Raspberry Pi I2S to SPDIF Hat

Discussion in 'Digital: DACs, USB converters, decrapifiers' started by Michael Kelly, Apr 30, 2016.

  1. Lasollor

    Lasollor Friend

    Friend
    Joined:
    Apr 18, 2016
    Likes Received:
    282
    Dislikes Received:
    0
    Trophy Points:
    63
    Location:
    Japan
    I have been using a 502DAC (one of the early review units) for 2 years now, almost daily. At the moment I have LSR305 speakers directly connected to the RCA out and I digitally change the volume in Roon. I have been very happy with this setup although recently I mostly use it to play lullaby music to my newborn girl. Anyways now I have realtime PiCore distro installed as a Roon output. It doesn’t support RAAT but works very well. It was supposed to be just a test but I was too lazy to put dietpi back.

    Before that I’d used the 502DAC as an AES transport to my Yggdrasil and that time I had first RoonBridge installed for about 6 months then dietpi for about year. To tell the truth I couldn’t hear significant differences between the distros but dietpi was the easiest to set up for me (because it has graphical interface to set up wifi etc.) All distros worked without freezes, restarts, bugs etc. I had 0 problem with them and with the 502DAC.
     
    earnmyturns, Michael Kelly and Azteca like this.
  2. lehmanhill

    lehmanhill Acquaintance

    Contributor
    Joined:
    May 3, 2018
    Likes Received:
    78
    Dislikes Received:
    0
    Trophy Points:
    18
    Location:
    Michigan US
    My 2 cents. The XLR will be welcome for most users. I just changed out an XLR and installed a TRS on an existing digital cable.

    With regards to what kind of i2s connection, it seems that HDMI is more popular than RJ45, but the test needs to be whether the buffered i2s output will drive an HDMI cable of some nominal length. Something for Michael to breadboard and test.
     
    Michael Kelly likes this.
  3. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

    Joined:
    Apr 22, 2016
    Likes Received:
    883
    Dislikes Received:
    0
    Trophy Points:
    93
    Location:
    Rhode Island, USA
    Home Page:
    The LVDS driver will drive an hdmi cable to several meters. The buffered single ended signals can drive a few feet.

    Michael
     
    lucser and lehmanhill like this.
  4. lehmanhill

    lehmanhill Acquaintance

    Contributor
    Joined:
    May 3, 2018
    Likes Received:
    78
    Dislikes Received:
    0
    Trophy Points:
    18
    Location:
    Michigan US
    Does anyone know what i2s format that Metrum uses? If not, I have an Onyx with i2s input. Is there a simple, safe test that I could make to determine if the Onyx is balanced or unbalanced i2s input?

    Earlier, I asked Metrum about this and didn't get an answer. That was probably because I made the question too complicated. The first step is probably ask the question simply and directly, if no one knows already.
     
  5. earnmyturns

    earnmyturns Friend

    Friend
    Joined:
    Sep 25, 2016
    Likes Received:
    1,377
    Dislikes Received:
    2
    Trophy Points:
    93
    Location:
    Palo Alto
    Home Page:
    I got this pinout spec from them a while ago when I was trying to connect an Ambre to a Holo Spring (which never worked, probably because I did not know enough about the different incompatible I2S electrical encodings). It's the same as M2Tech's wiring spec (M2Tech and Metrum are now part the same company, BTW; I now realize that what I needed is likely what's on Fig 5 of the M2Tech spec).

    upload_2019-2-10_8-13-4.png
     
    Last edited: Feb 12, 2019
    Michael Kelly and Clemmaster like this.
  6. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

    Joined:
    Apr 22, 2016
    Likes Received:
    883
    Dislikes Received:
    0
    Trophy Points:
    93
    Location:
    Rhode Island, USA
    Home Page:
    There is a small quantity of 502DAC’s in the store right now for those who wish to pick one up. Once these are gone we will be building another batch of 30 or so, and will be enabling pre-ordering of these in about two weeks once we have a firm schedule on all the parts.

    Regards,
    Michael

    www.pi2design.com
     
  7. lucser

    lucser Rando

    Joined:
    Nov 8, 2016
    Likes Received:
    8
    Dislikes Received:
    0
    Trophy Points:
    3
    Location:
    South Korea
    I’m using a RPi+502DAC Pro mainly as digital output hat (AES) and I’m really happy with it. This is great as I was looking for long time to add some boards to add an I2S HDMI output to my setup for the Holo Spring DAC. I’m now investigating using some of IanCanada(DIYAudio) boards with AudioGD I2S HDMI module.
    Nevertheless I look forward for this board as it will be a more integrated solution offering exactly what I need: AES & I2S HDMI outputs for my RPi or Odroid C2 players.
     
    Michael Kelly likes this.
  8. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

    Joined:
    Apr 22, 2016
    Likes Received:
    883
    Dislikes Received:
    0
    Trophy Points:
    93
    Location:
    Rhode Island, USA
    Home Page:
    Please be aware that we do not support the Odroid C2 I2S interface. The C2 does not conform to the PI standard 40-pin as regards placement of the I2S signals They are located on a separate 7-pin header on the C2 which we do not interface with.

    Regards,
    Michael
     
  9. skem

    skem Friend

    Friend
    Joined:
    Nov 1, 2017
    Likes Received:
    911
    Dislikes Received:
    16
    Trophy Points:
    93
    Location:
    Cambridge, MA
    I’d love to compare this to my DigiOneSig on my ps audio dac
     
    msommers and Michael Kelly like this.
  10. lucser

    lucser Rando

    Joined:
    Nov 8, 2016
    Likes Received:
    8
    Dislikes Received:
    0
    Trophy Points:
    3
    Location:
    South Korea
    Hi,
    Well aware about it. I use it with IanCanada’s Isolator Pi board that has connector also for Odroid C2 I2s and make it available at the isolated 40pin GPIO.
    In this configuration + your board is possible to have a simpler (less boards) configuration for a digital streamer with I2S HDMI out.
     
    Last edited: Mar 1, 2019
    Michael Kelly likes this.
  11. lucser

    lucser Rando

    Joined:
    Nov 8, 2016
    Likes Received:
    8
    Dislikes Received:
    0
    Trophy Points:
    3
    Location:
    South Korea
    @Michael Kelly Do you have a rough estimation when the board (AES + I2S )could be available?
     
    Michael Kelly likes this.
  12. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

    Joined:
    Apr 22, 2016
    Likes Received:
    883
    Dislikes Received:
    0
    Trophy Points:
    93
    Location:
    Rhode Island, USA
    Home Page:
    Protos are being built next week. We had a delay getting the Pcb’s. I will post an update once we do the initial tests. I will still need a way to test the I2S over HDMI.

    Cheers,
    Michael
     
    HumanFly likes this.
  13. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

    Joined:
    Apr 22, 2016
    Likes Received:
    883
    Dislikes Received:
    0
    Trophy Points:
    93
    Location:
    Rhode Island, USA
    Home Page:
    Initial proto testing for the PI2AES digital Audio shield is complete. This is the actual unit:

    [​IMG]

    502DAC is a very good board, but PI2AES take to another level. In addition to the sonic improvements, the PI2AES adds direct I2S output, both buffered parallel over header and LVDS differential over HDMI. Now you can grab your favorite DIY DAC board and create the ultimate audio setup.

    Test results and comparisons to 502DAC. Note that the 502DAC board I have here on the bench has a broken XLR. Once I get another in hand I'll add that test. I can't even keep a unit for myself since we are always back ordered!

    Cheers,
    Michael

    502DAC BNC. This is what everyone has been very happy with, yet clearly there was room for improvement.

    [​IMG]

    PI2AES RCA. Noticeably better than 502DAC BNC.

    [​IMG]

    502DAC OPTO Jitter. Yikes!

    [​IMG]

    PI2AES OPTO Jitter. Huge improvement over 502DAC Opto, but still not as good as P2AES RCA

    [​IMG]


    PI2AES XLR Jitter. Note that the results seem to be a bit worse then the PI2AES RCA. But XLR is needed for long cable runs or interfacing with pro audio equipment.
    [​IMG]
     
    Last edited: Mar 24, 2019
    Roman, FlySweep, lehmanhill and 5 others like this.
  14. HumanFly

    HumanFly Acquaintance

    Joined:
    Jul 23, 2017
    Likes Received:
    69
    Dislikes Received:
    0
    Trophy Points:
    18
    Location:
    Netherlands
    So...when can I order? Too soon?
    And will there be a new housing too?
    Or maybe just the one housing panel with xlr-hole ?

    And where did the powerinput go? I can`t find it on the picture. Or does it now take 12v-48v?
     
    Last edited: Mar 24, 2019
    Michael Kelly likes this.
  15. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

    Joined:
    Apr 22, 2016
    Likes Received:
    883
    Dislikes Received:
    0
    Trophy Points:
    93
    Location:
    Rhode Island, USA
    Home Page:

    I expect to be able to start shipping in about four weeks time. We’re trying to decide if we want to do any kind of crowdfunding campaign or simply start taking pre-orders. Obviously we need to clarify our pricing first. At this point I can only say it will be between 100 and $200. It will simply come down to cost and where we think the market is for this product.

    There will be a case and also some analog optional add-ons. In fact the first one that we did and is up and running is a hybrid tube headphone amplifier. Very similar to our original 503HTA and 502HTA boards. So we are going to need to create some different cases for the various options including having no add on.

    I have already done the case mechanical designs but I have not yet gone off and fab any of the acrylic cases for it. I will probably do that in the next two weeks so that they are back and test fitting is complete before were ready to start shipping. The case price will likely be the same as it always has been at $15.

    Cheers,
    Michael
     
  16. HumanFly

    HumanFly Acquaintance

    Joined:
    Jul 23, 2017
    Likes Received:
    69
    Dislikes Received:
    0
    Trophy Points:
    18
    Location:
    Netherlands
    Maybe think of a way to use that screwhole on the XLR socket to give the socket some extra rigidity.
    Did you see my edit about the powerinput?
     
    Michael Kelly likes this.
  17. Scott Kramer

    Scott Kramer Friend

    Friend
    Joined:
    May 3, 2016
    Likes Received:
    915
    Dislikes Received:
    0
    Trophy Points:
    93
    Damn, now I want to see native BNC ;D AES is for long runs/pro gear... I think people get that confused with analog Balanced as *must* be better! Optical, no surprise there.

    Awesome, isolated i2s.

    Nice measurements, you're upping your game!
     
  18. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

    Joined:
    Apr 22, 2016
    Likes Received:
    883
    Dislikes Received:
    0
    Trophy Points:
    93
    Location:
    Rhode Island, USA
    Home Page:
    The case will have holes for rigidity. The combo rca/opto needs it as well.

    As for the power input (middle left in the photo) it is correct that it can take between 12V and 48V. The 48V is useful when you have the tube add on since that directly drives the tube plate and higher is always better.The downside of 48V is it the power supplies are a little more money, so the base unit without an add-on will come with a 12V supply. When you order the tube out on if it’s not at the same time as the base we will ship it with a 48V supply.

    Cheers,
    Michael
     
    HumanFly likes this.
  19. Yethal

    Yethal Rando

    Joined:
    Sep 23, 2018
    Likes Received:
    23
    Dislikes Received:
    0
    Trophy Points:
    3
    Location:
    Poland
    Will it require an update to RPi images or will it work out of the box using the existing 502 driver?
     
    Michael Kelly likes this.
  20. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

    Joined:
    Apr 22, 2016
    Likes Received:
    883
    Dislikes Received:
    0
    Trophy Points:
    93
    Location:
    Rhode Island, USA
    Home Page:
    On the 502DAC the PCM5122 was the interface master and thus the DAC PRO+ driver is used. On the PI2AES the WM8804 is the master and so you need the DIGI+ Pro driver instead. As you've seen the WM8804 is a much better clock master and by doing this any DAC add-ons we develop (or you attach via I2S) will not require any drivers. Though there may be options controlled via I2C, but basic functionality will not require any changes.

    The PI2AES also eliminates the weird issue where the WM8804 can not work at 176.4Khz when in slave mode (as it is on the 502DAC).

    Cheers,
    Michael
     
    lehmanhill likes this.

Share This Page