Network Bridge DSD to PCM

Hi, I am auditioning a new DAC in my system, which is connected via AES to my DCS Network Bridge. The DAC does not support DoP and requires a USB connection in order to play native DSD, which of course the Bridge does not have. However all is good through AES except for a low level hiss when playing DSD. I have tried every setting and found that the the lowest noise is achieved with the Bridge set to down convert to 96K on the AES output. My question is why the hiss if the Bridge can convert DSD to PCM for use with legacy DACs? Is it that the DAC must support DoP on its AES input in order for it to work correctly?

No this is not the case. Network Bridge was designed to provide additional connectivity to legacy dCS units. Not only is it not necessary for the DAC to have DoP via AES, none of the legacy dCS DACs have that themselves. In fact the first generation of DCS products were made before DoP was even invented.

As Network Bridge was not designed for use outside of the dCS family of products the successful use of it with other components is unpredictable. You have not provided any information on this new DAC so it is not possible any other users of this combination to comment.

Your post describes a new DAC. So presumably you were using Network bridge with another DAC before? If Network Bridge operated correctly with the previous one it is reasonable to conclude that this new DAC has a faulty or poorly implemented AES input.

Thank you for such a quick response Pete. You have echoed my understanding but if the Bridge simply outputs standard PCM I’d like to understand what is generating the hiss since the DAC plays all formats other than DSD perfectly.

The DAC is an AM (Audio Music) but it’s very new and from a boutique manufacturer so there are almost none in existence. It accepts native DSD on USB input and does not support DoP but the Bridge does not provide a USB output. Any idea why the hiss? It’s far worse when downsampling to 192 BTW. Out of curiosity are there any plans for a USB output in the future?

As the DAC is a boutique product and as a properly operating Network Bridge will not produce hiss when converting DSD to PCM my suspicion lies with the DAC manufacturer who would be my first port of call about this issue. dCS have been part of the DSD story since the beginning, for example being Sony’s expert partner which engineered the packing of DSD data for CD. They also invented DoP. They do not make cock-ups in this area.However it is feasible that your Network Bridge may be faulty so I wouldn’t overlook this if you are unsuccessful at the DAC end of things.

There is a statement somewhere in FAQs or in the archives about why there is no USB output on Network Bridge. In short DCS engineers found the basic engineering of the USB output did not meet their standards and were dismayed that other companies were prepared to fit such a thing. They spent some time and money trying to re-engineer it but realised that the problems were so fundamental that they were not prepared to invest in any further re-engineering.

So, no, there will not be any USB output for Network Bridge. In fact there will not be any further development of Network Bridge as dCS had to discontinue making it last year due to rising costs and the unavailability of parts. Of course you will still get service support.

Hi there,

DSD, especially DSD/64, has a high level of quantisation noise. This will be present even if the system is converting to PCM to allow it to be transmitted to your DAC. So, the equipment which is connected to the Network Bridge here, such as the amps, or potentially the DAC output stage, may not get on well with the level of noise. This will be especially true for certain DAC types.

I must admit I am struggling to find any info on the AM DAC, though that may be a lack of digging far enough into Google results on my part! Any info you can give on the DAC, such as what filtering it uses or for example if it is a non-oversampling DAC, would be helpful in explaining where this noise is coming from.

I appreciate that it likely is already turned off from what you have said, but could I ask you to double check that DSD Downsampling is definitely turned on on the Network Bridge? If not, and DoP from the Network Bridge is played as PCM by the DAC, the result will be music, but with a lot of hiss (at -48dB).

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Thank you for your response James.

I checked my settings this morning and it confirmed my recollection that for some reason turning DSD downsampling on or off makes no difference. From what you said I concluded that this setting turns DoP on and off so this makes no sense as my understanding is that the AM DAC does not support DoP.

More confusing is that the hiss had all but disappeared this morning except for one album out of about twenty that I played, each of which previously exhibited the noise to a greater or lesser extent. Both DSD64 and DSD128 played with no more hiss than one might hear from a good analog master tape, which has never happened before. Thank goodness I previously recorded some tracks with significant hiss or I’d be questioning myself now.

I too thought that the issue had something to do with quantitisation but now I’m not sure. Unfortunately the DAC is so new that virtually no information exists. It is an extremely well built two box unit (seperate PSU) and has very few settings, the only significant one being DSD2, DSD4 and DSD8, which I assume are used to upsample. None of these settings make any difference to the level of hiss.

I have an engineering background but have to admit that digital is not my fortaight. However such variability makes no sense to me. I could happily live with things as they were this morning but I know it won’t last …weird.

To recap, by far the best setting on the Bridge is downconverting AES to 96K, with no difference whether DSD downconverting is on or off.

BTW, I love the Bridge!

I also hold the dCS Network Bridge (NWB) in high esteem! I have used in my system since autumn 2019 and I still think it is the best streamer out there. I am right now enjoying listening to an album from Qobuz (Joe Henderson: Ballads and Blues in CD quality) via ethernet to NWB, then via S/PDIF rca to my headphone amp (Focal Arche) to my Sennheiser HD800S. Excellent sound quality!

I have connected several non-dCS dacs to the NWB – via AES and via S/PDIF. I have tried to force dacs to receive DSD files but have found it best to use the dacs only as PCM dacs capable of playing maximum 24/192 files.

This means I set the NWB in Mosaic to the values you will find on page 12 in the manual. Downsample DSD and PCM to the level of your dac – in my cases 24/192.

One dac – the original Musical Fidelity M6 dac – sounded the best via AES (110 ohm cable) from NWB to M6dac, the others I have tried work best via RCA 75 ohm cable from NWB to dac.

I have compared SQ of music played this way to music played via USB from laptop (Win11 with Fidelizer Pro) and still prefer the NWB to handle the first steps in the process.

Thank you for the additional information.

Would it be possible for you to take a screenshot of the settings page in Mosaic for the Network Bridge, with DSD Downsampling etc.? It would be very useful to see exactly what is going on in the settings, as I believe there may be something we are missing that is causing this issue to occur. A screenshot should allow me to see exactly what is going on the dCS end!

Here you go James, hope I have it right. I listened for some time again yesterday and the hiss has remained low. I’d really like to understand the improvement as it’s definitely not in the settings. Now I only have one or two DSDs that are objectionable.