dCS Rossini Player & Rossini Clock

It has been 20 years since I first became aware of the British company Data Conversion Systems, which manufactures audio products under the dCS brand. Rather than use off-the-shelf conversion chips, the groundbreaking dCS Elgar D/A converter, which I reviewed in our July 1997 issue, featured a then-unique D/A design that they called a Ring DAC. This featured a five-bit, unitary-weighted, discrete DAC running at 64 times the incoming data's sample rate—2.822MHz for 44.1kHz-based data, 3.07MHz for 48kHz-sampled data and its multiples—with upsampling and digital filtering and processing implemented in Field Programmable Gate Arrays (FPGAs). Oversampling to a very high sample rate allows the word length to be reduced without losing resolution, and use of a low-bit multi-bit DAC makes for very high accuracy in the analog voltage levels that describe the signal. (If this seems like voodoo, for a given signal bandwidth, bit depth and sample rate are related. To oversimplify, double the rate, and you can reduce the bit depth by one bit while preserving the overall resolution.)

dCS followed the Elgar with other models of D/A processor and SACD player, all using variations on the original Ring DAC, until 2012, when the company launched the Vivaldi series—D/A processor, SACD transport, upsampler, and master clock—based on a comprehensive revision of the concept, and which Michael Fremer reviewed in January 2014.

The earlier Ring DAC used quad latches (a circuit element that can be instantaneously "flipped" between two stable states) to select current sources based on metal-film resistors. The new Ring DAC design still included high-speed latches and precision metal-film resistors, but instead used 48 individual latch chips said to eliminate between-latch, on-chip crosstalk, resulting in lower jitter. A pair of high-speed, software-updatable FPGAs replaced the earlier models' mapping ROM chips, which allows individual errors in the DAC's current sources to be randomized, which was claimed to reduce the level of distortion and spuriae by 3dB.

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The Vivaldi components are expensive—the SACD Transport costs $41,999, the DAC $35,999—so it was welcome news to see, at the 2015 Rocky Mountain Audio Fest, the introduction of the somewhat less costly Rossini models, which also use the new Ring DAC. The line comprises the upsampling CD/Network player ($28,499), an upsampling D/A processor ($23,999), and a master clock ($7499). As Michael Lavorgna had reviewed the Rossini DAC and the Clock for our AudioStream site, I asked for a sample of the Rossini Player to review (footnote 1). It arrived accompanied by a sample of the Rossini Clock.

Rossini Player
Superficially, the Rossini Player resembles the dCS Puccini SACD player ($18,999), which I reviewed in the November 2009 issue, along with the matching U-Clock ($5499). But while the Rossini doesn't play SACDs, it accepts digital audio from external sources via: a USB Type B port; two AES/EBU ports that can be used singly or in parallel to handle DSD data from a dCS Vivaldi, Scarlatti, or Paganini SACD transport; a TosLink input; and two S/PDIF inputs, one on an RCA, the other on a BNC jack. A USB Type A port accepts a thumb drive so that audio files stored on the drive can be played, and an Ethernet port permits audio files stored on other devices on the network to be played, as well as music from online streaming services Spotify, and Tidal, and from Apple devices via Apple's AirPlay. File formats supported include all major lossless PCM codecs up to 24 bits sampled at up to 384kHz, plus DSD in DoP format and native DSD up to DSD128. The only format it doesn't support is 32-bit floating-point WAV, which Pro Tools now works with.

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As with earlier dCS players, a standard feature of the Rossini is upsampling to the DSD format, and it adds selectable DXD upsampling (PCM at 352.8kHz or 384kHz) as an option. Like the Vivaldi, the Rossini offers a choice of reconstruction filters; Filters 5 and 6 operate at 44.1kHz and 176.4–384kHz, while Filters 1–4 work at all sample rates from 44.1 to 384kHz. From the manual: "Filter 1 offers the sharpest cutoff, least Nyquist imaging but longest energy smear. Filter 4 gives the gentlest rolloff (usually with significant Nyquist imaging) but the shortest transient response with least energy smear." The four filters available for DSD playback progressively reduce the level of ultrasonic noise.

The front-loading CD mechanism is the Stream Unlimited JPL-2800 SilverStrike. The Rossini's Ring-DAC analog board is claimed to be the fifth generation of the one originally designed for the dCS950 Pro DAC and is the same as used in the Vivaldi line. The power supply features separate transformers for the digital and analog sections, and multistage voltage regulation.

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The panels of the Rossini's enclosure are machined from aerospace-grade aluminum, with internal damping applied to reduce vibration. The front panel echoes the "wave" contouring first seen on the Vivaldi, but in simpler form. A rectangular display to the left of the CD drawer shows source, file, and setup information; when the volume is adjusted either with the app (see later) or with the control on the other side of the drawer, this changes to a large numeric display in dB that can be seen from across the room.

Rossini Master Clock
The Rossini Player can be used by itself or with one of the dCS Master Clocks. The two word-clock inputs on its rear panel are on 75 ohm BNC jacks; one accepts a 44.1kHz TTL-level signal, the other 48kHz. These inputs use a multistage Phase Locked Loop (PLL) system to minimize jitter. The Rossini Master Clock can output to the Rossini Player's word-clock inputs, via two short lengths of coaxial cable, both 44.1 and 48kHz clock signals. The Player is then set to auto-clocking mode ("W" on the Player's display), so that each family of sample rates—44.1, 88.2, 176.4, and 352.8kHz, or 48kHz and its multiples—is decoded using the appropriate master clock.

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dCS says that the Rossini Master Clock uses a microcontroller to ensure smooth frequency correction as the temperature changes, this approach claimed to give "a more stable result than either oven-controlled crystal oscillators or even atomic clocks."

I don't need to be convinced of dCS's philosophy of using an external word-clock generator. In 2005 I reviewed the dCS Verona clock, then priced at $6995. With the Verona clocking dCS's Verdi SACD transport and Elgar Plus DAC, I wrote: "there was an authority to the sound that I didn't remember from the system pre-Verona." Without the Verona the "sound was the same, but there was less 'there' there . . . the soundstage was slightly less developed, and the sense of images of musicians and a vocalist hanging there in the space between and behind the loudspeakers was slightly diminished."

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Like the Verona, the Rossini Clock offers the choice of applying to its clock signals dither—a small random timing offset—this selected with two front-panel buttons. Dither avoids the "dead zone" that receivers using a PLL with a very narrow acceptance window can suffer from. I had no problems using the Clock without dither, but ended up leaving it switched on. I'm a belt-and-suspenders guy.

Rossini App
Perhaps as important as the technology used in the Rossini hardware is the fact that every function of the Rossini Player can be controlled with an iOS app. And not only such regular functions as source selection, CD transport controls, and the choices of reconstruction filter and upsampling, but selecting files to be played from a USB stick or, via the UPnP interface, files on any network devices running a UPnP server software. The Rossini app also features a configuration wizard to allow easy setup of a Rossini Player or DAC.

I began my auditioning using v.1.1.8 of the app, then a beta version of the upgraded version, v.1.2.3, which includes Roon endpoint integration as well as some unspecified enhancements. I loved the app. My only criticisms are: 1) With the app that controls the Aurender N10, I've gotten used to the music fading down when I press Pause. With the Rossini app, the music stops immediately. 2) The volume-control icon on my iPad mini is a bit too small for my fat fingers to repeatably set the level. I know—First World Problems!

Listening
The first matter to address with the Rossini was which upsampling algorithm to use. In general with CD-sourced music, I preferred the DSD upsampling, which slightly increased the sense of spaciousness of the soundstage. But some hi-rez rock recordings—such as "Under Pressure," from Ray LaMontagne's Pink Floyd–tinged Ourobouros (24/96 FLAC download from RCA/PonoMusic)—sounded a little less aggressive in the treble with DXD upsampling. This was with Filter 4 (see later).



Footnote 1: I actually ended up with two samples of the Player. I began with the first sample (serial no. '51423), but continued with a second sample (serial no. '52118) when dCS discovered that the first sample had a minor manufacturing fault that had affected the first five units to come off the production line.
COMPANY INFO
dCS (Data Conversion Systems), Ltd.
US distributor: Data Conversion Systems Americas, Inc.
PO Box 541443
Waltham, MA 02454-1443
(617) 314-9296
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COMMENTS
Axiom05's picture

I have come across several 24-bit files that are identified as 32-bit in Soundirok, the iPad app that I use as a client for mpd. No idea why.

Panagiotis Karavitis's picture

Known issue, the first 8 bits are null, files are indeed 24bits

Joao1's picture

JA - thanks for the detailed review. Are the Shunyata Research Dark Field cable elevators part of your regular system, or are they being tested? Good results?
Thanks.