ESL Series
ESL 2805
ESL 2905
USER MANUAL
Quad Electroacoustics Ltd.
IAG House, Sovereign Court,
Ermine Business Park,
Huntingdon PE29 6XU. England.
Tel : 0845 458 0011 / +44 (0) 1480 447700
Fax : +44 (0) 1480 431767
www.quad-hifi.co.uk
User Cautions
CAUTION!
RISK OF ELECTRIC SHOCK
DO NOT OPEN
TO REDUCE THE RISK OF ELECTRIC SHOCK
DO NOT REMOVE COVER (OR BACK)
NO USER-REMOVEABLE PARTS INSIDE
REFER SERVICING TO QUALIFIED PERSONNEL
ADVERTISSEMENT: RISQUE DE CHOC ELECTRIQUE-
NE PAS OUVRIR
IMPORTANT SAFETY INFORMATION
Read these instructions.
Keep these instructions.
Heed all warnings.
Follow all instructions.
Do not use this apparatus near water.
Clean only with dry cloth.
Do not block any ventilation openings.
Install in accordance with the manufacturer's instructions.
Do not install near any heat sources such as radiators, heat
registers, stoves, or other apparatus (including amplifiers) that
produce heat.
Do not defeat the safety purpose of the polarized or grounding
type plug. A polarized plug has two blades with one wider than
the other. A grounding type plug has two blades and a third
grounding prong. The wider blade or the third prong are
provided for your safety. If the provided plug does not fit into
your outlet, consult an electrician for replacement of the
obsolete outlet.
Protect the power cord from being walked on or pinched,
particularly at plugs, convenience receptacles, and the point
where they exit from the apparatus.
Use only attach ments/acc essorie s spec if ied by the
manufacturer.
Use only with a cart, stand, tripod, bracket, or
table specified by the manufacturer, or sold
with the apparatus. When a cart is used, use
caution when moving the cart/apparatus
combination to avoid injury from tip-over.
Unplug this apparatus during lightning storms or when unused
for long periods of time.
Refer all servicing to qualified service personnel. Servicing is
required when the apparatus has been damaged in any way,
such as power-supply cord or plug is damaged, liquid has been
spilled or objects have fallen into the apparatus, the
apparatus has been exposed to rain or moisture, does not
operate normally, or has been dropped.
Warning: To reduce the risk of fire or electrical shock, do not
expose this product to rain or moisture. The product must not
be exposed to dripping and splashing and no object filled with
liquids - such as a vase of flowers - should be placed on the
product.
No naked flame sources such as candles should be placed on
This symbol indicates that there are
important operating and maintenance
instructions in the literature
accompanying this unit.
This symbol indicates that dangerous
voltage constituting a risk of electric
shock is present within this unit.
the product.
Changes or modifications not expressly approved by
Caution:
the manufacturer could void the user's authority to operate this
device.
Warning: The mains power switch for this appliance is located on
the rear panel. To permit free access to this switch, the
apparatus must be located in an open area without any
obstructions.
NOTE: This equipment generates, uses and can radiate radio
frequency energy and, if not installed and used in accordance
with the instructions, may cause harmful interference to radio
communications. However, there is no guarantee that
interference will not occur in a particular installation. If this
equipment does cause harmful interference to radio or television
reception, which can be determined by turning the equipment off
and on, the user is encouraged to try to correct the interference
by one or more of the following measures:
! Reorient or relocate the receiving antenna.
! Increase the separation between the equipment and receiver.
! Connect the equipment into an outlet on a circuit different
from that to which the receiver is connected.
! Consult the dealer or an experienced radio/TV technician for
help.
IMPORTANT NOTICE TO UK USERS
The appliance cord is terminated with a UK approved mains plug
fitted with a A fuse. If
BSI approved BS1362 fuse rated at 3A must be used. If you need
to change the mains plug, remove the fuse and dispose of this
plug safely immediately after cutting it from the cord.
Connecting a Mains Plug
The wires in the mains lead are coloured in accordance with the
code: Blue: NEUTRAL, Brown: LIVE:
As these colours may not correspond to the coloured markings
identifying the terminals in your plug, proceed as follows:
The B L U E w i r e m u s t b e
connected to the terminal
marked with the letter N or
coloured BLUE or BLACK.
The BROWN wire must be
connected to the terminal
marked with the letter L or
coloured BROWN or RED.
3 the fuse needs to be replaced, an ASTA or
GREEN
&
YELLOW
(EARTH)
BLUE
(NEUTRAL)
FUSE
(3 A)
BROWN
(LIVE)
Warnings
The base stabiliser is a safety feature and must be securely attached to the product in accordance with the installation
instructions. Alternatively the speaker may be securely attached to the floor. No other form of operation is permissible.
Quad ESL loudspeakers have 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.
ESL SeriesESL Series
The Closest Approach
Quad - The Closest Approach by Ken Kessler
A 240 page hard-back, authoritative history with
commentaries and contributions from every corner
of the hi-fi industry. Technical chapters from Tim
De Paravicini and Gordon Hill and interviews with
Peter Walker, Ross Walker, Stan Curtis and Mike
Albinson. Along with a series of stunning new
photographs, fascinating historic documents and
reproductions of AES and other technical papers,
this is the definitive guide to the history and
achievements of Quad.
Available through all good book retailers or any of
our Dealers, from the Hi-Fi News Accessory Club,
the Hi-Fi Collective, or the Quad Service
Department
ISBN number 0-9545742-0-6
Introduction
Congratulations, you have become the owner of a pair of QUAD ESL
loudspeakers.
For 50 years Quad Electroacoustics has produced the world’s finest
loudspeakers, considered by many to be the most accurate and
neutral of all loudspeakers.
The ESL 2805 and 2905 represent the latest evolution of the
unique Quad electrostatic concept. Radically redesigned using the
most up to date materials and processes, these new evocations of
our design philosophy achieve levels of detail, clarity and
perspective that will be a revelation and source of continuing
delight to all music lovers.
The ESL loudspeaker is a doublet or dipole, which produces a
spherical sound field from a point source. All naturally created
sounds emanate from a point source and the ESL speaker concept
more nearly recreates this point source effect than any other
speaker currently available. Another key feature of our unique linear
motion design is very low distortion - your Quad ESLs are probably
the lowest distortion loudspeakers ever made - and this includes
the bass region where conventional speakers suffer from time
related delays and associated distortions.
The result is a loudspeaker of unsurpassed accuracy and one which has stood the test of time. Major
recording studios have ESLs amongst their reference monitoring loudspeakers and our loudspeakers
are consistently in demand by audiophiles who value the clear natural sound that is uniquely the
hallmark of all QUAD products.
Contents
CAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IFC
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
WHAT’S IN THE BOX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
UNPACKING THE EQUIPMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
POSITIONING THE LOUDSPEAKERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
CONNECTING THE LOUDSPEAKERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
FINAL ADJUSTMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
MAINTENANCE AND SERVICE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
QUALITY ASSURANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
ABOUT YOUR LOUDSPEAKER. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
MAKING AN ELECTROSTATIC LOUDSPEAKER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
THE CLOSEST APPROACH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
16
1
ESL SeriesESL Series
The Making of a Quad Electrostatic Loudspeaker
At Quad we pride ourselves on our long tradition of impeccable craftsmanship.
Here are just some of the stages an ESL goes through on its long journey into your home. At every
stage the most rigid standards of construction and inspection are applied, in clinically dust free
conditions, to ensure that every loudspeaker maintains its performance over time.
This rigorous attention to minutiae is what makes Quad unique. In a world of near-instant
obsolescence there is no junk-pile of Quad products - anywhere. Almost every product we have ever
made is still in daily use - somewhere; some are now well over fifty years old, and still giving
pleasure to their proud owners.
Stage 1
Steel Chassis
Stage 2
Piano Lacquered
Front Trim
Lower
Fixing Plate
Vertical Rails
Extruded
Aluminium
Unpacking and Assembly
These loudspeakers are heavy! It needs two people to lift and manoeuvre the loudspeakers into position.
DO NOT USE THE TENSIONING BRACE TO LIFT OR MANOEUVRE THE ESL OR YOU WILL DAMAGE THE LOUDSPEAKER!
WHEN MOVING THE LOUDSPEAKER HOLD IT BY THE SIDES OR THE SIDES AND BASE.
Always use the supplied cotton gloves when handling exposed surfaces.
Before you unpack the loudspeakers, ensure that you have a large and completely clear area of floor on which to work.
Remove or protect any fragile carpets, etc to avoid any damage.
Each ESL loudspeaker is packed in a cardboard outer carton and then packed on a pallet for safe transportation. The carton
has a lidded top and a tabbed seam down one long edge which is taped over.
Place the speaker upright, standing on its wooden pallet. Open the top first, and then open the tabbed seam all the way
down. Remove the top packing insert, and then remove the box containing the accessories. Remove the side packing pieces.
The loudspeaker may now be lifted out of the base packing.
The stabiliser block is strapped to one of the side packing pieces. Cut the
ties and remove the block.
Caution The block is heavy - exercise care.
The ESLs are provided with both spiked and standard feet which screw
into the threaded holes in the baseplate. The heights of individual feet can
be adjusted to ensure that the loudspeaker sits secure and level on the
floor. Determine whether you will be using the spiked or the standard feet.
Remember that spiked feet are only suitable for use with carpets as they
will damage wood and stone floors. When using spikes take care to avoid
the tips which are quite sharp.
Spikes and feet
Piano Lacquered
Side Trim
Stage 3
Aluminium Extruded
Side Rails
Base with
Electronics
Moulded
Grille Top
Steel Perforated
Fabricated Grille
Moulded
Lower Plate
Gently lay the loudspeaker down on its front. If the floor surface is hard place a soft cloth such as a towel under the speaker
first. Spin one collar onto each foot all the way down but do not tighten.
Attaching the front feet: Insert the two front feet in the threaded inserts on the base and thread them fully in but only hand-
tighten them at this stage. Refer to Illustration A below
Attaching the stabiliser and rear feet: It is essential that you attach the stabiliser as this is both a safety and operational
feature. (As an alternative the speaker may be attached to the floor - see Page 7)
First, attach the two clamps to the block using the provided screws and shakeproof washers. Line up the assembly with the
mounting holes in the base. Insert the feet through the support brackets and thread them into the base. Ensure that the feet
protrude below the clamps by an equal distance. When the speaker is operational the weight/clamp assembly should be
clear of the floor surface. Tighten both rear feet. Insert the collar locking bar into a hole in the clamping ring and tighten.
Progressively move the bar from hole to hole until the feet are fully locked in place. Refer to Illustration B below
Attaching the stabiliser and rear feet
B
Insert bar
and tighten
clamping ring
clockwise
A
14
3
ESL SeriesESL Series
Q is for Quality
Quad’s attention to detail and standards of quality management are
a byword in the hi-fi industry.
The finest C-core transformers are
used in the audio path providing
excellent linearity, wide bandwith
and very low phase shift.
Inspecting a panel
Choosing and Preparing Loudspeaker Cable
Specialist audio cable will usually offer better performance than general purpose 'bell' or 'zip' wire. Audio
cable is polarised, with two cores of different colours, or often, in the case of twin cable, a coloured tracer
or ridge along one wire to indicate polarity. Choose a cable of suitable diameter - cable that is too thin will
limit the dynamics of the sound and may impair the bass response. Split the twin cores to a depth of about
25mm. Carefully strip the insulation from each end, leaving about 7mm of bare wire. If the cable is
stranded, lightly twist to gather any loose strands.
Connecting Your Loudspeakers
Lift the cover off the connections panel box and store it safely until you have
finished connecting the speakers. The cover is magnetic for easy removal and
replacement.
Choose an equal length of twin core speaker cable for each channel, and prepare
the ends as described above. Unscrew each speaker terminal. Thread the bared
end of each cable through the hole in the bottom of the terminal post. Ensure that
there are no loose strands which may touch adjacent terminals. Retighten the
terminal securely.
Section of a panel - note the
concentric rings.
12
The delay line - the ingenious
solution that gives the ESL its
legendary point-source capability.
Connect the positive(+) terminal of the Left loudspeaker to the corresponding positive(+) amplifier terminal.
Connect the negative(-) terminals similarly. Repeat this procedure for the Right Channel. Note that the
positive(+) terminals are located on the right.
RIGHT
L
R
LEFT
INPUTINPUT
Phase
If there is any doubt about the way the loudspeakers are connected, their phasing can easily be checked by
playing a mono source - 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.
12
5
ESL SeriesESL Series
Horizontal Directivity
Quad ESL-2905
Horizontal Directivity
100Hz
30 0
27 0
24 0
250Hz
30 0
27 0
24 0
315Hz
30 0
27 0
24 0
500Hz
30 0
27 0
24 0
800Hz
30 0
27 0
0
33 0
-10
-20
-30
-40
-50
Clio
15 021 0
18 0
0
33 0
-10
-20
-30
-40
-50
Clio
18 0
0
33 0
-10
-20
-30
-40
-50
Clio
18 0
0
33 0
-10
-20
-30
-40
-50
Clio
18 0
0
33 0
-10
-20
-30
-40
-50
Clio
Final Adjustments
After you have finalised the position of the loudspeakers you should level the speaker by adjusting the feet.
30
60
12 0
30 0
27 0
90
24 0
2000Hz
1000Hz
30
60
12 0
15 021 0
30 0
27 0
90
24 0
3000Hz
30
60
12 0
15 021 0
30 0
27 0
90
24 0
4000Hz
30
60
12 0
15 021 0
30 0
27 0
90
24 0
5000Hz
30
60
30 0
27 0
90
0
33 0
21 0
33 0
30
-10
-20
-30
-40
-50
Clio
15 0
18 0
0
30
-10
-20
-30
-40
-50
Clio
6000Hz
60
90
12 0
30 0
27 0
24 0
8000Hz
60
90
30 0
27 0
0
33 0
30
-10
-20
-30
-40
-50
Clio
60
90
Tensioning the Speaker
This is the final adjustment. Tighten the tensioner clockwise. This pulls the
tensioning bar tight and makes the assembly rigid. As this significantly improves
performance at high power levels, do not omit this stage. The tensioner should
be periodically checked to ensure the speaker is fully rigid as temperature and
12 0
21 0
33 0
15 0
18 0
0
30
-10
-20
-30
-40
-50
Clio
60
90
humidity variations may cause the tension to slacken slightly.
After all the adjustments have been completed, gently drop the connection panel
cover into place.
Mounting Alternatives
After finalising the position of the loudspeakers, for added safety and to improve the coupling with the floor
12 0
21 0
33 0
21 0
33 0
15 0
18 0
0
30
-10
-20
-30
-40
-50
Clio
18 0
0
-10
-20
-30
-40
-50
Clio
60
12 0
15 0
30
60
24 0
21 0
18 0
10000Hz
30 0
90
27 0
24 0
15000Hz
30 0
90
27 0
0
33 0
-10
-20
-30
-40
-50
Clio
21 0
18 0
0
33 0
-10
-20
-30
-40
-50
Clio
12 0
15 0
30
60
90
12 0
15 0
30
60
90
still further, the loudspeakers may be screwed to the floor.
Disconnect each loudspeaker from the mains supply and the amplifier. Mark the position of all four feet
with tape or chalk. Place a soft towel or similar item on the floor and lay the loudspeaker carefully on its
front. Remove the stabilising block. Undo the collars on the rear feet half a turn to loosen the bracket and
rotate each bracket so that it is facing the rear of the loudspeaker. Retighten the collars.
Floor Spikes on Carpet: The pointed foot should only be used with carpets. Adjust the rear feet so that the
tapered section of the spike protrudes below the bottom of the bracket. When you screw the bracket into
the floor through the carpet, the bracket will rest on the carpet thus avoiding damage to the carpet surface.
CARPET
FLOOR
12 0
21 0
33 0
15 0
18 0
0
30
-10
-20
-30
-40
-50
Clio
60
90
24 0
21 0
18 0
12 0
15 0
Standard Feet: The bottom of the floor clamp should be
marginally above the bottom of the foot. Make sure the
feet rest firmly on the floor and that the bracket is not
supporting the weight of the loudspeaker.
FLOOR
24 0
18 0
12 0
15 021 0
24 0
21 0
18 0
12 0
15 0
Stand the speaker upright. Carefully manoeuver the loudspeaker so that the feet are standing on their
marked locations. Now screw the clamps to the floor using suitable screws and fixings.
Check that both front feet support the speaker. Reconnect both loudspeakers to the amplifier and the
mains supply.
10
7
ESL SeriesESL Series
Specifications
SPECIFICATION
CONSTRUCTION
Format: Floor Standing Dipole With 3º Fixed Tilt Back
Type: Multiple Electrostatic Drive Membranes
Membrane: Ultra Low Mass ( 0.5gm ) Tensioned Film
Panel Elements: 4 6
Time Delay: Progressive Concentric Rings
Chassis Structure: Heavy Duty Composite Aluminium / Steel
ACOUSTIC PERFORMANCE
Maximum output: 2 N/m at 2m on axis
Sensitivity: 1.5 mbar per volt referred to 1m.
Impedance: 8 Ohms nominal
Impedance Variation: 4 - 15 Ohms 4 - 20 Ohms
Maximum Input: Continuous input voltage (rms): 10V
Frequency Response: 37Hz - 21KHz (-6dB) 32Hz - 21KHz (-6dB)
Directivity Index: See Polar Diagrams
Distortion: (100dB at 1 metre)
ELECTRICAL
AC Input: 220-240V or 110-120V
Power fuse: 63 mA anti-surge, 200-240V
GENERAL
Power consumption: 6W
Dimensions: (HxWxD) 1040mm x 695mm x 385mm 1430mm x 695mm x 385mm
Weight: Net 34.8 kg Net 41.6 kg
All measurements made with a 230V AC supply
The right is reserved to alter performance and specification as required
This equipment complies with the radio interference requirements as laid down in EU regulations
ESL 2805 ESL 2905
2
2
(86 dB/2.83V rms equivalent)
Programme peak for undistorted output: 40V
Permitted peak input: 55V
33Hz - 23KHz (useable) 28Hz - 21KHz (useable)
Above 1000Hz 0.15% Above 1000Hz 0.15%
Above 100Hz 0.5% Above 100Hz 0.5%
Above 50Hz 1.0% Above 50Hz 1.0%
100 mA anti-surge, 100-120V
(add 25 - 55mm for feet) (add 25 - 55mm for feet)
Horizontal Directivity
These are actual measurements taken from our reference samples. The directivity pattern is exceptionally well maintained
from very low frequencies to well beyond audibility. This consistent pattern ensures smooth spatial response with no
peaks and troughs. In addition, the virtually massless diaphragms of the ESL ensure near-instantaneous starting and
stopping with an almost total absence of hysteresis, providing lightning fast transients and phenomenal bass response.
Quad ESL 2805
Horizontal Directivity
100Hz
250Hz
315Hz
500Hz
800Hz
0
33 0
30 0
27 0
24 0
33 0
30 0
27 0
24 0
33 0
30 0
27 0
24 0
33 0
30 0
27 0
24 0
33 0
30 0
27 0
30
-10
-20
-30
-40
-50
Clio
15 021 0
18 0
0
30
-10
-20
-30
-40
-50
Clio
15 021 0
18 0
0
30
-10
-20
-30
-40
-50
Clio
15 021 0
18 0
0
30
-10
-20
-30
-40
-50
Clio
15 021 0
18 0
0
30
-10
-20
-30
-40
-50
Clio
1000Hzz
60
12 0
30 0
27 0
90
24 0
2000Hz
60
12 0
30 0
27 0
90
24 0
3000Hz
60
12 0
30 0
27 0
90
24 0
4000Hz
60
12 0
30 0
27 0
90
24 0
5000Hz
60
30 0
27 0
90
0
33 0
21 0
33 0
21 0
33 0
21 0
33 0
21 0
33 0
30
-10
-20
-30
-40
-50
Clio
15 0
18 0
0
30
-10
-20
-30
-40
-50
Clio
15 0
18 0
0
30
-10
-20
-30
-40
-50
Clio
15 0
18 0
0
30
-10
-20
-30
-40
-50
Clio
15 0
18 0
0
30
-10
-20
-30
-40
-50
Clio
6000Hz
60
90
12 0
30 0
27 0
24 0
8000Hz
60
90
12 0
30 0
27 0
24 0
10000Hz
60
90
12 0
30 0
27 0
24 0
15000Hz
60
90
12 0
60
90
30 0
27 0
24 0
0
33 0
21 0
33 0
21 0
33 0
21 0
33 0
21 0
30
-10
-20
-30
-40
-50
Clio
18 0
0
-10
-20
-30
-40
-50
Clio
18 0
0
-10
-20
-30
-40
-50
Clio
18 0
0
-10
-20
-30
-40
-50
Clio
18 0
60
90
12 0
15 0
30
60
90
12 0
15 0
30
60
90
12 0
15 0
30
60
90
12 0
15 0
24 0
18 0
12 0
15 021 0
8
24 0
21 0
18 0
9
12 0
15 0
ESL SeriesESL Series
Operation
The ESL loudspeaker requires an energising voltage for operation and needs to be connected to an AC power supply.
Before connecting to the AC power supply check that the voltage range marked on the base corresponds with that of the
supply.
The on/off switch has a rocker action; press the bottom to switch the ESL on and the top to switch it off. An LED next to
the on/off switch indicates that the speaker is on. As supplied, the Quad logo on the speaker bezel is switched off. To
switch it on, turn the Front Light Control clockwise so that it clicks. The intensity of illumination may also be altered via
this control.
AC220-240v/50Hz
FUSE 63mA
6VA
On/Off Switch
Mains Input
OFF
ON
Front Light
Control
Mains
Indicator
INPUT
Care and Cleaning
SWITCH THE LOUDSPEAKERS OFF AND DISCONNECT THEM FROM THE MAINS BEFORE CLEANING.
The surfaces of the speaker should be wiped occasionally with a barely damp soft cloth. The grille cloth may be cleaned
with a soft brush or a hand held vacuum cleaner. The loudspeakers are protected against the ingress of dust etc. Regular
cleaning 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.
Servicing
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
Warranty
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.
Amplifier Requirements
The ESL loudspeaker should be used with an amplifier of output capability of 20V - 30V rms (40-100W into 8 Ohms).
The impedance characteristic presents no problems to the amplifier. Protection circuits limit the maximum input voltage
to 40V and there is no 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 such as pure sine waves 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. Even so, care should be taken to ensure that the
loudspeakers are not driven for long periods (minutes) with no AC power applied.
There are no user replaceable or serviceable parts inside this equipment. Unauthorised attempts to service or modify
this product will invalidate the warranty.
Service Agents Worldwide
U.K.
QUAD Electroacoustics Ltd., IAG House, Sovereign Court, Ermine Business Park, Huntingdon, Cambs PE29 6XU, England
Tel:+44 (0)1480 447700 Fax:+44 (0)1480 431767 www.quad-hifi.co.uk
USA
IAG America, Inc., 15 Walpole Park South, Walpole, MA 02081
Tel: +1 508 850 3950 Fax: +1 508 850 3905 www.iagamerica.com
AUSTRALIA
IAG Australia Pty. Ltd., 30/398 The Boulevarde, Kirrawee, NSW 2234, Australia.
Tel: +612 9540 2469 Fax: +612 9540 2855 Email: iagaus@bigpond.com.
CANADA
Korbon Trading Ltd., 6800 Kitimat Road, Units 19-20, Mississauga, Ontario
Tel: +1 905 567 1920 Fax: +1 905-567-1929 www.korbon.com
GERMANY
IAG Germany Ltd., IAG(Deutschland) GmbH Johann-Georg-Halske-Str. 11-41352 Korschenbroich.
Tel: +49(0)2161-61783-0 Fax: +49(0)2161-61783-50 Email: info@wharfedale.de
HONG KONG
Sanecore Limited., Room 2607, 26/F., ING Tower, 308 Des Voeux Road, C., Sheung Wan, Hong Kong.
Tel: +852 2581 9178 Fax: +852 2581 9717 Email: info@sanecore.com
R.O.C.
Sea Power Co. Ltd., 4/F, No.5 Wu Chung 2th Road, WuKu Industrial Area, Taipei County, Taiwan, R.O.C.
Tel: +886-2-2298-2688 Fax: +886-2-2298-2396 Email: haikuo@ms23.hinet.net
6
11
ESL SeriesESL Series
Positioning the Loudspeakers
However good the loudspeaker, the final results will depend 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.
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. This will excite both sets of
horizontal axial modes although this excitation will be 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. Placing the ESLs too close to rear walls will adversely affect their
dispersion characteristics. It is not advisable to operate the loudspeakers across corners, in
alcoves or behind furniture. Because ESLs are a 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 is placed at an angle to the side wall, there will be no audible reflection at the listening
position.
5
º
º
-
0
2
>50mm
About your ESL loudspeaker
Your ESL loudspeaker consists of a vertical multiple element or membrane
line array mounted on top of an electronic matching circuit contained within
the base structure.
In order to achieve the efficiency needed for full range audio operation a
large moving diaphragm is required. This is achieved using several
individual elements connected within a rigid frame. The smaller ESL 2805
features 4 elements, whilst the ESL 2905 features 6 elements.
The membrane (diaphragm) in each element is a highly charged ultra thin,
immensely strong plastic film, pre- stretched and fixed to an open frame. To
achieve constant-charge conditions this membrane is coated with a
specially formulated high-resistivity coating. This membrane is one tenth of
the thickness of a human hair and virtually massless compared to other
types of loudspeaker. Again, unlike a conventional loudspeaker, the
membrane when energised is driven simultaneously over its entire surface.
This combination results in an extremely fast transient response - the
diaphragm responds to alternating motion without introducing any time lag -
completely unlike the sluggish, high-mass conventional loudspeaker.
The ESL is a dipole - the sound radiates equally from both sides of the
diaphragm.
The centre two panels in each loudspeaker incorporate divisions in the
diaphragm. These can be seen as concentric rings on the outer grid plates
surrounding the diaphragm. Each ring is subjected to a minuscule time
delay and attenuated by its own individual circuit, the sound spreading
gradually from the centre outwards through each successive ring. This
carefully structured delay line creates a near-perfect spherical wave front
originating from an apparent point 400mm behind the loudspeaker. In the
vertical plane the elements are line arrayed, the mid and high frequency
elements being centrally sited to preserve the spherical shape.
In order to eliminate even the slightest cancellation effect caused by
diaphragm motion interacting with the speaker frame, the base is weighted
at the rear with a steel mass spaced away from the cabinet base. An
adjustable strut further increases rigidity and improves cabinet coupling.
The result is a structure of immense stability and rigidity.
The ultimate design goal of any high-fidelity loudspeaker is faithfully to
preserve the illusion of a naturally occurring sonic event. That this is fully
realised by the Quad ESL in practice can be seen from the loudspeakers’
polar plots reproduced on Pages 9 and 10. These loudspeakers give a truly
three dimensional sound stage like no other.
1: A perfect point source produces
a spherical wave pattern
2: Air particle movement at a
plane some distance from the
source
3: An identical movement in the
ESL membrane produces an
identical wave front
Electrodes
Input
Transformer
4: The membrane carries a
constant charge. The charge on
the electrodes fluctuates
according to the music signal
Input
High Resistivity
Membrane
Polarising
Voltage
2.5-5m
4
>600mm
5: The music signal is fed first to
the centre section, then to each
ring in turn via delay coils
13
What’s in the Box?
ESL SeriesESL Series
The packaging contains the following items:
# The Quad ESL loudspeaker
# AC power lead 3m with a mains connector suitable for your area
# This Instruction Manual
# Warranty Registration Form
# A set of four spiked feet
# A set of four standard feet
# Four clamping collars
# One collar locking bar
# Base Stabiliser Weight
# Two securing brackets, screws and shakeproof washers.
# Two pairs of cotton gloves
Consult the dealer from whom you purchased the equipment if any of these items is not
present.
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 timber, 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. In the unlikely event that you pass this
product on to a third party, please include all the accessories and this instruction manual.
Stage 4
Anti-Dust
Cover
Piano Lacquered
Top Trim
Stage 5
2 Side Trims:
veneered, lacquered
and steel braced
Anti-Dust
Cover
Stage 6
Rigid
Tensioning
Brace
Steel
Plinth Cover
Terminal
Panel
Stage 7
Acoustically
Transparent
Cloth: front and rear
Tensioner
Drive
Circuitry
2
15
READING ORDER
PRINTING ORDER
COVER
COVER
CAUTIONS
WHATS IN THE BOX
POSITIONING
OPERATION
SPECS
IFC
2
4
6
8
1
3
5
7
9
INTRO/CONTENTS
UNPACKING
CONNECTING
FINAL ADJUSTMENTS
POLAR -1
CAUTIONS
QUAD BOOK
MAKING AN ELS-1
ABOUT YOUR ELS
POLAR -2
INSIDE
COVER
16
14
12
10
1
3
5
7
INTRO/CONTENTS
UNPACKING
CONNECTING
FINAL ADJUSTMENTS
POLAR -2
ABOUT YOUR ELS
MAKING AN ELS-1
QUAD BOOK
10
12
14
16
11
13
15
IBC
SERVICE AND WARRANTY
ADDRESSES
HOW IT WORKS
MAKING AN ELS-2
SPECS
OPERATION
POSITIONING
WHATS IN THE BOX
8
6
4
2
9
11
13
15
POLAR -1
SERVICE AND WARRANTY
ADDRESSES
HOW IT WORKS
MAKING AN ELS-2
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