ESL 2812X

The ESL X concept began in 2019 as part of an intensive review of the QUAD Electrostatic manufacturing facility—a suite dedicated solely to the production of QUAD ESL loudspeakers.

In a unique four-panel design but sharing the same treble and midrange panels as the flagship ESL 2912X, the more compact 2812X model delivers the signature QUAD sound—ultra‑transparent, highly detailed and effortlessly natural, with a midrange so lifelike that vocals and acoustic instruments appear in the room. Yet, all of this is provided in a smaller, lighter and less imposing format - at just 1070mm high.

ESL 2912X

The ESL X concept began in 2019 as part of an intensive review of the QUAD Electrostatic manufacturing facility—a suite dedicated solely to the production of QUAD ESL loudspeakers. 

The ESL 2912X is the flagship QUAD electrostatic loudspeaker. Featuring an expanded six-panel design for increased radiating area, higher sound pressure levels, dynamics and extension, the ESL 2912X delivers an immersive listening experience with deeper bass and rich textures, bringing even the most complex music to life. Built for the ultimate audiophile experience, it offers enhanced dynamic range, improved headroom, and a spacious soundstage.

The Beginning

The ESL-X concept began in 2019 as part of an intensive review of the QUAD Electrostatic manufacturing facility—a suite dedicated solely to the production of QUAD ESL loudspeakers. Under the expert leadership of Paul McConville, (a gentleman recognised as the world’s foremost authority in QUAD ESL engineering, with 40 years of experience), every aspect of the original design underwent a comprehensive evaluation and meticulous refinement.

This approach encompassed a thorough analysis of every process, step, technique, material, tool, and jig employed in the construction of a QUAD ESL, with the aim of improving the quality and precision of the electrostatic loudspeaker assembly.

Leveraging techniques such as advanced laser-precision metrology, QUAD undertook an exhaustive review of the foundation of the ESL design. Systematic enhancements were implemented in the processes of spraying, etching, tensioning, and assembly to ensure peak performance. Rigorous upgrades were applied to implement both passive and active components, enhancing the overall system integrity of the then-current ESL2912 and 2812 models.

The team of QUAD engineers considered the results of this lengthy and time-consuming self-appointed audit so significant that they deemed it worthy of a new model in the lineage of the ESL programme.

It is widely accepted that enhancing an ESL is fundamentally an exercise in building upon existing frameworks through incremental improvements rather than pursuing radical innovations. Consequently, QUAD did not require a complete overhaul of established methods. Nonetheless, these incremental advancements have now culminated in a significant transformation of the 2912 and 2812 models into what is now known as ESL X.

The Heart

One would be rightly forgiven for knowing of the ESL but not knowing how the ESL differs from typical loudspeakers. It us correct to begin with the fact that a QUAD ESL is not your typical loudspeaker! Unlike conventional speakers that use moving-coil drivers, the ESL employs a completely different principle: an electrostatic panel.

At the heart of a QUAD ESL are panels containing a diaphragm of fine Mylar film, ten times thinner than a human hair. The Mylar film is coated with a high resistance conductive material and suspended between two perforated metal plates called stators.

This unique diaphragm is incredibly light and therefore dynamically responsive. It is much lighter than any moving-coil driver cone and can therefore respond to signal transients with incredible speed and accuracy.

The Mylar diaphragm is charged up to a constant high voltage exceeding 5.2kV DC. An audio signal is applied across to the two stators to create an alternating electric field, which causes the charged electrostatic Mylar diaphragm to be alternativley pushed and pulled towards them. As a result, the diaphragm vibrates accurately in response to the music signal, and so produces the ultra-pure sound reproduction for which QUAD ESL loudspeakers are well-known.

Due to the diaphragm's lightweight nature and uniform drive across its entire surface, the sound it generates is exceptionally clean, responding accurately to musical transients, and exceptionally low in distortion, particularly intermodulation distortion. This is particularly evident in the midrange frequencies, where human hearing is most attuned.

“Point Source” Design

QUAD's ESL mid-high frequency panels are configured with a "concentric ring” electrode design, initially conceived for the ground-breaking ESL-63. Rather than allowing all sections of the diaphragm to move uniformly, the speaker is meticulously engineered to ensure that the audio signal seems to emanate from a singular point in space. This sophisticated arrangement produces an exceptionally precise stereo image, wherein instruments and vocal performances appear to hover within the auditory environment — akin to being enveloped by the musicians themselves. This point-source characteristic is expertly facilitated by an innovative delay line system, which supplies the outer rings of the stators with gradually delayed iterations of the audio signal.

High Voltage & Low Distortion

One critical factor influencing the ESL’s performance is its notably high operating voltage – approximately 5,250 volts. This elevated voltage substantially enhances the diaphragm's control and linearity, allowing it to move with precision in response to musical signals while significantly reducing distortion.

A QUAD ESL rigorously regulates this high voltage via a multiplier circuit that amplifies standard AC power, complemented by a protective circuit designed to prevent overdriving (excessive input power), thereby safeguarding the speaker from potential damage and distortion.

The Improvements

The intricate details of the manufacturing process contribute significantly to the refinements that are more than audible in the ESL X. For one, the time taken to manufacture a single QUAD ESL panel is extended, therefore the time frame for a full ESL loudspeaker system to be assembled is much more considered. The process is one of extreme care and attention to detail.

However, dig even deeper and QUAD engineers have taken things to the ‘X level’ with some intriguing further enhancements.

Specifications

Model ESL 2812X
Format Floor standing dipole with 3° fixed tilt
Type Multiple electrostatic drive membranes
Point Source Time Delay Progressive concentric rings
Chassis Structure Heavy duty composite aluminium / steel
Panel Elements 4
Maximum Output 2 N / m2 at 2m on axis
Sensitivity 1.5 mbar per volt referred to 1m
(86dB/2.83V rms equivalent)
Nominal Impedance 8 Ohms
Impedance Variation 4 - 15 Ohms
Maximum Input Continuous input voltage (rms):
10V Programme Peak for undistorted output: 40V
Permitted peak input: 55
Frequency Response 37Hz - 21kHz (-6dB)
33Hz - 23kHz (useable)
Directivity Index See Polar Diagrams
Distortion (100dB @ 1m) Above 1000Hz <0.15%
Above 100Hz <0.5%
Above 50Hz <1.0%
AC Input 220 - 240V, 100-120V
Power Fuse 100mA anti-surge, 200 - 240V
200mA anti-surge, 100 - 120V
Power Consumption 8W
Dimensions (H x W x D) 1070 x 690 x 380 (mm)
Net Weight 35kg

Specifications

Model ESL 2912X
Format loor standing dipole with 3° fixed tilt
Type Multiple electrostatic drive membranes
Point Source Time Delay Progressive concentric rings
Chassis Structure Heavy duty composite aluminium / steel
Panel Elements 6
Maximum Output 2 N / m2 at 2m on axis
Sensitivity 1.5 mbar per volt referred to 1m
(86dB/2.83V rms equivalent)
Nominal Impedance 8 Ohms
Impedance Variation 4 - 20 Ohms
Maximum Input Continuous input voltage (rms):
10V Programme Peak for undistorted output: 40V
Permitted peak input: 55V
Frequency Response 32Hz - 21kHz (-6dB)
28Hz - 23kHz (useable)
Directivity Index See Polar Diagrams
Distortion (100dB @ 1m) Above 1000Hz <0.15%
Above 100Hz <0.5%
Above 50Hz <1.0%
AC Input 220 - 240V, 100-120V
Power Fuse 100mA anti-surge, 200 - 240V
200mA anti-surge, 100 - 120V
Power Consumption 8W
Dimensions (H x W x D) 1470 x 690 x 380 (mm)
Net Weight 44kg