Chord Quartet – Reference Digital Upscaler with Blackbird WTA Filter

The Chord Quartet is a reference-class digital upscaler representing one of the most significant technological developments ever created by Chord Electronics. Designed to address one of the fundamental limitations of digital reproduction, namely the subtle but critical timing error of transients, Quartet employs the new Blackbird WTA (Watts Transient Aligned) filter with four million filter taps.

The result is an extremely sophisticated digital processing platform capable of significantly improving the temporal accuracy of the signal. Thanks to five Xilinx FPGAs, 3,700 DSP cores and more than two million lines of proprietary code, Quartet delivers unprecedented processing power for a Chord upscaler.

The New Blackbird WTA Filter

At the heart of the Chord Quartet is the new Blackbird WTA filter, developed from decades of research by Rob Watts into digital signal reconstruction. With four million filter taps, the filter provides approximately 10 times greater transient timing accuracy compared with previous WTA designs.

Unlike solutions that use software-based shortcuts based on FFT convolution, Quartet performs its processing directly at the hardware level. This approach avoids the time-domain/frequency-domain conversions associated with such processes, helping preserve signal integrity and transient timing accuracy.

Five FPGAs and Extreme Processing Power

To handle the complexity of the Blackbird WTA filter, Quartet uses five Xilinx FPGAs with a combined capacity of 3,700 DSP cores and more than two million lines of proprietary code. This hardware platform allows the algorithms to be processed in real time while maintaining extremely high precision.

The architecture is designed to achieve exceptionally accurate waveform reconstruction, with particular attention to the temporal component of the musical signal.

Pulse Array ADC for Analogue Sources

One of the most important innovations of the Chord Quartet is the integration of a proprietary Pulse Array ADC. For the first time in a Chord Electronics upscaler, analogue sources can also directly benefit from the device's advanced processing capabilities.

Through the RCA analogue inputs, sources such as turntables and other high-end analogue components can be connected. The converter uses sophisticated decimation filtering designed to eliminate traditional aliasing distortion, allowing analogue sources to enter Quartet's processing chain.

Two-Box Architecture and RF-Rejecting Power Supply

Quartet uses a sophisticated two-box architecture that physically separates the sensitive audio circuitry from the power supply. The independent power supply, designed by Rob Watts, uses a proprietary RF pinch-off filtering architecture to reduce noise originating from the mains supply.

This configuration helps achieve an extremely high level of signal purity, approaching the operating conditions of a battery-powered device while still using mains power.

108-Bit Lossless Digital Equalization

The Chord Quartet also incorporates a 108-bit lossless digital equalization system consisting of ten shelf-type bands. Each band allows adjustment of up to ±18 dB without degrading the quality of the original signal.

This function makes it possible to precisely adapt the system's response to the characteristics of the listening environment and loudspeakers while maintaining the integrity of the processed signal.

Comprehensive Connectivity and Support up to 768 kHz

The rear panel provides an extensive range of connections, including galvanically isolated BNC, optical and USB-B inputs. The Dual BNC outputs support a maximum resolution of 768 kHz, making Quartet an ideal partner for Chord Electronics DACs equipped with Dual BNC inputs, particularly the flagship DAVE.

Quartet is compatible with Chord Electronics DACs and can be used to further enhance the performance of models such as Qutest, Hugo TT 2 and DAVE.

Programmable Latency for Audio-Video Systems

For use in audio-video systems, Quartet provides programmable latency from 10 milliseconds up to 3 seconds. This function makes it possible to compensate for processing delays and maintain correct audio-video synchronization, making the unit particularly versatile in AV configurations.

Chord Electronics Design

Like other Chord Electronics components, Quartet features a chassis designed with great attention to mechanical construction and heat dissipation. The main unit and power supply share extremely compact dimensions of 335 × 152 × 78 mm, allowing easy integration into high-end Hi-Fi systems.

The Choral Ensemble Stand can be used as a dedicated support for installing the Quartet, but it is sold separately.

Key Features

• Reference-class digital upscaler
• New proprietary Blackbird WTA filter
• 4 million filter taps
• Approximately 10 times greater transient timing accuracy compared with previous WTA designs
• 5 Xilinx FPGAs
• 3,700 DSP cores
• More than 2 million lines of proprietary code
• Filter processing performed directly at the hardware level
• Integrated Pulse Array ADC for analogue sources
• Analogue input via 2 RCA connectors
• 108-bit lossless digital equalizer
• 10-band equalization with ±18 dB adjustment
• Two-box architecture
• Separate power supply with proprietary RF filtering
• BNC, optical and galvanically isolated USB-B digital inputs
• Dual BNC outputs up to 768 kHz
• Programmable latency from 10 ms to 3 seconds
• Compatible with Chord Electronics DACs
• Optimized to take full advantage of the performance of the Chord DAVE
• Jett Black and Argent Silver finishes

Why Choose Chord Quartet

The Chord Quartet is designed for those who want to take digital processing in their Hi-Fi system to an exceptionally high level. The combination of the four-million-tap Blackbird WTA filter, enormous FPGA processing power, Pulse Array ADC and separate power supply architecture makes it a unique solution in the world of digital upscalers.

The ability to process both digital and analogue sources, together with connectivity up to 768 kHz and lossless digital equalization, makes Quartet an exceptionally versatile component. In particular, pairing it with a high-end Chord Electronics DAC allows the full capabilities of its sophisticated processing platform to be exploited.

Technical Specifications

Warranty

2 years