Has anyone used an upsampling DCS Purcell with a Naim DAC?

vintageaxeman posted:

Whoosh! Over MY head at least!!!

i don’t know even if the dcs upsampler can be connected to non dcs dacs, like esoteric or wadia which have their own external  upsamplers  or clocks? 

can an external clock be connected to a dave dac  for example ?    

The problem isn't the clocking, it's the fact that the DCS Purcell has DUAL AES/EBU XLR outputs, one for each stereo channel. I need to combine these and format convert them into a single datastream if I am to put them through my Naim DAC. Otherwise, I have to change my DAC. Any further advice, guys?

Putting Muttonjef and Analog's side discussion on external DAC clocks to one side (possibly one for it's own thread?), I would be cautious using the DCS Purcell  with anything other than other DCS kit as they were designed to be a kind of modular system.  Perhaps consider using it with a matching DCS DAC such as the Delius, or with the Verona Clock and maybe an Elgar. 

p.s. You don't have to use the AES/EBU XLR digital outputs do you?  Aren't there also regular s/pdif outs on RCA and BNC?

With the Naim DAC, the natural upgrade is XPSDR or PS555DR.

The Naim Dac also greatly benefits from a great source and a good SPDIF cable like DC1 or the various Chord Tuned Aray digital cables. The Naim DAC also benefits from a great interconnect like Hi-Line or Superlumina upgrade

There is no word clock input on a Naim DAC.

The Naim DAC is already doing upsampling internally through the advanced SHARC processor it has.

 It's all about the musicality in the end though, not number crunching or upsampling to DSD or whatever various companies do. I would say Naim's first and foremost goal is to get to the heart of the music.

So how does it help to replace a Naim DAC you already like? 

Why not try a Superlumina interconnect or a Chord Tuned Aray SPDIF cable?

These are serious and real game changers, but yes cost serious cash.

I recently heard an Naim HDX vs Auralic streamer into a top of the line Blu2/Dave DAC, and the HDX was clearly audibly superior.

I would have thought a good partner for the Naim DAC would be the new Naim Core source?

CD player is a Krell KPS20i, pushing out 44.1, into my Naim Dac. By using the Purcell upsampler I can up the 44.1 to 176.4 or 192 into the Naim DAV, but ONLY if I can convert the dual AES/EBU format output of the Purcell to SPDIF RCA to go into the DAC. So I’m searching for a way to do 2 things at the same time: 1. Combine the DUAL AES/EBU cables into a single cable, and then 2. Format convert the ARS/EBU to SPDIF RCA.

Why do you feel you need to upsample with the Purcell here?  Upsampling is not without controversy - after all it's another process and doesn't necessarily improve on the source file.  FWIW, for best sound, I don't think Naim recommend upsampling 44.1kHz source files when feeding the Naim DAC.  The DAC itself oversamples - 16 times.  You can read about it here: NAIM DAC White Paper

My Krell CD has analogue outputs (balanced) of course RCA, and digitally it ONLY has an SPDIF RCA output running at 44.1kHz.

The dCS Purcell Upsampler has all the different types of digital inputs (AES, SPDIF Coaxial, SPDIF BNC, and Optical.)

So I connected the SPDIF RCA output of the Krell CD player to the SPDIF RCA input of the dCS Purcell.

I set up the Purcell to recognise the 44.1kHz signal from the Krell, and to upsample it to 176.4kHz OR 192kHz (my choice....very easy to switch the output signal between the two rates and compare)

The Purcell has TWO AES/EBU output sockets, an SPDIF RCA etc etc.  The issue for me was to maximise the Purcell's potential in my system and to maximize my choice. The ONLY output socketry on the Purcell that allows 176.4 or 192 output is if you use BOTH AES/EBU XLR output sockets.  Any other output sockets are limited to 96kHz. I did in fact try the Purcell's RCA SPDIF output straight into my Naim DAC, and it worked like a dream, but I decided to try to go the extra mile and access the higher two rates.

To do this, I was going to take 2 XLR 110ohm XLR-XLR cables from the Purcell into the only format converter that I could find which ALSO had a DUAL AES/EBU input option, and that was an old used Apogee Big Ben that I had for studio purposes.

Once I connected the Krell to the Purcell (upsampler) to the Apogee Big Ben (as a format converter) and fed it into the Naim DAC, the High Resolution LED on the Naim DAC lit up and the sound WAS better than at 96kHz, better in fact than I'd ever heard from my CD player.

Simples.

Upsampling is generally BAD for many reasons.. get your favourite DSP engineering text books to see why, oversampling (usually with with zero samples)  is benign and can be beneficial in the digital reconstruction filtering process. 

The Naim DAC - along with the streamers -  only employs oversampling not upsampling -  although there is on the original streamers an upsampling fixed output rate that can be selected on the digital out - though I never understood why anyone would want to use that.... not sure if its there on the new streamers.

 

Well, Simon, I respect that view, but it really does sound much more airy, spacious and detailed to me. dCS have made a huge reputation for themselves by building high end kit which DOES upsample, and I don't think that can be just 'written off'.

I would love to be in the position to just buy a CD555, and be done with it.

But I have done two things recently which cemented this idea of upsampling in my head as worth trying out.

The first was when I took along my Krell KPS20i to a top Naim dealer to compare it to a CDS3 which was for sale. Both the dealer and I agreed that neither was 'better', that both had significant strengths, but we had no preference for either. They both sounded excellent. Now that really WAS a test for my 1997 player.

Then, more recently, I have got to know a guy who used a full dCS CD/Upsampler/DAC system as the source for his Naim preamp, 135 power amps and Naim speakers. We compared both systems at each others' houses, and I in fact recognised the importance of the spaciousness and soundstage of his system compared to the solidity, drive and power of mine.

He very kindly offered to lend me his upsampler to use in my system, and it is due to that very brief opportunity that I decided I had to take the plunge and obtained a used Purcell upsampler.

I am VERY pleased with the result. It was a very worthwhile move.

I suspect it might be oversampling then and not upsampling. Oversampling is an integer multiple of the sample frequency so there are no arithmetic interpolation issues when zero samples are used (zero x anything = zero). Upsampling is used for a non whole integer, therefore arithmetic rounding errors are introduced which produces noise and sample error artefacts. They might be just using the wrong terminology (a risk with consumer products when they in appropriately use engineering and scientific terms)  or perhaps you prefer the artefacts - always possible.

Easy way to find out - what is the source sample rate of the media.. and what is the sample rate fed to the DAC after it has been through your device.. if the the output is an exact multiple of the input then it is oversampling - and if implemented correctly can make up for deficiencies, if any, in your DAC oversampling circuity and implementation, though Naim take a lot of care here.. 

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