Roon endpoint - ethernet input and I2S (HDMI connector) output

Noted but this is a Roon networked endpoint, as per the thread title.

If was a point of reference and not a suggestion. The unit is discontinued. The rest of the comments still apply.

There are some measurements on the i2s output of a pi here:

The moral of the story is that i2s on small ARM boards are not up to the task because they do not have proper clocking onboard for audio. The product you mentioned appears to have worked around the issue with external clocking and that is a much better solution. Now the thing to check for is isolation which by definition means that the reclocking board needs it’s own independent power supply.

In regards to the LVDS i2s output configuration there many specifications used by companies. PCM alone would be easy enough to swap cables on, but now a days PCM and DSD are multiplexed over the same wires and that complicates things. This means the pin assignment has to be correct our strange things will happen like no sound, swapped channels, channels out of phase, etc. I’m not aware of a small arm board that allows the user to configure the pin assignment. I maintain this i2s database and it can make your head spin.

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Thanks for the explanation and I appreciate the complexities involved.

So let’s cut to the chase - when is the 2017 Roon Ready version of the Signature Rendu (with I2S output) coming out? :wink:

I already know about the USB output version (the ultraRendu with a linear PSU in the one case).

There is no chase…I just like the subject matter of this thread. The original Rendu with i2s and SPDIF output was discontinued because of poor sales. I’m using one right now because my USB gear left for RMAF yesterday and I really like this setup.

@Jesus_Rodriguez You may want to add the Matrix Audio X-SPDIF 2. :slight_smile:

Page 6 of the manual has the pinout. I’m resigned to making a custom cable for use with my HOLO Spring.

Cool. I’ll add it later today. To bad on a quick look it appears to be missing the DSD pin assignment:)

Yeah, I’m wondering if I’ve screwed up and an custom cable might not be able to solve everything. I’m too new to this stuff…

I am building a Roon endpoint with I2S out right now. I am cheating though because there is USB in the mix as the interface between the network/Roon card and the output PCB so it isn’t a ‘pure’ solution. Input is an Atom powered NUC board running ROCK as an endpoint. Output is the AudioByte Hydra Z board. I am waiting for a few bits to arrive and still trying to determine its final configuration but if it works well I may end up with something worth keeping.

What DAC and what source are you trying to use?

The Hydra Z is a pretty good i2s source…good audio clocks, isolation, clean power to the digital board, and selectable output configuration.

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@Jesus_Rodriguez 4 posts up :slight_smile: (Matrix X-SPDIF 2 and HOLO Spring)

Edit: FYI, the info I have is that the Spring’s DSD channels are reversed with respect to the PS Audio “standard”. If so, it looks like I’m going to have to correct in software.

Sorry I got replies mixed up.

It looks like you could use the “B” setting. No clue what will happened with DSD though.

Yeah, that’s what Jeff Zhu at HOLO Audio said!

The Pi2Design 502AES HAT is due for release in October. It has a balanced AES and HDMI i2s outputs. Not sure if it will do DSD.

The Allo Kali Reclocker will output i2s up to 32bit 384kHz and is probably best paired with an Allo Sparky (better Ethernet implementation than the Pi). It has it’s own power input and the Sparky can also be run from that.

The Kali is designed to fit between the Sparky and a slave DAC. This is the pinout of the i2s 40 pin connector output:

KALI I2S PINOUT: Pin Number Signal Name
1 12 BCLK
2 35 LRCLK
3 29 MCLK
4 40 DATA

@joel do you think it would be possible to construct a short 40 pin to HDMI cable that might take this output into the Spring ? I’ve read that the Spring doesn’t reclock an incoming i2s input. Is that the same thing as being a ‘slave Dac’ ?

The supplied PS is 5v/3A so it may be that an LPS-1 can’t be used as it maxes out at 1.1 amp continuous. The Sparky and Kali can be separately powered however, so it may be possible to power the Kali only from an LPS-1, can’t say.

@andybob, i2S over HDMI is not the raw signal. It needs to go via a balanced driver to enable it to be used via HDMI and so requires more than a 40 pin to HDMI cable. Audio-GD make input and output modules that do this so you would need one after the Kali Reclocker which then goes via HDMI to your DAC. I would power the Kali with the LPS-1 if I needed and keep it separate from the Sparky.


Thanks Henry,

This thread on the Volumio forum had some interesting posts and I think this Output module is one of the modules you are referring to. This could be an interesting project. I’ll take it over to Tinkering if I can confirm it’s viable.

It may be that the Allo people can be persuaded to do a Kali with an HDMI output.

It is the same module. How will Roon recognise it as an end point?