Why Timing, Not Just Resolution, Drives the Quartet’s Design
Chord Electronics’ Quartet upscaler is framed as a solution to a specific weak point in digital playback: timing. Rob Watts argues that conventional A/D and D/A chains smear transients, the leading edges of notes that inform our perception of pitch, timbre, and space. When these transients are fractionally mistimed, soundstage depth collapses and instruments lose their natural placement, even when headline specs like bit depth and sample rate look impressive. The Quartet upscaler is built to reconstruct those missing temporal cues with much finer granularity, targeting what Chord describes as a more accurate analog-like waveform from existing digital files. Rather than treating upsampling as a cosmetic sharpening filter, the company positions the Quartet as a timing reconstruction engine for serious systems, particularly when paired with reference DAC components and high-resolution sources where upstream weaknesses in digital audio timing are most audible.
Four Million Audio Filter Taps and Five Xilinx FPGAs
At the heart of the Chord Quartet upscaler is the new Blackbird WTA filter, implemented with four million audio filter taps spread across five Xilinx FPGA audio processors. Chord’s earlier M Scaler already used an ambitious one million taps; Quartet quadruples that figure and adds five times the processing power of the flagship DAVE DAC. In practical terms, taps represent how many coefficients an interpolation filter can use to calculate what should exist between digital samples. More taps, properly implemented, allow closer approximation to the theoretical sinc reconstruction filter that underpins ideal digital-to-analog conversion. Chord claims the Blackbird WTA delivers a tenfold improvement in both overall filtering performance and transient timing accuracy versus its prior WTA design, while avoiding FFT-convolution shortcuts. Instead, the filtering is executed directly in hardware on those Xilinx FPGAs, an approach intended to minimize the very timing errors many software-based solutions may inadvertently introduce.
Built-in ADC: Bringing Analog Sources into the Timing Machine
In a first for Chord’s upscalers, Quartet integrates a bespoke analog-to-digital converter so analog sources can enter the same timing-focused pipeline as digital ones. The ADC uses a custom Pulse Array topology and proprietary decimation filters to tame aliasing from a 104 MHz noise shaper, with the goal of preserving low-level detail without adding noise-floor modulation. This matters because any timing damage introduced at the ADC stage becomes permanent; downstream DACs can only work with what they receive. With Quartet, turntables, tape machines, or other line-level components can be digitized and then upscaled using the same four-million-tap Blackbird WTA filter that treats digital sources. For purists, running vinyl through a digital timing engine may sound heretical, but it also opens the door for more consistent system voicing and allows analog collections to benefit from Chord’s most advanced reconstruction technology.
Synergy with DAVE and Positioning as a Reference DAC Companion
Quartet is explicitly designed to partner with Chord’s DAVE DAC, pushing it to its full 768 kHz capability and forming a digital front end aimed at reference-level systems. With five Xilinx FPGAs handling upscaling and interpolation, DAVE can focus on conversion using its own Pulse Array architecture, effectively splitting tasks between a dedicated timing engine and a flagship DAC. For system builders, this positions Quartet as a central hub for both digital and newly supported analog sources, feeding a DAVE-based chain that aspires to minimize timing errors from input to output. The stack also underscores Chord’s belief that solving digital audio timing is a multi-stage process rather than a single-chip fix. Quartet’s role is to refine the data before DAVE ever sees it, potentially yielding improvements in bass definition, spatial specificity, and transient clarity that align with Chord’s long-term digital design philosophy.
Does the Quartet’s Engineering Justify Its Premium Price?
With a list price of USD 35,995 (approx. RM170,000), the Chord Quartet upscaler targets a narrow audience of listeners committed to incremental gains at the very top of the digital audio hierarchy. From an engineering standpoint, the extensive use of Xilinx FPGA audio processing, the four million filter taps, and the new Blackbird WTA algorithm constitute a genuine step beyond the already ambitious M Scaler. The inclusion of a high-spec ADC broadens its role from digital accessory to system nucleus. Whether that justifies the cost depends on how much value one places on timing refinement over more conventional upgrades such as speakers, amplification, or room treatment. For systems already optimized in those domains, Quartet offers a focused attempt to address residual digital timing errors. It is less a universal recommendation and more a statement piece for reference DAC components and listeners who prioritize temporal accuracy above all.