dCS Rossini Apex D/A processor

The textual content, from Gary Bruestle, a speaker-positioning wizard at Definitive Audio in Seattle, left my mouth watering: “Have you listened to the Apex variation of a Rossini or Vivaldi still? It really is stunningly good. Addictive, even. … I normally have a hard time calming and listening to audio in the showroom, but the Rossini Apex DAC experienced me in its thrall for a couple of several hours yesterday.”

Before long thereafter, I listened to from Peter McGrath, Wilson Audio’s director of revenue, that he was blown absent by the audio of his dCS Vivaldi Apex DAC—the flagship DAC from Info Conversion Devices (dCS) of Cambridge, England. Nor was dCS precisely shy when it proclaimed, in its March 3, 2022, press release, that the Apex edition of its Ring DAC was “using the Ring DAC’s environment-top efficiency to a new degree.”

When Gary advised me, for the duration of the cellphone chat that followed his text, that he considered the Apex DAC elevated the Rossini’s bass response to that of the Vivaldi, I sat up in my seat. For the year the prime-of-the-line Vivaldi DAC sang in my procedure, I reveled in its expansive soundstage, bigger, weightier, extra lifelike photographs, and excellent presentation of texture, overtones, and bass. It obtained me as near to the are living-effectiveness expertise as I could get with medium-size floorstanders in a medium-dimensions listening area. Might the Rossini Apex be capable of transporting me as close or nearer?

My opportunity to discover out came just a couple months afterwards, when a Rossini Apex DAC arrived for assessment. But ahead of I began my audition, I sought to clarify what was heading on within the DAC’s chassis.

The Ring DAC foundation
In a YouTube video clip titled dCS—The New Ring DAC Apex (footnote 1), Chris Hales, dCS’s director of item development, claims, “With the Ring DAC, we’re sitting somewhere in the sweet spot amongst complete [voltage] precision and timing precision.” The preference of filter—the Ring DAC consists of six for PCM, 4 for DSD, and just one for MQA—determines where by you sit in that fragile harmony. In a stick to-up e mail, Hales famous, “Although the filter preference can impact the listening knowledge, it doesn’t have an affect on the operation of the Ring DAC alone, which stays incredibly linear whichever filter is selected.”

dCS’s specialized director, Andy McHarg, whose vision drove the Apex project, claimed that creating the new Apex Ring DAC components necessitated inspecting just about every component of the technologies to see what could be improved. “Marginal gains mount up in excess of time,” he states in that movie (footnote 2).

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The Apex edition of dCS’s Rossini and Vivaldi methods is dependent on a reconfigured Ring DAC circuit board with an all-new analog output phase. The obstacle dCS confronted as it produced the Ring DAC Apex, Hales stated, was the inability of typical exam devices to evaluate the Apex’s general performance values with ample precision. In an e mail, dCS VP of Gross sales and Advertising and marketing John Giolas wrote, “the linearity of our DACs is so [much higher than] the sector norm, we have experienced to develop our personal examination tools to measure it. Traditional examination devices is wholly inadequate to measure what our DACs are capable of.

“Audio measurement methods [can] introduce sound, or distortion, or limit the frequency reaction, just like the thing they’re striving to evaluate, and there can come a point in which, even if they are not dominating what you might be measuring, these artefacts are influencing it one way or a further.”

Hales discussed, “A superior illustration is when measuring harmonics, exactly where the 2nd harmonic inherent in the take a look at equipment can cancel the 1 in the product you might be making an attempt to measure. This can final result in a measurement that is substantially lessen than [what] it really should be, a person which tends to behave unexpectedly as the functionality of the item less than exam is modified” (footnote 3).

Giolas corrected a handful of misconceptions about the proprietary Ring DAC technology uncovered inside all dCS goods. dCS commenced to produce the Ring DAC more than 3 decades back and was the first corporation to supply a electronic-to-analog conversion procedure that could approach audio alerts at 24-little bit resolution.

“It is not fully intuitive to quite a few audiophiles that the Ring DAC is an analogue system,” Giolas wrote. “In all dCS DACs, the Ring DAC architecture is discrete and analogue. It consists of a resistor array, a voltage regulation bus, and a buffer/output attain phase that connects to the preamplifier or energy amplifier (among the many other matters)” (footnote 4).

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Hales elaborated in an email, “On the floor, the Ring DAC could seem like a Ladder DAC. There is a latch and a resistor for each individual present supply, and these present sources are fed to a summing bus. The important big difference between the Ring DAC and Ladder DACs … is that the Ring DAC makes use of present-day resources of equivalent value. This is what is recognised as a ‘unitary-weighted’ or ‘thermometer coded’ DAC architecture.

“On top of that, the Ring DAC does not use the same present source(s) for the exact little bit each and every time.” (The emphasis is Hales’s.) There are 48 current resources within the Ring DAC, all of which produce an equivalent total of current. The Field Programmable Gate Array (FPGA)–controlled mother nature of the Ring DAC enables the sources to be turned on and off in this kind of a way that any component price faults are averaged out over time. Firing the identical little bit 3 moments on the Ring DAC might give just one output a little large, the next a bit small, the next someplace in the center, as opposed to outputting the sample marginally high just about every time or a little bit lower every single time (as seen in a Ladder DAC, for example).

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“It requires a significant total of sign-processing ability and know how to optimally operate a thermometer-coded DAC, but the reward with this strategy is that it virtually completely eliminates the linear distortion from the sign. (Bear in intellect that the remarkably artificial distortion numerous DACs produce is pretty recognizable to people and has a detrimental affect on perceived sound high quality.)

“The Ring DAC procedure might be believed of as decorrelating mistakes. History sounds (an uncorrelated mistake, one which is not connected to the audio signal alone) is quite common in character, whilst artificial distortion (a correlated error) is not. This success in the Ring DAC possessing class-foremost distortion effectiveness, notably at reduced sign stages. This implies that more good musical detail can be settled and listened to.”

Giolas took it from there: “The dCS Digital Platform (DDP) instructs the Ring DAC which resistor ‘latches’ to convert off and on via a dCS-intended computer software procedure we get in touch with the ‘mapper’. Its complex quasi-randomization accomplishes this in this sort of a way that any element benefit faults are averaged out, vastly improving upon linearity around ladder DACs and other conventional DACs.” dCS experienced formerly tackled and improved its mapper technological know-how in 2017, when the Rossini 2. improve presented a choice of new or legacy mapping algorithms. David Steven, controlling director of dCS, observed by electronic mail, “The mapping course of action is very important to the performance of the DAC and is done in programmable logic (FPGA). As we enhance it, we can update the functionality of units in the field (eg, most just lately with Bartók 2.). The Apex components variations get whole advantage of and establish on the superior-speed mappers that had been installed in the course of the 2. computer software update to the Ring DAC.”

“The new Ring DAC Apex hardware features various modifications,” Giolas ongoing. “The reference offer that feeds the Ring DAC circuit board was a single of the to start with regions that dCS engineers appeared at all through the study and growth period. Their investigation led them to make some major adjustments and enhancements. The engineers also extensively modified and enhanced all subsequent stages of the Ring DAC, like the summing and filter phases. The Ring DAC output phase accountable for buffering the analogue signals produced by the Ring DAC was redesigned (footnote 5). Other variations to the Ring DAC’s hardware bundled changing unique transistors on the Ring DAC circuit board with a compound pair, thus strengthening symmetry and linearity, and changing the structure of factors on the Ring DAC circuit board. The outcome of these numerous variations is a new, enhanced analogue board that is quieter than prior iterations and around 12dB additional linear in the second harmonic.”

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Set up
I positioned the Rossini Apex DAC on a shelf less than my reference Rossini DAC, the two DACs resting on Wilson Audio Pedestals. A Stromtank S 1000 battery ability supply provided electricity by way of Nordost Odin 2 cables. A Rossini Quality 1 master clock ($10,200), which I contemplate critical for exceptional playback, paced both of those DACs. Settings on equally units had been equivalent: mappers (Map 1), filters (F5 for Crimson Guide, F3 for 24/88.2 up to 24/192, F6 for bigger PCM resolutions, F1DSD for DSD, and M1 for MQA), voltage output (2V, footnote 6), and upsampling format (DXD). I soon found that my preference for the Map 1 mapper stays unchanged with the Rossini Apex DAC I discover it richest in shade saturation and contrast.


Footnote 1: See youtu.be/tZEKEYniLTo. John Giolas and Rachael Steven executed the interviews and collaborated on the story and enhancing.

Footnote 2: A identical sentiment was expressed by Nuno Vitorino, director of research and enhancement at Innuos, who wrote in an e-mail to me and Editor Jim Austin, “It really is the sum of a pretty big number of little enhancements on the supply that stop up delivering a quite audible advantage.”

Footnote 3: Much more in depth details about Apex technological innovation can be located at dcsaudio.com/edit/apex-a-closer-glance.

Footnote 4: For additional on the dCS Ring DAC, see dcsaudio.com/property/dCS-Ring-DAC-Discussed.pdf.

Footnote 5: In accordance to Hales, “The objective of the output stage is largely to interface us to what is unidentified territory after we depart the dCS realm. We seriously don’t have much regulate over what cables men and women are likely to connect, what exterior devices persons are likely to link, and these can have quite various enter properties, so it is really significant to have an output stage which is capable of driving plenty of existing, which is not sensitive to balance troubles that these may perhaps induce. … The resolution, then, is to isolate the summing phase from the outside world so that we can optimize the effectiveness of the summing phase and push the enormously uncertain masses that cable and amplifier combinations can existing.”

Footnote 6: Listening checks executed decades back discovered that, to my ears, Rossini’s 6V output delivers the most colourful and engaging seem. But considering the fact that some preamps and built-in amplifiers that arrived for critique couldn’t take care of 6V, I reluctantly switched to 2V. Then, while making ready the specs for this review, I noticed that specified residual sounds levels are lowest at the 6V output. With this affirmation for my 6V preference, it truly is now again to 6V.

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