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S R S E R I E S OW.:NER H A N D B O O K 2
Effective,from serial number 501001 onwards.
This manual includes operating and service information for all models of the SR
Series currently in production. Where differences between models exist, such as
four bus and two bus models, this is indicated in the text.
CONTENTS PAGE
Online version PART 1
INTRODUCTION ...................... Specification
Service & Guarantee Info
Electronic Performance
PANEL CONTROLS .................... Input Channel
Group Channel
Output Section
Master Section
USE OF FACILITIES ................. Input Channel
Group Channel
Output Section
Master Section
Online version PART 2 Recording with the SR range
INSTALLATION ...................... Connexions
Connexion Diagrams
Earthing
Online version PART 3 AC Supply Voltages
USER CONFIGURED OPTIONS ........... Access to Mixer Circuits
Service Notes
Phantom Power
Aux Send - Input Channel
Fx Return
Electronically Balanced O/Ps - Groups
Stereo
Online version PART 4 Mono
SERVICE INFORMATION ............... Spare Parts List
Dimensions Diagrams
Schematic Diagrams
Block Diagram
ALLEN & HEATH BRENELL LTD ISSUE 4 DEC 1988
S R S E R I E S O W N E R H A N D B O O K
INSTALLATION
CONNEXIONS
Operating System -- Connexions
and Audio
Typical uses of SR Series mixers are shown with connexion schematics. All
recorders require connexion to the mixer in the same manner, but recorder
input/output connector types may differ from those shown in CONNEXION DETAIL.
Equipment List
SR SERIES mixer
Microphones and Instruments
Multitrack Recorder
Stereo Recorder
Monitor power amplifier and loudspeakers
Echo FX unit
Cue headphone amplifier and outlets.
Connexion - Microphones and Instruments
of
CHANNEL MIC (microphone) inputs are low input impedance, high gain inputs for
the connexion of all types of microphones. Best performance will be obtained
using balanced microphones of 200 to 600 ohm output impedance connected via
screened 2 core cable. In this configuration, the mixer phantom power
distribution may be used to power condenser microphones. Unbalanced microphones
should be connected with the signal on pin 3 and screen on pins 1 and 2
together. In this configuration, phantom power should NOT be applied. (See
user configured options - phantom power). The mixer input withstands the +48
volts put out by certain types of condenser mic external powering units.
Mic inputs can also be used with instruments such as guitars, and direct
injection boxes if required to impedance match the instrument to the preamp and
balance the circuit to reduce interference pick up. Instruments with medium
output levels (50-500 mV), such as keyboards, may also be connected to the mic
inputs if the instrument output is low impedance. Connect the instrument as you
would an unbalanced microphone (see above) and observe the cautions described
there. Should the instrument output be high impedance, loss of signal will
occur and signal-to-noise ratio will suffer. Selecting the mic PAD may produce
an acceptable input.
Channel Line Inputs
These are high impedance, medium gain inputs for the connexion of high level
signals. Four to eight 1 ine inputs wi 11 be required to replay the tape tracks
for remix. The rest are available for connexion of instruments with high output
levels, such as echo returns, additional tape machines, etc.
The input is balanced. Connect balanced equipment to tip and ring of the jack;
screen to case. Connect unbalanced signals to the tip and link ring and case to
the screen of the cable.
SR SERIES O W N E R H A N D B O O K 23
Connexion - Stereo Recorder
of
Mixer main outputs LEFT and RIGHT are the stereo output for the mastering
recorder. The output level is adjustable for any tape machine input level and
balanced output available. Refer to OPTIONS section of this handbook for more
information.
The outputs are supplied unbalanced. Connect signal to pin 3 on the XLR type
connectors and screen to pin 1. Stereo machine outputs should be connected to
any adjacent pair of available line inputs. Generally, these are the last two
on the mixer (channels 15, 16 - 23, 24). See CONNEXION DETAILS.
Connexion - Monitor Output
of
The operators monitor output is available o' 1/4" jack socket and is labelled
na
"MON OUT". This is an unbalanced stereo circuit designed for use with stereo
power ampl ifiers with an input sensitivity rating of lOOmV to 1V (approximately)
for full rated output. Connect the TIP of the monitor output jack to the LEFT
amplifier channel, and the RING to the RIGHT channel, SCREEN to case. Mixer
outputs generate turn-on thumps, which can strain loudspeakers if the mixer is
turned on while the power amp is on. To avoid this, it is good practice to
always have ALL other equipment in your system turned on BEFORE turning on any
power amps.
Connexion -- Devices
of Fx
As supplied, AUX A and AUX B would generally be used as FX sends as they are
factory wired to take their signal AFTER the channel fader. Wired like this, if
a channel which is being sent to the FX device is turned down in the mix, the
level of signal send from that channel is also turned down proportionally. This
prevents that channel from leaking into the mix via the FX device when it is not
wanted there. As with other mono unbalanced outputs, connect TIP tokthe device
input, SCREEN to earth.
----- C as Additional --
Use of Aux Fx Send
As mentioned above, it is generally undesirable to take FX sends from any but
post fader sources for the reasons described. Provision has been made within
the mixer to allow the user to select the source from which an aux send control
derives its source. As supplied, AUX C is a PRE-EQ send from the input
channels, but no send from the tape return section is provided. It is therefore
suggested that the POST FADER source option be selected for AUX C, making it an
additional FX send which can be returned to any available INPUT channel.
Connexion -- (Foldback) Amp1 ifiers
of Cue
In recording applications, AUX D is intended for use as the CUE, or foldback
mix. Provision has been made within the GROUP section which allows tape tracks
to be mixed to this bus for the purpose of monitoring them during overdubs.
This is a MONO, UNBALANCED output, and can be fed to a mono amplifier, stereo
ampl ifier, (using a suitable adaptor cable) or a stereo amp "strapped" for mono
operation as shown in CONNEXION DIAGRAM. See amp manufacturers instructions for
mono operation. For distribution of CUE program to several pairs of headphones,
the power amplifier output should be divided by a suitable resistor.
S R S E R I E S OWNER H A N D B O O K
Connexion -- Output
of Mono
The mono out is an XLR connector with signal to pin 3 and screen to pin 1.
Balanced output is an option, refer to options section. If desired, the mono
output can be used to drive a power amplifier connected to a loudspeaker in the
studio for the purpose of track playback. While not practical for the purpose
of overdubbing, it can be quite handy if you have a large number of people in
the studio as it can keep them from running in after a track is completed and
crowding the control room where you are trying so hard to keep a semblance of
order.
SR SERIES O W N E R H A N D B O O K
SR RANGE: CONNEXION DETAIL
MULTITRACK RECORDIN0
connexion viewed f r o m r e a r of mixer
FX UNIT 1
IN OVI
416.424
A ONLY
1 A
n
PHONES
M O N I T O R OUT
0INOCRT
1r
r INEERT a AT ANY INBERT
@'
FX F I L T l
0 b 4
v w
a
AUX W T
l Q R O U P OUT a LINE IN LINE I N
M O N O OUT
R OUT
SR RANGE: CONNEXION DETAIL LOUO=PIAK.~
SOUND REINFORCEMENT APPLICATIONS
0
VIEW F R O M REAR O F MIXER
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CCRODDOVER IN I I - A M P t O M I E M . 3
29
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MONOITOR OUT
D R U M MONITOR
oa SlOE FILL (cLOOI MONITORS
FX UNIT P
hA'
AUX A OUT
FX UN~Ti
I OROUP OUT
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I L I N E IN
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SR S E R I E S OWNER HANDBOOK 28
IMPORTANT - PLEASE READ AND UNDERSTAND!
EARTHING
Mains electricity is dangerous and can kill. Most pieces of mains powered
equipment have an earth wire running from the case to the mains plug. (Some are
"double insulated" and do not need this.) This earth wire is there for safety.
Unfortunately with many earthed items wired together sound quality can suffer.
It is common practice in studios to disconnect some of these earth wires for
sound quality reasons. This can be dangerous.
Equipment will still work even if it is not earthed. This does not mean it is
safe! Government and insurance underwriters' electrical codes must be observed.
These codes take precedence over any suggestions contained in this manual.
The sound quality problems mentioned are hum and interference, caused because
there are several paths to earth (along the audio screens and down a1 1 the mains
earths). The problem can be overcome by having just one piece of equipment
connected to mains earth (usually the power amp).
Do not leave the earth wire loose in a mains plug as it may touch the live
termina 1.
Having only one item connected to mains earth means that all the others rely on
the audio screen or ground for safety. It is important to remember this. Test
regularly that all exposed metal gear including microphones, guitar strings and
D I boxes have a low resistance to mains earth.
This A1 len & Heath mixer case is not connected to mains earth, for the audio
reasons mentioned. The mixer power supply is however, and this earth must not
be removed.
It is best to plan ahead and have your installation checked by a competent
engineer before you commence. Do not trust equipment and installations modified .
by others before you.
SR S ' E R I E S OWNER HANDBOOK 29
SUPPLY VOLTAGES
Supply type MPS8P, MPS9 or RPSl provides the DC supply for all mixer .functions.
It is factory set for operation on the required AC supply as follows:
Europe 220/240v AC 50Hz
North America 110/120v AC 60Hz
Japan 1OOv 50/60Hz.
The supply voltage setting may be altered to suit local requirements if
required.
HEALTH AND SAFETY NOTICE -
The DC power unit is intended for connection with high voltage supply as stated
above. Interference with the internal assembly while connected to the supply
presents a risk of lethal electric shock. When service work is called for
first, DISCONNECT THE EQUIPMENT FROM THE AC SUPPLY. DO NOT RECONNECT UNTIL THE
WORK I S COHPLETE AND COVER I N PLACE.
Refer to the circuit diagram MPS8P, MPS9 or RPSl for reconnection details.
This work should be carried out by qualified service personnel to avoid risk of
damage to the equipment and operators.