Output Board Ideas

[feurkils]

Pavel,

Hadn’t really thought about how a single 8 channel usb connection would considerably reduce cable counts vs spdif… I’ll have to give this option some serious thought.

On the input side, any chance that more than just HDMI is possible? Having a suite of spdif inputs would increase the usefulness of this for those who have non HDMI sources. At that point it could be a spdif to usb converter with ASRC, diagnostic info, channel routing, etc.

Really great work sir!

[AP]

Hi there,
We have progressed a little to the point of having firm specs available for the USB board and also I2S board.

The former one has also two BNCs, one input and one output. The output is simply a stereo (front) SPDIF output from the USB interface to make it more flexible either for audio monitoring or synchronization of another device. The input is a general purpose digital audio input that one could switch between HDMI/ARC/SPDIF-IN. The board is significantly more expensive to build and it will need to be a paid option.
[img]http://audiopraise.com/img/VPRO_USB_Output_Module_final.png[/img]

The I2S board has 4 HDMI connectors for 8-channel I2S with "PS Audio pinout". Therefore it should be straight forward to connect it to a I2S compatible DAC(s).

[img]http://audiopraise.com/img/VPRO_I2S_Output_Module.png[/img]
All traces are carefully length matched
[img]http://audiopraise.com/img/VPRO_I2S_Output_Module_front.png[/img]
Regards,
Pavel

[edo]

For the stereo unit I'd like to see I2S on HDMI. Given the choice I'd take it over the HDMI video pass through. Happy to see the BNC & AES/EBU.

[AP]

Hi edo,
The HDMI output (pass through) is hard wired to carry HDMI signal and it would not be easy to mux with I2S. We will take your suggestion of I2S via HDMI for the stereo out module on board. The tricky bit would be the same as for the multichannel version - there are just too many different pinouts, even signals in differential pairs swapped from the original HDMI pinout, that makes it virtually impossible to make the I2S output universal enough to cover all possible configurations. Once we get some feedback on the multichannel version we will definitely consider adding I2S output to the stereo version.
Regards,
Pavel

[OnaIp]

8-channel ADAT Lightpipe please. It will make it easy to connect to professional D/A converters with ADAT inputs (RME) with a small, lightweight, inexpensive cable.

Thanks!

[AP]

Hi OnaIp,
Good suggestion, thanks! Isn't ADAT limited to 48kHz per channel in 8-channel configuration? I think beyond 48kHz there is some multiplexing over multiple light-pipes going on. It has been a while I did anything with ADAT, so time to refresh the knowledge .
Regards,
Pavel

OnaIp Wrote:
-------------------------------------------------------
> 8-channel ADAT Lightpipe please. It will make it
> easy to connect to professional D/A converters
> with ADAT inputs (RME) with a small, lightweight,
> inexpensive cable.
>
> Thanks!

[OnaIp]

You can implement higher sampling rates using ADAT S/MUX mode, but you'll need to add more physical toslink connectors to support 8-channel. That's how all pro audio interface manufacturers implement it as far as I'm aware.

From [url=https://en.wikipedia.org/wiki/ADAT_Lightpipe#Data_transfer]https://en.wikipedia.org/wiki/ADAT_Lightpipe#Data_transfer[/url]:
"Higher sample rates can be accommodated with a reduced number of channels. While the original ADAT machines did not support this, the Lightpipe format was modified using bit-splitting techniques by the company Sonorus. Known as S/MUX (short for 'sample multiplexing'), this connection allows 4 channels at up to 96 kHz, or two channels at up to 192 kHz, on one optical cable. Most manufacturers implementing ADAT Lightpipe now support this S/MUX interface extension."

Cheers!

[MultiChMaven]

This is great! Can't wait. Good work guys!

[Karl W.]

Would it be possible to design a board with HDMI in and regular HDMI out? I am asking could the VanityPro be used to "clean up" the HDMI signal before inputting the into a surround processor? Or does converting back to HDMI recreate the problem that you have fixed?

[AP]

Karl W. Wrote:
-------------------------------------------------------
> Or
> does converting back to HDMI recreate the problem
> that you have fixed?

Hi Karl, you are right, the problem is largely inherent to the HDMI protocol and it's implementation and there isn't much that can bo done about it. I have pointed that out in the HDMI jitter article [url=https://audiopraise.com/documents/HDMI_Audio_Jitter_v1.pdf]HERE[/url], where I question the benefits of "audio only" HDMI outputs, which is probably the best you can get from that technology.

Regards,
Pavel