HPEL Transducers

The ideal loudspeaker transducer would have zero mass, respond infinitely quickly to any signal, be perfectly damped, have no distortion and be perfectly linear. Until now, the technology that best exemplifies those characteristics is electrostatic. Introduced almost 60 years ago, electrostatic headphones have remained the choice of discerning listeners who demand the highest audio quality. Now, a revolutionary new electrostatic transducer, derived from the world of ultrasonics, has been developed in the UK by Warwick Acoustics. The patented High-Precision Electrostatic Laminate (HPEL) audio transducer ushers in a new paradigm in the field of electrostatic drivers, and the Sonoma M1 is the first headphone system in the world to use it.

Handmade carbretta sheepskin ear-pads

Comfort in a headphone is of paramount importance. We want you to enjoy the M1 for extended listening sessions. Producing an excellent sounding, lightweight design would all be for naught if the ear and headband pads induced any discomfort. So, to ensure maximum listening pleasure, the pads on the M1 are all handmade from top-grain Cabretta sheepskin leather. Cabretta leather is renowned for its light weight, smoothness, suppleness, and durability.

The leather used in the M1 is sourced from Ethiopia. The hides are then tanned by Pittards in the UK, who have been tanning leathers since 1826. Finally, the pads are hand sewn in Germany.

Discrete Single-Ended Class-A Amplifier

Like all electrostatic transducers, the HPEL requires a high-voltage drive amplifier in order to function. In the case of the M1, the drive comes from a high-performance, single-ended, discrete FET Class-A amplifier with very low distortion and wide bandwidth which is optimally matched to the HPEL. The amplifier was designed and optimised to drive the inherent capacitive load of an electrostatic transducer, and the Class-A output stage is operated at a high bias level, and delivers a very high slew-rate. Operating at such high bias levels results in improved linearity.

Custom 64-bit Fixed-Point Digital Signal Processing

Anyone who is familiar with loudspeaker or amplifier measurements will undoubtedly have seen plots of flat frequency response from a few tens of Hz all the way up to 20+ kHz. A flat frequency response is the ultimate goal for those components, and is quite easily achieved in an amplifier, but more difficult to achieve in a loudspeaker, especially in a real-world listening room (as opposed to an anechoic chamber).