Quad ESL-2905 Brochure

E l e c t r o s t a t i c L o u d s p e a k e r s

2 8 0 5 - 2 9 0 5

E S L

2

The

Quad ESL

Contemporary Electrostatic loudspeaker design

The new ESL-2805 and ESL-2905
loudspeakers are Quad’s latest
reference loudspeakers and like their
predecessors should be regarded
amongst the finest loudspeakers in
the world today. In areas such as
transparency, and lack of colouration,
they are without peer.

For those with a passion for music,
Quad ESLs can create a window on the
recording - every nuance and subtle
detail preserved and reproduced with
unerring accuracy.

Perhaps their most striking ability is
to create a holographic soundstage

- in which each voice and instrument
occupies a precise location and is
easily discernable within even complex
pieces.

To live with a Quad ESL is to

revolutionise your appreciation of
music. The pleasure of rediscovering
previously forgotten recordings and
enjoying the real beauty of the music
without colouration is often the start
of a love affair that lasts a lifetime.

It should be noted that whilst moving­coil loudspeakers are the norm, the
physical principles upon which they
work are fatally flawed - and not even
the latest advances in materials science
can address their shortcomings.

Quad alone has sought a different
path - to push the boundaries of
electrostatic technology to the point
where our ESLs are closer to the ideal
loudspeaker than any other.

Quad’s patented panel technology
results in a combination of the speed
and accuracy only possible from an

electrostatic loudspeaker; together
with the imaging and soundstaging
only possible from a theoretically ideal
point source; and the coherence and
continuity of a single drive unit.

With possibly the lowest distortion
of any loudspeaker, the ESL can be
enjoyed for hours on end without
fatigue; never adding or subtracting
from the original recording. Even at
low volume levels, they retain the full
detail and drama of the music.

In short, the Quad ESL technology is
unique in its clarity of sound, lack of
distortion, lack of interference and
continuity of response.

The ESL-2805 and ESL-2905
loudspeakers are the absolute pinnacle
of that technology. Engineered without
compromise, they are destined to
become modern classics.

4

Quad products stand alone in the hi-fi
world - renowned for their longevity;
quality of build; and consistently high
standard of performance. Our award­winning service department regularly
maintains products over 50 years in
age. Products which still bring their
owners immeasurable pleasure.

Quad products are designed with the
single aim of reproducing recorded
music as accurately as possible.
Simplicity of use and elegance of
design are purely consequential to the
application of sensible engineering
principles.

We have never sought to design
statement pieces or style icons, yet
almost every Quad product has
become regarded as such.

The

case for a
closer

approach...

A moving-coil speaker consists of a
wire coil suspended inside a magnet.
When an audio signal passes through
the coil a varying magnetic field is set
up which interacts with the magnet
and causes the coil to move back
and forth. A cone (or in the case of
high frequency speakers, a dome) is
attached to the coil, which compresses
and rarifies the air generating sound
waves.

Because large speaker drive-units
cannot reproduce high frequencies
well, and small ones cannot reproduce
low frequencies at all, practical hi­fi loudspeakers use two or more
drive- units connected via a ‘crossover
network’ which divides the frequencies
between the bass and the treble units.
Additionally, because even a large
bass- unit is very small compared to
the length of a low-frequency sound
wave, some form of box is needed to

prevent the waves from the back of
the cone cancelling the sound from
the front.

Moving-coil speakers have undeniable
advantages of cost and ease of
manufacture, and the cabinets can be
designed in many different shapes,
sizes and finish. However, the cabinet
is also a prime source of colouration
in the bass region. Additionally,
because the cone of a bass-unit is large
and heavy, it cannot start and stop
instantaneously. Some of the energy is
stored and releases over time, causing
smearing and ‘boom’ in the bass. In
the cross-over region, where not only
are the masses between the drive
units hugely dissimilar but so are
their dispersion patterns, this shows
up as unevenness of response and
a confused image, precisely in the
critical area where the ear is at its most
sensitive.

The moving-coil conundrum

6

‘Quads can deliver a sublime
performance. They still take
my breath away with their
profound revelation’

– Hi-Fi World , Noel Keywood

Although deeply flawed, their cost
and convenience advantages are such
that the overwhelming majority of
loudspeakers in today’s marketplace
are moving-coil, and at Quad we
manufacture some of the finest
examples of this genre. But, as a
counsel of perfection, we have to look
elsewhere.

Electrostatic speakers have long been
renowned for their superlative accuracy
and clarity in midrange and upper
frequencies but deficiencies in the bass
response and indifferent dispersion
characteristics have presented
difficulties which few manufacturers
have satisfactorily overcome. Many
hybrids have been attempted over
the years which combine moving-coil
speakers in the bass with electrostatics
handling the upper registers, but these
designs have not been successful.

An electrostatic speaker is a plastic
membrane which is coated with a
resistive material and suspended
between two perforated metal plates. A
polarising voltage of several thousand
volts is connected to the membrane

which at rest is suspended at an equal
distance between the two plates. When
an audio signal (also stepped up to a
few thousand volts by a matching
transformer) is applied to the metal
plates, the varying signal across the
plates attracts or repels the membrane,
and sound is reproduced. Because
the membrane is extremely light,
and driven across its entire surface,
transient response and freedom from
overhang is exemplary – quite unlike
moving-coil loudspeakers.

Of course, if it were as simple as this,
there would be many more electrostatic
loudspeakers. The challenge has
been to produce an electrostatic
loudspeaker with extended bass
response and a satisfactory dispersion.
Virtually none have succeeded. A
combination of acoustic problems and
extreme difficulties of manufacture
has resulted in a bare handful of true
full-range electrostatic loudspeakers
being available to the audiophile and
in this field Quad are pre-eminent.

Naturally produced sound emanates
from a point. Virtually no loudspeaker

comes close to achieving this – but the
patented Quad approach comes closest
of all.

The ESL is dipolar, producing front
and rear radiation. It has no box so
there is no colouration. Using large
panels ensures well-maintained bass
to well below 40Hz. The centre two
panels in each Quad ESL Loudspeaker
incorporate concentric rings on
the outer grid-plates around 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.
Imaging is pinpoint and there is no
‘sweet spot’ – all listeners receive a full
sonic presentation.

The result is a loudspeaker of
unsurpassed accuracy – the Quad
ESL is probably the lowest distortion
loudspeaker ever made – and with a
truly three dimensional sound stage
like no other.

8

Ask many of the most respected music
industry professionals in the world
what their speaker of choice is - the
answer is surprisingly common. The
Quad ESL opens a window on a
recording unlike any other speaker.

More hi-fi critics regard the Quad
ESL as an absolute reference for their
listening than any other loudspeaker.
They are regularly praised by leading
magazines, winning Golden Ears
from The Absolute Sound (USA); and
not just ‘Product of the Year’, but
also ‘Component of the Year’ from
Stereophile (USA); a Diapason D’Or
award (France); and a ‘System of the
Year’ award from Hi-Fi News magazine

- all of these within the last three years
alone.

For those involved in the recording
industry, their reputation is
unsurpassed. The transparency of
their reproduction has won them
many fans

For professional musicians and
studios, this is an invaluable asset.
It allows them to hear exactly what

has been recorded in perfect balance.
Because of their speed and neutrality,
they are unaffected by the overhang
and self-imposed character of moving­coil alternatives.

The Quad ESL has been used by Tony
Faulkner (shown left recording at
Henry Wood Hall in London) for many
years. He started using the ESL-63, the
ESL-63 Pro, and now uses a pair of
ESL-989s for his critical monitoring.

Tony has produced over a thousand
classical music recordings using the
Quad ESL because he knows he can
trust what he hears - that the very
essence of the performance is being
transferred.

Using the Quad ESLs for listening
at home, you can be sure that your
experience will mirror that of the
concert hall. You will hear detail and
depth never before noticed and each
listening session will draw you into the
music - transforming your appreciation
of every great performance and every
great recording.

The

original

sound...

Quad ESL

2905

The ESL-2905 is the larger of the two
models - it employs a grand total of
six electrostatic panels; the inner
two utilising the concentric rings
of anodes used to create the point
source image.

The ESL-2905 has a fifty-percent greater
diaphragm area than its smaller brother.
This increase allows for a markedly
improved bass response, and greatly
enhanced dynamics. The ESL-2905 is
therefore a good choice for those in
larger rooms, or those seeking more

drama on big pieces. However, this
speaker doesn’t compromise on detail
and subtlety - far from it. After all, it
is an electrostatic design and so has
considerably less inertia and overhang
than any moving-coil loudspeaker.

Construction is a combination of
tensioned aluminium extrusions
coupled to stainless steel support
structures, with a piano gloss wooden
trim. The substantial base construction
is finished with piano gloss side cheeks
and high-quality terminations.
Internally, the highest quality

components are used, including rare
c-core transformers and high-grade
audiophile capacitors. Three types of
protection system are used to ensure
the speakers are difficult to damage
when over-driven.

A rigid three-dimensional structural
support system, combined with
an overall speaker mass of 41.6kg
ensures the maximum transmission of
sound energy. This results in the most
dynamic and powerful Quad ESL ever
produced.

10

Pictured above: the sleek, tinted cover
for the speaker terminals, power
socket, and switch and dimmer for
the front display. The cover fits tightly
over the panel, and is held in place
with magnets.

12

The ESL-2805 is the smaller of the two
models and uses four panels rather
than six. The inner two panels of the
ESL-2805 again utilise the concentric
anode rings for point source imaging,
and the outer rings are again linear in
their response.

Whilst the absolute bass extension
and dynamic ability are less than
its larger brother (it lacks the two
supplementary panels of the 2905), the

ESL-2805 offers a sublime performance
nonetheless. In all other areas the
ESL-2805 will sound identical to the
ESL-2905 - particularly with regard to
imaging, detail resolution, and lack of
colouration. This is due to both
speakers sharing the same technology
and components.

The clarity of mid-range - for which
the Quads are most famed - is fully
in evidence; the sparkling detail and

transparency has long been the hallmark
of this series.
With a base weight of 34.8kg, together
with the rigid bracing, the ESL-2805
is an incredibly stable platform that is
ready for a lifetime’s work.

Afficionardos not requiring the
additional bass extension and weight
of the larger model will find the ESL­2805 to be your perfect transport for
the journey into audio nirvana.

Quad ESL

2805

Specifications

14

Model

ESL 2805 ESL 2905

Construction

Format

Type

Membrane

Panel Elements

Time Delay

Chassis Structure

Acoustic Performance

Maximum Output

Sensitivity

Impedance

Impedance Variation

Maximum Input

Frequency Response

Distortion (100dB at 1m)

Electrical

AC Input

Power Fuse

General

Power Consumption

Dimensions (HxWxD)

Weight

Floor-Standing Dipole with 3˚ Tilt Back

Full-range Elecrostatic

Ultra Low Mass (0.5g/m2) Tensioned Film

4

Progressive Concentric Rings

Heavy Duty Composite Aluminium / Steel

2N/m2 at 2m on axis

1.5 mbar per volt referred to 1m.

(86 dB/2.83V rms equivalent)

8 Ohms nominal

4 - 15 Ohms

Continuous input voltage (rms): 10V

Programme peak for undistorted output: 40V

Permitted peak input: 55V

37Hz - 21kHz (-6dB)

33Hz - 23kHz (useable)

Above 1000Hz 0.15%

Above 100Hz 0.5%

Above 50Hz . 1.0%

220-240V or 110-120V

63mA anti-surge, 200-240V

100mA anti-surge, 100-120V

6 Watts

1040mm x 695mm x 385mm

(add 25 - 55mm for feet)

Net 34.8kg

Floor-Standing Dipole with 3˚ Tilt Back

Full-range Elecrostatic

Ultra Low Mass (0.5g/m2) Tensioned Film

6

Progressive Concentric Rings

Heavy Duty Composite Aluminium / Steel

2N/m2 at 2m on axis

1.5 mbar per volt referred to 1m.

(86 dB/2.83V rms equivalent)

8 Ohms nominal

4 - 20 Ohms

Continuous input voltage (rms): 10V

Programme peak for undistorted output: 40V

Permitted peak input: 55V

32Hz - 21kHz (-6dB)

28Hz - 21kHz (useable)

Above 1000Hz 0.15%

Above 100Hz 0.5%

Above 50Hz . 1.0%

220-240V or 110-120V

63mA anti-surge, 200-240V

100mA anti-surge, 100-120V

6 Watts

1430mm x 695mm x 385mm

(add 25 - 55mm for feet)

Net 41.6kg

Full range

Quad Hi-Fi

Quad Classic

11L Bookshelf Loudspeaker

The Quad Hi-Fi range make up the largest portion of the Quad product line-up, with the
award winning L-series loudspeakers and a wide range of Quad’s famed electronics - to
supply all tastes in music and home cinema.

12L Bookshelf Loudspeaker

L - Subwoofer

L - Centre Channel

21L Floorstanding Loudspeaker

22L Floorstanding Loudspeaker

L-ite

ESL - 988

ESL - 989

99 CDP-2

99 CD-S

99 FM

99 Pre-Amplifier

99 Stereo

QC24

99 Monobloc Amplifier

909 Power Amplifier

Quad ll-Forty

Quad ll Classic

L-Series Surround package

Quad’s Classic range is built on products that Quad has had in development since its
beginning. The timeless range of valve amplifiers, and electrostatic speakers.

Qu. ESL .9. 200 5

Qua d Electro acous tics Ltd,

IAG House, S overeig n Court, Er mine Busi ness Pa rk,

Hun tingd on, Cambs

PE2 9 6XU

Tel :- 01480 447 700, Fax :- 0 1480 4317 67

www.quad-hifi.co.uk

The info rma tio n in this bro chu re is su bje ct to chang e wit hou t
not ice .Al l rig hts r ese rved © 200 4 Qua d
Qua d is a mem ber of the I ntern ati ona l Aud io Gr oup