To DSD or not to DSD?

[hardline]

I came across this interview today, "John Siau: Benchmark Audio Guru" by AIX owner Mark Waldrep.

 

 

John Siau: Benchmark Audio Guru | Real HD-Audio

 

 

The interview raises in my mind some questionable benefits of DSD for the playback and production of music.

 

 

This is my first post in Computer Audiophile and I am interested in what my fellow members think of this article.

 

Weldon

[Richard Dale]

I came across this interview today, "John Siau: Benchmark Audio Guru" by AIX owner Mark Waldrep.

 

 

John Siau: Benchmark Audio Guru | Real HD-Audio

 

 

The interview raises in my mind some questionable benefits of DSD for the playback and production of music.

 

 

This is my first post in Computer Audiophile and I am interested in what my fellow members think of this article.

 

Weldon

 

An excellent complement to the 'Why did SACD fail?' thread! Thanks for posting the link to the interview.

[Hiro]

The interview raises in my mind some questionable benefits of DSD for the playback and production of music.

 

From what I see the arguments themselves are questionable.

 

Take this one, for example.

 

John Siau apparently assumes that multi-level delta sigma (as utilized by Sonoma DAW) is PCM, but it's still a delta-sigma technology.

 

MW: DSDs are not mixed in DSD?

JS: No, DSD signals are not 1-bit wide in the DAW. DSD becomes 4-bits wide or 8-bits wide or 16-bits wide depending on what word length the DAW can handle.

 

MW: Really. So is it true to say as a complement to what they say in here that every DSD file or project actually goes through a PCM stage as well?

JS: Shh! Please don’t use the PCM word! But OK yes

[Hiro]

Another one...

 

MW: Yeah, that’s the purple haze you see at the high end of the spectrum in DSD recordings.

JS: The spectrum analysis of DSD shows a huge amount of noise at high frequencies. You’ve got 6 dB of signal to noise ratio – at best.

 

Archimago has recently posted a review of the TEAC UD-501 128xDSD DAC and he showed that the amount of noise in inaudible frequencies for DSD and 24/192 PCM was basically the same up to 45kHz (that's more than twice the human hearing range). And let's not forget that all DSD64fs recordings can be easily upsampled to DSD128.

[REShaman]

I came across this interview today, "John Siau: Benchmark Audio Guru" by AIX owner Mark Waldrep.

 

 

John Siau: Benchmark Audio Guru | Real HD-Audio

 

 

The interview raises in my mind some questionable benefits of DSD for the playback and production of music.

 

 

This is my first post in Computer Audiophile and I am interested in what my fellow members think of this article.

 

Weldon

 

Hardline,

Thank you for posting this interview. I may not fully understand the content of the interview, but I can read and the conclusion is fairly complex and simple at the same time. I believe Barry Diament is his back and forth with certain members also advocated that 192/24 PCM done right has the best SQ. At least that is what I came away with after reading this interview. Did I get this right?

Best,

Richard

[Hiro]

And another...

 

MW: And so what a mastering engineer or an equipment manufacturer would do is simply would apply a low pass filter to remove the “purple haze” out of the equation.

JS: Unfortunately, the ultrasonic noise cannot be removed in mastering unless the DSD source is being transferred to PCM. The ultrasonic noise is always present in DSD signal, it cannot be removed until the DSD signal is converted to analog or to PCM. This means that the noise must be removed in the playback hardware.

 

You don't have to convert DSD to PCM to get a lower noise level in the inaudible frequencies. Upsampling DSD64 (2.8MHz) to higher DSD sampling speeds has been shown to be very effective way of reducing the noise level in the ultra-sonic region.

[Hiro]

If the DSD DAC is equipped with a well-designed analog low-pass filter, we can achieve signal to noise ratios that start to rival some of the better PCM systems. DSD doesn’t approach the 144 dB SNR performance of a 24-bit system , but it certainly exceeds the -96 dB SNR performance of the CD format. With a well-designed filter, DSD can achieve a 120 dB signal to noise ratio, roughly equivalent to a 20-bit PCM system.

 

As a matter of fact not even the best ladder-type 24-bit PCM chips like the BB PCM1704 deliver 144dB performance (its THD is at 17bit level, DR at 19bit). Most delta-sigma DACs (that convert 24bit PCM to low bit DSD) don't achieve 24bit resolution either. Their real-world performance is closer to 20bit.

 

The whole "144dB performance" achieved by DVD-Audio format is a marketing myth.

[Hiro]

MW: Why would they continue to make the claim that the bandwidth, just like in analog systems, goes up to 100 kHz?

 

 

JS: Well, it does before the analog low pass filter. Unfortunately the low pass filter is an absolute necessity.

 

DSD recordings far surpass the capabilities of analog systems when it comes to the available bandwidth. The usable bandwidth of the recent Five/Four DSD recording goes to 130kHz. You can read more about it here:

 

http://www.computeraudiophile.com/f15-music-general/worlds-highest-resolution-recording-16011/

[Hiro]

JS: Yeah. The high-frequency noise is a disaster if it reaches power amplifiers and speakers. 128x DSD offers some improvements which allow expanding the usable bandwidth above the 50 kHz limit of 64x DSD.

 

 

MW: But then the files are going to get huge.

 

 

JS: Yes, but file size is less of an issue these days.

 

You can actually upsample all current DSD64 recordings to DSD128 or DSD256 on-the-fly without increasing the size of DSD64 file.

 

Native DSD128 recordings take more space but so do 192kHz PCM recordings.

[Hiro]

MW: Is that inclusive of any of the things that I do? I’ve got Wallace Roney and the spectragraphs that I look at that and other things that we’ve done exceed 40-45 kHz. And my justification is that I don’t really care whether the speakers and the rest of the hardware can actually reproduce the increased fidelity. But if there was a musical sound in the room when they were performing, I want to be able to capture it and preserve it through the entire production chain. And because Blu-ray and DVD-Audio can deliver frequencies higher than the traditional human limits, I say let’s try to reproduce everything. Given the situation with SA-CD and DSD and this whole noise shaping thing, it doesn’t sound like that is an option for them.

JS: Right. These frequencies are above the playback capability of DSD.

 

Wrong. Again.

 

This really gets boring...

[Hiro]

Remember, you’ve got a 50 kHz low pass filter that means you haven’t got a chance for accurately reproducing anything over about 47 kHz in DSD. The filter introduces phase distortion, amplitude errors, and ringing as we approach the 50 kHz cut-off frequency. In contrast, 96 kHz PCM will capture your ultrasonics just fine.

 

Actually DSD128 is far better at capturing ultrasonics than 96kHz PCM.

 

See the below PDF:

 

http://www.korg.com/services/products/mr/Future_Proof_Recording_Explained.pdf

[Hiro]

I have a product that supports DSD playback and I support DSD playback because…the theory being that if you have DSD material that you want to playback I want to give you a way to do it. It shouldn’t be absolutely necessary to convert it first. If you want to play it back directly we’ll give you a way to do that.

 

Finally! That's actually correct.

 

Pity you didn't give us a way to play DSD128 recordings and DSD64 files upsampled to DSD128.

 

Given the amount of time you spent talking about the noise level in the inaudible frequencies, it remains a mystery to me why you decided not to enable the double-rate DSD feature (which is, btw, supported by the ESS Sabre DAC you're using).

[Hiro]

JS: We do not recommend it at all for any kind of studio production work. It’s just completely unsuitable for professional applications…for any production work. The only way it should exist, if it exists at all, should be as the final output from a mastering room, where for whatever reason we want to distribute this in a DSD format. Okay, let’s create a master in a DSD format that we can distribute.

 

DSD recordings offer the highest resolution audio today, so IMO it is advisable to use the technology in the studio. Five/Four records has just set an example with their new recording of Boston Baroque. I don't see a reason why not to also use the highest resolution DSD technology when archiving master tapes. That doesn't mean that the ultra high res recordings must be distributed to consumers in that form. As DSD128 (and higher) capable DACs become ever more ubiquitous, that's an increasingly viable option, but you may always downsample a 5.6 or 11.2MHz DSD recording to 4x or 2x PCM, if you're afraid some people are not set for the native DSD playback yet. That's not the problem.

 

Recording to 11.2MHz DSD is more future-proof than using 96kHz PCM you're recommending IMO.

[wisnon]

Dont forget DSD's superior impulse response too...

[hardline]

For some background into this subject, one may wish to look at some of the information (by no means authoritative nor comprehensive) in the DSD Wiki entry (Direct Stream Digital - Wikipedia, the free encyclopedia) under subheading DSD vs PCM wherein the over-decade long back and forth debate is charted by references listed showing a 2001 paper authored by Lipshitz and Vandercoy (as mentioned by Mr. Siau), the ensuing response and counter-response papers, and a concluding reference that points to a draw between the two (http://old.hfm-detmold.de/eti/projekte/diplomarbeiten/dsdvspcm/aes_paper_6086.pdf).

 

I do not wish to retread any “limits of human perception” arguments please also refer to these two excellent forum discussions:

 

Double-blind test of SACD and DVD-A vs. Redbook 16/44 in JAES Septembe - Hydrogenaudio Forums and

CD vs SACD vs DVD-A - Long but interesting read

 

However I keep coming back to thinking and wondering about the difficulties of DSD recording/editing and will the audience actually hear the difference in quality of recordings made between DSD and PCM .

[Hiro]

Would love to have this conversation happen on the RealHD-Audio.com site.

 

It's strange they entitled the article "DSD: a reality check" when it's so far removed from reality.

 

The interview gives the reader a misguided view on the current situation of the DSD format.

[sjoc2000]

DSD recordings offer the highest resolution audio today, so IMO it is advisable to use the technology in the studio. Five/Four records has just set an example with their new recording of Boston Baroque. I don't see a reason why not to also use the highest resolution DSD technology when archiving master tapes. That doesn't mean that the ultra high res recordings must be distributed to consumers in that form. As DSD128 (and higher) capable DACs become ever more ubiquitous, that's an increasingly viable option, but you may always downsample a 5.6 or 11.2MHz DSD recording to 4x or 2x PCM, if you're afraid some people are not set for the native DSD playback yet. That's not the problem.

 

Recording to 11.2MHz DSD is more future-proof than using 96kHz PCM you're recommending IMO.

 

 

Thankyou Hiro for your well structured and written rebuttal of the first reference given. I can understand the hesitation of potential buyers of a DSD capable Dac for $1500-3000 +. My own experience is that DSD is different - better different than hi rez PCM. IMO even a 24/196-24/176 PCM converted to DSD sounds better

 

The technical discussion is great, but in the end, those who question the sq of DSD as compared to PCM or are considering purchasing a DSD Dac should make arrangements to listen with an open mind first, before judging this issue.

 

 

Jim

[wisnon]

Doesnt Benchmark make a DSD Dac???

[Hiro]

For some reason, someone at Realhd-audio.com has just removed a link to this thread posted under the article (initially accepted by the website's moderator). I bet that my comment, currently awaiting moderation, will be removed as well. It's sad to see the misinformation campaign about DSD started all over again...

[REShaman]

For some reason, someone at Realhd-audio.com has just removed a link to this thread posted under the article (initially accepted by the website's moderator). I bet that my comment, currently awaiting moderation, will be removed as well. It's sad to see the misinformation campaign about DSD started all over again...

 

That is chilling! Someone in another thread posted he was banned from Hoffman's forum for commenting on a preferred edition of one album versus another. Banned!

Best,

Richard

[Dr. AIX]

For some reason, someone at Realhd-audio.com has just removed a link to this thread posted under the article (initially accepted by the website's moderator). I bet that my comment, currently awaiting moderation, will be removed as well. It's sad to see the misinformation campaign about DSD started all over again...

 

Hiro, I'm the administrator at RealHD-Audio.com and for obvious reasons prefer that any comments or discussion remain at the source of the article. To quote large portions of the post on another site and then make comments detracts from my efforts.

 

If you or others wish to comment on the merits of John's statements, then you're certainly welcome. In fact, I encourage knowledgeable people to comment. John is a very well respected engineer with decades of experience working in analog and digital and has designed and created a DAC with great native DSD conversion. I do believe he is knowledgeable about this field.

 

But if you have conflicting viewpoints, then please make them at Real HD-Audio | Information about the world of high quality audio

 

Regards, Mark

[Dr. AIX]

REShaman...please read the comment below. And no, I have never been banned from Steve's forum or any other.

[REShaman]

Hiro, I'm the administrator at RealHD-Audio.com and for obvious reasons prefer that any comments or discussion remain at the source of the article. To quote large portions of the post on another site and then make comments detracts from my efforts.

 

If you or others wish to comment on the merits of John's statements, then you're certainly welcome. In fact, I encourage knowledgeable people to comment. John is a very well respected engineer with decades of experience working in analog and digital and has designed and created a DAC with great native DSD conversion. I do believe he is knowledgeable about this field.

 

But if you have conflicting viewpoints, then please make them at Real HD-Audio | Information about the world of high quality audio

 

Regards, Mark

 

That's fair and reasonable.

Best,

Richard

[REShaman]

REShaman...please read the comment below. And no, I have never been banned from Steve's forum or any other.

 

Mark, if you read my post correctly, I did not identify you as the person banned. In fact my post precedes your post so I am trying to understand what would make you respond to my post thusly. That is neither fair, reasonable nor intelligent. I was merely commenting on certain treatment about removing posts or people in general.

 

I did read your comment below and responded with my own comment. And I stand by both of my posts which have nothing to do with you personally.

 

With moderation,

Richard

[Hiro]

Hiro, I'm the administrator at RealHD-Audio.com and for obvious reasons prefer that any comments or discussion remain at the source of the article. To quote large portions of the post on another site and then make comments detracts from my efforts.

 

Frankly, I don't buy this excuse, yesterday it was OK to have a link posted under your article to the CA discussion thread, and today it's not? Keep in mind that if it wasn't about the link posted on the Computer Audiophile forum we wouldn't even be aware of the article in the first place.