Hi-Rez Highway

RE: OK - so I just listened to the 6-minute DSD256 excerpt

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Hi Chris,

The answer to your "why not just record in DXD in the first place" is there is no such thing as a direct DXD (or for that matter any PCM) recording method or hardware. Not at least with any A/D converter made in the last fifteen years used by any recording production outfit. The last really good direct PCM (20 bits on a really good day) A/D converter made was the Pacific Microsonics Model One/Two. These two products have been out of manufacture by at least fifteen years, but can be heard used today (by one of its inventors) by Keith O. Johnson on Reference Recordings.

PCM recording, including DXD (352.8KHz/24 PCM) is today accomplished by A/D conversion performed by Delta-Sigma modulation (a 1-bit or multi-bit DSD like Pulse Density Modulation process, then converted in the converter box to any sample rate PCM supported. The disadvantage of recording in DXD in the A/D converter are two:

1- The digital processing power available within the A/D converter is not as much as available in a reasonable PC, thereby limiting the robustness of the filter and conversion algorithms used. Plus, offline conversion in post does not have to be in realtime, further adding to the conversion choices.

2- This first PDM to PCM conversion, which is a lossy process, can not be undone in the future. Since native DSD content will increase in value in time as the format becomes the industry standard, the future value would be undermined.

If this sounds self serving, I'm happy to demonstrate to anyone visiting Boston the degradation of even one DSD > DXD conversion. You can experience this yourself with the DSD256 and converted DXD files available on NativeDSD. It helps of course to perform the demonstration with surround files, where the localization cues are much more recognizable, and using a DAW like Pyramix to facilitate A/B switching on the fly.

Until DSD post processing becomes available and commonplace, the best practice for complex large scale recordings in record in DSD, post process in DXD, then offer deliverables in all playable formats. When DSD processing is made available, the original DSD masters will be available for reprocessing, and the DXD edited masters discarded.



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