Raspberry Pi I2S to SPDIF Hat

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

  1. Miggie78

    Miggie78 New

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    Interesting! As I was previously mostly listening to Spotify (where all content is 48Khz as far as I know) I might've gotten away with it, then maybe I tried to play something with a different sample rate which caused the stack to stop working.
    I'll do some tests with the Isolator having this in mind and see if that's causing issues.

    Without the Isolator 44.1Khz and 48Khz files play fine (at least the leds on the 502 light up accordingly).

    Thanks for the investigative work :D
     
  2. Miggie78

    Miggie78 New

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    Wow. Mind blown. How did you figure this out? Was it mentioned somewhere? I'm just wondering why is there a resistor on this GPIO in the first place if the Isolator is supposed work transparently without any modifications (besides the jumpers)?
     
  3. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    The isolator manual (J5: 40-pin isolated GPIO connector) mentions the pullups on GPIO pins 15, 22 and 31 as " Pull up to 3.3V with 4.7K resistor, reserved for some audio cards". I suspect that the HifiBerry Digi uses a strong pulldown to overcome this, but we do not. Frankly we did not test with this isolator card, nor did we expect any other card to touch those pins. Perhaps those of you who have the isolator card sends some feedback to the maker and ask that these pins be jumpered.

    In any case, I am very glad you now have your setup working. Enjoy the music! :)

    Cheers,
    Michael
     
  4. Miggie78

    Miggie78 New

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    Just performed surgery on the Isolator :) All seems to be working perfectly now. I think we can close this one.
    Huge thanks linh and Michael!

    Going to go and enjoy my stack now :D
     
    Last edited: Feb 10, 2018
  5. Scott Kramer

    Scott Kramer Friend

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  6. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    Thanks for that information. I don’t feel so bad now! Still, this is something the isolator board manufacturer should take into account. As a manufacturer myself though, I do understand that it can take some time to make these changes reflected into the actual products.

    Cheers,
    Michael
     
  7. Miggie78

    Miggie78 New

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    @Michael Kelly

    No need to feel about something that's not your fault :) The 502 works fine.
    I think the Isolator is a great board as well, it definitely benefits my setup. Right now the two just need some love to work together it seems.

    I think the nature of Pi/SBC audio is such that if you stick to the basics it's relatively easy to get things working. If you start mixing things up then a lot of skills need to come into play (software, hardware and electronics even). I'm definitely not an electronics guru so finding the cause and figuring out the solution on my own would've been pretty much impossible.

    Since SBCs have sort of entered the mainstream hobbyist space now, I think you as manufacturers are going to find some customers struggling with your products even though there's nothing wrong with them. It's when people use them in unexpected ways/setups and then either lack the software or technical skills to get things working on their own. You can't prepare for every possible combination or use case no matter how hard you try :)

    What I find great is the awesome support a lot of smaller manufacturers still manage to provide for their products (and for things that are not even of their own make!). I hope you take pride in that!
     
  8. zeed

    zeed MOT: Gaudio

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    @Michael Kelly : any update about the availability of 502DAC boards?
     
  9. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    We have been having major issues with getting the NDK clocks and that has resulted in these unforeseen delays. But, we have secured enough units to do another run of the 502DAC. We will build 100 units and they will be available the middle of May. Because of the clock issues and its overall cost and complexity, we have decided to cancel the 502DAC pro. Ultimately the most common use has been as a digital streamer to other DAC units and as such, the 502DAC works very well. The basic PCM5122 DAC on board is useful and not very expensive, so it stays.

    In the meantime we have developed a series of DAC/Amps based on the AK4452 and a single tube architecture as well as an LME49600 based version. These units support USB, Optical and Coax input up to 24-bit @ 192Khz. As such they are a great companion to the 502DAC/Pi setup. More information is on the MJK Audio web site:

    http://www.mjkaudio.com/mercury-series---dacamp.html

    As you can easily guess, it is also a company of mine, but focused exclusively on audio.

    On the Pi 2 Design front, in addition to the 502DAC, we have developed the DTS1 Digital Streamer/Transport. It is somewhat similar to the BDP-Pi in that it uses an actual Pi SBC inside and has the digital circuitry from the 502DAC. It also has internal mSATA storage and a 256x64 OLED screen with Rotary Encoder. We plan a Kickstarter campaign later this month. We will be offering some units here on SBAF for beta testers and SW developers to help us round the functionality out. We will publish full specifications so anyone who wants to can install their own choice of Pi compatible player and OS. More info on the DTS1 is currently on the MJK Audio web site here:

    http://www.mjkaudio.com/dts1---digital-transportserver.html

    As always we love to hear your comments and suggestions. Sometimes I even follow them! ;)

    Cheers,
    Michael
     
  10. Poleepkwa

    Poleepkwa Friend

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    @Michael Kelly, I have the original board Rev P1 from the "prototype" days (December 2016 - The one with the noise on the RCA output). Does the final version offer any improvements on the digital side, or is it just the RCA's that where fixed? Wondering if I should replace the prototype with the final version or the 502DAC Pro. Any thoughts?
     
  11. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    The digital has stayed the same. But, the 502DAC Pro is no longer in production as mentioned in my last post. We will only be supporting the 502DAC going forward.

    Cheers,
    Michael
     
  12. bigbear1997

    bigbear1997 Acquaintance

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    Sign me up for the digi transport beta 8)
     
  13. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    That’s great! Don’t get too excited though, we are going to have to charge you for them. Probably half price which is enough to cover the costs.

    I am the prototype PCBs build up now and I’m doing some initial testing. But I won’t have the cases until the middle of April. So we have some time to get some documentation together for folks to look at and begin thinking about how they would approach.

    I am inclined to start a new thread for this, I’d like to hear what folks think about that. Even though this is in many ways the derivative of the 502 DAC It is still separate project.

    Cheers,
    Michael
     
  14. Scott Kramer

    Scott Kramer Friend

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    @Michael Kelly Any chance you are trying the new "A" version NDK's ? -->

    NZ2520SD --> NZ2520SDA

    Seem pretty sketchy to get anywhere A or non A (digikey/mouser) etc.
     
  15. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    We have not tried that, and as you surmised, they are as unobtainium as the non-A.

    Regards,
    Michael
     
  16. bigbear1997

    bigbear1997 Acquaintance

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    Wonder if the transport can use WM8805 instead of the WM8804so DSD can be decoded.
     
  17. bilboda

    bilboda Florida boomer

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    Maybe a massdrop version of the streamer?. Just looking at my lovely 502dac clear case and wondering how it might look in a MD black case sitting on top of my MD CTH amp.
     
  18. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    I will look into that. Thanks for the idea.

    Cheers,
    Michael
     
  19. HumanFly

    HumanFly Acquaintance

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    Has anybody here tried the Raspberry 3B+ yet? Does it already work with Volumio and the 502DAC?
    I usually hold off buying the latest pi for a while untill the bigger issues with compatibility etc. are resolved but I could really use the bit of extra speed and the waaaaay faster ethernet this time around.
     
  20. bigbear1997

    bigbear1997 Acquaintance

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    Volumio already has an image for the b+
     

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