QUAD Speaker ESL 988 User Guide

ESLmanual Feb02 11/02/04 9:14 AM Page 1  
ESL-988 & ESL-989  
Electrostatic Loudspeakers  
Instruction Manual  
CONTENTS  
IMPORTANT NOTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2  
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3  
PACKING LIST AND UNPACKING THE EQUIPMENT . . . . . . . . . . . . . . . . . . . . . . 3  
GUARANTEE AND PRODUCT REGISTRATION . . . . . . . . . . . . . . . . . . . . . . . . . . 4  
SERVICE ARRANGEMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4  
ACCESSORIES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4  
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5  
CARE AND MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8  
CONNECTION PANEL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8  
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9  
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INTRODUCTION  
The Quad ESL loudspeaker is a full range electrostatic loudspeaker doublet. It  
consists of a very light electrically polarised diaphragm suspended between two sets  
of concentric annular electrodes. Signal is fed to the electrodes via sequential delay  
lines causing the diaphragm to move and the motion of the diaphragm produces a  
sound pressure pattern which is an exact replica of that from an ideal source placed  
some 30cm behind the plane of the loudspeaker diaphragm.  
WARNING: The Quad ESL loudspeaker has very high internal voltages. No  
attempt should be made to remove the protective grilles or the baseplate.  
Amplifiers which are not short circuit protected may be damaged by the  
protection circuits in this loudspeaker and should not be used with the Quad  
ESL.  
PACKING LIST AND UNPACKING THE EQUIPMENT  
The packaging contains the following items:  
The Quad ESL loudspeaker  
AC power lead 3m with 13A 3 pin plug (3A fuse), QUKES23  
(UK only)  
Instruction Manual  
Warranty Registration Form  
One set of packing materials comprising:  
One set of packing pieces  
One cardboard carton  
One polythene protective bag  
Consult the dealer from whom you purchased the equipment if any of these items is  
not present.  
The Quad ESL loudspeaker is completely assembled. To remove it from the packing,  
spread out the flaps from the open end of the cardboard carton and then invert the  
complete pack on to the floor, taking care not to let the contents slide out. Lift off the  
cardboard carton.  
Please retain the packing materials for future use or return them to your dealer. If  
you decide not to keep the packing, please dispose of it sensibly. The paper and  
plastics components are recoverable and may be taken to an appropriate recovery  
service.  
Please retain the user manual and the information concerning the date and place of  
purchase of this equipment for future reference.  
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GUARANTEE AND PRODUCT REGISTRATION  
Your Quad equipment is guaranteed against any defect in material and workmanship  
for one year from the date of purchase (proof of purchase required). We ask you to  
complete and return the enclosed Warranty Registration Form (UK). This will also  
enable us to keep you informed of future Quad products. Within the guarantee  
period, Quad will undertake replacement of defective parts free of charge provided  
that the failure was not caused by misuse, accident or negligence. Your statutory  
rights within the territory in which you purchased the equipment are not affected by  
this guarantee.  
Quad carries out a regular review of its products and reserves the right to adjust the  
specifications and performance from time to time.  
There are no user replaceable or serviceable parts inside this equipment.  
Unauthorised attempts to service or modify this product will invalidate the warranty.  
SERVICE ARRANGEMENTS  
If your Quad equipment requires servicing you should return it to the dealer from  
whom the equipment was purchased.  
If you are abroad and there is no suitable dealer in your area, please contact the  
distributor for the country in which it was purchased or Quad Electroacoustics Ltd.  
Equipment returned for service should use the original packing. You should enclose  
a brief note with your name and address and the reason for returning the equipment.  
ACCESSORIES  
Quad accessories are designed to match Quad equipment and to provide the best  
possible performance.  
Please contact your dealer or Quad direct for further information.  
Item  
Order No  
AC power lead 3m with Euro/13A 3 pin plug (3A fuse)  
AC power input connector Euro/straight  
QUKES23  
PSR0413  
Note: We do not supply loudspeaker cables terminated with  
4mm plugs nor the 4mm plugs themselves.  
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INSTALLATION  
The ESL loudspeaker requires an energising voltage for operation and therefore  
needs to be connected to an AC power supply.  
Checking the AC power supply  
The ESL loudspeaker is designed to operate on one range of AC power supply only,  
50/60 Hz. Either 200-240V or 100/120V. The correct operating voltage is clearly  
marked on the base. It may be changed from 220V to 110V operation or vice versa  
by a suitably qualified technician.  
Before connecting to the AC power supply check that the voltage range  
marked on the base corresponds with that of the supply.  
Connecting to the AC Power Supply (UK only)  
The ESL is supplied with an AC power lead with a moulded 13A 3 pin plug with 3A  
fuse. Do not cut off this plug or use it with its fuse cover removed. If however for any  
reason the plug has to be removed then it must be disposed of and under no  
circumstances plugged into a 13A socket outlet. A suitable plug can be fitted, as  
explained below:  
IMPORTANT: Fitting a mains plug.  
The wires in the mains lead are coloured:  
Brown = Live Blue = Neutral  
The Brown wire must be connected to the terminal marked L or coloured Red. The  
Blue wire must be connected to the terminal marked N or coloured Black. If the  
lead also has a Green/Yellow wire than this must be connected to the terminal  
marked E or coloured Green or Green/Yellow.  
Note: When a fused 13A plug is used a 5A fuse (ASTA approved to BS1362) will  
be adequate for a typical Quad system. For other types of plug, then fit a 5A fuse  
either in the plug, or adaptor, or at the distribution board. If in doubt consult a  
qualified electrician.  
Connecting to the AC Power Supply (other markets)  
The ESL should be supplied with a power lead terminated with the correct plug to  
match your local regulations. If the plug is an incorrect type or if you experience any  
problems with installation you should consult your dealer or local Quad distributor.  
Connection to the Amplifier  
Audio input is via binding posts. For runs up to 10m a cable with a rating of 6A  
(24/0.2mm) should be adequate. Longer runs may require heavier cable. The basic  
rule is that the total resistance of the cable should not exceed 5% of the loudspeaker  
impedance, ie 0.4 Ohms. Inductance should not exceed 1mH per metre and  
capacity can be ignored.  
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Each loudspeaker should be connected to its appropriate amplifier output so that the  
two pairs of wires are connected in the same way, to ensure that the speakers  
operate in phase.  
Switching On and Off  
The on/off switch has a rocker action; press the bottom to switch the ESL on and the  
top to switch it off. A red LED next to the on/off switch indicates that the speaker is  
on.  
Amplifier Requirements  
The ESL loudspeaker should be used with an amplifier of output capability between  
20V and 30V rms (40-100W into 8 Ohms). The impedance characteristic is  
essentially resistive and presents no problems to the amplifier. The ESL protection  
circuits limit the maximum input voltage to 40V and there is no volume benefit from  
using an amplifier with an output greater than 30V rms (100W into 8 Ohms).  
Amplifiers with an output capability in excess of 35V rms (150W into 8 Ohms  
approx) may be used but with caution – see Loudspeaker Protection.  
If the Quad 405/2 power amplifier is used, the amplifier voltage limiters should not  
be fitted.  
Loudspeaker Protection  
The ESL loudspeaker is fitted with a protection circuit, incorporating a special device  
called a multifuse, which prevents damage from excessive programme input signals.  
Should the loudspeaker be severely overdriven, for any length of time, the circuit will  
operate and effectively reduce the drive to the loudspeaker, causing a reduction in  
the volume level with some loss of quality. If this occurs, then the volume control of  
the amplifier should be turned down. After a delay of a few seconds to allow the  
circuit to reset, the volume can be increased, but only to a point below which the  
protection circuit initially functioned, otherwise the circuit may operate again.  
Persistently overdriving the loudspeaker will cause the multifuse to completely fail,  
necessitating its replacement by a qualified engineer.  
The above conditions are unlikely to occur in normal use or with amplifiers with a  
power output rating of less then 100W. Steady state signals in excess of 10V rms  
should not be fed to the loudspeaker.  
When the AC power to the loudspeaker is switched off or disconnected, the signal  
input protection circuit operates to prevent excessive signals being fed to the  
loudspeaker elements – though care should be taken to ensure that the  
loudspeakers are not driven for long periods (minutes) with no AC power applied.  
Positioning the Loudspeakers  
However good the loudspeaker, the final results will depend very largely on the  
acoustic characteristics of the listening room and the position of the loudspeakers in  
it. Do not be afraid to experiment with both position and orientation and make a point  
of trying some of the less obvious as well as the more obvious positions. The  
benefits obtained from the time spent doing this can be very rewarding. The subject  
of room acoustics is complex and beyond the scope of this manual. It is assumed  
that the loudspeakers will be used in a room with moderate reverberation, neither  
too bright nor over damped. Furnishings can alter the acoustic characteristics of the  
listening room, and here common sense is the best guide.  
The loudspeakers have constant directivity over a wide angle in both horizontal and  
vertical planes, so the response does not vary with the height of the listener’s ears  
from the floor.  
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When experimenting, it is preferable to use good recordings or works with which you  
are familiar in the concert hall or good quality speech.  
The ESL loudspeaker, being a dipole source, has considerable advantages over  
conventional loudspeakers in terms of room placement. No energy is radiated in the  
plane of the diaphragm and as a consequence, the respective axial room modes are  
discriminated against. Normally the loudspeaker is placed at an angle to both  
horizontal room axes and will excite both sets of horizontal axial modes, 3 dB less  
than with a conventional source and discriminate entirely against the vertical axial  
modes.  
The loudspeakers should be placed at least 60cm (2 ft) from the rear wall of the  
listening room and angled towards the listener and never in corners or alcoves or  
behind furniture. Because the ESL is a totally homogeneous sound source it will be  
found that they can be placed considerably further apart than normal, broadening  
the stereo sound stage. Close proximity to the side walls is not detrimental to  
performance. Simple geometry will show that if the ESL loudspeaker is placed at an  
angle to the side wall, there will be no audible reflection at the listening position.  
The ESLs are provided with optional floor spikes which screw into the four threaded  
holes in the baseplate. The heights of the individual spikes can be adjusted to  
ensure that the loudspeaker sits securely level on the floor.  
Take care to avoid the tips of the spikes which are quite sharp.  
ESL BASE AND SPIKES  
Programme Material  
A small note of caution. We believe that a pair of Quad ESL loudspeakers give a  
more realistic picture of an acoustic event than has been possible before, but only if  
the best source material is used. They are very revealing of faults in recording  
techniques and ownership of these loudspeakers will cause you to re-assess the  
virtues of your collection of recordings.  
Loudspeaker Phasing  
If there is any doubt about the way the loudspeakers are connected, their phasing  
can easily be checked by playing a mono source when the sound should appear to  
emanate from a point midway between the two loudspeakers. If this is indefinite,  
then the connections to one of the loudspeakers should be reversed. When correctly  
connected, the loudspeakers will give a definite centre sound source with more full  
bodied tenor and bass registers.  
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CARE AND MAINTENANCE  
The grille cloth may be cleaned with a soft brush or a hand held vacuum cleaner.  
They are protected against the ingress of dust etc. Periodic servicing at two year  
intervals is recommended to keep your speakers in pristine condition. Great care  
has gone into the selection of materials to ensure long term stability under a wide  
range of temperatures and humidity. In countries where the relative humidity  
regularly exceeds 90% it is recommended that the listening room be air conditioned  
for optimum performance.  
CONNECTION PANEL  
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ESL-988 SPECIFICATIONS  
All measurements made with a 230V AC supply.  
2
Maximum output  
Sensitivity  
2 N/m at 2m on axis  
1.5m bar per volt referred to 1m. (86 dB/2.83V rms)  
8 Ohms nominal  
Impedance  
Maximum  
Continuous input voltage (rms): 10V  
Programme peak for undistorted output: 40V  
Permitted peak input: 55V  
Directivity Index  
125 Hz  
500 Hz  
1 kHz  
5.0 dB  
6.4 dB  
7.2 dB  
10.6 dB  
8 kHz  
Axis band limits  
(low level)  
-6 dB at 35 Hz 3rd order  
-6 dB >20 kHz  
AC Input  
220-240V or 110-120V  
(double insulated)  
See rating details on base of unit  
Power fuse  
63 mA anti-surge, 200-240V  
100 mA anti-surge, 100-120V  
Power consumption  
Dimensions  
6W  
Height 94cm (including 10cm base) , width 67cm,  
depth 31.5cm (including terminals)approx.  
Weight  
Net 20.5 kg approx. Gross 23 kg approx.  
The right is reserved to alter performance and specification as required.  
This equipment complies with the radio interference requirements as laid down in  
EEC (European Economic Community) regulations.  
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ESL-989 SPECIFICATIONS  
All measurements made with a 230V AC supply.  
2
Maximum output  
Sensitivity  
2 N/m at 2m on axis  
1.5m bar per volt referred to 1m. (86 dB/2.83V rms)  
8 Ohms nominal  
Impedance  
Maximum  
Continuous input voltage (rms): 10V  
Programme peak for undistorted output: 40V  
Permitted peak input: 55V  
Directivity Index  
125 Hz  
500 Hz  
1 kHz  
5.0 dB  
6.4 dB  
7.2 dB  
10.6 dB  
8 kHz  
Axis band limits  
(low level)  
-6 dB at 30 Hz 3rd order  
-6 dB >20 kHz  
AC Input  
220-240V or 110-120V  
(double insulated)  
See rating details on base of unit  
Power fuse  
63 mA anti-surge, 200-240V  
100 mA anti-surge, 100-120V  
Power consumption  
Dimensions  
6W  
Height 133.5cm excluding feet (including 10cm  
base), width 67cm, depth 31.5cm including terminals  
approx.  
Weight  
Net 25.3 kg approx. Gross 28 kg approx.  
The right is reserved to alter performance and specification as required.  
This equipment complies with the radio interference requirements as laid down in  
EEC (European Economic Community) regulations.  
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ESLmanual Feb02 11/02/04 9:14 AM Page 1  
IAG House  
Sovereign Court  
Ermine Business Park  
Huntingdon  
Cambs  
PE29 6XU  
England  
Telephone: +44 (0) 1480 447700  
Facsimile: +44 (0) 1480 431767  
 
ESLmanual Feb02 11/02/04 9:14 AM Page 2  
Instruction Manual for Electrostatic Loudspeakers ESL 988 and ESL 989  
 

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