digital upgrade of older equipment via I2S with jitter attenuating S/PDIF receiver evaluation board ??
26 Jun
2010
26 Jun
'10
1:20 a.m.
There's this interesting product I came across: an evaluation board
from Wolfson Micro for the WM8804 high-performance SPDIF transmitter:
http://www.wolfsonmicro.com/news/258 . This might be an interesting
way to upgrade older soundcards (e.g upgrading 10 year old ICE1712
designs w/ modern DACs & reduced jitter while still retaining stable
snd-ice1712 drivers) or digital synthesizers and other A/V equipment
to give older perfectly serviceable equipment the latest D/A's and an
improved output section.
http://www.wolfsonmicro.com/products/WM8804
http://www.wolfsonmicro.com/uploads/documents/en/WM8804EV1M_Configurations.…
http://www.wolfsonmicro.com/uploads/documents/en/WM8804_Schematic%20and%20L…
Lots of potentially useful applications with this evaluation board,
all ready to go:
* optical/coax --> spdif with de-jitter.
* i2s --> spdif with de-jitter
* resync incoming i2s stream w/ external spdif clock
* USB control (?)
* onboard monitoring via WM8726 high performance stereo DAC up to
24bit/192k, w/ hardware selection of data interface format, mute,
de-emphasis, justification, etc. (which should make it easy to work
with or emulate existing computer soundcard DAC's that one might want
to update to the latest technology).
I'd like to hear people's opinions on whether this is a useful or good
product to invest time into? Specification-wise, the de-jittering
capability looks impressive, appears to better some of the competing
products "on paper." All of which might make the $200.00 pricetag (for
the evaluation board, not the chip itself) palatable (I've called the
local distributor for samples). Once proven, such a circuit could be
constructed for far less than $200 cost of the evaluation board. The
WM8804 itself is pretty cheap and fairly self-contained, and so is the
included DAC.... Then again, so is
http://cgi.ebay.com/24bit-192KHz-DAC-DIY-KIT-FULL-ASSEMBLED-KIT-PCM1798-/33…
or
http://cgi.ebay.com/HIgh-End-CD-Player-DAC-Upgrade-Mod-Kit-BB-PCM67U-DAC-AE…
versus
http://www.mouser.com/ProductDetail/Wolfson-Microelectronics/WM8804-6152-DS…
WM8804-6152-DS20-EV1
Manufacturer: Wolfson Microelectronics
Description: Audio Modules & Development Tools WM8804 Eval Board
........
The WM8804 is a high performance S/PDIF transceiver which offers a
state-of-the-art jitter attenuating S/PDIF receiver design. The WM8804
customer evaluation board provides full functionality for the
evaluation of the WM8804 device. ... Software to configure the
evaluation board can be downloaded from
http://www.wolfsonmicro.com/support/drivers
(unfortunately, all the drivers SW is for Windows, and
http://opensource.wolfsonmicro.com/ doesn't mention the 8804...).
....
Niels
http://nielsmayer.com
26 Jun
26 Jun
3:50 p.m.
BTW, one potential area of concern, interest, and legality of
I2S-vampirism-enabling hardware such as the Wolfson WM8804 is w/r/t
AACS: http://en.wikipedia.org/wiki/Advanced_Access_Content_System
This "feature" is coming to an HD-audio device near you beginning Jan 1, 2011 .
Consider the following scenario from "2010: The Year AACS and HDMI
Kill Off Component Video"
( http://www.audioholics.com/news/industry-news/aacs-hdmi-kill-component-2010 ):
We've even read stories about Hollywood-based
mastering engineers having to use Slysoft
AnyDVD HD software in order to circumvent AACS and BD+ restrictions just to get their
work done.
There are certainly legitimate digital uses of the audio content one
has purchased on bluray, no? For example, consider a "fair use"
scenario of an online review of HD content that would give a snippet
of the content, it it's original form, for the purpose of evaluating
the "HDness" of the content.
So after Jan 1 2011, it appears any HD hardware people might buy, such
as bluray players used for HD audio playback, will only allow for
analog audio connections for audio as well. Wouldn't HDMI-carried
digital audio be "secured" in the same way video content is? This
would leaving only low resolution video output (
http://en.wikipedia.org/wiki/Advanced_Access_Content_System#Analog_Outputs
) and "audio watermarked" audio (
http://en.wikipedia.org/wiki/Advanced_Access_Content_System#Audio_watermark…
)...
Given the above, it appears that a soldering iron and a I2S "vampire"
is the only solution, other than buying the appropriate unlocked
equipment now, and hoping that new "features" don't obsolete your
purchase. (Which is one of the many reasons why people aren't going
all-in with any DRM'd hardware if they can help it... this has got
"sony/betamax" written all over it and people will be choosing
openness and "http://" instead.)
Is I2S vampirism as needed for "fair use" or professional/creative use
of media-content one has purchased, feasible on AACS enabled equipment
by tapping straight in to the DAC I2S stream?
-- Niels
http://nielsmayer.com
9:11 p.m.
It appears that others have successfully tapped into the I2S signals
on existing Envy24-based soundcards, such as the ESI Juli@ using Via
ICE 1724HT ( http://alsa.cybermirror.org/manuals/icensemble/Envy24HT091DS.pdf
), and have also used the technique to get improved sound out of
older digital devices:
http://www.diyaudio.com/forums/digital-source/22741-high-resolution-multi-c…
http://www.diyaudio.com/forums/digital-line-level/36252-dcx2496-mod-digital…
The following details the simple mod for an ESI Juli@:
http://www.diyaudio.com/forums/digital-line-level/102851-i2s-juli-pci-sound…
I have an ESI Juli@ sound card ( new from ebay about
$129 ) and was using the spdif to drive an external DAC in the Box. I upgraded to a used
Perpetual P-3A and wanted to investigate an I2S connection. I use foobar2000 and Kernel
Streaming and flac files.
The Juli@ has an interesting design - there are two circuit boards connected by dual in
line headers ( a 20 pin designated J3 and a 10 pin designated J7). The "digital"
board has the PCI connection and the Envy-24 HT ( 1724 ) controller chip. The analog board
has an AK4358 DAC and an AKM ADC chip as well. The "analog" board can be rotated
180 degrees to change from RCA unbalanced connectors to Balanced 1/4" Phono plugs.
Therefore there are matching connectors on opposite sides of the analog board.
I downloaded the datasheets for the Envy and the AKM DAC. The 1724 is capable of
multichannel I2S outputs, and the AK4358 has multiple I2S inputs. I figured the I2S
interface was going through the pin headers from digital to analog boards.
I took a multimeter and buzzed out the connectors and the chips, and found the following
signals:
J3 ( 20 pin header )
J3 Pin 1 -> 1724 PSDOUT[0] ( I2S data out) -> AK4348 SDTI1 (I2S data in)
J3 Pin 5 -> 1724 PSYNC ( I2S Word Clock ) -> AK4348 LRCK (I2S Left/Right Word
clock)
J3 Pin 7 -> 1724 PBCLK ( I2S bit clock out ) -> AK4348 BICK ( I2S bit clock in )
J3 Pin 9 - > Xilinx on the digita board -> AK4348 MCLK ( I2S Master Clock in )
J7 ( 10 pin header )
J7 Pin 5 -> Digital VSS ( Actually several pins on J7 are VSS )
Here I had all the I2S signals ( Except DEEM as in Audio alchemy, but that does not exist
on the Juli@ board )
[...]
Believe it or not, this works perfectly with the P-3A DAC. I get I2S lock and can drive
it with 16/44 up to 24/96 signals. It sounds great on my system, much better than the
spdif connection. The only weirdness is the P-3A phase invert light is on all the time.
Maybe I need to invert the word clock or something. I may send an email to Perpetual Tech
and see what they say.
......................
Same potential for Via ICE 1712 (
http://alsa.cybermirror.org/manuals/icensemble/Envy24pb1_7.pdf ) as
used on M-audio Delta series, Terratec DMX6Fire. The Delta 1010 looks
like the best bet -- find an ebay special with a failed rackmount
breakout box (the capacitors in these are known to go bad and people
get rid of them cheap) and tap directly into the DB25 connector:
http://www.diyaudio.com/forums/digital-line-level/102851-i2s-juli-pci-sound…
Look for a Delta 1010 (not the LT - the full version
with the breakout box).
All the I2S lines are brought out to a DB25 connector.
......................
http://www.diyaudio.com/forums/digital-line-level/152753-i2s-pc-firewire-et…
[Envy24 has] I2S input I2S output all over the place.
All the inputs and outputs are 'slaved' you could say together, in that they will
all switch to work at one sample frequency - so you cant for example have an input working
at 96khz and an output going at 192.
It's easy enough to find the I2S clocks on the cards with the ENVY chips, I've
done it with great success.
I buffer the I2S with some logic (
http://www.nxp.com/acrobat_download/datasheets/74LVC126A_5.pdf ) , although this is for
protection of the sound card more then anything else, the DAC/ADCs I've built are
housed inside the PC case.
The buffer has a decent output current so I'd imagine it'd be fine driving cables
over a distance.
Niels
http://nielsmayer.com
PS: I think I'll start this experiment by soldering on my $0.99 Dynex
dx-sc51 since it has a total piece of crap analog section, and a
perfectly good VIA ICE1723 (
http://www.via.com.tw/en/products/audio/controllers/tremor/ ) sporting
a single i2s input (2 channels) a separate i2s output. (2 channel-6
channel), and a separate subdevice providing TOSLINK output.
29 Jun
29 Jun
8:03 p.m.
FYI lots of interesting digital and analog circuits and modules
available at http://www.twistedpearaudio.com .
I found one that has a WM8804 for $75.00 assembled, or $14.00 for the
PCB, but I don't think it's configured correctly. Regarding whether it
can be configured differently, here's a question I posted to their
forum, and some links to similar mods on the Roland SoundCanvas SC-88,
the Yamaha MU-10, and a Nintendo Gamecube....
......................
http://www.twistedpearaudio.com/forum/default.aspx?g=posts&m=5968&
I'm interested in tapping internal I2S outputs from working
soundcards&syths with outdated analog sections and exporting their
output to S/PDIF, rather than S/PDIF to I2S (see
http://linuxaudio.org/mailarchive/lau/2010/6/25/170787 ). I was
excited to find that this module was cheaper than the $200.00 WM8804
evaluation board that appears to be able to perform this task, but
less enthusiastic after clicking on the "transceiver" link and landing
on the "S/PDIF receiver" link instead.
Is there a way to enable the other direction of signalling --
I2S->S/PDIF -- on this "S/PDIF receiver" board?
Or do I need to the Wolfson WM8804-6152-DS20-EV1 board (
http://www.mouser.com/ProductDetail/Wolfson-Microelectronics/WM8804-6152-DS…
)
Another alternative is to find a hard to find and overpriced Toshiba
TC9231N ( http://pdfserv.datasheetpro.net/ToshibaSemiconductor/TC9231N.pdf
-- $76.00 just for the chip ) using a circuit like
http://gamesx.com/wiki/doku.php?id=av%3Anintendogcda
but using a 11.2896Mhz xtal for 44.1K instead of a 12.288Mhz crystal
for 48K rate of Nintendo box from above link.
Other older devices interfaced similarly include a Roland SoundCanvas
SC88 and a Yamaha MU-10:
http://nfggames.com/forum2/index.php?topic=4063.0;imode
http://www3.big.or.jp/%7Efujikko/sc88vl/kaizo.html
http://www.uyouyo.com/special/soundcrd/sc88.htm
-- Niels.
http://nielsmayer.com
5355
days inactive
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Niels Mayer