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108.3.18.39
In Reply to: RE: New Developments in USB DSD DAC's and ADC's posted by alexcount on December 16, 2010 at 14:18:59
Howdy
I've heard rumors of various "dometic" DSD USB devices, I'm not sure what the current licensing issues are with Sony tho.
I have thousands of SACDs (and more CDs) so I'm not likely to rip them all to my computer for any hardware. But I have snagged a few of my favorites.
I've got an expensive solution that's not generally available: a Meitner CDSD transport and hardware I built myself to snarf DSD and then I use the same AT&T glass interface to drive a DSD DAC I built (or my Meitner DAC6e). Also I've tapped into the signals of a DVP-S9000ES for stereo DSD (tho I haven't bothered to record it, I just did it as a quick transport prototype till my latest DAC with more standard PCM interfaces was built.) DSD sounds great off of the computer but since most software players I have don't handle DSD directly, for casual listening I usually play files that I've converted from DSD to 24/88.2 or 24/176.4 PCM: they still sound pretty good tho it pains me to convert DSD down to, say, 24/88.2 and then back up to DSD128 in the DAC...
I'll put a USB port on my next DAC but I'll probably not add USB DSD firmware in the FPGA/PIC until there is some sort of consensus about the interface/OS drivers.
The Sony DVP-S9000ES as a DSD transport:
My DAC's discrete DSD, TOSLink, AT&T glass DSD, AES and S/PDIF inputs:
-Ted
Follow Ups:
Hi Ted,
Wow, very impressive, glad to see someone else playing with this stuff.
Yeah, it all comes down to software/drivers.
The ElectrArt FPGA has a custom driver and very basic playback/recording software, definitely proprietary. The USBPAL supports the ASIO 2.1 standard, which has had official support for DSD for years, yet I still don't know any software which will playback DSD with an ASIO interface (wonder what mytek plans to play dsd with, maybe they will release some simple playback software along with there new DAC).
I am aware of the pyramix systems, which can playback dsd, not cheap, and they do not support ASIO standards for DSD, they demand their dedicated hardware. If something doesn't develop I am almost ready to start programming, this needs to be added to some open source projects like VLC, cPlay and Audacity.
I am really interested in your glass interface. Please tell us more. I have not seen DSD optical links. I have been trying to find the IC's detailed in the sony SDIF-3 paper to make my own SDIF-3 link, as this seems to be the only standard interface established for dsd data.
-Alexander
Viva Vinyl!
http://www.foobar2000.org/components/view/foo_input_dsdiffconverts to PCM it seems:
http://www.hydrogenaudio.org/forums/index.php?showtopic=76080
Edits: 01/01/11
HowdyIt's not my glass interface :)
The EMM Labs equipment (both pro and consumer) use AT&T ST glass fiber e.g. http://www.frys.com/search?query_string=4706599 )
They use transceivers of the type pictured: Avago HFBR-2416TZ ( http://www.avagotech.com/pages/en/fiber_optics/general_purpose_industrial_control_data_link_820nm/hfbr-2416tz/ ) Some relevant app notes are: Application Note 1121, Application Bulletin 78 and Application Note 1123.
In general Meitner uses three links between the transport and the DAC, clock out from DAC to Xport, clock into DAC from Xport and data into DAC from Xport. The clock from the DAC to the transport is optional in which case the transport shoves data down the DACs throat :)
The data is simply bytes of samples @ 64Fs (or 128Fs), each bit for a different channel. The clock runs slower and they obviously use a PLL to multiply it up. There are other details but since all I know is by using my scope and FPGA, any more would be speculation :)
I chose to put two HFBR-2416TZ interface modules on my board simply because I have a EMM Labs CDSD transport and it's simpler hooking up a fiber cable (or two) than hooking five clips onto chips in a S9000ES...
The problem is that Sony doesn't like raw DSD bits running around so I wouln't count on anyone supporting this interface.
I'll write ASIO drives first if I write my own USB drivers, but there are now some turnkey USB chip/driver solutions which don't involve licencing issues and support the expected USB modes as well as async.
-Ted
P.S. For more details about my board if you are curious: http://www.audioasylum.com/forums/pcaudio/messages/8/80732.html I am having fun with it.
Edits: 12/20/10
"The problem is that Sony doesn't like raw DSD bits running around so I wouln't count on anyone supporting this interface."
Why do you think that Sony could stop people from sending raw DSD bits around? How might they do it?
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Howdy
I never said that you couldn't send bits around: in fact I've told people that I do it. Sony doesn't care about random DSD bits, they only care about bits which are copyrighted flying around loose :) The SACD pit width code and encryption seems to work well and is well designed.
I just said that I double that the interface as implemented will ever fly for a company. There are two obvious issues if you market an interface:
.) In my mind the moral issue of facilitating others to break the copyright laws. (I only rip SACDs I own and I don't share bits.)
.) If you send the bits (sourced from SACDs) around unencrypted you'll never be able to market your device as a SACD device and I believe it's also a violation of the DMCA.
-Ted
All bits are born copyrighted. You have to buy a first license from Mr. One and a second license from Mr. Zero. :-) In Fascists states, breaking DRM on material that you own so you can enjoy "fair use" is a crime, but then there are many other innocent activities that are crimes in Fascist states.
There are patents on the method of storing the encryption key ("pit processing") on SACD disks, but these certainly don't apply here. There are other patents on editing DSD, none of which really work anyhow. There are patents on DSD compression and on DSD modulators. The basic format (pulse density) has been used for a long time—I was using it in some code I wrote for an Apple II in the late 1970's, but I won't say what the code used for. :-)
I don't mess with SACDs because of the DRM. It was one of several reasons why SACD failed in the marketplace.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
HowdyOr one of the reasons it's done as well as it has...
(Not that I like the RIAA)
-Ted
P.S. That's the beauty of good encryption: you can know everything about it and still not break it (or at least have a devil of a time.)
Edits: 12/23/10
The Playback Designs MPD-3 will be out at CES and will be able to accept DSD and DXD over USB.
You might want to talk to fmak (usually in the PC Audio forum at AA) about the SDIF interface.
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