What the Chord Quartet Upscaler Is Trying to Fix
The Chord Quartet upscaler is billed as a reference audio equipment component designed to attack a specific problem: timing errors in digital playback. Chord’s digital designer Rob Watts likens conventional digital audio to putting a steak through a mincer and then trying to reassemble it; you get the broad strokes, but the fine structure is lost. The critical casualty, he argues, is transient timing – the leading edges of notes that inform our sense of pitch, timbre, and spatial placement. When these are even slightly smeared, depth collapses, instrument separation blurs, and recorded spaces feel artificial. Quartet’s role in a high-end system is to reconstruct the missing information between samples with extreme precision before the DAC sees it. Instead of chasing sample-rate bragging rights, it aims to restore temporal coherence so music sounds like musicians in an acoustic environment, not merely high-resolution data.
Four Million Taps and Five FPGAs: Inside Blackbird WTA
At the heart of the Chord Quartet upscaler lies the new Blackbird WTA filter, which pushes digital audio upscaling far beyond the M Scaler’s million-tap architecture. Quartet deploys four million filter taps spread across five Xilinx FPGAs, giving it five times the processing power of Chord’s DAVE DAC. Filter tap processing matters because taps determine how sophisticated the interpolation between samples can be. More taps allow the filter to approximate the ideal sinc function more closely, which, in theory, yields more accurate time-domain reconstruction. Chord claims a tenfold improvement in transient timing accuracy over its previous-generation WTA filter, arguing that Quartet approaches the mathematical ideal for a reconstruction filter. Crucially, all this is implemented directly in hardware rather than via FFT-based convolution, avoiding the conversion to frequency data and back that Watts believes can reintroduce timing errors. On paper, Quartet is unapologetically extreme digital engineering.
A First for Chord: Built-In ADC and System Integration
Unlike Chord’s earlier upscalers, the Quartet adds a built-in analog-to-digital converter to its digital arsenal. This Pulse Array ADC is designed to convert analog sources—turntables, tape machines, or line-level components—into high-precision digital data before applying upscaling. Chord’s stance is that conventional ADCs often rely on half-band filters that can introduce aliasing and compromise timing, effectively baking in errors at the recording or capture stage. Quartet counters with proprietary decimation filters that work on a 104 MHz noise-shaper output, targeting cleaner conversion and minimal noise floor modulation. For system builders, this means an entire reference chain—vinyl included—can be routed through the same timing-optimized engine. Integration with the DAVE DAC is central: Quartet is intended to push DAVE to its maximum 768 kHz capability, simplifying the path to a consolidated, timing-focused reference front end rather than a patchwork of disparate digital boxes.
Listening Priorities and the Value of Reference Audio Equipment
The Quartet is described as a reference-class digital audio component and flagged by Chord as one of the most important products in its multi-decade history. That positioning, coupled with its premium pricing—USD 35,995 (approx. RM167,600)—makes it clear this is not a casual upgrade for mid-tier systems. The value proposition hinges on how much you prioritize time-domain performance over more conventional metrics like bit depth or sample rate. If you already own a DAVE and have built a revealing system around it, Quartet promises deeper soundstage layering, more intelligible bass pitch, and more lifelike timbre and reverberation. In such a context, improved transient accuracy can be audible and addictive. For others, especially those using more modest DACs or speakers, the leap to four million taps may exceed the resolving power of the rest of the chain. Quartet is best viewed as an endgame tool for timing-obsessed audiophiles willing to chase the last few percent of realism.
