User Manual
Contents
1. AUDIO Lie P E16 Dual 31 Band Graphic Equaliser User Manual Copyright AUDIO 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 LA Audio 2004 2 1e 1 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 units 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 LA Audio 2004 3 3e yx e Contents Contents IMPORTANT SAFETY INSTRUCTIONS 5 Safety Information 6 1 Introduction 7 2 Installation 8 3 Operating Instructions 11 4 Ap2. 125 160 200 250 315 400 500 630 800 1k 1k25 1k6 2k 2k5 3k15 4k 5k 6K3 8k 10k 12k5 16k 20k Frequency accuracy Better than 5 96 of nominal Power Consumption 15 Volt Amps 115 220 VAC 50 60 Hz Weight 6 2 kg Dimensions mm 483 W x 230 D x 135 H Note OdBu is referenced to 0 775 V RMS Product information and specifications are subject to change without notice E amp OE LA Audio 2004 17 Kepka vei 6 Repairs and warranty 6 Repairs and warranty The EQ231G is a ruggedly constructed solid state unit that requires no preventative or routine maintenance The unit is constructed from the highest quality components which are selected to provide consistent long lasting performance Each unit is soak tested before despatch sifting out any rogue components before they leave the factory If correctly installed and operated the unit should give years of problem free operation Your EQ231G comes with a manufacturers warranty for one year from the date of despatch to the end user The warranty covers faults due to defective materials used in manufacture and faulty workmanship only During this warranty period LA Audio will repair or at its discretion replace any faulty unit provided it is returned carriage paid to an authorised LA Audio service centre We will not provide warranty repair if in our opinion the fault has resulted from unauthorised modification misuse negligence act of Go
3. can t cure every problem you re likely to encounter as an engineer Not only that but it s highly unlikely that you ll ever get a truly flat room response without calling in some builders Consequently a compromise must be struck between technical perfection sonic quality and very often the time taken to reach such a balance There are three things worth remembering when using your graphic EQ Avoid extreme settings unless for an effect they will most likely sound unnatural and may exacerbate balance problems Boost tends to sound more obvious to the ear so cut troublesome frequencies rather than boosting nice ones And finally remember that while the legend and calibration markings on your EQ231G are a useful guide they are just that a guide so be sure to trust your ears LA Audio 2004 16 5 Block Diagram amp Specifications 5 Block Diagram amp Specifications Block Diagram Balanced Input Output Gain A DI 15 Band 16 Band Bypass o L relay Peak Detector Specifications Frequency Response 20 Hz 20 kHz 1 1dB Signal to Noise Ratio 2 4dBu output 96dB Input impedance 20 kQ balanced Output impedance 100Q balanced Maximum Output Level 20dBu into 6000 Load 1 kHz 600 Ohms Load Total Harmonic Distortion 0 003 96 1kHz 4dBu Output Peak indicator Threshold 2 before clipping Centre frequencies 20 25 31 5 40 50 63 80 100
4. d or accident We accept liability to repair or replace your EQ231G as described above We do not accept any additional liability This warranty does not affect any legal rights you may have against the person who supplied this product it is additional to those rights LA Audio 2004 18
5. e amounts of cut and boost between 12 and 412 dB Each fader has a centre detent which allows you to quickly return it to its inactive OdB position 2 On switch allows the graphic filters to be taken out of circuit for comparison checks The adjacent LED s illuminate when the filters are IN circuit i e the graphic is functioning 3 Gain control adjusts gain at the input stage ranging from to 6dB The centre detent allows the unit to quickly be set to unity gain OdB 4 Peak LED This illuminates when the audio signal is within 2dB of clipping 18dBu at the output When this light is on there is a good chance that boost applied in the equaliser s filters will cause clipping To combat this reduce the input gain or the source s output level 5 High pass filter bypass switch allows the filter to be taken out of circuit This allows you to hear its effects when compared to the unfiltered sound and also to allow low frequencies to pass unaffected LA Audio 2004 11 Kepka 3 Operating Instructions contd 6 Filter Frequency The Hi pass filter has a 2nd order 12dB octave slope This control varies the turnover frequency from 16 to 160Hz This feature is particularly useful for protecting smaller loudspeakers which will not be able to reproduce very low frequencies or to reduce sub bass response in problematic rooms Should the power on the unit fail the unit automatically switches into bypass t
6. ected 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 20k and an output source impedance of 1000 200 with the transformer option fitted Its minimum following stage input impedance should equal or exceed 6000 LA Audio 2004 9 eF c 2 Installation conta 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 LA Audio 2004 10 O251G 3 Operating Instructions 3 Operating Instructions 3 1 Controls AUDIO EQ faders allow high resolution control over EQ gain at 31 ISO frequencies The frequency is indicated on the front panel as are th
7. he 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 LA Audio 2004 7 1e P k1 c quies 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 e The Unit EQ231G Graphic Equaliser e Power cord e Technical Manual this book If any of the above items are missing notify your supplier immediately 2 2 Operating Environment The un
8. he only tool at an engineer s disposal for improving GBF good microphone and speaker placement will often reduce the severity of EQ required to achieve sufficient gain g Graphic equalisers and dynamics In most instances it is good practice to place graphic equalisers before any dynamics processors such as compressors or limiters This is for two main reasons LA Audio 2004 15 Kepka E 4 Applications amp Techniques contd As the graphic equaliser is essentially a set of volume controls albeit frequency specific ones and dynamics units respond to volume it is best to cut or boost frequencies as desired before applying compression This ensures that the compressor or limiter only acts on frequencies that will be present at the output This is particularly important with low frequencies which are more likely to trigger the compressor or limiter Placing the graphic equaliser after dynamics could cause the compressor or limiter to react to frequencies not audible in the output creating unusual undulations in volume not associated with the program material The second reason for placing the graphic equaliser before dynamics occurs where the dynamics processor is being used to safeguard PA systems or digital recorders As the equaliser can create changes in volume both with EQ and input gain placing it after a limiter or compressor may cause increases in gain beyond safe limits 4 2 word of caution Sadly graphic EQs
9. hrough a fail safe relay circuit LA Audio 2004 12 Kerki 4 Applications amp Techniques 4 Applications amp Techniques A graphic equaliser may be used in numerous situations in many different ways It is impossible to document every implementation but we hope that the following examples will serve as a useful starting point 4 1 Some Examples a Room equalisation Every room whether it be in a studio theatre or home has a different acoustic response depending upon room dimensions fixtures and fittings and any other absorptive or reflective materials such as people tables or mixing consoles A graphic equaliser may be used to correct the room i e tailor the sound being reproduced so that the room appears to have an even or flat response throughout the audio frequency range thus providing a correct reproduction of the original sound improved intelligibility or helping to achieve loud volumes without an abrasive tonal character There are several ways of measuring a room s frequency response and these are usually all similar in technique although differing in hardware Using a Real time analyser inconsistencies in the system s frequency response can be detected and corrected with the graphic EQ Alternatively adjustments can be made by ear in response to trial system output such as CD playback It is important to remember that the ear responds differently to the frequency spectrum at different volumes
10. it is designed to operate between 0 and 50 32 122 F in an atmosphere of relative humidity up to 8096 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 LA Audio 2004 8 eF c 2 Installation conta 2 4 External connections TRANSFORMER BALANCED OUTPUT OUTPUT 2 INPUT 2 OUTPUT 1 INPUT 1 z QO QO z 2 QO Designed in the UK by LA Audio 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 MALE XLR FEMALE XLR 2 5 Impedance amp 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 conn
11. plications amp Techniques 13 5 Block Diagram amp Specifications 17 6 Repairs and Warranty 18 LA Audio 2004 4 Kep c User Manua IMPORTANT SAFETY INSTRUCTIONS IMPORTANT SAFETY INSTRUCTIONS CAUTION ATTENTION RISK OF ELECTRIC SHOCK RISQUE DE CHOC DO NOT OPEN NE PAS ENLEVER 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 LA Audio 2004 5 Kepri c ser Manva Safety Information Safety Information EARTH COVERS VOLTAGE FUSES MOISTURE HEAT LA Audio 2004 This unit is connected via its power cord to the mains safety earth NEVER OPERATE THE UNIT WITH THIS EARTH CONNECTION REMOVED DO NOT remove the covers Refer servicing to qualified personnel only 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 CHECK that the fuse fitted is of the correct type for the local mains voltage ALWAYS replace fuse with the correct type DO NOT expose the unit to rain or moisture If your EQ231G should become so exposed REMOVE the mains power immediately ALWAYS site the unit away from sources of heat including direct sunlight and ensure adequate ventilation around the unit Ke c 1 Introduction T
12. rce some interest in a stereo mix the graphic equaliser can be used to create variances in each side of the stereo signal thereby widening the sound Route the mono signal to both channels of the EQ231G and on each channel cut alternate frequencies by around 6dB With certain source material you may need to cut less at low frequencies to avoid an imbalance in the stereo image f Reduction of feedback In many auditoriums a graphic equaliser may be used to increase the gain before feedback GBF Essentially this involves cutting the frequencies associated with feedback to allow the system to be safely turned up The usual method is to set the graphic equaliser to a flat position i e all sliders at OdB and to increase the overall level in the auditorium until feedback commences Then reducing the level to just under the feedback point each frequency band in turn is boosted until the feedback frequencies have been identified Some practice will enable you to identify frequencies by ear to speed this adjustment By notching the offending bands down slightly the overall level may be increased This may be repeated until the overall gain reaches the required level It is worthwhile to note that if boosted sufficiently all frequencies will eventually feed back so a balance should be struck between gain and tonal integrity as extreme EQ adjustments can have a detrimental effect on audio quality Moreover the graphic equaliser is not t
13. seems counterintuitive boosting increases the compressor s sensitivity to these frequencies meaning that when they are most present the compressor will reduce the signal level thereby stopping the sibilance from reaching its full volume Because the EQ is inserted into the compressor s sidechain and not the signal path the EQ boost will be inaudible at the compressor s output d Elimination of proximity effect Cardioid microphones usually have a low frequency emphasis which in certain situations can present problems For example speech over a public address system can sound muffled and lose intelligibility if the microphone s response is particularly bassy The graphic equaliser can eliminate this by reducing or removing the unwanted frequency e Sound effects By using the graphic equaliser creatively a sound may be completely changed and effects obtained The most common sound effect created in this way is the telephone voice which can make even an expensive studio microphone sound like a telephone handset To create this effect first set the hi pass filter to its highest frequency 160Hz Then cut completely frequencies between 20 and 315Hz and those between LA Audio 2004 14 Kepka 4 Applications amp Techniques contd 4K and 20kHz The remaining band is roughly equivalent to the bandwidth of a phone line Another useful effect that can be created with a graphic EQ is a Comb Over To give a mono sou
14. so adjustments made by ear should be done at or around the intended operational volume While the graphic equaliser is a powerful tool it is worth noting that speaker positioning and balancing along with room adjustments such as using drapes will often prove to be more effective solutions to balance issues than heavy handed equalisation The graphic EQ is usually best for fine tuning system response b Sound shaping The graphic equaliser may be used to change an original sound to make it more pleasing to the ear or to blend it in with other audio signals without overlap This LA Audio 2004 13 Kepka 4 Applications amp Techniques contd technique is quite common in recording or production studios to tailor a sound for its eventual reproduction medium c Elimination of sibilance Sibilance is the noise which occurs when someone is speaking who either has a hissy voice or who is using words with the letter s in them e g sibilance This can become annoying to a listener and the graphic equaliser can be used to overcome this problem by either removing or reducing the offending frequency Graphic equalisers can also be used in conjunction with compressors to create a de esser which can respond to s sounds in a signal and reduce the level accordingly To create this effect insert the graphic EQ into the compressor s sidechain and boost the frequencies in which the sibilance occurs While this
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