Chord Electronics Quartet Scaler

A reference-class digital audio upscaler featuring groundbreaking proprietary Blackbird WTA filter technology for unprecedented timing accuracy. Powered by 5x Xilinx FPGAs, the Quartet upscaler also benefits from an integrated Pulse Array ADC to upgrade analogue sources, too. Supplied with a sophisticated RF-rejecting power supply.

The Quartet represents the most significant advancement in digital audio technology in Chord Electronics’ history. A reference-class digital upscaler, the Quarter addresses a fundamental flaw inherent in standard digital playback: the subtle but critical mistiming of transients.

At the core of the Quartet’s performance is the all-new Blackbird WTA (Watts Transient Aligned) filter. Representing the culmination of 46 years of specialised research, the Blackbird filter utilises a staggering four million filter ‘taps’—the technical measure of interpolation complexity. The Blackbird WTA represents a tenfold increase over previous WTA designs, achieving a tenfold improvement in transient timing accuracy, plus it has even more ‘taps’ at its disposal for even better performance.

To process this complex interpolation algorithm without compromise, the Quartet utilises five (5x) Xilinx FPGAs, (five times the processing power of the reference DAVE DAC).

Technically, nearly 100 per cent of the filter’s mathematical coefficients reach the theoretical ideal ‘sinc function,’ in other words, the ‘gold standard’ for perfect waveform reconstruction. Crucially, all filtering is executed directly within the hardware architecture. By avoiding the software-industry shortcut of FFT convolution, which converts audio to frequency data and back, introducing further timing errors, the Quartet preserves pure signal integrity, delivering unmatched transient fidelity.

For the first time in a Chord Electronics upscaler, the Quartet integrates a proprietary Pulse Array ADC (analogue-to-digital converter). This allows analogue sources, including high-end turntables, to benefit directly from the device’s upscaling power. By employing advanced decimation filtering, the integrated ADC eliminates traditional aliasing distortion, outperforming even dedicated studio-grade conversion hardware.

To protect the digital signal from interference, the Quartet benefits from a two-box configuration. The sensitive audio circuitry is isolated from an independent, Rob-Watts-designed power supply that incorporates a proprietary pinch-off RF filter architecture, achieving the exceptional sonic purity of a battery-powered device from a mains-connected unit.

The rear panel features comprehensive, isolated connectivity, including USB-B, optical, and dual BNC outputs capable of supporting maximum resolution up to 768 kHz. The Quartet is compatible with all Chord Electronics DACs.

Key Features

• Advanced proprietary Blackbird WTA Filter: Utilizes the most advanced interpolation algorithm to deliver a tenfold improvement in transient timing accuracy.
• Five Xilinx FPGAs: Features massive processing capability with 3,700 DSP cores running over two million lines of proprietary code.
• Hardware-level processing: All digital filtering is implemented directly in hardware, completely avoiding the timing errors caused by software FFT convolution shortcuts.
• Integrated Pulse Array ADC: The first Chord Electronics upscaler to accommodate analogue sources (such as turntables) via RCA inputs, eliminating traditional aliasing distortion through advanced decimation filtering.
• Two-box architecture: Separates the sensitive audio circuitry from a dedicated power supply featuring a proprietary pinch-off RF filter architecture to reject mains-borne noise.
• 108-bit lossless digital EQ: A ten-shelf equalization system providing ±18 dB of adjustment across frequencies with zero degradation of signal quality.
• Comprehensive digital connectivity: Equipped with isolated USB-B, optical in, BNC in and dual BNC outputs supporting maximum resolution up to 768 kHz (optimized for pairing with the DAVE DAC).
• Programmable Latency: Offers selectable delay from 10 milliseconds to three seconds to ensure perfect lip-sync during audio-visual playback.

Specifications