DigiOne Coaxial/BNC output for RPI

DigiOne specs :

RCA and BNC outputs (gold plated) only (absolutely no optical, it has by definition 4ns of jitter). No AES either its not a good medium for digital signals.
Noise level under 100uV ,we hope for 50uV, at the output.
Jitter target at BNC/RCA under 3ps on both outputs (we hope for 1ps).

That means no transformer for galvanic isolation , what we do is isolate the board at the input (after the wm8805) and then reclock with NDK Oscillators feed with own LDOs+ filters. (with meta-stability solved)

In total we use 10 LDOs on the board, 12 low pass filters, multiple buffers (with 0.07ps added jitter), digital isolator, common mode choke , isolated DC/DC convertor with filter on input and output.

We have a target price of 119 Eur…but its not set in stone.
Target release date April 30 (Sunday)…we will do our best but don’t take it as a guarantee.
Basically what we think, its that DigiOne will be the best digital transporter on the market at ANY price (yes including those 5kEUR/USD transporters). Please correct me if I am wrong (if we hit those targets)

Any questions ?

@allo, wauw! Great specs…

Few questions :slight_smile:

  • The board getting its own DC/DC converter, is that similar to the power input of the Kali?
  • Will it power the Pi as well?
  • Is the size and position of the board in a way that it sits nicely on top of the Pi to fit in one of the many Pi cases out there? Or does it have the same ‘challenges’ as the Kali when it comes to the board size and positioning?
  • Does it get the LEDs as the Kali has too to indicate detected sample frequency and crystal it uses? Which is a great feature to check if things work as expected (having the correct I2S output signal feeding the board).
  • If it gets the LED (I hope), would it be possible to turn them off using a switch/jumper of via software/driver?
  • Does it get its own driver? And what options (if any) would that driver give?
  • Can you explain why the design uses the WM8805 and not the 8804?

I guess the price is right if the board reaches the high quality level it is aimed at. The powersupply is not included I assume? Including a very good low noise powersupply as a package deal makes sense to reach the potential of the board. Going over the 100EUR/USD mark could be a psychological barrier for some people as all other components (like the Pi, etc.) are all below this mark.

But I probably buy it anyway :wink:

Good points.

DC/DC isolated convertor is a specific https://www.digikey.com/en/product-highlight/c/cui/3-w-isolated-dc-dc-converters component unlike a wallwart

Position is like the BOSS or Piano

It has some LEDs , but not for frequency (will check more on that)

Any i2s generic drivers should work, but we will also make our own.

Wm8805 choise was from engineering team , I will check why.

You can use any PSU for your RPI, we took great care to clean everything (multiple filters LDOs etc)

We do understand thats a more expensive board, but frankly, for the level of tech its cheap. Like I said , this will become the most advanced spidif transporter with lowest jitter specs.

Will DigiOne still have I2S output?
Will it be possible to power isolated side with external 5V regulator?
Will the board have footprint for better clocks like Cyrstek or PulsarClock?
Will it have 3.3V out for powering e.g.: isolator on dam1021 board or digital logic board for old R2R dac like pcm1704. 3.3V out would be usefull in general in many cases when connecting external dac.
Will it have possibility to switch between buffering (0,7s) of samples or not? - Buffer 0,7s for music playback, no buffer for watching movies (no lag).

My only question: does it also support I2S output? If yes, I will buy one when it will be available.

My 2 cents:
I understand all of those features requests are just a wishlist, but remember than designing a new product is always a balance beetween features and manufacturing costs. So adding all of those would probably make the DigiOne not affordable for the majority.
Also, increasing the complicacy would increase time to market and decrease stability of such solution…

I’ve experienced lot of times this wish-list attitude (especially on kickstarter) and I think that everyone should know what it means to design a product in order to make more constructive requests

Don’t get me wrong, I’m not blaming for feature requests, but rather suggesting a more practical thinking to the matter , which will yeld to better suggestions and a better co-design process with the community :wink:


I am software product manager so “I know where you coming from” :slight_smile: Building product is complex thing and you have to take a lot into consideration, exactly like you wrote. It is not like “happy” RaspyFi development anymore … :wink:
Still … good job. Thanks. Thumbs up! Patiently waiting.

Its a master i2s…no buffering.

Ok. Got it. So it is rather something like Hifiberry Digi+ Pro. What are the differences then?

Basically the jitter sent out…its comparable with Kali. Almost nil

Also the noise on the output…its almost nil

If you want to use spidif to your favorite dac/amp, we wanted to give you the choice of the best spifif transporter including any commercial solution (not only RPI solutions)

Great. I understand DigiOne will serve many.
However only toslink gives 100% electrical isolation from transmitter and reclocking should be done at the receiver (I2S signal just before the dac chip) not at the transmitter. So for me something like Allo Reclocker with toslink input would be the best design in terms of jitter reduction and electrical isolation from transmitter.
In such case I could use whatever transmitter I want, be it: rpi, pc etc and whatever I2S DAC I want.

You might have a look at this debate from a while back (stereophile.com/content/coaxial-or-optical-1); the TL;DR view would appear to be that cheap plastic optical is markedly worse in introducing spurious data and timing issues than coax, whilst being much lower bandwidth. If you do have single-mode glass links plus the equipment to drive them, then no problem but on the RPi/domestic hifi level, this isn’t the case. Copper would appear to be the better pragmatic solution, irrespective of the theoretical maxima…


Chris M


isolation on Digione will happen after the WM8805…basically at the output you have a bunch of flipflops , clock circuit (for reclocking) and connectors.

Both clocks and flipflops have separated/ dedicated LDOs to reduce the noise. Thats your output and that is what you will connect to.

Rest , like RPI , WM8805 are on the other side (isolated input)

Great! Then the only missing part in Volumio would be embeding chromecast audio protocol.

Thats interesting… is Chromecast open source ?

Not as such but you could have a look at github.com/lanceseidman/picast and see if there’s anything that would work for you.

Wow. I did not know such development exists. If PiCast really works then, for me Pi with PiCast + DigiOne (I2S out) would be ultimate audio streamer! I love my chromecast audio in term of usability for spotify and tidal streaming, because you can use native apps for control.

First testing on Digione…jitter of 1.7ps :smiley:

Anxiously awaiting more details…
Measurement results…
And anything else we can get :slight_smile:

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Pics of the unit. We are still testing