small fader signal. Interrupts loudspeakers and meters only. After fade listen is post pan-pot and mute.

Solomute for small fader, mutes other small faders not soloed.

Mute small fader, cuts aux sends and pan output. This mute responds also to solo commands and the mute processor

synchronised memory system.

Small fader, normally the mic/line fader but see 15 source reverse. 60mm ultra smooth type fader, optionally
P+G 3000 series.

Status reminder LEDs, grouped near the fader for high visibility.

Select large fader source either tape input or bus output.
Large fader source trim pot +16dB, -6dB range.
Mix mute cuts large fader from the stereo mix only.
PFL-AFL for large fader signal, operates as PFL AFL for small fader. Any number of sources can be selected
simultaneously.
Solo safe prevents the large fader from being muted by other solos, useful for preserving echo returns.
Large fader pan pot, affects output to the stereo mix and the assign section.
Large fader mute, this mute is a superior fast acting pushbutton. It responds also to solo commands and the mute
processor sync memory system.
Solo mute for large fader, mutes other large faders not soloed. Small and large fader solo systems have master enable
controls in the M450 module.
Fader (not shown) 100mm large fader, normally the bus/tape fader but see 15 source reverse. Operates with the control
group immediately above. Choice of ultra smooth regular carbon type,

. 18K ohm impedance.

from 3.6K ohm.

.

Bv

, ti

p +, ring -, 47K ohm impedance.

P+G 3000 series and fader automation.