Soundcraft SM12 USER GUIDE

SOUNDCRAFT

USER GUIDE

12

 Soundcraft Electronics Ltd. 1994
All rights reserved
Parts of the design of this product may be protected by worldwide patents.

Part No. ZM0075-01

Information in this manual is subject to change without notice and does not
represent a commitment on the part of the vendor. Soundcraft Electronics Ltd.
shall not be liable for any loss or damage whatsoever arising from the use of
information or any error contained in this manual.

No part of this manual may be reproduced, stored in a retrieval system, or
transmitted, in any form or by any means, electronic, electrical, mechanical,
optical, chemical, including photocopying and re co rd ing, fo r a ny purpose
without the express written permission of Soundcraft Electronics Ltd.

It is recommended that all maintenance and servic e on the pro duc t should be
carried out by Soundcraft Electronics Ltd. or its authorised agents. Soundcraft
Electronics Ltd. cannot accept any liability whatsoever for any loss or dama ge
caused by service, maintenance or repair by unauthorised personnel.

Soundcraft Electronics Ltd.
Cranborne House
Cranborne Industrial Estate
Cranborne Road
Potters Bar
Herts.
EN6 3JN
England

Tel: [phone]
Fax: [phone]

&RQWHQWV

Introduction 1

Introduction 2
Precautions and Safety Instructions 4

Installation 7

Connections 9

Module Block Diagrams 11

Input Module 17

Module Description, Operation and Specification 18

Output Module 23

Module Description, Operation and Specification 24

Master Module 27

Module Description, Operation and Specification 28

Appendices 35

Specification Notes 36
Performance Specifications 37
Configurations 38
Dimensions 39
Warranty 40
Glossary 41

Introduction

Introduction 1

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The SM12 is a 12 bus dedicated monitor console to complement the Vienna and
Europa FOH desks.

The key features of the SM12 are:

• 12 mono sends

• stereo send

• PRE/POST fade switching on each pair of sends and the stereo send

• 4 programmable mute groups

• 4 band sweep EQ

• 100mm linear faders on all inputs and outputs

• sophisticated solo system with autocancel, central global clear and

switchable input priority.

• metering for all inputs and outputs

• external inputs for all group and stereo mix buses, with level control and

listen facility

Frame Sizes

Power Supplies

• balanced inserts on all outputs with bypass switching, and pre-insert solo

facility

• balanced inserts on all inputs

The SM12 is available in three frames sizes, 32, 40 and 48 c hannels. The consoles
are configured, from left to right:

• inputs 1 - 24

• master

• groups 1 - 12 (6 modules)

• inputs 25 - 32 (32 channel)

• inputs 25 - 40 (40 channel)

• inputs 25 - 48 (48 channel)

All frame sizes use the PSM300 PSU. Connection to the console is via a 10-way
SRC connector below inputs 21-24. The console rear panel also carries a ground
binding post.

Lamps

Two 4-pin XLR connectors for lamps are fitted to all frame sizes - one at either end
of the console on the end trim. These are suitable for Littlite or simila r 12V lamps
taking up to 330mA each.

2 Introduction

Metering

Each input module has its own 8-segment bargraph meter and peak level indicator
adjacent to the fader. The groups are metered by 16-segment bargraphs which are
next to the faders on the output modules.

The two 16-segment bargraphs on the Master module meter either the PFL/AFL
signals or the Stereo Mix signal depending on the wedge defa ult inte rna l se tting.

Introduction 3

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General Precautions

Caution!

Handling and Transport

Power Supplies & cables

Avoid storing or using the mixing console in conditions of excessive heat or cold,
or in positions where it is likely to be subject to vibration, dust or moisture. Do not
use any liquids to clean the fascia of the unit: a soft dry brush is ideal. Use only
water or ethyl alcohol to clean the trim and scribble strips. Other solve nts may cause
damage to paint or plastic parts.

Avoid using the console close to strong sources of electromagnetic radiation (e.g.
video monitors, highpower electric cabling): this ma y cause degradation of the audio
quality due to induced voltages in connecting leads and chassis. For the same
reason, always site the power supply away from the unit.

In all cases, refer servicing to qualified personnel.

The console is supplied in a wooden crate. If it is necessary to move it an y distance
after installation it is recommended that this packing is used to protect it. Be sure
to disconnect all cabling before moving. If the console is to be regularly mov ed we
recommend that it is installed in a foamlined flightcase. At all times avoid applying
excessive force to any knobs, switches or connectors.

The power supply unit incorporates automatic mains input voltage sensing and
therefore no adjustment is needed to match local mains supplies.

Warning!

Always use the power supply and cable supplied with the mixer: the use of
alternative supplies may cause damage and voids the warranty; the extension of
power cables may result in malfunction of the mixing console.

Always switch the power supply off before connecting or
disconnecting the mixer power cable, removing of installing
modules, and servicing. In the event of an electrical storm, or large
mains voltage fluctuations, immediately switch off the PSU and
unplug from the mains.

Always ensure that you use the correct PSU for your mixer. The SM12 uses the
PSM300 power supply.

4 Introduction

Signal Levels

It is important to supply the correct input levels to the console, otherwise signal to
noise ratio or distortion performance may be degraded, and in extreme cases,
damage to the internal circuitry may result. Likewise, on all balanced inputs avoid
sources with large commonmode DC, AC or RF voltages, as these will reduce the
available signal range on the inputs. Note that 0dBu = 0.775V RMS.

The microphone inputs are designed for use with balanced low impedance (150 or
200 ohms) microphones.

Caution!

DO NOT use unbalanced microphones or battery powered
condenser microphones without isolating the +48V phantom power:
degraded performance or damage to the microphone may result.

The sensitivity of the XLR inputs is variable from -2dBu to -70dBu and +10dBu to

-20dBu in two ranges (for +4dBu at the Mix outputs). T he maximum input le vel is
+28dBu on the lower sensitivity range, and +18dBu on the higher range.

The Hi-Z inputs have a sensitivity variable between +10dBu and -20dBu. The
maximum input level is +30dBu.

The main outputs of the console (stereo mix, groups, wedge and mix and group
insert sends) are balanced at a nominal level of +4dBu, with a maximum output
level of +26dBu.

The input insert sends are balanced at a nominal level of +4dBu, with a maximum
output level of +26dBu.

All external inputs and mix and group insert returns have a nominal level of +4dBu,
and a maximum input level of +26dBu except the AFL/PFL external inputs which
are unbalanced at a nominal -2dBu, with a maximum input level of +20dBu.

Insert returns are balanced at a nominal level of + 4dBu, and a maximum input level
of +26dBu.

Introduction 5

6 Introduction

Installation

Installation 7

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The SM12 is designed for reliability and high performa nce, and is built to the highest
standards. Whilst great care has been take n to e nsu re tha t insta llation s a r e ma de a s
troublefree as possible, care taken at this stage, followed by correct setting up will
be rewarded by a long life and reliable operation.

Wiring Considerations

Power Supply

Warning!

A For optimum performance it is essential for the earthing system to be clean and
noise free, as all signals are referenced to this earth. A central point should be
decided on for the main earth point, and all earths should be ’star-fed’ from this
point. It is recommended that an individual earth wire be run from each electrical
outlet, back to the system star point to p rovide a safety earth reference for each piece
of equipment.

B Install separate mains outlets for the audio equipment, and feed these
independently from any other equipment.

C Avoid locating mains distribution boxes near audio equipment, especially tap e
recorders, which are very sensitive to electromagnetic fields.

D Where possible ensure that all audio cable screens and signal earths are
connected to ground only at their source.

Always ensure that you use the correct PSU for your mixer. The SM12 uses the
PSM300 power supply.

The power supply incorporates automatic mains input voltage sensing and therefore
does not require adjustment for different local mains supplies.

Before switching on your SM12 console, check that the fuse is of
the correct rating and type. This is clearly marked on the case of
the power supply. Do not replace the fuse with any other type, as
this could become a safety hazard and will void the warranty.

8 Installation

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Wiring conventions

1

/4" ‘A’ Gauge Stereo Jack Plug used as balanced input:

Hi-Z inputs, insert returns, external inputs

The SM12 uses two different types of audio connector: 3-pin XLR and
jacks. These are used in several configurations, as shown below.

MICROPHONE INPUTS

TALKBACK MIC

TALKBACK INPUT

STEREO MIX L, R & WEDGE OUTPUTS

GROUP, TB & OSCILLATOR OUTPUTS

1

⁄

" 3-pole

4

1

/4" ‘A’ Gauge Stereo Jack Plug used as ground compensated output:

AFL/PFL outputs

1

/4" ‘A’ Gauge Stereo Jack Plug used as balanced output:

Insert sends, oscillator

1

/4" ‘A’ Gauge Stereo Jack Plug used as stereo output: Headphones

Installation 9

10 Installation

Module Block Diagrams

Module Block Diagrams 11

Input Module

12 Module Block Diagrams

Group Output Module

Module Block Diagrams 13

Master Module

14 Module Block Diagrams

Stereo Mix

Module Block Diagrams 15

16 Module Block Diagrams

Input Module

Input Module 17

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1

42

3

5

6

7

Input

1

The sensitivity of both the XLR and the HIGH IMPEDANCE (HI-Z jack) inputs

is adjusted by the

The

+48V

2

XLR for powering condenser microphones.

The

The

PHASE

RNGE

3
4

and +10dBu to -20dBu to allow line level signals to be used when the switch is
pressed. The signal is still taken from the input XLR, unless a jack is inserted into

SENS

control. Both inputs are electronically balanced.

switch, when depressed, applies +48V phantom power to the input

switch reverses the phase of the selected input.

(Range) switch selects between an input range of -2dBu to -70d Bu

the HI-Z input socket, when the signal from that is used instead.

Note that when the RNGE switch is released the HI-Z input socket cannot be used,
and that phantom power is not applied to the Hi-Z jack.

5

Pressing the

FILTER

switch activates a pre-insert high-pass filter section.

Frequency Response Curves of th e Hi g h-Pass Filter

Highpass Filter

dB

10.0

5.0

8

0.0

-5.0

-10.0

-15.0

-20.0

-25.0

-30.0

10 100

1k 10k

Frequency/Hz

12

9

10

11

13

Equaliser

This section is a four band, peaking sweep EQ.

6

The HF section has a maximum cut or boost of 15dB and the frequency is

variable between 1kHz and

HMF

The

(High Mid) section has a maximum cut or boost of 15dB and the

frequency is variable between

LMF

The

(Low Mid) section has a maximum cut or boost of 15dB and the frequency

is variable between 60Hz and

20k

Hz, with a Q of 1.3.

450

Hz and

1k5

Hz, with a Q of 1.3.

12k

Hz, with a Q of 1.3.

14

The LF section has a maximum cut or boost of 15dB and the frequency is variable

350

Hz, with a Q of 1.3.

15

between 12Hz and

7

The EQ section is switched in when the EQ switch is depressed.

18 Input Module

The Frequency Response Curves of the Equali ser

dB

LF Section

20.0

15.0

10.0

5.0

0.0

-5.0

-10.0

-15.0

-20.0
20 100

LF EQ

dB

LMF Section

20.0

15.0

10.0

5.0

0.0

-5.0

-10.0

-15.0

-20.0

20 100

LMF EQ

Frequency/Hz

Frequency/Hz

1k 10k

1k 10k 20k

dB

HF Section

20.0

15.0

10.0

5.0

0.0

-5.0

-10.0

-15.0

-20.0
20 100

HF EQ

dB

HMF Section

20.0

15.0

10.0

5.0

0.0

-5.0

-10.0

-15.0

-20.0
20 100

HMF EQ

Frequency/Hz

Frequency/Hz

1k 10k 20k

1k 10k 20k

Groups

8

The input signal is sent to the group 1 - 12 buses via individual

These have unity gain when fully clockwise.

The group sends are switched pre- or post-fader in pairs by the
pre-fade signal may be sourced either pre-mute or post-mute, and sele ction is done
in three blocks of four sends, using push-on jumpers.

The factory default is post-mute.

Level Controls

PRE

buttons. The

Stereo Mix

9

The post-fader signal is sent to the stereo mix bus via the
The mix bus send may be set pre- or post-fade by the
signal may be sourced pre- or post-mute using push-on jumpers.

The factory default is post-mute.

10

The PAN control allows the channel signal to be positioned within the stereo
mix. Rotation fully anticlockwise sends the signal to the Left bus, rotation
clockwise sends the signal to the Right bus. There is a 4.5dB drop in the centre
position.

L/R

(level) control.

PRE

switch. The pre-fade

.

Input Module 19

11

The signal in the module is turned on and off by the

1

MUTE buses (see below).

CUT

switch and by the

42

3

5

6

7

An integral red LED in the CUT switch indicates when the signal is cut.

12

The Post-fader signal level is controlled by a 100mm
fed to the Groups and the Stereo Mix buses.

13

The red
clipping at the output of the input amp (after the high-pass filter), the o utput of th e
EQ or the post-fader amplifier.

A three colour, 8-segment bargraph meter be side the fader meters the signal dire ctly
after the input amplifier. The meter has a peak-reading characteristic.

PEAK

LED illuminates when the signal level is within 6dB of

FADER

before being

Muting System

14

Each Input module is assigned to the four mute buses using the
buttons. The module is assigned to its respective mute bus when each switch is
pressed.

Pressing the
and reinstates the previous mute selection when released.

When the module is muted by any of the mute buses, the LED in the CUT switch

8

illuminates.

SAFE

switch isolates the module from the effect of the Master Mutes,

MUTE 1 - 4

12

10

11

13

14

PFL

15

The electronically latching
the PFL bus, which in turn feeds the engineer’s wedge speakers and phones outputs
via the Master section. An integral amber LED indicates when the PFL switch is
active.

PFL

switch feeds the pre-fade, pre-mute signal to

Insert Point

9

The module insert point uses a balanced send and a balanced return, at a nominal
level of +4dBu. The signal is accessible via separate 1/4" jacks on the rear connector
panel.

The insert point may be set to pre- or post-EQ by push-on jumpers. The factory
default is pre-EQ.

15

20 Input Module

Jumper Options
(RH PCB)

Function Options Default

Insert point pre-EQ

J1, J2, J3 jumpers IN for pre-EQ
J4, J5, J6 jumpers IN for post-EQ

Group 1-4 Pre-fade signal post-mute

J11 jumper IN for pre-mute
J12 jumper IN for post-mute

Note: only one of the above two jumpers to be fitted at any one time.

Group 5-8 Pre-fade signal post-mute

J9 jumper IN for pre-mute
J10 jumper IN for post-mute

Note: only one of the above two jumpers to be fitted at any one time.

Group 9-12 Pre-fade signal post-mute

J7 jumper IN for pre-mute
J8 jumper IN for post-mute

Note: only one of the above two jumpers to be fitted at any one time.

Mix L-R Pre-fade signal post-mute

J13 jumper IN for pre-mute
J14 jumper IN for post-mute

Input and Output Levels

Note: only one of the above two jumpers to be fitted at any one time.

XLR INPUT (electronically balanced)

Sensitivity -2dBu to -70dBu (hi sens.),

+10dBu to 20dBu (low sens.)

Maximum Input Level +28dBu (low sens.), +18dBu (hi sens.)
Input Impedance 2KΩ

HI-Z INPUT (electronically balanced)

Sensitivity +10dBu to -20dBu
Maximum i/p level +30dBu

Input Impedance >10KΩ balanced

INSERT SEND

Nominal Level +4dBu
Maximum Output Level +26dBu into 2kΩ
0utput Impedance <75Ω

INSERT RETURN (electronically balanced)

Sensitivity +4dBu
Maximum I/P Level +26dBu

Input Impedance >10KΩ balanced

Input Module 21

Rear Connectors

The connections to the rear connector panel are as follows:

INPUT (3 pin female XLR)

Pin 1 Ground
Pin 2 Signal (Hot)
Pin 3 Signal (Cold)

HI-Z INPUT, INSERT RETURN (1/4" 3-pole Jack)

Tip Signal (Hot)
Ring Signal (Cold)
Sleeve Ground

INSERT SEND, (1/4" 3-pole Jack)

Tip Signal (Hot)
Ring Signal (Cold)
Sleeve Ground

22 Input Module

Group Output Module

Group Output Module 23

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14

10

11

13
12

1
2

3

5
6
7

8

9
4

External Input

An external input, from a jack socket on the rear panel, may be added to the group
bus. The input is balanced with a sensitivity of +4dBu.

1

provides a maximum 10dB gain when it is fully clockwise.

2
3

to the ’phones or wedge output. LISTEN is not affected by the AUTO CANCEL
or SOLO CLEAR functions, and overrides any output AFLs if INPUT PRIORITY
is active. Pressing LSTN will not cancel other solos.

Six output modules are fitted in each console. The output module contains two
group output sections, stacked one above the other. The lower sections control
groups 1 - 6, while the upper sections control groups 7 - 12 . The two sections have
identical facilities.

EXT IN

The

The latching

The momentary

control adjusts the level of the external signal to the group, it

ON

switch activates the external input when pressed.

LSTN

(Listen) switch provides a pre-level control, pre-ON solo

Level Control

The group summing amp is assigned to one of the twelve group buse s using internal
push-on jumpers.

4

The 100mm
amplifier, which is fed to the insert send and ultimately the Group Output, with
10dB of gain at maximum.

FADER

controls the level of the signal from the summing

Insert Point

5

The insert point is post-fade, and uses an electronically bala nced send and return
at a nominal level of +4dBu. The insert SEND and RETURN are on separate 1/4"
jacks on the rear connector panel. The insert point may be bypassed using the
INSERT

OUT

switch.

Output Switching

6

itself is electronically balanced at +4dBu, on a male XLR on the rear connector.

7, 8

buses respectively. This feature allows subgroups to be created, if the console is
used in a FOH application.

9

selected). The switch has an integral red LED which indicates when the signal is
cut.

PHASE

The

The L and R switches route the group signal to the left and right stereo mix

CUT

The

switch reverses the phase of the group output. The group output

switch mutes the signal to the group output and stereo mix bus (if

24 Group Output Module

Talkback

10

The momentary TB switch feeds the signal from the TALKBACK
MICROPHONE to the group output; it is independent of the Fader position and the
CUT switch. The existing group output is dimmed by 6db, and the engineer’s
wedge speaker is dimmed by 20dB while the TB switch is active.

Talkback may also be routed to all the group buses simultaneously by the INT
talkback function on the master module; in this case the group CUT a nd fa de r will
affect the talkback level.

Metering

Jumper Options

11

The group output level is metered by an integral peak-reading

LED bargraph

+4dBu output. An internal jumper allows the meter response to be set to
average-reading instead of peak-reading.

which is situated next to the Fader; the meter is calibrated for 0 at

16-segment

Solo

12

The electronically latching
feeds the post-fade, post-insert group signal to the engineer’s wedge speakers and
phones output; however, if INPUT PRIORITY (see the Master Mo dule) is ena bled
then any active input PFLs will replace the AFL signal, and the group will not be
heard until the inputs are un-PFLed. If solo AUTO CANCEL (see the Master
Module) is selected, then the AFL will cancel any othe r a ctive PFLs or AFLs. Th e
AFL may also be cleared with the Master Module’s SOLO CLEAR function.

The

The

PRE INSERT

AFL TRIM

control gives +/-10dB of level adjustment.

switch moves the AFL signal before the insert point.

13
14

Function Options Default

AFL

switch, which has an integral amber LED,

Lower group bus programming *

J101 - J106 Group 1 - 6 According to
Module Position

Upper group bus programming *

J201 - J206 Group 7 - 12 According to

Module Position

Lower Meter Response

J109 Peak or Average Peak

Upper Meter Response

J209 Peak or Average Peak

* only to be changed if the module is moved to a different position within the
group section.

Group Output Module 25

Input and Output Levels

Rear Connectors

Insert Sends, Group Outputs (electronically balanced)

Nominal level +4dBu
Maximum output level +26dBu into 600Ω
Output impedance <75Ω

Insert Returns, External Inputs (electronically balanced)

Sensitivity +4dBu
Maximum i/p level +26dBu

Input impedance >10KΩ balanced

External Inputs (1/4" 3pole Jack)

Tip Signal (Hot)
Ring Signal (Cold)
Sleeve Ground

Insert Return (1/4" 3pole Jack)

Tip Signal (Hot)
Ring Signal (Cold)
Sleeve Ground

Insert Send, (1/4" 3pole Jack)

Tip Signal (Hot)
Ring Signal (Cold)
Sleeve Ground

Group Outputs, (3 pin male XLR)

Pin 1 Ground
Pin 2 Signal (Hot)
Pin 3 Signal (Cold)

26 Group Output Module

Master Module

Master Module 27

34

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The master module contains the stereo mix or sidefill output, the operator’s
headphones and wedge speake r outputs, a noise or sine wave test oscilla tor, the solo
mode controls and master solo clear function, and internal/external talkback
functions.

PSU Status Indicators

1

7
8

9
10

15
12

17
16
18

11

14
13

1

The two PSU Status Indicator LEDs (red) show that the

rails are working.

2

+/-17V

and

Talkback

The talkback system allows communication by the operator to the group and mix
outputs, and to and from the front of house (FOH) console.

29
30

2

The

gooseneck.

31

3

The TALKBACK

32

input. The sensitivity of the mic input is variable between -20dBu and -50dBu.

33

4

The TALKBACK TO BUSSES
the group and mix buses when FOH talkback is active to allow the front-of-house
engineer to talk to the pe rformers via th e monitor outputs.

3

5

The TALKBACK/OSC TO BUSSES

4

from the mic to all group busses and the stereo mix bus simultaneously. The

5

oscillator is also routed via this switch if it is turned ‘on’.

6

6

The momentary action

25

console using a Soundcraft proprietary system. The talkback mic signal is switched
to the FOH OUT XLR, with a +15v DC common-mode voltage to signal the FOH

26

console that talkback is occurring. The signal present on the FOH IN XLR is fed to

27

the ’phones, dimming the existing signal by 15dB. The wedg e is dimmed by 20dB.
An internal jumper disables the common-mode DC voltage, to allow use with

28

non-Soundcraft desks.

TALKBACK MIC

LEVEL

FOH

XLR accepts a local talkback microphone or

control adjusts the sensitivity of the talkback mic

EXT

button sends the T/BACK IN signal to

INT

button routes the talkback signal

button initiates talkback to the front of house

+48V

PSU

If a 15v common-mode voltage is detected on the FOH IN XLR, indicating ta lkback
from the front-of-house console, then the FOH IN signal is switched to the ’phones

20

output, dimming the existing signal by 15dB, and dimming wedge output by 20dB.
The FOH switch also lights.

21

19

22

The signal from the talkback mic. may be routed to the group or mix outputs
individually by pressing the TB button on each output; this also dims the wedge
output by 20dB.

24

23

28 Master Module

External Input

7

mix.

8

to the mix buses. The inputs are balanced with a sensitivity of +4dBu. The

IN

clockwise.

9
10

to the ’phones or wedge output. LISTEN is not affected by the AUTO CANCEL
or SOLO CLEAR functions, and overrides any output AFLs if INPUT PRIORITY
is active. Pressing LSTN does not cancel other solos.

MONO

The

A stereo external input, from XLRs on the rear connector panel, may be added

control adjusts the level of the external signals, with 10dB of gain fully

The latching

The momentary

switch sums the external signal to mono before it is fed to the stereo

EXT

ON

switch activates the external input.

LSTN

(listen) switch provides a mono pre-fade, pre-ON solo

Stereo Mix

The stereo mix path is similar in function to the group outputs, but provides a stereo
output.

11

The 100mm stereo mix
summing amplifiers. This stereo signal is fed to the left and right insert sends and
ultimately to the left and right outputs, with 10dB of gain at the maximum.

FADER

controls the level of the signal from the

Insert Point

The inserts are postfade, using electronically balanced sends and returns at a
nominal level of +4dBu. The insert SENDs and RETURNs are on separate 1/4"
jacks on the rear connector panel.

12

Both left and right inserts may be bypassed using the
Note that the sends are always active.

INSERT OUT

switch.

AFL

13

The electronically latching
feeds the stereo post-fade, post-insert signal to the engineer’s wedge speakers and
phones output.

The

The

PRE INSERT

AFL TRIM

pot gives +/-10dB of level adjustment.

switch moves the AFL signal before the insert point.

14
15

AFL

switch, which has an integral amber LED,

Talkback

16

The momentary TB switch activates the signal from the TALKBACK
MICROPHONE and feeds it to the stereo mix output; it is independent of the Fader
position and the CUT switch. The stereo output is dimmed by 6db, and the
engineer’s wedge speaker is dimmed by 20dB while the TB switch is active.

Master Module 29

Talkback may also be routed to all the group buses and the stereo mix bus
simultaneously by the INT talkback function on this module; in this case the
Group/Stereo CUT and fader will affect the talkback level.

34

1

7
8

9
10

15
12

17
16
18

11

14
13

Output Switching

17

outputs themselves are electronically balanced at +4dBu, on male XLRs o n the rear
panel.

18

an integral red LED which indicates when the signal is cut.

2

Wedge and Headphones Outputs

The wedge (operator’s speaker) and headphones outputs share a common signal
source: when no PFL, AFL or LISTENs are active, then the source is either the
external PFL and AFL inputs, or the stereo mix signal, according to the position of

29

an internal jumper. The pupose of this jumper is to allow the wedge output to be

30

either quiet in the absence of any solo signals (preferred in monitor mixing
applications) or to monitor the stereo output in the absen ce of solo signals (preferred
for FOH mixing applications).

31

When a solo is active the signal is the console AFL or PFL signal, summed with

32

the external PFL and AFL signals.

33

19

is balanced at +4dBu on XLRs.

3
4

20

is available on a 1/4" 3-pole jack on the front panel.

5
6

21, 22

Wedge outputs. Similarly, when the R switch is depressed, the Right signal is fed

25

to both Wedge outputs. When the L and R buttons are both depressed, a
mix of the Left and Right signals is fed to both Wedge outputs.

26
27

23

28

(see 20 above)

PHASE

The

CUT

The

The stereo wedge output level is controlled by the 100mm wedge Fader and

The headphones output level is adjusted by the

When the L switch is depressed, the Left signal is fed to both Left & Right

HEADPHONES

The

switch reverses the phase of both left and right outputs. The

switch mutes the signal to the left and right outputs. The switch has

PHONES

jack. Output level is control by the PHONES control

control ; the output

MONO

20

Mute Masters

19

21

24

The four, latching, Mute Master buttons
red LED, control the four mute buses. Any inputs assigned to a mute bus will be

22

cut by the appropriate mute master, except those on which the SAFE switch has
been pressed.

24

M1 - 4

, which each have an integral

Using the Solo System

A solo system of pre-fade listen (inputs) and post-fade listen (outputs) feeds the

23

operator’s wedge/’phones outputs.

Normally, all active AFL, PFL and LISTEN signals are summed together and fed
to the wedge or phones outputs.

30 Master Module

25

The

PFL TRIM

control gives +/-10dB of level trim for PFL/LISTEN signals.

26

When INPUT PRIORITY is selected by the

ENBL

switch, an active PFL or
LISTEN will replace any AFL signals, which will be audible only when all the
PFL/LISTENs are released.

27

When AUTO CANCEL is activated by the

ENBL

button, any AFL or PFL

will cancel any currently active solo, so only one AFL or PFL can be active at once.

When INPUT PRIORITY and AUTO CANCEL are both pressed, the effect will b e
similar to ‘26’ above, but also with autocancelling between groups of outputs and
groups of inputs.

LISTEN buttons are not affected.

28

SOLO CLEAR

The

button lights when any AFL, PFL or LISTEN is active.

Pressing it will clear a PFL or AFL, but not a LISTEN.

The logic control modes are summarised below:

Mode

‘Normal’

‘Autocancel’

‘Input priority’

‘Input/output
Autocancel
with I/P priority’

Autocancel
button

0 (=off)

X (=on)

0

X

Input priority
button

0

0

X

X

Description

All output and input solos are
additive

All solos Autocancel, no distinction
between output and input

If an output is left on solo, soloing an
input will temporarily override the
output but will return to it when the
input is unsoloed

Combination of the last two

- as input priority, but also with
Autocancelling between groups of
outputs and groups of inputs

External Solo Signals

PFL, AFL Left

The
rear panel allow signals from another console to be a dded to the PFL and AFL buses.
The external PFL level is trimmed by the PFL TRIM pot. When no solos are active
on the console, both PFL and AFL left and right external signals are monitored by
the ’phones and wedge (if selected by internal jumper, see below). When INPUT
PRIORITY is not active, the external signals are mixed with any current internal
PFL, AFL or LISTEN signals; if INPUT PRIORITY is enabled and a PFL/LISTEN
is active then the external AFL input is cut.

Internal jumpers allow the signal fed to the ’phones/wedge wh en no solos are active
to be changed from the external PFL/AFL signals (as described above) to the ste reo
mix postfade signal. This will be replaced by any active solo signal. To monitor
the external PFL/AFL inputs in this case, a solo on the console must be pressed.
The purpose of these jumpers is to allow the wedge output to be either q uie t in th e
absence of any solo signals (preferred in monitor mixing applications) or to monitor
the stereo output in the absence of solo signals (preferred for FOH mixing
applications).

and

AFL Right

external inputs, from 1/4" jack sockets on the

PFL and AFL Outputs

The PFL, AFL left and AFL right output signals are available on 1/4" ja c k socke ts
on the rear connector panel, ground compensated a t -2dBu. These are for use whe n
linking the console (as a slave), or for additional monitoring.

Master Module 31

Oscillator

29

The oscillator, activated by the ON switch, produces pink noise or tone.

30

The oscillator signal is fed to the oscillator output, balanced at a nominal level
of +4dBu, on a 1/4" jack socket on the rear connec tor panel. The oscillator c an also
be fed to the group and stereo mix busses by pressing the TALKBACK/OSC TO
BUSSES ‘INT’ switch (see 5 on page 28). The
from off to 10dB above nominal.

31

When tone is selected (see 33 below) the oscillator tone frequency is variable
between 63Hz and 1kHz: it is adjusted by the

LEVEL

FREQ

control adjusts the level

control.

Jumper Options

32
33

X10

The

Pressing the

button changes the frequency range to 630Hz - 10kHz.

TONE

button switches the signal from pink noise to sine wave.

Metering

34

Two 16-segment bargraph meters at the top of the module monitor the level
of the stereo mix or the external AFL/PFL signal, depending on the wedge default
jumper setting, or the current solo signal when a solo is active; the AFL signal from
the stereo mix is displayed in stereo while mono AFLs (from the groups) and
PFL/LISTEN signals (taken after the PFL trim pot) are fed to both left and right
meters.

The meter response may be selected as peak-reading or average by changing the
position of internal jumpers.

Function Options Default

Phones/Wedge Signal

(RH board SC3425)

JMP1 jumper out for Stereo Mix Ext. PFL/AFL

(FOH applications)

jumper in for Ext. AFL/PFL

(Monitor applications)

FOH Out DC Voltage

(RH board SC3425)

JMP2 Enabled or disabled Enabled (jumper out)

Bargraph Response

(LH board SC3426X)

J301

(small meter board SC3426Y)

J401 ** peak or average peak

** The small meter board must be removed to change this jumper

32 Master Module

Input and Output Levels

INSERT SENDS, MIX, WEDGE AND FOH TALKBACK OUTPUTS
(Electronically Balanced)

nominal level +4dBu
maximum output level +26dBu into 600Ω
output impedance <75Ω

OSCILLATOR OUTPUT (Electronically Balanced)

nominal level +4dBu
maximum output level +14dBu into 600Ω
output impedance <75Ω

PFL, AFL LEFT AND RIGHT OUTPUTS (Ground Compensated)

nominal level -2dBu
maximum output level +20dBu into 2kΩ
output impedance <75Ω

INSERT RETURNS, GROUP & STEREO EXTERNAL AND FOH
TALKBACK INPUTS (Electronically Balanced)

sensitivity +4dBu
maximum i/p level +26dBu

input impedance >10KΩ balanced

PFL EXTERNAL INPUTS (Electronically Balanced)

sensitivity -2dBu
maximum i/p level +20dBu

input impedance >10kΩ balanced

TALKBACK MICROPHONE INPUT (Electronically Balanced)

sensitivity -20dBu to -50dBu
maximum i/p level 0dBu

input impedance 2kΩ

PHONES OUTPUT (Unbalanced)

nominal level +4dBu
maximum output level +20dBu into 600Ω

0dBu into 8Ω

output impedance 50Ω

Master Module 33

Rear Connectors

External (FOH) Talkback In and Talkback Mic
(3-pin female XLR)

Pin 1 Ground
Pin 2 Signal Hot
Pin 3 Signal Cold

Insert Returns, Ext. Inputs
(1/4" 3-pole Jack)

Tip Signal Hot
Ring Signal Cold
Sleeve Ground

Insert Sends, Oscillator Output (1/4" 3-pole Jack)

Tip Signal Hot
Ring Signal Cold
Sleeve Ground

PFL, AFL Left and Right Outputs (1/4" 3-pole Jack)

Tip Signal
Ring Ground Sense
Sleeve Ground

Mix, Wedge and Talkback Outputs
(3-pin male XLR)

Pin 1 Ground
Pin 2 Signal Hot
Pin 3 Signal Cold

Phones Output (1/4" 3-pole Jack)

Tip Left Signal
Ring Right Signal
Sleeve Ground

34 Master Module

Appendices

Appendices 35

6SHFLILFDWLRQ1RWHV

SPECIFICATION NOTES AND CONDITIONS

A The Console has a nominal output level of +4dBu: all input sensitivities are
relative to this, i.e., with line input gain set to ’0’, an input of 0dBu will give an
output of +4dBu at any group or mix output, and a sensitivity of +4dBu gives un ity
gain from input to output.

B Noise measurements are taken with 22Hz-22kHz bandwidth, rms-reading
response.

C Distortion measurements are made with a an input of +20dBu (line inputs at
unity gain) giving an output of +20dBu. The analyser reads THD+N with a n average
response over a 10Hz-30kHz bandwidth.

D Frequency response and EQ measurements are made with an input of 0dBu to
line inputs at unity gain: outputs are quoted relative to 0dBu.

E Crosstalk and rejection measurements are made with an input level of + 20d Bu
(line inputs at unity gain) giving an output of +20dBu on the active signal path . The
ratio quoted is relative to +20dBu output.

F Gain tolerance is +/- 1.5dB or 10% of the indicated value, whichever is the
greater.

G Group Noise: noise measured at the group output with faders at unity, and
channel send pots down.

H Mix Noise: noise measured at the stereo mix output with faders at unity, and
channel sends off.

36 Appendices

3HUIRUPDQFH6SHFLILFDWLRQV

Measured on a 40 channel console.

Frequency response

Line input to any output: 20Hz - 20kHz, +0/-0.5dB

Crosstalk

Channel CUT isolation >100dB
Channel Fader isolation >95dB
Channel Send Pot isolation >75dB
Group Fader isolation >95dB
Group CUT isolation >95dB

Noise

XLR input at maximum sensitivity <-127.5dBu
(200ohm source)
Group Output noise <-82dBu
(Group faders at unity, channel sends down)
Mix output noise <-84dBu
Mix faders at unity, channel sends off)

Distortion

Line In to Group or Mix out <0.005% @ 1kHz

(measured at 1kHz)

(22Hz-22kHz bw, unweighted rms)

(THD + Noise, measured at 20dBu, 30kHz bw)

<0.025 @ 10kHz

Appendices 37

&RQILJXUDWLRQV

Inputs 1-24 Outputs

Master

Inputs 25+

Console Rear View

External

Inputs

PSU

Socket

38 Appendices

'LPHQVLRQV

SM12 Outline Dimensions

All dimensions are in millimetres

262.28

9.80

32 Channel = 1392mm
40 Channel = 1646mm
48 Channel = 1900mm

110.10

722.80

Appendices 39

:DUUDQW\

1 Soundcraft means Soundcraft Electronics Ltd.

End User means the person who first puts the equipment into regular operation.
Dealer means the person other than Soundcraft (if any) from whom the End

User purchased the Equipment, provided such a person is authorised fo r th is
purpose by Soundcraft or its accredited Distributor.

Equipment means the equipment supplied with this manual.

2 If within the period of twelve months from the date of delivery of the Equipme nt

to the End User it shall prove defective by reason only of faulty materials and/or
workmanship to such an extent that the effective ne ss an d/or usability thereof is
materially affected the Equipment or the defective component should be returned
to the Dealer or to Soundcraft and subject to the following conditions the Dealer
or Soundcraft will repair or replace the defective components. Any components
replaced will become the property of Soundcraft.

3 Any Equipment or component returned will be at the risk of the End User whilst in

transit (both to and from the Dealer or Soundcraft) and postage must be prepaid.

4 This warranty shall only be available if:

a) the Equipment has been properly installed in accordance with instructions
contained in Soundcraft’s manual; and

b) the End User has notified Soundcraft or the Dealer within 14 days of the
defect appearing; and

c) no persons other than authorised representatives of Soundcraft or the Dealer
have effected any replacement of parts maintenance adjustments or repairs to the
Equipment; and

d) the End User has used the Equipment only for such purposes as Soundcraft
recommends, with only such operating supplies as meet Soundcraft’s
specifications and otherwise in all respects in accordance Soundcraf t’s
recommendations.

5 Defects arising as a result of the following are not covered by this Warranty: faulty

or negligent handling, chemical or electro-chemical or electrical influences,
accidental damage, Acts of God, neglect, deficiency in electric al powe r,
air-conditioning or humidity control.

6. The benefit of this Warranty may not be assigned by the End User.

7. End Users who are consumers should note their rights under this Warranty are in
addition to and do not affect any other rights to which they may be entitled
against the seller of the Equipment.

40 Appendices

*ORVVDU\

Auxiliary Send an output from the console comprising a mix of signals from channels and groups

derived independently of themain stereo group mixes. Typically the feeds to the
mix are implemented on rotary level controls.

Balance the relative levels of the left and right channels of a stereo signal.
Clipping the onset of severe distortion in the signal path, usually caused by the peak signal

voltage being limited by the circuit’s power supply voltage.

CR (Control Room) Monitors loudspeakers used by the operator (engineer) in the control room to listen to the

mix.

dB (decibel) a ratio of two voltages or signal levels, expressed by the equation

dB=20Log10(V1/V2).
Adding the suffix ’u’ denotes the ratio is relative to 0.775V RMS.

DI(Direct Injection) the practice of connecting an electronic musical instrument directly to the input of

the mixing console, rather than to an amplifier and loudspeaker which is covered
by a microphone feeding the console.

Equaliser a device that allows the boosting or cutting of selected bands of frequencies in the

signal path.

Foldback a feed sent back to the artistes via loudspeakers or headphones to enable them to

monitor the sounds they are producing.

Frequency Response the variation in gain of a device with frequency.
(sub) Group an output into which a group of signals can be mixed.
Headroom the available signal range above the nominal level before clipping occurs.
Highpass Filter a filter that rejects low freque ncie s.
Line Level Signals at a nominal level of -10dBV to +6dBu, coming from a low impedance source.
Noise Gate an electronic switch which only passes signals exceeding a set threshold level.
Pan (pot) abbreviation of ’panorama ’: co ntrols levels se nt to le ft and right outputs.
Patchbay a connection panel providing access to most input/output signals on the console,

allowing the operator to redirect or rearrange internal and external connection s using
flexible patch cords.

Peaking an equaliser response curve affecting only a band of frequencies i.e. based on a

bandpass response.

PFL (Pre-fade Listen) a function that allows the operator to monitor the pre-fade signal in a channel

independently of the main mix.

Rolloff a fall in gain at the extremes of the frequency response.
Shelving an equaliser response affecting all frequencies above or below the break frequ ency

i.e. a highpass or lowpass derived response.

Spill acoustic interference from other sources.
Talkback the operator speaking to the artistes or to tape via the auxiliary or group outputs.

Appendices 41

42 Appendices