Chord DAC64

Chord DAC64Launched at the 2001 Las Vegas Consumer Electronics Show, this was a sensation. It wasn’t just the company’s first ever digital-to-analogue converter, it was the result of a chance encounter between Rob Watts and John Franks. The former is a brilliant audio engineer who first cut his teeth at Deltec Precision Engineering, the latter is the founder of Chord Electronics. With circuitry from Watts and industrial design and manufacture from Franks, it was a breathtaking combination.

In a world of pressed steel black boxes, the DAC64 looked boldly different. It appeared to be hewn from a billet of aluminium and had a completely – for a DAC – innovative lens through which you could see the jewel in the Chord’s crown, its powerful Xilinx Field Programmable Gate Arrays. Instead of buying DAC and/or digital filter chips in from outside silicon suppliers such as Wolfson, Burr Brown or Philips, the DAC64 used Rob Watts’ own digital filtering code flashed onto the FPGA.

Inside the window, different coloured LEDs light up to denote status and sampling frequency. Blue indicates the power is on, then red LEDs light to give a purpley colour showing the unit has locked on a digital signal. When either of the RAM buffers is selected, yellow LEDs illuminate. The unit is fun to use, and a completely different experience to standard DACs. The rear panel has three digital inputs switched via a small toggle; TOSLINK optical, coaxial and AES/EBU on an XLR – no USB, of course, which dates it now. An additional toggle switch gives a choice of two RAM buffer settings, or off, and there’s a choice between RCA unbalanced and XLR balanced outputs.

As its name suggests, the converter has 64-bit internal architecture, with the Pulse Array digital conversion chip using seventh-order noise-shaping done with 64-bit accuracy. This means that filtering and noise-shaping calculations are done extremely precisely, giving minimal digital noise. The RAM buffer is basically a very large first-in, first-out stack that is designed to minimise jitter. The DAC64 also sports the first ever Watts Transient Aligned digital filter, designed to minimise timing errors; it boasts 1024 taps instead of the 256 normally used back at that time…

Rob Watts told me that, “ever since the early eighties when I studied electronics at university, I realised that the interpolation filters in use then and today were fundamentally limited, and had severe timing problems. This was based on studying sampling theory, which clearly states that to perfectly reproduce a sampled bandwidth limited signal you need an infinite tap length filter. Using conventional filters (about 100 taps max.) would have severe timing problems. Via the WTA, the missing timing is reconstructed by the interpolation filter.”

In its day the DAC64 presented in a stunning way. Not only did it look like nothing else around, it sounded uniquely different. It had a musical fluidity that I hadn’t heard from any other DAC at that time; the sound just seemed to flow along like a fast moving stream. It is lucid, cohesive, spacious, agile and dextrous. Compared to leading digital sources of the day, like the DAC section of the Meridian 808i, the Chord was a revelation, seeming so much more natural and effusive. Tonally too, it was a surprisingly warm performer – in many ways not too dissimilar to high end analogue in its sumptuously padded yet articulate low end and a smooth, sophisticated treble that seemed just a touch rolled off at the very top. Bass was particularly fulsome and tuneful when driven by a high end CD transport, such as an Esoteric P30 or Sony CDP-R1. The DAC64 also gave the sort of instrumental timbre that I’d never quite heard from digital before.

Nowadays, the Chord DAC64 still sounds very impressive, albeit in a slightly opaque and romantic way. Subsequent Chord DACs – also done by Watts but using more processing power – sound faster, tighter and punchier. But still the ’64 has real charm and that lovely musical flow. When new it sold for a shade under £3,000, which was an amazing bargain then, and nowadays they’re on sale for £800 or less – if you can live without USB functionality, it remains brilliant value for money.

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