Audiophile and Pro-Audio Drive Systems

Warwick Audio Technologies has developed fully integrated drive electronics in the form of an assembled printed circuit board (PCB-A) that provides a turn-key solution for a multitude of audio products, including:

Warwick’s HPEL Drive Electronics PCB-A is meant to be driven from AC mains power, and integrated within stand-alone products that demand the ultimate in audio performance for home and studio use.

Warwick HPEL Drive Electronics PCB-As are supplied exclusively by Warwick Audio Technologies Ltd. and are available to OEMs and ODMs for licensing in a range of headphone and loudspeaker products.

The design and specifications of HPEL Drive Electronics PCB-As are subject to change at any time by Warwick Audio Technologies Ltd.

  • Complete 2-channel integrated drive electronics for stereo applications
  • Discrete FET, single-ended Class A output amplifiers are optimised to drive HPELs
  • Analog inputs – high level (RCA) and low level (3.5 mm)
  • Digital inputs – USB and digital coaxial (SPDIF)
  • Accepts all high resolution audio input formats at native rates
  • Ultra-high performance 32-bit/384 kHz ADCs and DACs
  • Exceptionally low phase noise and jitter
  • 64-bit, double-precision, fixed-point DSP
  • 6-band parametric EQ for sound optimisation and customisation
  • Distortion reduction pre-processing
  • High-precision output level control
  • Proprietary, customisable firmware included
  • PCB layout optimised for superior high resolution audio performance
  • Isolated, multi-stage, low noise voltage regulation
  • Powered by 24 VDC (outboard, universal voltage SMPS)
  • USB updatability of firmware
  • Integrated protection/shutdown and fault indication
  • Meets North American, European and Asian regulatory compliance for EMC, safety and environmental certification

The world-class audio performance of Warwick’s HPEL Drive Electronics PCB-A is exemplified by the attention to detail and refusal to compromise evident in all aspects of the circuitry design. A brief description of a few of the design elements illustrates Warwick’s commitment to audio performance.

Class A Energizing Amplifier

Like all electrostatics, the HPEL transducer requires a high voltage drive amplifier in order to function. The supplied drive comes from an optimally-matched, high performance, discrete FET Class A amplifier with very low distortion and wide bandwidth.

Custom 64-Bit Double-Precision Fixed-Point DSP

We digitally process all signals using custom 64-bit, double-precision, fixed-point arithmetic. Fixed-point is known to be superior in the world of audio processing. And our 64-bit arithmetic exceeds even the performance of professional audio workstations.

AKM Premium ADC

All incoming analog signals must be converted to digital ahead of the DSP. To achieve this, we utilise a multi-channel 32-bit/384 kHz AKM Premium ADC, which delivers a measured signal-to-noise ratio in excess of 120 dB.

CRYSTEK Ultra-Low Phase Noise Oscillator

The ultimate performance of any digital system is determined by the quality of its master clock. To guarantee the highest performance regardless of the input signal format, we utilise an ultra-low phase noise oscillator from Crystek. Operating at 100 MHz, it features extremely low close-in phase noise (< 90 dBc/Hz at 10 Hz from the center frequency) and an industry-leading rms jitter level, at 100 MHz, of 82 femtoseconds (82 x 10-15 s). All other clocks used are derived from this exceptionally accurate master oscillator via a sophisticated clock distribution scheme using Texas Instruments frequency dividers.


ESS is universally recognized as the world’s premium DAC chip manufacturer, and we have opted for their 32-bit Reference DAC. Each DAC chip is operated in mono mode to provide a measured 129 dB signal-to-noise ratio.

Optimum PCB Layout

The use of premium parts alone does not guarantee high quality audio performance. In the design of the PCB-A, meticulous attention was paid to circuit layout to ensure the lowest noise and distortion levels possible. Through careful component positioning, we were able to lower the noise floor to below -129 dB.

Two-Stage Power Supply

All audio circuitry is supplied by multiple stages of ultra-low noise, high current linear regulators from Analog Devices. Isolated power regulation stages are used for both analog and digital sections as well as high and low level circuit stages. These regulation stages are fed by a custom-designed, universal voltage, outboard switch-mode power supply unit, capable of delivering about 3.5 times the maximum power the amplifier is designed to draw under steady-state conditions. In addition, the unit uses a fixed high frequency switcher (operating at over 85 kHz) to avoid the possibility of any switching noise entering the audio band. This unit is designed with improved internal filtering to yield extremely low noise and ripple (< 50 mV peak-to-peak).

USB Input

USB 2.0, type B; accepts digital audio formats up to 32-bit/384kHz PCM and DSD (DoP64/128) 

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


Dual mono, 32-bit/384 kHz DACs with balanced outputs


32-bit/384 kHz multi-channel ADC with balanced input buffers

Digital Signal Processing (DSP)

64-bit (double-precision) fixed-point processing


Discrete FET, single-ended, high bias Class A output

Bias Voltage

1350 VDC

Maximum Output

145 Vrms

Distortion + Noise

< 0.05%


> 65 kHz

Power Draw

24 VDC at 1.1 A typical

Power Supply

External: 24 VDC, 65 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


233 mm (L) x 165 mm (W) x 25.8 mm (H)

The design and specifications of HPEL Drive Electronics PCB-As are subject to change at any time by Warwick Audio Technologies Ltd.

Warwick HPEL Drive Electronics PCB-As are supplied exclusively by Warwick Audio Technologies Ltd. and are available to OEMs and ODMs for licensing in a range of headphone and loudspeaker products.

HPEL Drive Electronics PCB-As can be customised as follows:

  • Overall size and shape of PCB – PCB can be adjusted dimensionally to fit customer requirements
  • Input/output jacks and location – different jack types can be fitted, and location can be changed to fit customer requirements
  • Switches and volume control – type and location of switches and volume control can be altered to fit customer requirements
  • Indictor LEDs – color and location of indicator lights can be changed to customer requirements
  • Equalisation settings – EQ settings can be tailored to adjust sound character of system
  • Distortion reduction pre-processing – can be optimised for different system conditions and acoustical loading of the HPEL transducer
  • MCU control (UI functions) – user interface functions can be implemented to customer specifications
  • Outboard power supply – custom outboard power supplies can be utilized