Allen&Heath GR1 USER GUIDE

ALLEN&HEATH

GR1

24 Input 3 output Zone Mixer

USER GUIDE

(Installation)

PUBLICATION: AP2057

LIMITED ONE YEAR WARRANTY

This product has been manufactured in the UK by ALLEN & HEATH and is warranted to
be free from defects in materials or workmanship for a period of one year from the date of
purchase by the original owner.

To ensure the high level of performance and reliability for which this equipment has been
designed and manufactured please read this User Guide before use.

In the event of a failure notify and return the defective unit to ALLEN & HEATH or its
authorised agent as soon as possible for repair under warranty subject to the following
conditions:

CONDITIONS OF WARRANTY:

GR1

1. The equipment has been installed and operated in accordance with the instructions in the User Guide.

2. The equipment has not been subject to misuse either intended or accidental, neglect, or alteration
other than as described in the User Guide or Service Manual, or approved by ALLEN & HEATH.

3. Any necessary adjustment, alteration, or repair has been made by ALLEN & HEATH or its authorised
agent.

4. The defective unit is to be returned carriage prepaid to ALLEN & HEATH or its authorised agent with
proof of purchase.

5. Units to be returned should be packed to avoid transit damage.

These terms of warranty apply to UK sales. In other territories the terms may vary according to legal

requirements.

This product complies with the European Electromagnetic
Compatibility Directives 89/336/EEC & 92/31/EEC and the
European Low Voltage Directives 73/23/EEC & 93/68/EEC.

ALLEN & HEATH AGENT:

copyright © 2001 ALLEN & HEATH. All rights reserved Publication ............. AP2057 Issue 4

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U.K. FACTORY:

Allen & Heath Limited.
Kernick Industrial Estate,
Penryn.
Cornwall. TR10 9LU.

USER GUIDE

GR1

INTRODUCTION

The GR1 continues ALLEN & HEATH’s commitment to provide high quality audio equipment engineered to meet
the exacting requirements of today’s audio business. It brings you the latest in high performance technology and
offers the reassurance of over two decades of manufacture and customer support.

This user guide presents a quick reference to the function, application and installation of the GR1. For further
information on the basic principles of audio system installation and engineering please refer to one of the specialist
publications available from bookshops and audio equipment dealers.

Whilst we believe the information in this guide to be reliable we do not assume responsibility for inaccuracies. We
also reserve the right to make changes in the interest of further product development.

SERVICE AND TECHNICAL SUPPORT

Under normal conditions the GR1 does not require user maintenance or calibration. Internal links and preset controls
may be set to configure the unit during installation. Any service work required should be carried out by qualified
service personnel only.

We are able to offer further product support through our worldwide network of approved dealers and service agents.
To help us provide the most efficient service please would you keep a record of the unit serial number, and date and
place of purchase to be quoted in any communication regarding this product.

SAFETY WARNING !

Mains electricity is dangerous and can kill. Mains voltage is present within the GR1. Do not
remove the top cover with mains connected. Do not carry out any work within the unit while
it is powered except for installation calibration. High voltage components are insulated for
safety but should not be touched with power applied. The mains voltage setting is factory wired
and marked on the rear panel. Check that this matches your local mains supply. Check your
mains wiring and earthing before switching on.

DO NOT REMOVE THE MAINS EARTH CONNECTION!

The chassis is always connected to mains earth to ensure your safety. An internal link may
be set to remove audio 0V from mains earth (ground lifted) to avoid ground loop problems.

PRECAUTIONS.

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z AC POWER: Check the rear panel power supply label for the correct AC mains voltage setting.

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z CONNECTIONS: Use audio connectors and cables only for their intended purpose. Do not connect any

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source of AC or DC power to the console audio inputs and outputs. Do not connect the
output of power amplifiers directly to the console.

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z VENTILATION: Do not cover the unit in any way. Position the unit in a well ventilated location in the

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rack.

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z CLEANING: Avoid the use of chemicals, abrasives and solvents. The control panel is best cleaned

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with a soft brush and lint-free cloth.

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z LUBRICATION: The switches and potentiometers are lubricated for life. The use of electrical

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lubricants on these parts is not recommended.

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z DIRT, DUST, SMOKE and MOISTURE: Prevent damage to the moving parts, such as switches and

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potentiometers, and cosmetics by avoiding drinks spillage, tobacco ash and smoke, and
exposure to rain and condensation. Protect from excessive dirt, dust, heat and
vibration.

USER GUIDE

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GR1

INTERCONNECTIONS

Where possible use balanced connections for the inputs and outputs to minimise noise pick-up. Avoid running audio
cables near to mains or lighting cables or thyristor dimmer units, power supplies etc. These may cause audible hum
and buzz. The use of low impedance sources significantly reduces interference pick-up. Check the cables for correct
wiring to avoid problems with phase reversal and unreliable connection. The GR1 follows the convention for XLR
pin 2 and jack tip = signal hot (+). Always use balanced cables when connecting to phantom powered microphones.

MAKE SURE THAT +48V IS DISABLED USING THE INTERNAL LINK OPTIONS WHEN THE
CHANNEL INPUT XLRS ARE CONNECTED TO NON-PHANTOM POWERED OR LINE SOURCES.

If ground loops cause problems connect the cable screen at one end only as described below. Balanced outputs may
be connected to unbalanced inputs and vice versa by linking the signal cold (-) to 0V ground as follows:

 Balanced output to Balanced input - Connect cable screen at destination only using the output XLR pin 1

ground lift internal option link.

 Balanced output to Unbalanced input - Connect screen at source only. Link the -ve output to 0v at the output

connector.

 Unbalanced output to Balanced input - Connect cable screen at destination only using the output XLR pin

1 ground lift internal option link. Link the -ve input to 0V at the input connector.

ADJUSTING THE LEVELS

For best performance it is important that the audio signal levels are adjusted for “normal operating level”. 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.

For best results operate the unit with the output meters averaging ‘0’. This gives a nominal internal operating level
of -2dBu with ample headroom of +23dB to allow for the peaks. The corresponding XLR output level may be set
to one of three standard line levels: -10dBV (300mV low level), 0dBu (0.775V), +4dBu (high level). The 1/4" jack
line inputs may also be set to one of these three levels. The XLR MIC inputs may be set to match the connected source
by adjusting the rear panel gain trimmers. A 20dB attenuator pad may be enabled by setting the internal link options
for high output microphones or line level sources. The GR1 offers comprehensive signal level checking. Each
channel includes a PEAK indicator which shows signal peaks 5dB before clipping. Reduce the gain trim setting or
set the line inputs for a higher operating level if the indicator flashes continually. The signal quality and level of a
single channel may be checked by setting its level control fully on (clockwise) and the other channels off. Adjust
the gain for an average '0' reading on the output meter. If only the output PEAK indicators flash when several channels
feed the mix then reduce the overall channel levels.

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USER GUIDE

GR1

0 dBu = 0.775 Volts RMS
0 dBV = 1 Volt RMS
Line level options: +4dBu (high level), 0dBu, -10dBV (300mV low level)

INTERNAL OPERATING LEVEL: -2 dBu

INTERNAL HEADROOM: ........... +23 dB

MAX OUTPUTS: .......................... balanced +26 dBu 600 ohms max load

unbalanced +21 dBu 2kohms max load

METERS: ..................................... Individual bargraphs for L,R,M

-20VU (signal), 0VU, +16VU (peak)

PEAK LEDs: ................................ Turn on 5dB before clipping

DUCKING: ...... Signal override system.

Depth -6dB, -12dB 0r -18dB (internal option)
Release fast or slow (internal link)
Controlled by CH1,2,3 PRIORITY switches
Individual channel ducking disable (internal option)

COMPRESSOR/LIMITERS: ........ L,R,M individually controlled

Ratio 2:1, 4:1, 10:1 (internal option)
Threshold -30dB to +15dB (internal preset)

Width ............... 19.0" standard 19" rack ........ (540mm)

Height ............. 1.75" 1U rack space ............. (130mm)

Depth .............. 10.3" ......................................... (390mm)

weight ............. 10lbs ................... (4.5kg)

packed ............ 11lbs................... (5kg)

CONSTRUCTION: All metal chassis.
Standard 19" rack mount in 1U space.
Removable top cover for calibration and service access.
Internal power supply unit with low radiation torroidal trans­former.

SPECIFICATION

FREQUENCY RESPONSE: 20Hz to 30kHz +0/-1dB

DISTORTION: THD 0.04% Line in to mix out at 1kHz

CROSSTALK: . Channel shutoff better than -90 dB at 1kHz

Channel pan better than -75 dB at 1kHz
Interchannel better than -80 dB at 1kHz

NOISE: ............ 22Hz to 22kHz

MIC EIN -128 dB into 150 ohms
LINE pre-amp at 0dB -89 dBu
MIX noise -80 dBu

POWER REQUIREMENTS: 50/60Hz 25VA max
Mains voltage factory set for local requirements.

Mains input protection fuse ......... T315mA (220-240V)

T630mA (100-120V)

EMERGENCY DC POWER BACKUP:
External DC power supply or batteries.
+/-12 to 16VDC at 300mA
+12 to +48VDC microphone phantom power.

PHANTOM POWER: +48V DC
Global +48V ON switch, individual channel disable links.

CONNECTIONS

INPUTS:

MIC IN ............................ XLR ........................... pin 2 hot, 3 cold balanced ........ 2k ohms .......... variable -55 to -12dBu

....................................... LINE (pad selected) .. pin 2 hot, 3 cold balanced ........ 10k ohms ........ variable -35 to +8dBu

MONO LINE IN .............. 1/4" JACK .................. tip hot, ring cold balanced ........ 10k ohms ........ -10dBV, 0dBu, +4dBu

STEREO LINE IN .......... 1/4" JACKS ............... tip hot, ring cold balanced ........ 10k ohms ........ -10dBV, 0dBu, +4dBu

AUX IN (SYS-LINK) ....... 15way D female ........ unbalanced ............................... 10k ohms ........ -2dBu

ALARM IN (SYS-LINK) .. 15way D female ........ unbalanced ............................... 10k ohms ........ -2dBu

ALARM DC (SYS-LINK) 15way D female ........ opto-coupled ................ link to 0V to enable

REMOTE VCA DC IN .... 15way D male .................................................. +10V = level max, 0V = channel off

BACKUP DC IN ............. 15way D male ........... main supply +/-12 to +/-16V DC phantom power +12 to +48V DC

OUTPUTS:

L, R, M OUT .................. XLR ........................... pin 2 hot, 3 cold balanced ........ 50 ohms ..........-10dBV, 0dBu, +4dBu

DIRECT (SYS-LINK) ..... 15way D female ........ unbalanced ............................... 50 ohms .......... -2dBu

L, R, M (SYS-LINK) .......15way D female ........ unbalanced ............................... 50 ohms ..........-2dBu

ALARM OUT (SYS-LINK) 15way D female ...... unbalanced ............................... 50 ohms ..........-2dBu

ALARM DC (SYS-LINK) 15way D female ........ opto-coupled ............................. link to 0V to enable

HEADPHONES OUT ..... 1/4" jack .................... tip L, ring R .................. for stereo headphones 8 to 400 ohms

REMOTE VCA DC REF 15way D male .................................................. +10V, 0V reference voltage for remote VCA control

USER GUIDE

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GR1

INSTALLATION

The GR1 fits into a 1U space in a standard 19" rack system. Alternatively the unit may be mounted into a cabinet
or plinth, or simply used free standing.

Dimensions shown are case size in
millimeters. Allow extra space as nec­essary for the front controls (add
26mm) and for the rear connectors.

Mount the console using 2x M6 bolts
each side for maximum strength. These
should be provided by the supplier of
the rack kit.

The rack should allow a minimum side
to side opening of 445mm.

Provision should be provided for re­moval of the top cover for access to the
internal configuration links.

CONNECTING POWER

A 1.7 meter long captive power cord with fitted plug
connects the GR1 to mains power. Check that the rear
panel indicates the correct setting for the local mains
supply, and that the correct mains plug is fitted. The
unit may be supplied wired for 100, 110, 120, 220, or
240V.AC. The rear panel mains protection fuse is a
standard 20x5mm antisurge type T315mA for 220­240V or T630mA for 100-120V.AC.

PRECAUTION !

TO AVOID DAMAGE TO THE
INTERNAL ASSEMBLIES DO NOT
FIT SCREWS THROUGH SIDES
OR UNDERSIDE OF THE
CONSOLE. SECURE TO
EXTERNAL BRACKETS OR
FITTINGS THROUGH THE FRONT
PANEL RACK MOUNTING HOLES.

An emergency DC backup supply may be connected
so that the unit remains powered in the event of a
mains supply failure. This switches in automatically
when the internal DC supply voltages fall below the
level of the connected backup source. The front panel
ON indicator always shows when the unit is powered
either from mains or the backup supply.

DC BACKUP SUPPLIES

MAINS INPUT

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USER GUIDE