Warwick Acoustics APERIO Electrostatic Reference System

The APERIO reference headphone system strives to deliver the highest level of audio performance achievable, by means of our proprietary planar electrostatic technology. 

The APERIO utilises a highly-refined, evolutionary advancement of technology originally developed by Warwick Acoustics for it’s ground-breaking and multi-award-winning Sonoma Model One Headphone System. 

Headphones

For the APERIO headphone, Warwick Acoustics had two primary design objectives: 1) the headphone must provide the optimum mechanical and acoustical conditions for the BD-HPEL transducer that enable the best audio performance and sound quality possible to be achieved and, 2) the headphone must be comfortable for the user, even under critical monitoring conditions, for extended periods of time. 

BD-HPEL Transducer

The single most crucial component of any headphone system is the transducer. The ultimate performance of the complete sound reproduction system will be determined and limited by the acoustical performance and fidelity of the transducer. 

The APERIO utilises a new Balanced-Drive HPEL Transducer (BD-HPEL) – a symmetrically-driven variant of Warwick Acoustics’ High Precision Electrostatic Laminate (HPEL) transducer, originally developed for the Sonoma Model One headphone system.

Injected Magnesium Ear cups

Major structural components of the headphone, for example, the ear cups, are fabricated of injected Magnesium – a rigid material lighter and significantly better-damped than aluminium and most polymers. Because the Magnesium is injected, complex and precise components that typically would require CNC-machining are possible. 

Ear Cushions

In order to achieve outstanding low frequency performance, the APERIO requires a small sealed air volume between the transducer and listener’s head. The APERIO maintains this air volume and requisite air seal through key design features that eliminate air leakage, even with variations in head and ear shape. 

Headphone Comfort

The APERIO addresses comfort by minimising weight and optimising geometry. The advanced materials utilised in the design, such as Magnesium and Engineering polymers, result in a very low mass of 405 grams. 

Electronics

The APERIO is a complete sound reproduction system, thus the electronics are optimised specifically for the APERIO headphone. Every element of the sound reproduction chain between raw audio data input (from an analogue or digital source) and output to the headphone is included and fully optimised within the APERIO electronics. 

Every functional sub-section of the electronics has been designed to state-of-the-art standards, without compromise. 

Cutting-edge components

The APERIO is a complete sound reproduction system, thus the electronics are optimised specifically for the APERIO headphone. Every element of the sound reproduction chain between raw audio data input (from an analogue or digital source) and output to the headphone is included and fully optimised within the APERIO electronics.

Every functional sub-section of the electronics has been designed to state-of-the-art standards, without compromise.

Analogue Line Output

The Analogue Line Output section features a novel Class A circuit that can output very high voltages with prodigious current, allowing it to effortlessly drive outboard electronics in any professional or consumer application, even with extremely long cables. 

We’ve tested the Line Output section with 150-meter-long balanced cables driven to 15 dBu (12.3 Vp-p) without distortion. 

Dual 32-bit, 8-channel DAC’s

The DAC section of the APERIO electronics is truly state-of-the-art. Dual 32-bit, 8-channel DACs are utilised – one per channel in dual mono configuration, to achieve a SNR of 131 dB.

Input Cables

Warwick Acoustics supplies high performance input cables with the APERIO. These cables are custom designs, developed by Warwick Acoustics to match the performance and quality level of the rest of the APERIO system. 

Specifications

Headphones

Configuration	Open-back; circumaural type
Transducer	Balanced-Drive High Precision Electrostatic Laminate (BD-HPEL)
Effective Diaphragm Area	3570 mm2
Frequency Response	10 Hz – 60 kHz
Output Level (SPL)	Compliant with EN 60065/A12:2011 (EN50332) when driven by APERIO electronics (for all inputs); digital input: ∽ 104 dB; analog input: ≥ 106 dB (continuous, est.)
Ear and Headband Cushions	“Cabretta” top-grain, sheepskin leather; perforated surface on ear cushions
Input	Polarized, 4-pin, self-latching connectors for left and right channels
Drive Cable	Dual mono, shielded, ultra-low capacitance; silver-plated OFHC ultra-fine stranded copper, with silicone insulation and Kevlar reinforcement; 2 meter length
Weight	405 grams (14.3 oz.), without cable

Electronics

Balanced Analog Inputs	Dual (female) XLR jacks; switchable (high / low) input range; 18 dBu / 10 dBu
Unbalanced Analog Inputs	Dual RCA jacks; switchable (high / low) input range; 5.0 Vrms / 2.1 Vrms
USB Digital Input	Type B jack; USB 2.0; accepts digital audio formats up to 32-bit / 384 kHz PCM and DSD (DSD64/DSD128/DSD256) via DoP or Native
Network (Ethernet LAN) Digital Input	RJ45 jack; DLNA-compatible; accepts digital audio formats up to 32-bit / 384 kHz PCM and DSD (DSD64/DSD128/DSD256) via DoP or Native
AES3 (AES/EBU) Digital Input	XLR (female) jack; accepts digital audio formats up to 24-bit/192 kHz PCM
S/PDIF Coaxial Digital Input	RCA jack; accepts digital audio formats up to 24-bit/192 kHz PCM
Line Outputs	Balanced and unbalanced, high current outputs; +5 dB gain; switchable
Digital Formats	PCM: 16-32 bit / up to 384 kHz; DSD: up to 256 fs DoP and Native
Digital Signal Processing (DSP)	64-bit (double-precision) fixed-point processing at native sample rates
Switchable Gain	Rear panel switch; high level / low level selection for balanced analog input (professional audio and consumer levels) and unbalance analog input
Source Selection	Multi-position front panel selector with indicator LEDs for all sources
Level Control	Front panel, 31-position; digital and analog domain volume control (HP & Line Out)
Status Display	Front panel, 51 mm, full color, QVGA, TFT LCD (240 x 320 pixels)
Display Functions	Digital readout and bar graph of volume control setting; display of digital audio data format; display of rear panel analog input (gain) settings; display of Ethernet and USB data link transmission lock; display of detected fault modes and output clipping
Auto Fault Detection	Automatic detection, display and protection for: output amplifier clipping, unplugged connections and malfunctioning wiring, over-temperature conditions and internal electrical faults
DACs	2 x dual mono, 32-bit / 384 kHz DACs with balanced outputs, for PCM & DSD inputs
Amplifier/Energizer	Balanced, discrete MOSFET, high-bias, single-ended Class A output; dual mono topology, including power supply; 1800 VDC bias (charge) voltage
Distortion + Noise	< 0.001%
Bandwidth	> 65 kHz
Enclosure	CNC-machined 6063 aluminium; earth-grounded
Power Supply	External: world voltage compatible (90-264 Volt AC, 50-60 Hz); 24 Volt DC, 200 VA (8.333 A), fixed frequency, class B-compliant SMPS Internal: isolated, dual mono; switching and ultra-low-noise linear regulation
AC Mains	Types B, G, F, I; IEC-60320 C14, earth- grounded power cable; 1.5 meter length
Dimensions	H x W x D: 68 mm (2.68 in.) x 413 mm (16.26 in.) x 351 mm (13.82 in.)
Weight	7.4 kg (16.28 lbs.), without Power Supply