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DSD?

Woodface

pfm Member
Apologies for this low grade question but what the hell is DSD? I have just bought an Innuos Zen Mini, it has 3 ‘modes’:

No support for DSD, coverts to flac
DSD over PCM
Native DSD

I am pretty sure I don’t have any DSD material, a couple of Sault downloads are 20 bit - HD?

My Dac supports PCM audio & DSD?

What does this all mean?
 
In the late 90s, Sony came out with and promoted a new format of disc called a Super Audio Compact Disc. The music on these was encoded in a very different way from conventional cds by using a method called Direct Stream Data (DSD). Sony and Marantz made the SACD players to play the DSD encoded discs. Conventional CDs used the technique of Pulse Code Modulation for encoding data.

Most people thought it was an advance in audio quality but the discs were expensive and contained much more data which became an issue when people wanted to rip and store them for streaming.
 
I have a relatively large collection of DSD discs that I love.

But then again, I also have minidiscs, cassettes and 8-track tapes.

Plus VHS and DVD concert videos.
 
My view of DSD is perhaps coloured by the exchanges I have with some Sony/Philips people I had when I was trying to model and analyse the behaviour of the 'modulators' they used. (Their term for the equivalent of an ADC.) Every time I found a published arrangement from them and analysed it I encountered problems with idler patterns, state lockup-up etc. When questioned, they'd neither agree or disagree but then say they'd '"changed the modulator" to something then eventually hadn't ever published - so could not be fully checked.

They also started off assuming full range and a 100kHz output bandwidth, but then quietly cut this to 50kHz-ish and avoiding the signal ever going about -3dB of the (theoretically) full range. i.e. trying to avoid lock-up.

They could have used DVD for plain LPCM 'high rez'. But they could patent SACD/DSD and employ a physical protection system. That seems to me to be the real reasons for DSD existing. Not sound quality. Its a very inefficient and (mathematically) unreliable method IMHO. However provided the residual ultrasonic hash doesn't bother your playback kit, it can give decent results. But I don't mourn the passing of SACD.
 
Actually DSD was conceived for archiving purposes, long before SACD.

Faced with decaying analogue tapes Sony engineers started capturing and storing the raw 1-bit output of a sigma-delta modulator. Replay was the reverse. This allowed them to digitise old tapes without committing to any specific contemporary PCM format, keeping the door open for future high-res conversion. DSD was not meant to be a distribution format. It was not even meant as a pro recording format, being inherently not editable: it was just a 1:1 functional replacement of analogue tape and analogue tape machines, buying time.

The reason it got incorporated into SACD indeed has everything to do with a hunt on new royalties and license income, in a head-to-head confrontation with the DVD Audio Forum. An unnecessary war followed, with only losers.

Back then I rallied against it on my audio pages, until I got a cease-and-desist letter from a Sony lawyer.


SACD has much in common with MQA...


redbook.jpg
 
Actually DSD was conceived for archiving purposes, long before SACD.

Back then I rallied against it on my audio pages, until I got a cease-and-desist letter from a Sony lawyer.

IIRC Lipshitz explained early on why it was a BAD THING to use as an archiving or recording format. Even ignoring its other snags it can't be fully dithered.

When I looked into it the P/S people I spoke to kept agreeing with me... and shuffling the deckchairs to use something unpublished. In the end I didn't publish the details I got as it was impossible to nail down *exactly* what they did in real practice. And trying to explain semi-chaotic idler patterns and orbits in multi-dimensional spaces seemed a tad much for any Hi-Fi mag. :)
 
Ok another question, what the hell is ‘low latency’ in the context of outputting to a DAC. Some Dacs can accept this & some can’t?
 
It amazes me that people discuss a "sound quality" subject by going into great technical details wiithout mentioning the sound quality that they perceive.
OK, I'll admit that I think it sounds better than CD, but behind my very good analogue source. One thing to remember, you won't hear the benefits, unless the sound was recorded in DSD.
For example, if it was a hi bit rate digital file, it won't be worth changing it to a DSD file.
 
I actually asked what it was rather than what it sounded like which is rather moot.

I am surprised how I can hear a difference between a CD played via a CD player & one via a HD.
 
Ok another question, what the hell is ‘low latency’ in the context of outputting to a DAC. Some Dacs can accept this & some can’t?
Latency is the length of time a DAC takes to convert an input, or the length of time a DSP process in a computer takes. In a studio context low latency is important - if you are playing an electronic keyboard through a bunch of effects you don’t want there to be any delay between you hitting the key and the sound you hear. In a hifi context I can’t see what difference latency makes. Your music has been on a hard drive quite possibly for years; another microsecond won’t make a difference. Some DACs with long tap length filters such as Chord have very long latencies - to the point where they are useless for AV because of unacceptable lip-sync. They sound pretty good.
 
Apologies for this low grade question but what the hell is DSD? I have just bought an Innuos Zen Mini, it has 3 ‘modes’:

No support for DSD, coverts to flac
DSD over PCM
Native DSD

I am pretty sure I don’t have any DSD material, a couple of Sault downloads are 20 bit - HD?

My Dac supports PCM audio & DSD?

What does this all mean?
I'm not sure there are actual answers yet to these questions. But as others have written DSD (Direct Stream Digital) is an alternative way of representing digital audio compared to the more common PCM (Pulse Code Modulation).

I don't know the Zen Mini but the question does seem to refer to telling the streamer what your DAC will do. Almost all DACs handle PCM. If the DAC cannot accept DSD and convert that to audio then it looks like the Zen Mini will convert DSD audio files to PCM and then store that PCM in a FLAC-format file (which is compressed - in a lossless way - to save disk space). Some DACs will convert DSD to audio and they will either accept DSD natively on a digital input or (more commonly I think) accept DSD which is packaged up to look like normal PCM (that's DoP - DSD over PCM). Set the Zen Mini mode according to what your DAC will do. No support for DSD is pretty safe. You can download DSD test tracks from 2L High Resolution Music .:. free TEST BENCH to test it.

On the second query, PCM files come in CD-quality (16 bit 44.1 kHz) or high resolution /high definition (24 bits usually) or high rate (96 kHz, 192 kHz often - there are other rates). Standard DSD files are called DSD64 but it too has higher rates (e.g. DSD128, DSD256 - which rapidly get very large).

I'm not really sure if the above addresses what you were asking, though.
 
I'm not sure there are actual answers yet to these questions. But as others have written DSD (Direct Stream Digital) is an alternative way of representing digital audio compared to the more common PCM (Pulse Code Modulation).

I don't know the Zen Mini but the question does seem to refer to telling the streamer what your DAC will do. Almost all DACs handle PCM. If the DAC cannot accept DSD and convert that to audio then it looks like the Zen Mini will convert DSD audio files to PCM and then store that PCM in a FLAC-format file (which is compressed - in a lossless way - to save disk space). Some DACs will convert DSD to audio and they will either accept DSD natively on a digital input or (more commonly I think) accept DSD which is packaged up to look like normal PCM (that's DoP - DSD over PCM). Set the Zen Mini mode according to what your DAC will do. No support for DSD is pretty safe. You can download DSD test tracks from 2L High Resolution Music .:. free TEST BENCH to test it.

On the second query, PCM files come in CD-quality (16 bit 44.1 kHz) or high resolution /high definition (24 bits usually) or high rate (96 kHz, 192 kHz often - there are other rates). Standard DSD files are called DSD64 but it too has higher rates (e.g. DSD128, DSD256 - which rapidly get very large).

I'm not really sure if the above addresses what you were asking, though.
Thanks, my Dac can handle DSD & Hi Res PCM from what I can remember. I don’t have any hi-res files other than a couple of 20bit Flac downloads which are listed as ‘HD’.
 
Actually DSD was conceived for archiving purposes, long before SACD.

Faced with decaying analogue tapes Sony engineers started capturing and storing the raw 1-bit output of a sigma-delta modulator. Replay was the reverse. This allowed them to digitise old tapes without committing to any specific contemporary PCM format, keeping the door open for future high-res conversion. DSD was not meant to be a distribution format. It was not even meant as a pro recording format, being inherently not editable: it was just a 1:1 functional replacement of analogue tape and analogue tape machines, buying time.

The reason it got incorporated into SACD indeed has everything to do with a hunt on new royalties and license income, in a head-to-head confrontation with the DVD Audio Forum. An unnecessary war followed, with only losers.

Back then I rallied against it on my audio pages, until I got a cease-and-desist letter from a Sony lawyer.


SACD has much in common with MQA...


redbook.jpg
Interesting history, though the graphic is a bit over the top?

Also, it seems that DSD doesn't require a DAC, conversion can be done with a passive analogue circuit, a la PS Audio?
 
Interesting history, though the graphic is a bit over the top?

It's from my old audio site, around 1998 or so(*). There was a caption:

Avid audiophools cheer for SACD as they turn in their redbook CDs.

Also, it seems that DSD doesn't require a DAC, conversion can be done with a passive analogue circuit, a la PS Audio?

A DSD DAC is a very rudimentary thing, no more that a few switches driven from the raw DSD data stream, feeding into a switched-capacitor filter (IIRC).

I think it was Allen Wright who first, in the early 2000s?, realised that there is no fundamental difference between the post-DAC DSD current or voltage pulses as found in a regular player, and the pre-DAC raw bit stream. So he tapped into the latter and exported that via one of his own buffer/amp designs.

http://www.vacuumstate.com/index.dna



(* That same page explained in some detail my concept for a PCM-based recording and distribution format based on 96k or 192k sampling with low-order AA and AI filters matched to the natural spectrum of music. Sounds familiar?)
 
Interesting history, though the graphic is a bit over the top?

Also, it seems that DSD doesn't require a DAC, conversion can be done with a passive analogue circuit, a la PS Audio?

In principle, yes, you can 'convert' DSD by using a carefully chosen analogue low-pass filter. This then tries to mimic the behaviour of a digital DSD 'demodulator'. However the official demodulators have complicated feedback taps, etc, to try and get optimum recovery of the DSD, try to avoid signal-pattern-dependent idler patterns at audible frequencies, and minimise the ulstrasonic 'hash' that can upset later kit.

Doing all that is quite hard - indeed essentially mathematically impossible to do perfectly once you go above about 4th order. Too many plates to juggle.

SACD tries to avoid this as much as possible by measures like keeping the peak signal levels encoded well below the max range nominally possible. But you can't beat the maths...
 


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