High Fidelity

ong time ago when I tested the DSS 30 back in 2008, a product of the Italian company Bluenote (now Gold Note), I did not know how to name it. Company’s material referred to the Digital Static Source (DSS), a solid-state memory player. Today I would say that it was an audio files player (playing music from thumbdrives and HDDs connected to USB inputs). In spite of the nine years that have passed since then, this type of product still has no one common name. Manufacturers are usually disoriented by it, but from time to time someone is making a use of it and calling their product in a really interesting way. One of the latest examples is the NETWORK BRIDGE, a product of the British company Data Conversion Systems, known as dCS.

The most commonly used names for such device today are: “streamer”, “renderer”, “server”, etc. These names have been transferred from the computer industry since music file players are in fact specialized computers, and computer users are the biggest proponents of this kind of music source. In the audio industry we use other names, but – I think – there is nothing to argue about, ultimately it is people who decide about such things, simply by using one or another name. But one should know what these names mean.

For the benefit of this test, following “High Fidelity’s” practice, I suggest that we agree that the Network Bridge is an audio files transport. It performs an analog function to the optical discs (CD, DVD, Blu-ray) transports, ie it reads the signal from the storage medium and decodes it into a form understood by the digital-to-analog converter. On one end music files go in, on the other PCM or DSD audio goes out.

A complete source of digital signal based on music files consists of:

• An external storage – a thumb drive, USB disk or NAS or / and a network connection that allows streaming signal in real-time,
• Audio files transport,
• Digital-to-analog converter.

Such system might use separate devices or can be integrated into a single chassis. The most common are audio files players, that is, transport and DAC in a single enclosure to which we attach external storage media or stream files over network (see Lumin). This system can be further integrated by including memory storage device (hard drives, see Aurender A10, in Polish) or even add an amplifier, thus offering a complete audio source (See Lumin M1).

NETWORK BRIDGE

Since the DSSS 30 Tube, that I mentioned at the beginning, a lot has changed, because now – for example – an Ethernet port is an obligatory feature of any player, as it allows user to stream files from NAS (via router) plus allows him to use a control app installed on smartphone or tablet. The most important change, however, is how people listen to music from files. For a long time, it seemed that music was going to be downloaded on a hard drive, either after buying it in online stores or ripping it from CDs. Last year, however, proved that constantly improving download speed (bandwidth of network connections) and the emergence of several important streaming services led to the situation where only hard-core high-enders keep music locally, ie music on their disks, while most listeners move completely into the virtual world of streamed music.

The Network Bridge is supposed to be a “bridge” that connects both streaming and local data carriers to our digital-to-analog converter, and thus the audio system. Although I use the name “transport”, there is no “mechanism” on board and yet, it is “transporting” WAV, FLAC, AIFF, DFF and DSF files as well as those using lossy codecs and decoding them to PCM or DSD respectively. The bridge is UPnP compliant (the company calls it “UPnP renderer”) and it works in asynchronous mode. It comes with Wi-Fi card allowing user to connect his iPod, iPhone or iPad via Apple AirPlay. But it is also compatible with ROON, which opens up new possibilities for users.

ROON

ROON is an application that is used to manage music files stored on a server, that supports supports tagging and provides descriptions, and additionally facilitates an integration of various devices, so called “End points”. Network Bridge is compatible with Roon, so connecting it to a server working with this application significantly simplifies the use of music resources. What’s more, ROON integrates with the Tidal streaming service, facilitating the use of it, enriching the descriptions of tracks, records, artists, etc. Let’s say it: ROON is now a “hot” topic, this name is come up frequently in audio discussions.

The Network Bridge is a small silver or black device with a micro LED on the front panel. One controls it using an appropriate mobile app. From the signal source side, we connect it using a RJ-45 (Registered Jack-type 45) cable to the router. We can also connect a USB drive to it, but in the future this port will be used as an audio output. dCS supports files with music signals up to 24 bits and 384 kHz, and DSD64 and DSD128 in DoP format. If you use a DAC that does not support high sampling rates, dCS converts PCM and DSD signals down to 176.4 / 192 kHz or 88.2 / 96 kHz PCM.

There are three output options. The most recommended is a link based on two AES / EBU (Audio Engineering Society / European Broadcasting Union) sockets, a solution also used by Chord. Dual AES allows transmission of PCM signals up to 24 bits at 384 kHz plus DSD64 & DSD128 in DoP format. However, there are only few digital-to-analog converters on the market able to receive signal in this way. The second option is to use the SDIF-2 interface using two BNC sockets, for left and right channels, and a separate one for the clock, but – see above. So I think that until the USB output is implemented, most user will use the RCA output or a single AES / EBU. In both cases, it will allow the device to output PCM signal up to 24 bits / 192 kHz and DSD64 in DoP.

In the near future, a USB port that we can use to connect an external USB drive will work as a USB output with the same parameters as dual AES, ie PCM up to 24/384 and DSD64&128.

The audio files transport’s (renderer, streamer, bridge etc.) only job is to download signal from an external storage (NAS, USB, Internet), convert WAV, ALAC, FLAC, dsf and dff files to PCM or DSD respectively and send it to an external DAC. That is why I use the term “transport” – it is analogous to CD transport, it is an intermediary between the signal carrier and an external D / A converter.

So it is important both how the PCM and DSD signal is decoded, and what source delivers that signal. In the latter case, it would be analogous to the way of preparing different types of CDs – XRCD, UHQCD, Platinum SHM-CD, Blu-spec CD2, all of which are equivalent to different types of external drives. During the test I used both the Synology DS410j / 8 TB NAS disk and the Liksys WAG320N router as well as the Fidata HFAS1-S10U server / file player. I separate part of the test was performed using files stored on the USB drive connected directly to the dCS.

The hierarchy was clear: the best sound I achieved with Fidata, then Synology, and finally the USB drive. It is therefore worth devoting more than usual time to the proper configuration of the NAS. The dCS distributor, Audiofast, offers such configuration by equipping us with the ROON software.

The dCS transport was connected to the Chord DAVE digital-to-analog converter. Since the Bridge did not output the signal via the USB at the time of this test, I connected it with a DAC using a BNC digital cable with BNC-RCA adapter – dCS features RCA output and DAVE has BNC inputs only. This output allows transmission of PCM signals up to 24 bits and 192 kHz and DSD64.

I used Acoustic Revive LAN-1.0 PA cables with the RLI-1 filters on both ends connect dCS with the Fidata server and router. The Bridge was powered with the Acoustic Revive Power Reference Triple-C with the RSA-14 Triple-C filter and was placed on the top shelf of the Finite Elemente Pagode Edition rack. On top of it I put the Verictum X Block passive filter.

It would seem that – I will repeat what I already mentioned – the players (transports) of audio files should sound the same. After all, their task is to retrieve the signal from an external storage medium, convert the WAV, ALAC, FLAC, dsf and dff files to PCM and DSD respectively and send them to an external DAC. Theoretically, this kind of work should be done perfectly by any computer. In fact, however, the differences between these types of transports are greater than between Compact Disc transports – and these can be awful in some cases and ecstatic in others.

Network Bridge is no exception, it clearly has its own sonic character. And to no surprise, it largely resembles what I know from the Rossini and Vivaldi players, keeping proper proportions in mind, of course. Even using a completely different D / A converter, by simply comparing it to a CD transport and other file players, one could quickly and reliably determine the characteristics of the Bridge’s performance.