When Tim de Paravicini set out to design the DACute, I’m fairly certain that he sought to maximize its analog footprint. After all, analog is his métier. In fact, he freely admits to trying to equate digital performance to good analog practice, the payoff being that smooth and soothing sonic sensation analog tape and vinyl provide so well. Take, for example, the DACute’s DAC chip, a Wolfson WM8741 multi-bit delta-sigma DAC. It’s a high-performance stereo DAC designed for audio applications. It supports PCM data-input word lengths from 16-to 32-bits and sampling rates up to 192kHz. The folks at Wolfson included a smorgasbord of features such as fine resolution of volume and soft-mute control, digital de-emphasis, and a range of advanced digital filter responses. The digital filters include several selectable roll-off and performance characteristics. Tim’s approach was to minimize use of the internal digital filters. Because they cannot be totally bypassed, he set them for the highest frequency point and then implemented analog LC elliptic filters for 3dB down at a frequency of 40kHz.
This is the sort of analog filter Tim has always used on analog tape recorders for bias and other ultrasonic-noise filtering. An LC elliptic filter is rather economic in terms of parts count for a given slope, but does produce a nonlinear phase response over its passband. In Tim’s view, the filters “are quite good as far as phase response is concerned over the audio band to about half an octave away from 3dB down, so up to 20kHz is more than good enough for me.”
According to Tim, all these DACs by Burr-Brown, TI, Wolfson, or whomever produce significant high-frequency (HF) noise. Tim believes that it’s important to filter out HF hash lest these artifacts upset some amplifiers and tweeters. However, he still requires that response at 20kHz be within 0.1dB of the midband and frowns on the practice of rolling off the top end for so-called sweetness.
The DACute uses a Cirrus SPDIF receiver and accepts up to 24/192 digital data from USB, coaxial SPDIF, and TosLink SPDIF inputs. After passing through the analog filters, the signal is fed to a line preamp stage that is configured like a single-ended amplifier. A 6922/ECC88 twin triode is used per channel. The two sections are cascaded with the second stage being transformer coupled. The output transformer incorporates two secondary windings, one of which provides unbalanced and the other balanced output. A tertiary winding provides some feedback. Maximum output is said to be 5V into 500 ohms with reasonable distortion figures.
Tim says that he’s not interested in vanishingly low distortion levels at max output since “we hear best the stuff that goes on at lower levels, just where many digital systems fall down.”
Dan Meinwald, the U.S. EAR distributor, sent along a pair of Philips JAN 7308 tubes, of which he is fond. And I have to agree; the Philips sounded gorgeous in this application and represents a big step up from the stock 6922. Needless to say, it didn’t take me long to make that call, and the Philips was used for the remainder of my listening tests. There’s not much to say about the motorized volume pot, except that I found the remote control a bit touchy to adjust and, as with other such volume controls, difficult to set to reproduce a particular volume setting. The presence of a volume control combined with an exceedingly low output impedance of under 60 ohms make it possible for this DAC to directly drive a power amp. However, should you desire to go through a preamp, simply set the volume control to about 2pm and let the preamp do the rest. Of course, one would expect some loss of immediacy when the signal is made to pass through two volume controls, and I can confirm that the most transparent soundstage to be had was with the DACute directly driving a power amp.
The fact that the output stage is tube amplified and transformer coupled is quite significant. In my experience, a DAC or CD player’s output stage plays a major role in its overall sound quality. Quite frequently this boils down to the mitigating effects of tubes versus transistors. Call it heretical or even anachronistic, but in my view digital wants tubes—digital needs tubes. Tubes are the requisite “cavalry” to the rescue with a dose of textural warmth and liquidity. Even in the highest echelons of high-end audio, the presence of a solid-state output buffer or gain stage often makes for a double whammy—digital crispness aided and abetted by solid-state tonal-color blindness that makes toast out of musical textures. And it’s that sort of a sorry combination that has pushed many discerning listeners away from digital sources and back to vinyl and analog tape. I’ve been advocating for many years the insertion of tubes, as early as feasible, into a digital front end as a means of controlling digital nasties. And that’s exactly what Tim has done, and it’s also the basis for ModWright Instruments’ modification of the Sony XA-5400ES SACD player.
At the heart of Dan Wright’s Truth Mod is a 6SN7-based output stage, which replaces the op-amp-infested stock analog stage. Not only that, but the tube stage is powered by an external high-voltage tube-rectified power supply. The Sony looks a bit odd with a couple of 6SN7 triodes sticking out of its top deck, but it has been a staple in my reference system for several years now. It really is that good. Naturally, I was curious to see how the DACute stacked up against my modified Sony. This comparison played out with the Sony acting as a transport for the EAR DAC, connected to one of its SPDIF inputs. Since both units are tube based I expected some common ground, especially when it came to imaging performance.
And while that, indeed, was the case, the DACute outperformed the Sony/Truth Modification in several areas, at least in the context of a high-efficiency speaker being driven by the Triode TRX-M300 monoblocks. It was capable of finer modulation of harmonic colors, the Sony sounding slightly more grey and less saturated. The boogie factor, the rhythmic drive that propels musical lines forward, was also enhanced. That coupled with exceptional resolution of dynamic contrasts made for a vibrant presentation packed with dramatic tension.
Harmonic textures ebbed and flowed with a natural edgeless fluidity and a heightened sense of purity due no doubt to freedom from digital hash. And all the while the DACute shone a light on low-level detail. But there was nothing forced about its presentation. Much like ripples in a pond, detail dotted the fabric of the music—a far cry from the surreal hyper-etched presentation being accepted by some audiophiles today as music. No sir, that’s not what the real thing sounds like.
Another comparison I was eager to try was with April Music’s Eximus DP1 DAC/preamp. The DP1 packs a fantastic DAC and a high-quality op-amp-based analog stage. This was to be a classic confrontation of tubes versus solid-state. Not surprisingly, the DP1 bettered the DACute in the areas solid-state designs have traditionally excelled in—at the frequency extremes. The DP1 exhibited a tighter bass range and was subjectively more extended on top. However, it lacked the smooth grainless textures of the EAR, which in the case of the DACute turned out to be a package deal. Much like red hair and freckles, the smoother textures and diminished top end came bundled with slightly softer transients. As a result, the EAR came across as a kinder and gentler purveyor of music, while the DP1’s crisper presentation was the more impressive and was responsible for an enhanced sense of soundstage transparency. In the end though, the DACute’s tube attributes shone through and won me over with a wonderfully palpable presentation that shimmered with dynamic energy.
That finally brings me to the DACute’s USB input and the subject of computer audio. Early this year I fell though the rabbit hole into the wonderland that is high-end computer audio. Actually, it was a deliberate move designed to take advantage of a technology that in the span of just a few years sprouted from infancy to a relatively mature state. In particular, I was intrigued by the possibility that 44.1kHz/16-bit files streamed off a computer hard drive could be reproduced with less jitter and greater fidelity relative to what even an expensive CD player or transport is capable of. The core of my computer audio system consists of a Mac BookPro laptop with 8GB of memory and a solid-state hard-drive running Sonic Studio’s Amarra Version 2.5 music player software. From my perspective, Amarra’s integration with Apples’ iTunes, support for up to 384kHz sample rates, memory cache playback, and playlist mode make it a clear winner. But that’s not the whole story. I found it essential to avoid using the Mac’s onboard DAC for clocking the datastream. The cleanest solution was to synch Amarra to an external digital data converter with an asynchronous USB input. Not all CD players or DACs possess a USB input and some of those that do, as is the case with the DACute, do not offer an asynchronous USB capability. My converter of choice was and still is April Music’s Stello U3 ($495). The U3 is a stand-alone device, powered directly by the computer’s USB port, that runs a custom xCORE 32-bit/500MIPS microprocessor from chip-maker XMOS. The Mac-to-Stello USB connection was made via a 1.5-meter Audio-Quest Carbon USB cable. The U3’s output was connected to one of the DACute’s SPDIF inputs via a 1-meter coaxial cable.
This system combined to produce an exceptional virtual transport. I was startled by my findings when comparing computer files ripped onto the Mac to the same CD’s digital feed from the Sony to the DACute. I didn’t expect much of a diference, but for the record, the computer file playback resulted in enhanced microdynamic shadings, purer textures, and an increased sense of transient clarity. The sound quality of the playback was so fabulous that I seriously doubt that any conventional transport under $25k could improve on it.
The next round of listening tests pitted file playback through the Stello U3 against a direct feed from the Mac to the DACute’s own USB input, the latter connection being made via an Audio-Quest top-of-the-line Diamond USB cable. Re-clocking the data through the Stello U3 made for a huge sonic difference. Simply put, the direct USB input resulted in loss of spatial integrity. What was a cavernous depth perspective flattened out considerably. What was precise image focus became diffuse. With the U3 in the chain, massed strings never sounded so pure and refined. Numerous complaints I’ve lodged in the past about digital reproduction of string tone being adulterated by an upper midrange hardness were now ancient history. The moral of the story is this: For best results, avoid the DACute’s USB input and resort to using an external asynchronous data converter.
If I were in the market to purchase an external DAC right now, the EAR DACute would be at the top of my shopping list. It’s mission accomplished for Tim de Paravicini, who has managed to reveal digital’s analog persona in convincing fashion. The DACute is a fantastically compelling DAC that has restored my faith in digital audio.
SPECS & PRICING
DAC chip: 24-bit, multi-level delta-sigma conversion
Inputs: USB, two 75-ohm coaxial SPDIF, TosLink optical SPDIF
Output level: 5V RMS
Tube complement: Two ECC88/6DJ8
Output Impedance: < 60 Ohms (balanced or single ended)
Weight: ??? lbs.
Dimensions: 435mm x 95mm x 320mm
Price: $5895 in black finish, $6595 in chrome
Huntingdon, Cambridgeshire England
+44 (0) 01480 210004
EAR USA (U.S. Distributor)
MartinLogan Summit X and Acoustic Zen Crescendo loudspeakers, Basszilla Platinum mk2 DIY loudspeaker; April Music Eximus DP1 DAC/Pre and Stello U3 digital data converter, Sony XA-5400 SACD player with ModWright Truth modification; FMS Nexus-2, Wire World, and Kimber KCAG interconnects; Acoustic Zen Hologram speaker cable; Sound Application power line conditioners
By Wayne Garcia
Although I’ve been a wine merchant for the past decade, my career in audio was triggered at age 12 when I heard the Stones’ Get Yer Ya-Ya’s Out! blasting from my future brother-in-law’s giant home-built horn speakers. The sound certainly wasn’t sophisticated, but, man, it sure was exciting.More articles from this editor
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