Warwick Acoustics SONOMA M1 Electrostatic System

An unparalleled listening experience of unrivalled transparency and tonality that will breathe fresh life into your music.

Warwick Acoustics has brought together some of the world’s leading professional audio engineers to create the Sonoma Model One (M1). An integrated headphone system (DAC, amplifier/energizer and open-backed headphone unit), the Sonoma M1 has been optimised from the ground up with one single minded goal. To deliver uncompromising, astonishing HiRes AudioTM performance in a truly exclusive package.

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.

Injected magnesium earcups

Compared to Aluminium, Magnesium is about ⅓ lighter and has superior acoustical damping. Combining excellent strength-to-weight ratio, high stiffness and outstanding EMI/RFI shielding, Magnesium is the ideal material in which to house the HPEL transducer to ensure optimum performance. The ear-cups of the M1 are formed by precision injection moulding at very high pressure. The result is a weight of 10.7 ounces (303 grams) which contributes to outstanding headphone comfort. Only high-grade stainless steel screws and fasteners are used in the headphones for high strength and resistance to corrosion.

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.

Custom low-capacitance cable

An electrostatic headphone does not present a normal load to any partnering amplifier. As a result, it is impossible to use just any cable to connect amplifier to headphone. Therefore, in collaboration with Straight Wire Inc., a totally new, ground-up design was done for the M1. The goal was to meet the following criteria:

1. Capacitance had to be minimised;
2. Mechanical noise pick up had to be minimised;
3. Signal purity had to be maximised;
4. The cable had to be thin, flexible and light weight.

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.

ESS sabre reference DAC

The Sonoma M1 system was developed to deliver true high-resolution performance. For the critical digital-to-analog conversion stage, we turned to an established leader in the field. ESS Technology is universally recognised as the world’s premier DAC chip manufacturer, and we have opted for their 32-bit Reference DAC. Two stereo DAC chips are used in a special mono mode to deliver a measured 129 dB signal-to-noise ratio (SNR).

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).

Headphones

Configuration	Open-back, circumaural type
Transducer	HPEL, single-ended electrostatic
Effective Diaphragm Area	3570 mm2
Frequency Response	10 Hz – 60 kHz
Output Level	Compliant with EN 60065/A12:2011 (EN50332) when driven by M1 Energizer/DAC (for all inputs)
Ear and Headband Cushions	Cabretta top-grain, sheepskin leather
Input	Polarized, 4-pin, self-latching connectors for left and right channels
Drive Cable	Ultra-low capacitance, silver-plated OFHC copper, with  foamed PE insulation and Kevlar reinforcement; 2 meter length
Weight	303 grams (10.7 oz), without cable

Energizer & DAC

USB Input	USB 2.0, type B; accepts digital audio formats up to 32‑bit/384 kHz PCM and DSD via DoP (DSD64/DSD128)
Digital Coaxial Input	S/PDIF; accepts digital audio formats up to 24‑bit/192 kHz PCM
Analog Input (High Level)	Dual RCA; 2.1 Vrms
Analog Input (Low Level)	3.5 mm; 850 mVrms
DAC	Dual mono, 32-bit/384 kHz DACs with balanced outputs
ADC	32-bit/384 kHz multi-channel ADC with balanced input buffers
Digital Signal Processing (DSP)	64-bit (double-precision) fixed-point processing at native sample rates
Amplifier/Energizer	Discrete FET, single-ended, high-bias Class-A output
Distortion + Noise	< 0.05%
Bandwidth	> 65 kHz
Enclosure	CNC-machined 6063 aluminum
Power Supply	External: 24 VDC, 60 VA, fixed frequency, class B-compliant SMPS; Internal: fully isolated, ultra-low noise linear regulation
AC Mains	World voltage compatible (90-264 V, 50-60 Hz); IEC-60320 C14, earth-grounded power cable; 1.5 meter length
Dimensions	H x W x D: 57 mm (2.24 in) x 190 mm (7.48 in) x 290 mm (11.42 in)
Weight	2.45 kg (5.40 lbs)