LA Audio EQ231G User manual

Dual 31 Band
Graphic Equaliser
User Manual

User Manual
Copyright
© LA Audio 2004 2
Copyright
Copyright 2004. All rights reserved.
The information in this document is subject to change without notice.
Audient plc makes no warranty of any kind with respect to the material in this
document and shall not be liable for errors contained herein or for incidental or
consequential damages related to the use of the material.
No part of this document may be reproduced without the prior written consent of
Audient plc.

User Manual
Thank you
© LA Audio 2004 3
Thank you for buying this product.
As can be found throughout the LA Audio range, your EQ231G has been designed and
manufactured to the highest possible standards of performance and reliability. To make
the most of your unit, we suggest that you take some time to acquaint yourself with the
contents of this manual before you get started.
The safety and installation information will help you set up your EQ231G with the
minimum of effort, while the operational guide describes the unit’s controls and
functions. The applications section gives useful hints on how to get the most out of
your unit in numerous situations, along with a couple of special effects with which you
can experiment.

User Manual
Contents
© LA Audio 2004 4
Contents
IMPORTANT SAFETY INSTRUCTIONS 5
Safety Information 6
1. Introduction 7
2. Installation 8
3. Operating Instructions 11
4. Applications & Techniques 13
5. Block Diagram & Specifications 17
6. Repairs and Warranty 18

User Manual
IMPORTANT SAFETY INSTRUCTIONS
© LA Audio 2004 5
IMPORTANT SAFETY INSTRUCTIONS
WARNING
THIS EQUIPMENT MUST BE
EARTHED. DO NOT EXPOSE TO
RAIN OR MOISTURE.
PLEASE READ ALL OF THE FOLLOWING
INSTRUCTIONS AND SAVE THEM FOR LATER
REFERENCE BEFORE ATTEMPTING TO
CONNECT YOUR UNIT TO THE AC POWER
SOURCE.
CAUTION ATTENTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN RISQUE DE CHOC
NE PAS ENLEVER

User Manual
Safety Information
© LA Audio 2004 6
Safety Information
EARTH This unit is connected via its power cord to the mains safety earth.
NEVER OPERATE THE UNIT WITH THIS EARTH CONNECTION
REMOVED.
COVERS DO NOT remove the covers. Refer servicing to qualified personnel
only.
VOLTAGE The EQ231G is set to operate only at the voltage shown on the outer
packaging. CHECK that the correct voltage is available before
connecting the AC mains supply.
FUSES CHECK that the fuse fitted is of the correct type for the local mains
voltage. ALWAYS replace fuse with the correct type.
MOISTURE DO NOT expose the unit to rain or moisture. If your EQ231G should
become so exposed REMOVE the mains power immediately.
HEAT ALWAYS site the unit away from sources of heat including direct
sunlight and ensure adequate ventilation around the unit.

User Manual
1. Introduction
© LA Audio 2004 7
1. Introduction
The EQ231G is a high quality dual 31-band 1/3 octave graphic equaliser with variable
12dB per octave Hi-pass filter. A delayed by-pass relay allows silent on/off switching
and also provides direct throughput when the unit is not powered. Centre detented,
45mm faders give up to 12dB of cut and boost at 31 ISO centre frequencies, covering
the entire audio spectrum (20 to 20KHz). Inputs and outputs are electronically
balanced. Each channel has a Peak Indicator illuminating for an equivalent output
signal of +18dBu.
Options
The unit can be augmented by parallel outputs offering a unique transformer distortion
cancellation circuit. This reduces distortion by an order of magnitude compared to
conventional designs and also provides galvanic isolation from connected devices for
the reduction of interference and hum.

User Manual
2. Installation
© LA Audio 2004 8
2. Installation
It is important to read this section before applying power to the unit.
2.1. Inspection and unpacking
The EQ231G is carefully packed at the factory in a carton which is designed to
withstand handling in transit.
However if transit damage is evident, DO NOT discard any of the packaging material
and notify the carrier and your dealer immediately.
The shipment should contain the following:
•The Unit, EQ231G Graphic Equaliser
•Power cord
•Technical Manual (this book)
If any of the above items are missing, notify your supplier immediately.
2.2. Operating Environment
The unit is designed to operate between 0 and +50C (32 - 122 F) in an
atmosphere of relative humidity up to 80%.
Should the unit be installed in an equipment rack, it is important to ensure that the
operating temperature inside the rack does not exceed the upper limit. This may be the
case where the rack contains power amplifiers and a cooling fan may be necessary in
such installations.
Although designed to withstand hum pick-up, it is VERY important that the unit is not
installed close to any strong electro-magnetic fields, such as power amplifiers.
2.3. Power Requirements
The voltage is pre-selected at the factory for the country of destination.
Fuse rating (Note: Fuse must be Slow – Blow T-Type)
115-125 Volts AC 50/60Hz T630mA
200-250 Volts AC 50/60Hz T315mA
(A 100 Volt special transformer is available for Japan).

User Manual
2. Installation (contd.)
© LA Audio 2004 9
2.4. External connections
The input and output connectors are wired on female and male XLRs respectively,
wired as follows:
Pin 1: Ground
Pin 2: Hot balanced signal
Pin 3: Cold balanced signal
2.5. Impedance & Termination
Most modern audio systems have cable runs of less than 100 meters; the devices
used usually have very low output impedance and relatively high input impedance.
This allows equipment to be connected in series without regard to "impedance
matching" (as long as the succeeding input is greater than the stated minimum for the
output it is connected to).
LA Audio products conform to this standard; therefore inputs and outputs are usually
indifferent to varying load or source impedance. The only exception to this rule is
where the unit is connected to a transmission line or some older vacuum-tube
equipment, which require proper impedance matching. This may be achieved by
shunting the correct matching resistor across the inputs or outputs. The EQ231G has
an input impedance of approximately 20kΩand an output source impedance of 100Ω,
(20Ωwith the transformer option fitted). Its minimum following stage input impedance
should equal or exceed 600Ω.

User Manual
2. Installation (contd.)
© LA Audio 2004 10
2.6. Signal levels
The unit is designed to accept an input signal level of up to +20dBu (dB referred to
0.775Vrms). Above this, clipping (distortion) of the signal will occur.
It should be noted that the filter amplifiers may be driven into distortion by excessive
boost in the unit, and where this is the case the input signal should be reduced
sufficiently to allow enough headroom.