DSD vs PCM

[Orb]

Hi Orb,

DXD is 24 bit 352KHz PCM. In all instances, it is derived from a Sigma-Delta Modulator operating either 1-bit, or multi-bit Pulse Density Modulation (PDM) as the front end of an A/D converter unit.

DXD is currently the best option for highest quality post processing sweetening, mixing, and track balance, of which the vast majority of deliverable media is produced. But it's not a A/D converted format per se, it's a processed/processing format. With availability of today's hardware, it's far better to record (track) in the highest available DSD bit rate (256fs with Merging's Horus/Hapi), and if required for post processing, convert off line one time to DXD, mix, sweeten, and balance.

That accomplished (edited master), the choice(s) of delivery format is market driven, with the best being DXD itself. Converting it back to DSD is just one more detail robbing function. Converting it to lower sampling rate PCM imposes the same decimation filtering (but to a lesser degree) than the decimation filtering necessary to convert the original PDM bit stream to DXD. The best fidelity is no conversions. This can/is done with either session analog mixing/balancing, or depending on the size of the musician group and venue purest microphone technique, then DSD recording and editing with no conversions.

Best we keep SDM out of this as really this discussion is about transparency converting between DSD and PCM, and the aspect you raise regarding SDM and what is native PCM or DSD products/solutions has been discussed at length in other threads that keep on growing
Yeah agree it has implications as discussed at length on those massive threads .

Thanks for clarifying DXD, I think some of it is technical semantics because I would say Philips and some of the DAW manufacturers mention transparency for transcoding-decimation or editing DSD to PCM is using DXD specified internally to the DAW at 32-bit fp (still technically PCM and I notice Bruce mentions using 32fp within the DAW as well); this is what I have seen mentioned by Bruno and Merging Technologies in the past *shrug*.

I agree with what you say as I did mention it is limited to 24-bit for ADC and DACs, and historically posted my views on being dubious regarding decimation-downsampling/upsampling/etc done by studios and labels; would be great to always be able to have the native resolution recording.
On your last point I am only going what was reported by Bruno when he was at Philips Research and they were looking at editing solutions for DSD, and in the past what Merging Technologies also said.
Edit:
OK maybe they wrongly lumped the 32-bit requirement in theory for the transparency of DSD editing/converting to PCM format with that of DXD to simplify the situation.
With you now on DXD being only 24-bit, which means reducing the reported "ideal" 32bit criteria for transparency if really comparing DXD and DSD.

Cheers
Orb

 

[tailspn]

Best we keep SDM out of this as really this discussion is about transparency converting between DSD and PCM, and the aspect you raise regarding SDM and what is native PCM or DSD products/solutions has been discussed at length in other threads that keep on growing
Yeah agree it has implications as discussed at length on those massive threads .

But that's exactly the point I'm trying to make; there's no such thing as a PCM/DXD A/D converter, with the exception of the 10+ year old Pacific Microsonics PM1/2 192KHz A/D converter. All professional A/D converters are Sigma-Delta Modulator front ended, yielding a PDM bit stream(s). Any PCM format out of them is derived through onboard realtime decimation filtering and conversion. So for folks expressing a sound quality preference for DXD/PCM, that has nothing to do with the technical merit of the format, but their preference to the coloration's of the conversion.

 

[Orb]

But that's exactly the point I'm trying to make; there's no such thing as a PCM/DXD A/D converter, with the exception of the 10+ year old Pacific Microsonics PM1/2 192KHz A/D converter. All professional A/D converters are Sigma-Delta Modulator front ended, yielding a PDM bit stream(s). Any PCM format out of them is derived through onboard realtime decimation filtering and conversion. So for folks expressing a sound quality preference for DXD/PCM, that has nothing to do with the technical merit of the format, but their preference to the coloration's of the conversion.

Ah ok and yeah, we are coming at this from slightly different angles and points (mine specifically the DAW and internal operation and transparency)
Cheers
Orb

 

[Tony Lauck]

Ah ok and yeah, we are coming at this from slightly different angles and points (mine specifically the DAW and internal operation and transparency)
Cheers
Orb

Terminology can be confusing. One person can be talking about function and the other mechanism. The AX24 performs the function of an analog to digital converter that converts an analog signal to the 352.8/24 PCM format marketed as "DXD". To achieve this function it uses two mechanisms, a multi-bit sigma-delta modulator and DSP firmware that does sample rate and bit depth conversion.

If one is worried about quality then the format will serve as an upper bound on potential quality, but the actual quality can be reduced by the particular mechanisms employed (their design, build quality, and state of repair at time of use).

 

[Orb]

The specification given for DXD is 352.8kHz, but no mention of bit-depth. It was my understanding that the bit depth had to be "at least" 24-bit, with workstations doing internal math at 32fp

Those who work with DSD everyday have been documented to say that they can hear when DSD has been edited with PCM.

Bruce just curious do you personally notice the difference when you take the DSD file into your DAW and convert to 32fp PCM and back again to DSD?
Thanks
Orb

 

[Bruce B]

Bruce just curious do you personally notice the difference when you take the DSD file into your DAW and convert to 32fp PCM and back again to DSD?
Thanks
Orb

Only on real quiet passages. If something is busy with larger amplitude, then no.

 

[Orb]

But that's exactly the point I'm trying to make; there's no such thing as a PCM/DXD A/D converter, with the exception of the 10+ year old Pacific Microsonics PM1/2 192KHz A/D converter. All professional A/D converters are Sigma-Delta Modulator front ended, yielding a PDM bit stream(s). Any PCM format out of them is derived through onboard realtime decimation filtering and conversion. So for folks expressing a sound quality preference for DXD/PCM, that has nothing to do with the technical merit of the format, but their preference to the coloration's of the conversion.

Tailspn this affects all including DSD as shown in the other threads, the majority of recordings (this needs to consider not just niche recordings but all offered) I would say are not true native DSD without influence of PCM/multi-bit in some way.
This goes beyond just the A/D converter but also mixing-editing and also DAC (could be argued the ESS Sabre chips are not the "normal" type of DSM applied to DSD).

That said I thought there were still some A/D that were not DSM such as MSB Technologies and a couple of others?
Although academic because we need to consider the whole chain, but this is different to my point that is specifically the capability/function of a DAW using 32fp to transparently convert between PCM and DSD; I see though that Bruce mentions some engineers still perceive a difference.

Cheers
Orb

 

[Orb]

Only on real quiet passages. If something is busy with larger amplitude, then no.

That is interesting and surprising due to the 32fp benefit vs integer.
Any idea what the trait you hear is, such as noise/detail smear/some kind of distortion/filter related/etc?
Much appreciated and thanks.
Orb

 

[853guy]

Indeed, those engineers making new digital recordings at 96/24 either suffer from inferior equipment or are slightly deaf, because otherwise they would be recording at 192/24 or higher resolution PCM formats (or in DSD). Just my opinion.

For me it was a matter of priorities. I'm not suggesting for a minute sample rate and bit-depth don't matter. In the studio, I’d always choose the best AD conversion the budget allowed. But when tracking, and especially for the indie rock/pop stuff that was my bread and butter, in terms of what mattered most to me, sample rate and bit-depth would come last, after (in reverse order of importance):

EQ
Compressor
Mic-pre
Mic placement
Mic
Room
Instrument placement
Instrument
Musician
Composition

That’s to say, I would much rather record everything at 24/96 and give my time and attention - not to mention the client/label’s budget - to maximizing the results with the above than compromise the above for the sake of a higher sampling rate. Heck, if it meant better outboard or room, I might even be willing to go 88.2, especially if the song and artist was killer.

If I was a purist two-mic guy recording chamber or choral music, the same would still apply all the way down to mic-pre. I could lose the comp and EQ, and get a RADAR which has some of the nicest, most stable and idiot-proof 24/94 conversion I've heard, and never have to use a DAW again.