What the Quartet Upscaler Is—and Who It Is For
The Chord Electronics Quartet is a reference-class digital audio upscaler designed to sit between your source and DAC, reshaping incoming data before conversion. Positioned as one of the most important products in the company’s 37‑year history, it is clearly aimed at listeners who treat digital playback as a system to be optimized, not a solved problem. Rather than being a generic high-end DAC upgrade, Quartet focuses on one thing: reconstructing timing information that Chord’s digital designer Rob Watts believes standard converters routinely smear. In practical terms, that makes it a niche component for owners of serious digital front‑ends—especially those already invested in Chord DACs—who want to push for reference‑grade performance from streaming, discs, or even analog sources. The question is whether its extreme engineering and promised leap in realism translate into enough audible benefit to justify such an obsessive focus on timing.
Blackbird WTA and Four Million Taps: Inside Chord’s Digital Engine
Quartet’s headline feature is its Blackbird WTA filter, the most advanced interpolation engine Chord has released in a consumer product. Where the previous M Scaler relied on one million filter taps, Quartet multiplies that to four million, spread across five Xilinx FPGAs. In the context of a digital audio upscaler, taps represent how finely the filter can calculate what should exist between samples; more taps mean more sophisticated reconstruction. Chord claims a tenfold improvement in transient timing accuracy over its earlier WTA design, with most coefficients approaching the theoretical sinc function ideal. Importantly, the filtering is executed directly in hardware rather than via FFT convolution, which Watts argues can reintroduce timing errors. The claimed sonic payoff is cleaner transients, more intelligible bass pitch, greater timbral nuance, and a more convincing sense of space—attributes that matter deeply to listeners chasing a truly reference‑grade, high‑end DAC upgrade path.
Timing, Transients, and the Digital Audio Problem Quartet Targets
Rob Watts describes conventional digital audio as putting a steak through a mincer and then expecting to reconstruct the original from the mince. His core argument is that standard digital conversion loses critical timing information, especially around transients—the leading edges of notes that help our brains parse pitch, timbre, and spatial cues. When these are even slightly mistimed, sound can flatten, depth collapses, and instruments lose their defined location in the soundstage. Quartet’s mission is to rebuild that timing with far greater precision using extreme‑tap interpolation. Instead of merely sharpening frequency detail, the Blackbird WTA filter attempts to reassemble when events occur, not just what they are. For listeners sensitive to imaging solidity, micro‑dynamics, and how convincingly a recording projects musicians into the room, this emphasis on audio timing precision is the defining reason to consider Quartet over more conventional digital upgrades.
Built‑In ADC: Bringing Analog Sources into the Upscaling Fold
Where previous Chord upscalers were strictly digital‑in, digital‑out, Quartet adds an important twist: a built‑in analog‑to‑digital converter. This means turntables, tape machines, and other line‑level sources can now be digitized, cleaned up, and passed through the same timing‑focused processing as your network streamer or CD transport. Rather than relying on standard professional ADC designs that often use half‑band filters and can suffer from aliasing artifacts folding back into the audible range, Quartet employs a custom Pulse Array ADC with proprietary decimation filters. These are designed to strip aliasing from its 104 MHz noise‑shaper output while avoiding measurable noise floor modulation. In practice, that promises more precise preservation of low‑level details and timing information from analog sources. For vinyl devotees who also embrace digital convenience, Quartet effectively turns your analog front‑end into a source that can benefit from Chord’s advanced digital audio upscaler architecture.
Value Proposition: From M Scaler to Quartet and Beyond
Compared to the M Scaler’s one million‑tap architecture, Quartet’s four million taps and five‑FPGA platform represent a substantial escalation in ambition and processing power. It is also explicitly voiced to partner with Chord’s DAVE DAC, pushing it to its full 768 kHz capability and providing five times DAVE’s own FPGA horsepower. On paper, that makes Quartet the logical apex of a Chord‑centric digital chain—a no‑compromise timing engine for listeners who hear clear gains from upscaling and want the state of the art. Whether those improvements justify investing in such a specialized component depends on your priorities. If you are already deep into high‑end DAC upgrades, obsess over imaging precision, and can reliably hear differences between filters and sample rates, Quartet’s engineering focus on timing coherence could be compelling. For more casual listeners, its extreme resolving power may be overkill relative to more conventional, cost‑effective digital solutions.