Astin Trew Concord DAC 1 digital converter

There are only so many audio engineers in the world, so some names keep cropping up. It’s in the essential nature of the engineering psyche that self-promotion and marketing go against the grain, so these people work away in the background and let others take the credit. But word eventually gets out, and one name that has slowly become known to the cognoscenti is Graham Fowler of Trichord Research. He was behind the clock upgrades sold by Tom Evans and a series of amplifiers for Michell Engineering, including the legendary Iso phono stage. The only full Trichord products are phono stages, the Dino and Diablo, but Fowler still does clock upgrades and is intrinsically linked to the Never Connected power supply technology. Recently, Fowler was commissioned by Astin Trew to develop this DAC’s electronics to their brief, using the Astin Trew hybrid tube single-ended output.

The Concord DAC 1 is an understated visual design. It sports either USB or of Firewire inputs for computer audio, plus S/PDIF coaxial and Toslink optical digital inputs. It also supports I²S, a protocol used for connections within digital components, but one that has never seriously taken off when used between digital components. It has seen a bit of a revival of late, however; Leema Acoustics has used it in its digital product line, and PS Audio has created a standard that at least one other manufacturer has professed adherence to, so it could be set for a comeback. Whether it will match the more familiar
S/PDIF standards is debateable, especially given that you won’t find one on any computer. You will, however, find it on Astin Trew’s forthcoming CD transport; being the first such creation in years, this might well put the I²S cat among the digital pigeons.

Firewire is an interesting option, because for a while it was the connection of choice for serious computer audio. However, it didn’t take off in audio hardware and Apple, which promoted it in the first place, has now dropped it. But if, like me, you have a Mac with this connection, it’s an interesting option. The Concord DAC 1 that I was sent only had USB for computer use so this was duly employed, but much to my and Astin Trew’s bafflement, it only managed to deliver a miniscule signal level when connected to my Macbook Air laptop. Even a replacement DAC failed to change matters, so I borrowed a Macbook from Michael Osborn at Astin Trew for the duration of the review.

The USB receiver is the well-regarded XMOS chip, which requires a driver in Windows set ups but runs to full 24/192 without such deliberations on a Mac. Beyond this is a pair of Burr-Brown PCM1794 converters, run dual-mono style for maximum channel separation. This also allows the option of balanced output.

As Astin Trew correctly points out, power supplies are critical to audio equipment, possibly more so with digital components than analogue. To this end, the Concorde DAC 1 has six separate power supplies with additional regulators for the digital and analogue boards. The first stage of the analogue output is class A, as one might hope of any decent line-level device. This is fed to the hybrid tube stage, which has a 6299 double triode on each channel and provides single-ended output (the balanced outputs are all transistor). Output level is naturally higher with the latter.

Once the aforementioned USB shenanigans were out the way, I was able to appreciate the many qualities that this converter brings to the musical party. For the most part, these were courtesy of the be-tubed SE output, first up was a pop song of all things. ‘Royals’ from Pure Heroine by Lorde  [Universal] has magnificent bass synth on it, but it’s also an entertaining track that doesn’t suffer from too much obvious compression. Here, it was possible to enjoy the texture of the sound and the variations in the synth bass, alongside hard edged percussive sounds. It became clear early on that the Concorde DAC 1 has a very transparent midband; the guitar presence on Paul Rodger’s ‘Muddy Water Blues’ [The Royal Sessions, Savoy] was delivered in very tactile form, but you quickly notice how good the backing vocals are and finally have to admit that Rodgers himself was in remarkable fettle for this session. All of which is underpinned by a solid bass line and full scale sound – one that revives the spirit of the blues rather well for computer-sourced audio. Michael Hedges’ acoustic guitar on Aerial Boundaries sounds cracking as well, with dark, chewy bass lines under sparkling high notes that the full Wyndham Hill polish (it’s classy stuff). After a few more tracks, it became obvious that the DAC digs way down into the mix; its noise levels are clearly low enough to let you hear loads of the fine detail that gives each note depth and body.

While the Concorde DAC 1 was being assessed I took delivery of a Chord Electronics Hugo, a compact and portable DAC that is capable of fighting above its weight. Hugo proved to be faster sounding than the Concorde 1 as a result of better defined leading edges; the transition felt like going from comfy shoes to track spikes. Going back to the Concorde DAC 1 made for a smoother ride however, and one that isn’t too far off in terms of timing. It’s certainly a more relaxing experience, which will suit many. Essentially, it’s a more tubey sound; not as quick perhaps, but with more depth of tone and fine detail.

This result was duplicated with a couple of other converters, including the Metrum Octave II, which likewise was harder and faster but didn’t have the scale, and my regular reference the Resolution Audio Cantata that produced a more definite and engaging sound. So the Astin Trew would seem to fit both its price point and the expectations of a tube output. I also tried the balanced output directly into an ATC P1 power amp, using the volume control in Audirvana Plus software. This gives an increase in dynamics and a sense of torque in some pieces, alongside excellent image depth. The latter is a result of better bass extension and control. However, the Concorde 1’s balanced output does give up some of the finesse available through the single-ended, but with non-acoustic instruments, the extra visceral grip makes for a rather more powerful musical experience.

With Steely Dan’s ‘Your Gold Teeth II’ on Katy Lied [ABC] the single ended output seemed restrained in dynamic terms but revealed an awful lot of inner detail, not least the remarkable guitar work provided by Denny Dias. Via an XLR to SE cable that put the balanced output at a slight disadvantage (in the cable-quality stakes), the balanced output delivered more grunt or low end power in the context of harder leading edges. This brought out the power of Steve ‘the metronome’ Gadd’s drum work, but conceded subtlety, which is what I would expect of the cable change alone. Using the single-ended output with Abdullah Ibrahim’s ‘Barakaat’ [African Suite, Enja] revealed lovely, expansive low end from the double bass and a beautiful sense of ease in the context of an open and dynamic recording. The single-ended output is the better choice for my system, but those with balanced amplification may well have the opposite impression.

Which output will work best also depends on the sort of volume levels you are after; the mellower output will be less fatigueing at higher levels, but the solid state output gives the physical side of the sound at lower levels. Alternatively, it produces even more punch at high outputs. The tube stage isn’t an obvious charmer, which in the short term puts it at a disadvantage next to more colourful designs, but ultimately a more neutral component and will let you hear more music, and that is the aim of the game. The Concord DAC 1 is like a lot of Graham Fowler’s designs – a little understated but capable of delivering long term satisfaction. The fact that this appears to be Graham Fowler’s first tube-equipped creation does not seem to have limited his design skills. You can hear the tube, but only by comparison with solid state alternatives, which means that in normal circumstances you will enjoy the music not the mechanics.

Technical Specifications

• Output Level: 2.6V_rms (RCA) 5.2V_rms (XLR)
• Digital Inputs: RCA, BNC, XLR, Toslink, I²S, USB/Firewire
• Frequency Response: 1Hz to 200khz (+0dB -3dB)
• Valve stage: 2 x 6922
• Power usage: 30W
• Size: 430mm x 120mm x 280mm
• Weight: 7 Kg each
• Price: £3,780

Manufacturer: Astin trew

URL: www.astintrew.co.uk

Tel: +44 (0)1491 629 629

Distributor: Nu Nu Distribution

URL: www.nunudistribution.co.uk

Tel: +44(0)203 544 2338

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