Does PCM processing at greater than DSD sample rate truly preserve DSD quality?


#1

The title says it all. I have long felt that a DSD source could be processed in PCM at DSD sample rate without losing the DSD qualities. I have nothing to back that up other than a gut feeling. I certainly lack the math skills to test the theory that way and no other way to test it. Ted’s signal processing in the DirectStream DAC does seem to back this up.



Hey, Ted… Do you think that you could build a 28MS/s workstation for Cookie? You think that she would find that acceptable for processing her DSD recordings? :slight_smile:



J.P.


#2

I partially addressed this in the “DIrectStream DAC First Impressions” thread.



It’s loosing information that’s “evil”. A faster sampling rate for processing is always better if the processing involved “smears” over time like a filter. A wider sample is always better if any processing at all is done. (Converting to a faster sample rate isn’t necessarily free, but you need to balance that conversion against the gains from further processing at the faster fate.)



There isn’t really a big divide between PCM and DSD. DSD is fast and noise shaped, but as soon as you do any processing on it you need wider samples. When you process PCM you may well need wider samples as well. And certainly for filtering you need a high sample rate to avoid loosing information that seems to matter.



For the final conversion to analog things are more complicated. The faster the sample rate the more jitter matters. The wider the signal the more the precision of all involved components matter. You get the most linearity with a single bit (two values define a line so with two values you are, essentially by definition, linear.) I chose the high sample rate (10 x that of DSD) and the intermediate sample widths in the DirectStream in order to loose the least information possible. I chose the output format to enable a clean analog stage and great jitter performance.



Gus Skinas keeps asking me to do a new DSD workstation. We worked on a digital audio workstation at WaveFrame together in the past. Recently I’ve had something else on my mind :slight_smile:


#3

Gus Skinas keeps asking me to do a new DSD workstation. We worked on a digital audio workstation at WaveFrame together in the past. Recently I've had something else on my mind :)


Lots of possibilities I'd think for next steps, post-DirectStream. Finishing up Bridge II, a Multichannel version of DirectStream, a lower cost, appliance-like product along the lines of Sony's HAP-Z1ES....

Will watch for more details on Ted's next adventures.

#4
bmoura said: Multichannel version of DirectStream


Doubt we'll see this happening. it does not seem that easy to implement.

#5

Ted, give that workstation a chance, I am sure that the industry needs a new current technology top end workstation. :slight_smile:



Anybody else have other opinions or gut feelings on the idea of processing DSD in PCM at DSD+ sample rates. Am I in that small of a group here in being interested in the technology and comparative qualities of DSD, PCM and processing? Of course, I am just learning most of this… :smiley:



J.P.


#6
bmoura said: Multichannel version of DirectStream


Doubt we'll see this happening. it does not seem that easy to implement.


I don't know. Ted did say that he owns a Meitner 6 Channel DSD DAC. And that his initial interest in DSD was started at a Sony Multichannel DSD demo. So, you never know....


#7

Bmoura, it’ll be fantastic news if it happens …

I, for one, do not want multichannel / surround if it compromises my stereo.


#8
Bmoura, it'll be fantastic news if it happens ...
I, for one, do not want multichannel / surround if it compromises my stereo.


I don't think that Ted, Paul or the PS Audio team would allow that. I'm very confident that a Multichannel DirectStream would be at the same level of quality - or even better. We will see.