Sonoma Acoustics unveil Electrostatic Headphones

Fanthorpes HiFi have recently taken on an exciting new manufacturer, Sonoma Acoustics. Offering something different to the headphone market, Sonoma have introduced a new electrostatic Headphone system.

There are three types of headphone drivers/transducers. Firstly, we have the most common dynamic driver, a metal coil is inserted into a magnetic field and fixed to a suspended driver cone. When a charge is applied to the coil, it reacts with the magnetic field, causing the driver cone to move and produce sound. Secondly, we have the planar magnetic driver, becoming more popular the planar magnetic driver uses a thin conductive film positioned between two magnets. When an electrical charge is applied, the film reacts to the magnetic field of the magnets and moves to produce sound.

Finally, we have the electrostatic transducers which consist of a thin conductive film suspended between two or one metal plates called stators. A bias voltage is applied to the film to create an electrostatic field and audio signals are sent to the stators, which attract and repel the film to produce sound.

The electrostatic design comes with a number of benefits. Because no magnets are involved, the driver can be made very light. Since the film is incredibly thin (micrometers), the frequency response of electrostatic headphones easily exceeds 20kHz - the upper limits of human hearing. In addition, the stators are perforated, allowing sound to pass through easily to your ears. These advantages are the reasons why electrostatic headphones have an unrivalled response and airiness in their sound.

However, for all of the fantastic advantages electrostatic headphones offer, there was one problem. They are expensive to make.

Warwick Audio Technologies are attempting to change this. Based in the UK, the company has developed a new electrostatic driver called HPEL or High-Precision Electrostatic Laminate. Measuring just 15 microns thick, the driver can be produced on a roll-to-roll process with remarkable consistency. Meaning more efficient manufacturing and lower manufacturing costs.

This provided a company called Sonoma Acoustics with the perfect platform to realize their dream of an electrostatic headphone system.

Who are Sonoma Acoustics?

Formed by a group of ex-Sony and Philips employees who worked on the Super Audio CD. The name Sonoma comes from the DSD recording and editing workstation that they helped to develop in the early days of the SACD. In short, the people behind Sonoma are the ones who helped to pioneer high-resolution audio. The end result is the Sonoma Model One electrostatic headphone system.

The Sonoma Model One headphone system consists of the headphones and its own dedicated headphone amplifier with built in DAC. Let’s talk about the headphones first.

The Sonoma Model One headphones have an open-back design and have large ear cups. The headphones are finished in silver, with the ear cups being made out of super light magnesium. Surprisingly considering their size, the Sonoma Model One headphones are incredibly light, weighing just 303g. The ear pads are covered with hand-stitched Cabretta sheepskin leather, an incredibly soft a durable leather. The ear cups are large and deep, and should be able to accommodate most ear sizes easily.

The headband is crafted using a special nylon material called Nylon12, which was chosen for its strength and durability. The internal components are stainless steel and feature vapor-deposited titanium to provide smooth operation. Again, the headband pad is covered with soft Cabretta leather.

As mentioned earlier, the Sonoma Model One uses an electrostatic transducer developed by Warwick Audio Technologies. Apart from ease of manufacturing, another advantage of the HPEL transducer is that it is single-ended in design, meaning it only uses a single stator. The stator is positioned behind the electrostatic film. A benefit of this is that sound produced by the film doesn’t need to pass through a stator, reducing distortion.

Completing the headphones is a specially designed low-capacitance cable. The cable is made using fine strands of silver-plated oxygen free high conductivity pure copper. A sense loop is also built into the cable, if the cable is disconnected from the headphone amplifier or the individual ear cups, the amp shuts itself down.

Moving onto the headphone amplifier. Because the headphones use Warwick Audio’s patented HPEL transducer, it requires a special amplifier from Sonoma Acoustics and cannot be mixed and matched with third-party headphone amplifiers. This is because the Sonoma Model One’s need for a very high 1350V DC bias voltage. Most other electrostatic headphones only require about 500V to 600V.

The Sonoma Model One’s headphone amplifier is made using a solid aluminium chassis, weighing at around 2.5kg. The headphone amp goes for the minimalistic look. On the front panel, you will find a flip switch that allows you to select either analogue or digital inputs, a large volume control knob, and the headphone output.

On the rear of the amplifier there’s two digital inputs in the form of USB and digital coaxial and two analogue inputs in the form of your standard RCA jacks and a single 3.5mm audio jack. The power switch is located on far left hand side, you will also find another switch on the right allows you to select between the two analogue inputs.

The headphone amp uses a single-ended Class-A design, also featuring an integrated DAC so you can take advantage of via USB or digital coaxial. The built in DAC uses two ESS Sabre Reference chips, one for each channel, that support PCM up to 32-bit and 384kHz as well as DSD up to DSD 128 (5.6MHz) via USB, and PCM up to 24-bit and 192kHz via digital coaxial.

But this is where things start getting interesting because the headphone amplifier features a 32-bit/384kHz AKM analogue-to-digital converter (ADC), which digitizes analogue signals coming in from either the RCA analogue input or 3.5mm analogue input. That’s because the Sonoma Model One headphone amplifier also features a custom-designed 64-bit double precision fixed-point arithmetic digital signal processing running on a multi-core XMOS processor. Sonoma Acoustics say that digital signal processing is crucial to achieving their target frequency response of the headphones.

Because audio signals are now digitally processed, the Model One headphone amplifier utilises a fully digital volume control system. According to Sonoma, advantages of this fully digital volume control system include no loss in fidelity and dynamic range, perfect stereo imaging, and no noise issues.

The Sonoma Model One is unashamedly digital in its approach to good sound.

The Sonoma Model One electrostatic headphone system is a fantastic first step into the electrostatic headphone market by Sonoma. Incredibly well built and featuring interesting, cutting edge technology with outstanding results. Fanthorpes HiFi think you will be pleased with what the Sonoma Model One has to offer.

RRP: £4995

Trade In

Of course, at Fanthorpes we love to trade in, so if you want to trade in your existing HiFi against the Sonoma Model One, contact us and we will let you know what it is worth as a trade in.

Finance Available

We can also offer buy now pay later on the Sonoma Model One, allowing you to spread or defer your payments over a year.