The latest version of highly acclaimed ESL series, the ESL-2812 and 2912 are a celebration of a classic. Using the signature mylar diaphraghm, yet while re-evaluating all circuitry and components, the result is an authentic ESL experience - incredible full range accuracy and startling realism.
The Original, Most Iconic Loudspeaker
The ESL was the world’s first full range, ultra low distortion electrostatic loudspeaker and set standards for accuracy and fidelity in loudspeakers that remains unsurpassed to this day. A labour of love for founder Peter Walker, the ESL-57, as it came later to be known, is still revered by audiophiles all over the world.
The ESL is the complete embodiment of our company ethos “The Closest Approach To The Original Sound” and the ESL series reproduces a sound which is indistinguishable between hearing a pair of loudspeakers and having the performers right there in front of you. We are equally proud of our latest models, the ESL-2912 and ESL-2812 which have built on the original concept with improved efficiency.
The ESL-57 was also recently voted into Stuff Magazines chart of “The Top 100 Best Gadgets Ever”, being the best gadget for 1957.
Quality Control, For A Quality Sound
Pictured is an image from the late '50s of the final hand-finished assembly process after mylar stretching and cabinet construction.
Although manufacturing is achieved today on a much larger scale, the same approach to quality has never faltered. Many processes from circuit board assembly to piano gloss finishing use hand-finished techniques, with quality control procedures each step of the way.
Matching wood-veneered panels now adorn the top of the speakers and the sides of their substantial bases, formed from high-density plywood to further damp frame resonances and smothered in layers of piano lacquer. The shielding cover on the base is embossed with the Quad logo and all typography is now in gold laquer paint; the gold-plated cable terminals, corresponding PCBs and wiring have also been enhanced.
Why is the Quad ESL more accurate than any other loudspeaker?
Why the Quad ESL is able to do so is simply because of the moving part of the Quad ESL, the electrostatic diaphragm, which is a thin layer of stretched Mylar, ten times thinner than a human hair and so light that it approaches the mass of air to which it is coupled.
As a result there is no inertia inherent in the moving parts of the Quad ESL and the diaphragm is able to respond to musical detail and transients with unparalleled precision. The Quad ESL is one of the few speakers that can reproduce a 1kHz squarewave precisely and cleanly.
To achieve this astonishing feat the Quad ESL uses a system of highly charged stator elements on either side of the diaphragm which is coupled to a power supply that produces the neccessary 5kV of EHT (Extra High Tension) charge that controls the diaphragm.
How this extremely high voltage charge is produced and consistently maintained at the diaphraghm to stator interface is the key to the low distortion of the ESL.
Attention To Detail
Attention is paid on the power supply section, especially the stators. Each stator consists of a layer of copper on a thin, insulating backing, which is punched with a pattern of holes to make it transparent to sound. The copper is etched to provide a conductive pattern which is necessary to re-create the point source attributes of the Quad ESL. After etching, the copper needs to be insulated from the diaphragm, which will lie in close proximity to it.
In the 2812 and 2912, the insulation is created by a triple coating utilizing a specific spraying technique that is perfected to avoid degradation of the EHT charge under high dynamic conditions, where the diaphragm comes into close contact with the stator. These latest versions of the Quad ESL can thus play louder and handle more power than the previous models.
Quad's engineers have evaluated the power supply for the EHT voltage. Creepage, the possibility of charge flowing across the PCB between components, was eliminated by a new PCB layout which ensured optimum insulation and distance between contacts and a symmetrical layout for the components. This new layout also provides a means to superior cable dressing and again reducing the effects of creepage, particularly in high humidity environments.
Component changes have also been introduced, including such audiophile components as Vishay resistors and Murata capacitors. Although not in the signal path, as such, these components have a direct effect on the consistency of the EHT supply and signal purity is created in the reproduction of music as a result.
Finally, to match the improved dynamics of the ESL elements, the mechanical aspects of the speakers have been enhanced. A new net cloth has been chosen to cover the elements which allows superior audio transparency as well as improving the appearance of the speakers. The underlying grille support has revised strengthening ribs to reduce the possibility of resonance as well as to ensure the grille cloth remains under tension without stretch marks.
To distinguish the 2812 and 2912 from their predecessors, there are cosmetic changes too. These changes improve the look of the speakers in domestic surroundings. As well as the new grille cloth, there are matching piano lacquered veneered panels on the top of the speakers and the sides of the base formed from high density plywood to further damp frame resonances.
The shielding cover on the base is embossed with the Quad logo and all typography is now gold lacquer paint.
Format Floor Standing Dipole with 3 degree Fixed Tilt Type Multiple Electrostatic Drive Membranes 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 1.5mbar Per Volt Referred To 1m
(86 dB / 2.83V RMS Equivalent)
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 - 21kHz (useable)
Distortion (100dB at 1m) Above 1000Hz 0.15%
Above 100Hz 0.5%
Above 50Hz 1.0%
Power Consumption 6W Dimensions (H x W x D) 1470 x 690 x 380mm Weight 44kg