Transforming VanityHD card for Oppo 203 into usable I2S


#1

I would like to ask for some advice or guidance. I was hoping that the I2S capability of the new VanityHD card for the Oppo 203 would include an HDMI port, so I could run directly to a DSD with a good HDMI cable (my current set up is stereo). When I asked awhile back, the company didn’t know, and now the manufacturer has just posted that the I2S will be “an on-board 14 pin IDC header with 8 channel I2S output, master-clock signal, ground and 3V3 power signals.” Given that in principle I2S sounds better than coax, my questions are 1) whether or not the mod proposed is likely to be worth it sonically, and 2) what do I need to know specifically to make it work with the Directstream. I’ve just asked if there are any step by step instructions to determine if I can handle the mod myself or will need some help. I haven’t received the board yet, but it is expected to ship in the U.S. next week. Currently, I’m running a Snake River Boomslang s/pdif between the units.

There’s a forum post from the manufacturer that goes into some details, which I’ve copied below. Here’s a link to it: http://www.audiopraise.com/forum/read.php?13,838,840#msg-840

Here’s a photo of the board: https://1drv.ms/i/s!AqsCKHVTj0ydlQyT2qipwdymA15d - and a page it comes from (click to expand): http://www.audiopraise.com/forum/read.php?13,794

And the I2S page from the manual: https://1drv.ms/i/s!AqsCKHVTj0ydlQ3titt-SeGttch8


Hi all,
There have been some questions how to connect the I2S output from the Vanity203HD board to a DAC with I2S input via HDMI or RJ45. Let’s recap the I2S port description from the user manual:

For added flexibility the Vanity203HD features an on-board 14 pin IDC header with 8 channel I2S output, master-clock signal, ground and 3V3 power signals.

The master-clock signal is either 22.5792MHz or 24.576MHz depending on the base sample rate. The audio channel assignment across the SDATA signals is the same as the channels order at the main S/PDIF outputs. SDATA1 contains both front channels, SDATA2 carries the surround channels, SDATA3 carries the center and subwoofer channels and finally the SDATA4 contains the surround-back channels. The I2S output has standard 3V3 LVCMOS signaling levels. If the downstream DAC accepts different signaling type or levels (e.g. I2S over HDMI or I2S over UTP/STP Ethernet) the user has to provide a suitable conversion circuit.

There are two reasons why we didn’t include a HDMI (or RJ45) connector with I2S signals directly. First, there is no unified pinout standard for I2S over HDMI. Different DACs have different pins assigned to different signals which makes it impossible to come up with something that would work for everyone. Second, there is no room or cutout for the HDMI connector in the back panel and we really wanted to keep the board as a drop-in replacement for the analogue board without any mechanical modifications.

But, if you want to use the I2S output, you can! smiling smiley

Electrically as well as mechanically the I2S requires just a bit of DIY. In order to feed your DAC with I2S you need a level converter module to convert standard 3V3 LVCMOS to HDMI signals (LVDS). The Vanity203HD has been tested with Audio-GD I2S module and this module is used as an example in the connection diagram below.

The user has to make a custom connection between the on-board IDC connector and the HDMI output module. Please note that the signal assignment must match with the one on the receiver side and there is no universal guide for that. Always refer to the manual of your DAC.

Regards,
Pavel


#2

The HDMI chart at http://www.i2s.sonore.us should be helpful. There’s a mini schematic of the PS Audio output circuit below the table and the input uses the same HMDI pins. You may want to use the DS90LV047A CMOS to LVDS chip instead since it has a better pinout. The DS doesn’t need the master clock so you don’t need to hook those wires up if you don’t want to. The PWD would need the master clock so you can hook up those wires if you want to. :slight_smile:

You want good solid grounding of your interface to both the HDMI cable’s shield and your device or you’d be better off with S/PDIF over RCA cables.


#3

Thanks, Ted. The chip you suggest has been replaced with the DS90LV047ATM/NOPB (http://www.ti.com/product/ds90lv047a/samplebuy). I’ll have to see what instructions are forthcoming. Otherwise, I’ll have to find someone to do the mod for me.

The other thing I’m not clear about is where an HDMI port for I2S fits in all this.


#4

I2S was designed for simple connections to DACs or from ADCs for digital audio on a board with traces. As such there’s no spec for connectors, cables, etc. It turns out that HDMI has 4 differential pairs (and a few other lines) that will handle the bandwidth required for I2S so it’s a good choice for being able to use cheap off the shelf connectors and cables for I2S. The companies in the chart above (and probably some others) support I2S over an HDMI connection, tho they don’t always use the wires identically (since there’s no spec.)

One way to hook up I2S to the DS would be to solder some other connector to the DS, but that would be quite difficult :slight_smile: Probably the best way is to hook up and HDMI connector to your source that uses the pinouts in the chart above and then you can use a normal HDMI cables to connect it to the DS (or whatever.)


#5

Thanks for the info, Ted. Sounds like a job for a good technician. Have to look around.


#6

Ted, Does the 203 VanityHD card and a switch of its I2S output affect HDMI version compatibility for audio? The Oppo 203 itself uses HDMI 2.0 and I found version 1.3/1.4 cables didn’t work right from cable box to Oppo or Oppo to TV. Thanks,


#7

I2S and HDMI signaling are different protocols. Using the HDMI cable and connectors is a cheap, reliable way to transport I2S from box to box but it’s got nothing to do with the HDMI protocols and won’t interoperate with standard HDMI equipment.


#8

Great, thanks.


#9

Ted, I’m not clear about a couple of your suggestions. When in your first post you suggest using the “DS90LV047A CMOS to LVDS chip instead,” you meant instead of what? The Audio-gd module linked in the manufacturer’s post - I assume output only is needed - has an HDMI port. How does the CMOS you suggest fit in with that? http://www.audio-gd.com/Pro/diy/I2Skits/I2SEN.htm

Also, you refer to the PWD needing the master clock. That applies to the Directstream (DSD) too? Thanks,


#10

It looks like the Audio-gd HDMI/I2S output kit has a compatible pinout for PS Audio DirectStream products.

I was mistakenly referring to what you had to do if you didn’t have the Audio-gd module and wanted to hook up to CMOS I2S lines.


#11

Oh, so the CMOS was not necessary… Also, you refer to the PWD needing the master clock. That applies to the Directstream (DSD) too?


#12

The DirectStream and DS Jr don’t use the master clock. The PWD does need the master clock.


#13

Just to be certain, mine is a Direcstream that started life as a PWD. Does that take the master clock out of the equation?


#14

A PWD modified to a DS is a DS, so you don’t have to worry about the master clock at all (the DS will ignore it if it’s there and doesn’t need it if it isn’t.) I only brought up the PWD since there’s another thread that’s active about I2S for a PWD and I didn’t want non-DS owners to think that they didn’t need the master clock.


#15

I’m assuming the audio-gd output module has to be mounted on the board and connects with various wires to the multi-pin unit next to the dip switches (see first post). If I’ve got that right, then I’m wondering how the HDMI cable gets in there to connect, and what the best way is. The back panel of the Oppo has some grill like openings to the other side of the back. Does that mean one has a choice of either expanding one of those openings; cutting and then splicing an HDMI cable after its fed through without having to expand an opening; or of running thin wires with HDMI connectors on each end (male-female) through the grill and then connecting a regular HDMI cable outside the back of the unit?


#16

Ted, The manufacturer is currently putting together instructions for installing the audio-gd I2S output unit, but is having a problem figuring out the best way to do it, as there are no simple solutions. He suggested two approaches, either…

  1. Mount the output unit underneath the Vanity board - there’s enough vertical space - and make a hole for the HDMI connector on the back of the Oppo’s panel or, alternatively, run an HDMI cable from outside to the mounted output board via one of the elongated vents; the vent would have to be widened or the cable spliced to get the HDMI connector through (eventually a PS Audio I2S cable); or

  2. Leave the output module outside the player and run a 14-conductor flat ribbon from the onboard IDC connector to the output board (using I2S signals) through one of the vents. I assume there would need to be a way to protect or enclose the output unit so as to protect it and me from harm. Any suggestions for that?

What do you think might be best? You mentioned sonic compromises if the output board isn’t anchored (inside). What about outside? I’m wondering if the flat ribbon solution, which on first glance seems the easier approach and doesn’t damage the case, would undermine the value of the project sonically, vs. using a good coax cable (currently Snake River Boomslang). Btw, I will be looking for someone to do this job (which may be the hardest part of all). Thanks,

Here are some photos (the one showing the whole insides has the stock audio board, which has been swapped out):

VanityHD-203-board-photo.JPGVanity-HD-for-Oppo-203-full-insides.jpgOppo-203-back-panel.JPGaudio-gd-output-unit-2.JPG