Direct Stream Digital and the Power of Imagination

[Jud]

Calling it SDM would be even worse. SDM is a process, not a format. It just happens to be a convenient method of producing low-resolution noise-shaped signals from a high-precision or analogue input.

 

[sigh.] Where I work, we tell people it is important not just to say something is incorrect, but to suggest an improvement; otherwise the criticism is not helpful.

[mansr]

[sigh.] Where I work, we tell people it is important not just to say something is incorrect, but to suggest an improvement; otherwise the criticism is not helpful.

There's no need to call the internal formats of DAC chip by any particular name. They are inaccessible to the user and often unique to a chip family anyway. The Burr-Brown/TI PCM179x chips even split the signal into two streams with completely different formats, so saying they "convert everything to DSD" is way off the mark.

 

What is your definition of DSD? Anything with a sample rate of 2.8 MHz or more? Anything with fewer than 8 bits per sample? Anything that has been subjected to noise-shaping? All of the above?

 

Whatever your answer, when debating PCM vs DSD (which is the context of the linked article and this thread), everybody always refers to a 1-bit format (because that is what is distributed as SACD and downloads), and this is not what any modern DAC uses internally. Please stop trying to score points by stretching the definition of DSD.

[徐中銳]

I prefer the view of Andreas Koch, a pioneer in the development of the format.

 

AK also said :

Recalling Koch's explanation to the flow chart of my previous Post' date=' extracted from his [/size']DSD - the new Addiction :

« The term Direct Stream Digital (DSD) was coined by Sony and Philips when they jointly launched the SACD format. It is nothing else than processed Delta-Sigma modulation first developed by Philips in the 1970’s. Its first wide market entry was not until later in the 1980’s when it was used as an intermediate format inside A/D and D/A converter chips.

 

Fig. 1:

 

Figure 1 shows how an analog source is converted to digital PCM through the A/D converter and then back again to analog via the D/A converter. The A/D internally contains 2 distinct processes:

 

1. Delta-Sigma modulation: the analog signal is converted directly to DSD with a very high sampling rate. Various algorithms are in use depending on the application and required fidelity. They can generate 1-bit DSD or multibit DSD oversampled at 64x or 128x compared to regular CD rate.
   
2. Decimation filter: the DSD signal from the previous step is downsampled and converted to PCM. Word length is increased (for instance 16 or 24 bits) and sample rate reduced to CD rate or a low multiple of it for high resolution PCM formats.
   

 

The D/A process is very similar where:

 

1. the PCM signal is upconverted to a much higher sample rate.
   
2. then converted to DSD via the Delta-Sigma modulator (to reduce word length)
   
3. then converted to analog.
   

 

This technology was chosen because of its improved linearity and consistent quality behavior across physical components, as most of the heavy duty signal processing was shifted to the digital domain where it was not susceptible to variability of electronic components. It was quickly adopted in most converter systems and we can say that since about the late 1980’s we have been listening to some form of DSD without even knowing it.

 

As science progressed as well as our experience with digital audio, we started to realize that the algorithms for the DSD-to-PCM and PCM-to-DSD conversions can have a profound impact on the sonic performance when they are developed according to classic formulas. These are relatively complicated algorithms and they introduced a new phenomenon that we describe as “digital sound” or ringing effects. Hence the motivation by the engineering teams of Sony and Philips to remove these steps altogether from the conversions between analog and digital. This simplified DSD path that bypasses the PCM path is shown in Fig. 1 above. As is usually the case most simplifications in the signal path lead to sonic improvements and so it didn’t come as a surprise when first listening tests were so astonishing that this format was considered as an archiving format for recording studios. That alone says something about its sonic fidelity. At the time no recording studio was even considering using any PCM format to archive its analog recordings. »

[Allan F]

Please stop trying to score points by stretching the definition of DSD.

You might want to heed a variation of your own advice:

 

Please stop trying to score points by being pedantic.

[徐中銳]

You might want to heed a variation of your own advice:

 

Please stop trying to score points by being pedantic.

Please stop trying to score points by stretching the definition of DSD.

 

I recall :

Could it be perhaps the blue face of your avatar? I've been curious about that for a long time. (;-)

 

I am a Professional and a reasonably successful Software Engineer. Why does my knowledge not count?

[mansr]

I recall :

Are you

a) a troll,

b) an AI research project, or

c) a performance art installation?

[徐中銳]

I prefer keeping to issues of music :[video=youtube;Qd1B-xKkwmM]

 

Or :

[Jud]

 

Whatever your answer, when debating PCM vs DSD (which is the context of the linked article and this thread), everybody always refers to a 1-bit format (because that is what is distributed as SACD and downloads), and this is not what any modern DAC uses internally. Please stop trying to score points by stretching the definition of DSD.

 

I haven't noticed people trying to "score points." For my part, neither of my posts in this thread has had anything whatever to do with the definition of DSD, so inasmuch as it was my post you replied to, your advice does not seem well aimed, and more important it is not yet helpful. But it has the potential to be if you would be kind enough to tell us the distinction(s) between the format(s) the bitstream goes through inside a DAC (either typically or using various specific examples) when the source is DSD, versus when the source is PCM.

[Jud]

Are you

a) a troll,

b) an AI research project, or

c) a performance art installation?

 

Are you

 

(a) the same person who was complaining of "insults" after far more temperate language from Miska in another thread?

[The Computer Audiophile]

It would be really interesting to read people argue the other side of the "issue." For example, DSD supporters must talk about the flaws with DSD and the benefits of PCM and vice versa. Anyone who can do this well, will likely understand what he is talking about and gain a lot of respect by those reading.

 

Fortunately every one of us can do our own listening tests to determine if DSD or PCM sounds better on individual releases.

 

There's the theoretical / intellectual exercise and there's the sonic exercise.

[The Computer Audiophile]

I haven't noticed people trying to "score points." For my part, neither of my posts in this thread has had anything whatever to do with the definition of DSD, so inasmuch as it was my post you replied to, your advice does not seem well aimed, and more important it is not yet helpful. But it has the potential to be if you would be kind enough to tell us the distinction(s) between the format(s) the bitstream goes through inside a DAC (either typically or using various specific examples) when the source is DSD, versus when the source is PCM.

 

At the end of the first quarter, Jud is leading 1 to 0.

 

Only joking. I couldn't resist a lighthearted comment in the face of what I consider overly serious comments in this thread :~)

[mansr]

It would be really interesting to read people argue the other side of the "issue." For example, DSD supporters must talk about the flaws with DSD and the benefits of PCM and vice versa. Anyone who can do this well, will likely understand what he is talking about and gain a lot of respect by those reading.

 

Fortunately every one of us can do our own listening tests to determine if DSD or PCM sounds better on individual releases.

 

There's the theoretical / intellectual exercise and there's the sonic exercise.

 

Excellent idea.

[Miska]

Of course sigma-delta modulation can produce multi-bit output. However, the term DSD specifically refers to a 1-bit format. That's how Sony defined it, and they own the trademark.

 

That's why I prefer to talk about "SDM" instead of DSD even when output is target to "DSD" DACs. I would like to get rid of the "DSD"* term.

 

Luckily DAC just sees a bitstream and doesn't know what is going on.

 

 

*) I bet it originally meant "Direct Sigma-Delta" but then some clueless guy from marketing department came up with something different that passes more easily as a trademark.

[Jud]

That's why I prefer to talk about "SDM" instead of DSD even when output is target to "DSD" DACs. I would like to get rid of the "DSD"* term.

 

Luckily DAC just sees a bitstream and doesn't know what is going on.

 

 

*) I bet it originally meant "Direct Sigma-Delta" but then some clueless guy from marketing department came up with something different that passes more easily as a trademark.

 

Guy from marketing (more likely Legal) was pretty smart. It is very difficult to try to trademark terms that already have a precise meaning that is being used quite often, like "sigma-delta." And "DSD" is easier to say.

[Jud]

It would be really interesting to read people argue the other side of the "issue." For example, DSD supporters must talk about the flaws with DSD and the benefits of PCM and vice versa.

 

 

The advantage to buying PCM is that converting to DSD yourself with available computer software can result in better sound than the chains some studios use to make SACDs or DSD files.

[Miska]

Guy from marketing (more likely Legal) was pretty smart. It is very difficult to try to trademark terms that already have a precise meaning that is being used quite often, like "sigma-delta." And "DSD" is easier to say.

 

Yeah, true, I can imagine Legal team saying that engineering team's "Direct Sigma-Delta" for "DSD" is a no-go, but after some thinking by marketing team, substituting it with fancy sounding "Direct Stream Digital" is good and easier for "average customer" to understand...

[jabbr]

The advantage to buying PCM is that converting to DSD yourself with available computer software can result in better sound than the chains some studios use to make SACDs or DSD files.

 

+1 -- us consumers are at the mercy of how the music is recorded, mastered but most importantly released-- regardless of where it came from, SDM on the computer is the way to go

[earnmyturns]

Modern DACs all have multi-bit sigma-delta architectures.

Anyone who wants to avoid delta-sigma in their DACs can. There are several well-reviewed resistor ladder DACs on the market, at price points starting at $600.

[徐中銳]

DSD supporters must talk about the flaws with DSD and the benefits of PCM and vice versa. Anyone who can do this well, will likely understand what he is talking about and gain a lot of respect by those reading.

 

Fortunately every one of us can do our own listening tests to determine if DSD or PCM sounds better on individual releases.

 

There's the theoretical / intellectual exercise and there's the sonic exercise.

 

Readers should pay attention to tailspn's work, eg :

Channel Classics released today the Ivan Fischer/BFO Mahler 1.

 

Mahler Symphony no. 1 in D major - Channel Classics Records

 

The accompanying video gives an intimate insight into Ivan Fischer's thoughts of this Mahler, and his admiration for it.

 

An historical note about this release is that it's the first DSD recording of a major orchestra to be offered as both a stereo and multi-channel DSD format download. Consumer/audiophile hardware is not far behind.

 

Encourage him to share more recommendations... And insights, e.g. :

If you're ever in Boston, I'd be happy to demonstrate for you, on full range five channel electrostatic speakers playing DSD recorded acoustic music session takes, that you can easily distinguish between 24/352.8KHz PCM and the DSD original, let alone 24/192. Now for much of the very post processed music you purchase in stereo, I'd be inclined to agree with you.

 

I'm quite satisfied that both personally and scientifically people can't tell the difference in 24/192 and DSD.

[Jud]

Readers should pay attention to tailspn's work' date=' eg[/url'] :

 

 

Encourage him to share more recommendations... And insights, E.g.

:

 

I know it's not part of the "game," but I'll say +1 to that recommendation.

[MikeJazz]

Are you

a) a troll,

b) an AI research project, or

c) a performance art installation?

 

LOL, priceless...

[徐中銳]

LOL, [gratuitous]...

 

Less so :

[Paul R]

The advantage to buying PCM is that converting to DSD yourself with available computer software can result in better sound than the chains some studios use to make SACDs or DSD files.

 

There you go -

[TubeLover]

The advantage to buying PCM is that converting to DSD yourself with available computer software can result in better sound than the chains some studios use to make SACDs or DSD files.

 

Great point, Jud. You have the option for the best of both worlds, as needed. What software do you find best for this purpose?

 

JC

[tailspn]

The advantage to buying PCM is that converting to DSD yourself with available computer software can result in better sound than the chains some studios use to make SACDs or DSD files.

 

I agree, particularly with the advanced modulators Jussi developed for his HQ Player product. It circumvents the limitations of DAC onboard processors doing the conversion(s), replacing them with much higher processing power CPUs implementing, in real time, much better designed modulators.

 

But for DSD supporters, that only solves part of the problem. The remainder lies in the recording chains producing the content you purchase. Since Merging Technologies brought out the Horus/Hapi hardware, supporting all the DSD recording bit rates as well as DXD, there's been a significant increase in labels recording in those formats. While the majority of those recordings are classical acoustic music, there's an increasing catalog of jazz and popular music becoming available.

 

If you're interested in seeing this trend continue and grow, search out these labels and support them, particularly with the ever increasing collapse of the CD/SACD distribution and retail business. Also question the major symphony orchestras who are releasing their concerts as both downloads and CDs on their own label, why they're not recording and distributing in DSD. A case in point is the Seattle Symphony, who have several Horus, yet record in 88.2KHz PCM. The CEO of the organization believe (from past studio production experience) that it's more than high enough. Really?