DSD Revolutions

Welcome Back!

After a long hiatus this site is returning to full time posting, so tune in for more DSD coverage.

This blog was created to educate on the (at the time) dismal state of consumer DSD. I am happy to say the past two years have treated DSD well, with driver standard DoP, or DSD over PCM taking hold in the market with dozens of manufacturers conforming to the specification. Hundreds of DSD capable USB DAC's are now available, from manufacturers such as Sony, Teac, Ayre, Benchmark Mytek, Korg, and many more. Popular crowdfunding projects have raised millions for DSD capable playback devices GeekPulse, and GeekWave, and most media servers now support DSD collections in standard file formats.

Open source Software such as foobar2000 (via sacd-decoder plugin), ffmpeg, VortexBox Linux mediaserver distribution, and cMP2/CICS all now support DSD decoding and native playback. A Modified version of Foobar named  'FoobarDSD' allows DSD playback easily with either DoP DAC's or native ASIO DSD, tested up to 256fs. Currently NO software is capable of native DSD recording via ASIO DSD drivers, even if the hardware and driver support this (e.g. the Rigisystems USBPAL support ASIO DSD, but no software is yet available) OS X mavericks now allows DSD 256fs playback using DoP.

There are even a few ADC's now sold employing a reverse DoP standard to allow recording via standard pathways, albeit limited to DSD128 (5.6Mhz) through DXD (352.8Khz) pathways in traditional PCM audio drivers (256fs DSD will require 700~768khz PCM support). Software support for this new recording DoP standard is limited, but includes the wonderful VinylStudio software for record and tape archival and digitization. The long awaited Arda AT1201 was released to greater commercial availibility, and combined with custom Multi-bit modulator to DSD FPGA's are offering reportably excellent sound quality rivaling the best in the industry.

Sources of DSD audio downloads are increasing every day, and combined with an ability to rip SACD's at home using modified PS3 gaming consoles, consumer can enjoy full quality playback with the signal chain and software of their choice. Portable DSD capable DAC's and iPod-like devices like the GeekWave are becoming popular mainstream, with coming options including high quality DAC IC's and headphone amplifiers. Portable playback of any format is soon a reality. Finally consumers have freedom of choice regarding their digital audio.

DSD is here to stay, and many new comers to the fold are introduced to DSD everyday as an alternative to poor quality PCM, MP3 downloads, or a convenient way to archive vinyl collections without handling or portability issues while travelling.

Keep on Groovin,
Alexander Countey

Via VT1730 & VT 1731 DXD Interface Chip

Via, the Taiwanese company known for producing IC's for the computing industry at highly competitive prices, has announced a DXD compatible set of chips for there new USB Audio Interface generation.

Hopefully this will allow cheap and common consumer goods to support DXD rate PCM, though the quality will have to be evaluated, it is the first step towards broader acceptance of the format.

I missed this when it was announced May 16, 2011, and am not aware of any products currently using it.

Sadly it seems Via, despite low price, do not respond to requests for evaluation kits from individuals. Hopefully this is another step toward common availability of DXD interface for consumers.

USB-Dual-Audio now named UDA, 2 Versions coming.

The USB-Dual-Audio from ElectrArt in Japan is now named the UDA. This will hopefully assist in finding it in searches, USB-Dual-Audio was IMHO too generic a name to yield proper search results.

The Newest release of the UDA mentioned on ElectrArt's website will apparently come in two versions. One called the "DoP" version, supporting the new dCs standard of DSD packed PCM and no recording facility. The other the "standard" version with a proprietary driver, and supporting recording and playback of DSD.
This makes the UDA compatible with many pieces of software, though it seems it can not be upgraded to achieve this functionality, and a new revision of the hardware is required.

There was a board shown giving SDIF support over BNC for interoperability with standard DSD equipment, a big feature. I have been waiting for this for years, and a major plus for studio use.  Hopefully the boards will be available soon, they have been shown for the past 6 months on the ElectrArt blog.

In addition, since the first release (1.0, which is the version I have) the clocks have been replaced with the excellent NDK NZ-series oscillators. The UDA features discrete oscillators, at 22.5792Mhz and 24.5765Mhz, for 44.4khz*X or 48Khz*X, respectively.

The exD interface, The sdtrans384, and the new USB DSD driver standard from dCs.

2012 IS the year of DSD on your PC (or Mac OS X, or *nix)!

There are commercial sources of DSD online, Multiple vendors supporting DSD over USB, mostly thanks to dCs for solidifying a standard way of easily adding cross-platform native DSD support. Plus the sacd-ripper project has created a way to create fair-use bit-perfect backups of your SACD's, allowing the building of music servers or collections of DSD audio, finally with the same freedom we are used to from CD's and DVD-A's. The Korg MR-2 Can be loaded with SACD's now, allowing iPod like freedom with DSD, this has been the last major hurdle to acceptance of DSD on a wider scale IMHO.
 
The exD Interface has been brought to my attention, available now in 3 versions, a PCM only version, a DXD/PCM version, and a DSD/DXD/PCM version. I have not yet tested this interface, but it seems to support the standard driver model as defined by dCs, allowing a good choice of compatible software.

Chiaki's sdtrans384, the newest incarnation of the legendary sdtrans192, support DSD files at up to DSD256! This is remarkable and makes it the first hobbyist DIY SD-card player capable of high speed DSD. Previously, the only commercial SD card player capable of DSD was the Korg MR-2, but it only supports up to 64fs (2.8Mhz). The sdtrans384has been given high praise in terms of sound quality, indeed the use of an sd card and dedicated hardware for playback is used as a means of minimizing jitter to levels below that obtainable with optical media or most USB interfaces...

The dCs standard for DSD over USB via packing into PCM samples, padded with 8 identifier bits, has seen more acceptance than any other consumer DSD driver model so far, with support from many hardware and software vendors, even across any platform. It does create an stream that must be stripped of the 8 padding bits with minimal jitter, no reports yet on any problems from processing.

 This is just a report on the basic situation, if I missed any software or hardware please contact me and I will list it.

Software supporting the dCs standard:

• mpd or music player daemon now supports the dCs packed DSD, from either DSF or DFF files. crossplatform and Open-Source
• Audirvana Plus supports DST (Lossless Compression for DSD) and SACD ISO files in addition to the standard DSD formats. OS X 10.6+
• Pure Music from ChannelD supports DSD and DXD, OS X 10.6+
• Sonic Studio Amarra supports DXD, DSD conversion to PCM in realtime, but possibly will support DSD native in the future.
• There are more coming every day!

Hardware supporting the dCs standard:

• Mytek Stereo 192-DSD DAC converter, possibly only via "pro" version
• ExaU2I interface
• exD interface
• XMOS Reference USB Audio 2.0 Interface
• Meitner Audio MA-1
• dCs Scarlatti and Paganini
• Playback Designs MPD-5 DXD and DSD up to 6.1Mhz (128fs x 48Khz)
• others have been demoed, many options are coming.

External Articles on the dCs Standard:
Positive-Feedback: Announcing the DSD Open Standards Movement
The AudioBeat: DSD Over USB: An Open Standard

DIYAudio Forum: DSD audio over USB: an XMOS Reference Design implementation

SixMoons: PureMusic DSD Native Playback Setup Guide

This site has no affiliation with any vendors mentioned, this information is provided to spread awareness of DSD.

The Open-NGDI Project - Definition Stage

I have started an Open hardware project named the Open-NGDI, or Open Next-Gen Digital Interface. The Goal of this project is to build an interface for connecting modern high dynamic range ADC/DAC's to a personal computer.

  

We need people like YOU to help define the project in this critical early phase before development starts!

Key Features:

• Maximum Sample rate is planned to be 512fs (24.576Mhz), at up to 8-bit, capturing what is commonly referred to as Multi-bit Delta-Sigma, or Sigma-DPCM. 
• Up to 8-Channel's per board is planned @ 512fs, with the capability of expanding channels through syncing of multiple boards. (48bit width I/O @512fs (24.576Mhz), either 6x 8-bit, 8x 6-bit, or 48x 1bit)
• Support PCM up to 1.5Mhz @ 32 bit depth
• Modular Architecture - Digital Interface, ADC, DAC, Power Supply, Analog Stages all on separate boards.
• Open Source Hardware license. All associated software/hardware and documentation will fall under an open source style license. GPL v2 for all software, OSHL v1.0 currently for the hardware license.
• Community developed and fully documented. An open community will be encouraged.
• Sister project the Open-NGSDR will be developed side by side with this project, and aims to create a version of the Open-NGDI optimized for SDR and measurement purposes.

Involvement is encouraged by anyone interested.

This project needs YOUR help. 

This project can not get off the ground without a community. 

Even if you have no experience in programming, designing PCB's, or writing VHDL code, you can help by showing support, and giving your idea's, opinions, and criticism.

I have created a Google Code site and a Google Group Site to consolidate information and facilitate starting a community. 

Prototype 1-bit 512fs (24.576Mhz) USB DAC Interface from the 1-bit audio consortium.

I have very exciting news. The 1-bit audio consortium has shown a high speed USB DSD DAC interface, capable of all known standard speeds of Delta Sigma, from 2.8Mhz (64fs or SACD) to 24.576 (512fs). It seems faster than 128fs DSD is finally getting some attention by designers. Hopefully this will mature into some product. Most of these demonstrations over the past few years have been only proof of concepts, such as Korg's 8-channel USB ADC/DAC interface and DAW software shown last year, or previous USB Interfaces shown by the 1-bit audio consortium.

Seeing this being developed shows people are still looking forward with Delta-Sigma for audio. The holy grail of perfect digital audio recording/playback has not been found yet in my opinion.

Link to to referring article:
http://puresuperaudio.blogspot.com/2012/02/no-speed-limits-on-hi-rez-highway-for.html

Theoretical New Formats

I want to discuss some of the new formats that have been mentioned
before, but not yet implemented commercially or by amateurs (that I
know of, please tell me if I'm wrong).


Specifically, the formats I am referring to are:

• Multi-bit Delta Sigma, either 5 or 6 bit at 11.2892Mhz or 12.288Mhz (256fs) sample rates or higher, which would effectively be a "RAW" capture from today's best cutting edge low SNR ADC's (there are 1gs/s+ adc's with worse SNR = less effective bits). 
• 1-bit DSD at 256fs and higher sample rates. Anecdotal reports mention that 256fs appears to be the first point in 1-bit audio where the noise and signal don't interfere, therefore removing the need for noise shaping.
• 768 Khz PCM. The highest bitrate PCM I've seen used, but at 16-bit, and only for scientific use. Not sure what ADC's support this, but the Arda AT1401 DAC supports up to 1.5Mhz PCM.
  

The reasoning behind the proposed format of 6-bit 12.288Mhz DSD, is
the same reasoning that created DSD. The highest quality ADC's of
today use a multiple order delta sigma converter, which is than
processed into either 1-bit Delta sigma, or multi-bit PCM,
theoretically loosing some information in either conversion. By
capturing the "raw" output of the ADC, all mathematical interpretation
can be done at a later point, allowing conversion to other 'future'
formats as they appear, or reinterpretation when new conversion
methods become standard.


It should allow capturing the maximum obtainable quality in archiving
priceless audio. All the disadvantages of DSD still hold true, lack of
ability to perform manipulations or process without conversion, but
now that we have moved past monolithic single-bit delta sigma ADC's,
the archival use of single-bit DSD is questionable. I believe the
"best" mathematical conversion is open to debate, as there is no
perfect solution. By capturing the "raw" output of a ADC allows the
highest amount of care in selecting which algorithm is best in down
conversion. It should allow the maximum quality to be obtained, and
allows choosing a possibly superior conversion at a later date should
another option arise.


I believe that this project has many applications beyond simply audio,
perhaps an open-source SEM (scanning electron microscope) would
benefit from a high speed interface for an ADC for capturing data for
processing, Hams could use it for extending the utility of SDR
(software defined radio's) to allow capturing/sending data, or a radio
telescope project could benefit from more precise digitization,
allowing linking up online and using aperture-synthesis to increase
the effective aperture. Ultrasound systems and other medical imaging
devices like MRI or CAT scans could be possibly utilize it. For
medical imaging lower starting costs are important for the developing
world. GPR (ground penetrating radar) could be developed for the
developing world to survey land quickly and cheaply, to find hidden
dangers or resources.


The uses are endless, as we are in a society where there is a never
ending need to capture, create, and analyze information. Open Hardware
and Software is a revolution, and everything entered into the public
domain can be reused and modified to find uses far beyond the original
intention. For this reason I hope to create some momentum behind
developing a General Purpose High speed ADC/DAC interface. Almost no
design details exist as of now, except the proposed format. This is a
similar project to the SDR-Widgit project, but with the expanded goal
of supporting the "RAW" output of modern Delta-Sigma ADC's. Possibly
SDR-Widgit or Audio-widgit will be used as a starting point in
development.


The need for a new archival and mastering format, as well as a format
for scientific research is becoming more needed every day. For studies
of psycho acoustics, echolocation, animals, sonar, ultrasound,
turbulence, aerodynamics, and virtual reality there is no lack of need
for increasingly precise digitization of audio. There are devices sold
today sampling at rates up to 768Khz for Bat studies.  As new
technologies develop, in addition to computers becoming faster at an
exponential rate, the need for easy ways to capture data accurately
have never been greater.


I am hoping to start an open-source community that can help to develop
a high quality high speed digital interface. This project will (*most
likely) require an FPGA and custom programing and hardware to take the
high speed multi-bit or single-bit data and accurately capture or
output it, without conversion to other formats.