Raspberry Pi I2S to SPDIF Hat

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

  1. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    I have always been reluctant to ascribe any sort of benefit to separating the power, because I have been unable to measure it using the fairly sophisticated equipment that I have. However I have also always been reluctant to equate specific measurement results with resulting sound quality.

    I think it is pretty clear that there will be some who will try it and hopefully they will report that information to the rest of us. My job is to give you the option.

    Cheers,
    Michael
     
  2. cxb1

    cxb1 Rando

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    Hi, newbie here, but very interested in this transport. Is there any simple guide to getting this transport up-and-running with the simplest recommended Pi configuration? I understand there are many options, but I'd appreciate a simple way of demonstrating its use, before launching out into other players/pi configurations etc. It also provides a base 'fall-back' configuration whenever a new configuration fails to work.
    Regards,
     
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  3. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    Sorry, I meant to reply to this a bit earlier. The problem you’re going to have is that there’s a fair amount of knowledge that you will need to absorb before you can make a reasonable set of decisions. The raspberry pi world is a DIY world. There are no fully buttoned up solutions that someone can point you to and say “follow all the steps and you will be successful”. There are just too many variables that can affect the end results unless you understand the decisions that are being made at each step.

    I don’t wish to discourage you from following the path of using the raspberry pi as an audio player. If you give yourself the time and make the effort the results are fantastic. It is a truly rewarding experience to put things together yourself and have it play awesome music!

    Google is your friend! Get yourself a raspberry pi and figure out how to get one of the common players such as [edit]Volumio running on it. Even using the crappy audio output built in to the raspberry pi, it will still prove out that you have all the software pieces is working. Then you could add something like our PI2AES board and an external DAC to get the best music you can.

    Cheers,
    Michael
     
    Last edited: Jun 1, 2019
  4. earnmyturns

    earnmyturns Friend

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    I found this Archimago article a great starting resource when I built my Pi-based stand-alone transport, which included a Pi 2 Design 502DAC instead of the HiFiBerry DAC+ Pro discussed in the Archimago article. But keep in mind that I'm a long-time Linux user and programmer who is very used to setting up and managing Linux systems with command line (shell) commands.
     
    Last edited: Jun 1, 2019
  5. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    New Photos, Datasheet and HW Reference Manual for revision P2 PI2AES are on our web site:
    http://www.pi2design.com/

    Cheers,
    Michael
     
  6. neogeosnk

    neogeosnk Friend

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    Is there still going to be 10 available soon? Thanks!
     
  7. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    We’re still going through the testing. I have spun off a new version that replaces the LDO’S with the LT3042 from analog devices/linear. It’s the same one we used on the 502DAC. Because we don’t have a D/A on this board we didn’t think they were justified. But some early feedback has indicated that although the sound is very good, it could potentially improve. I will know more in about two weeks when we build this next revision up and get it into the hands of the folks who have much better hearing than me!
     
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  8. Greg121986

    Greg121986 Almost "Made"

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    What's the limit for something like this to not support DSD? Is the WM8804 inherently not able to transmit DSD? Are there any alternatives that could be implemented to enable transmission of DSD?

    I have numerous DSD recordings that are excellent, so I'm not interested in discussing the technical merits of PCM vs. DSD. I just have dreams of a simple setup like this that would also allow DSD playback.
     
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  9. MisterRogers

    MisterRogers Friend

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    Glad to read about this change Michael - the LT3042 is garnering a reputation for good sonics. It's use in the LPS 1.2 accounts for much of its sonic improvement over the LPS 1.0.
     
  10. cxb1

    cxb1 Rando

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    Thanks: I'll look into this. I'm not exactly a newbie on Linux, having had a dual-boot system for 10 years, and I've a number of Pi's doing various things. But I try to avoid the command-line!!! I have this "thing" about a client system should always be able to use a mouse! Cut-n-paste is my friend... But I've never had to use Linux professionally, so it really helps to have someone point out a good Pi distribution, and any configuration details needed to get the i2s links working. I'm expecting this transport to drive some modded Behringer gear, and then into 8 active drivers (3+3+2).
     
  11. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    The source audio stream comes from the Raspberry PI which does not support DSD. It does however, support DSD over PCM (DoP). This would require a downstream DAC that supports DoP.

    Cheers,
    Michael
     
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  12. lehmanhill

    lehmanhill Acquaintance

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    I don't have a dog in this fight because I don't own any DSD files, but it is an interesting question. Is it a hardware or software problem for the Pi to process DSD?
     
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  13. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    It's hardware. DSD outputs a single left and single right data bit that is sampled every bit clock,. The data is basically telling the downstream dac to go up or down one bit at a time, while PCM changes 16 or 24 left and right bits/frame (48Khz, 44.1Khz, etc). So, while the fundamental HW to do this is similar, it's not the same. DoP (DSD over PCM) uses software to encode the bit changes into PCM by saving up 16 or 24 at a time then sending them to the I2S link. The DAC at the receiving end then changes it back to DSD to feed into the Digital-Analog subsection.

    DSD advocates argue that changing the bit one at a time is smoother and creates less "stepping" noise, ot at least that noise is at a higher frequency and easier to filter out. They also seem to argue that the same source material is somehow better when it's delivered as DSD. But I think almost all music is stored as PCM and then "re-encoded" into DSD. At least as far as I know. Others may know more. :)

    Cheers,
    Michael
     
  14. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    Quick update on PI2AEAS with LT3042's. Initial production begins next week, though limited quantities. Full production will be by mid July. Pre-ordering will begin end of next week with 2-3 week lead time.

    Cheers,
    Michael

    P.S. Customer in Italy that tested our protoype version posted his results (using a battery to power the unit) on Audio Science Review:

    https://www.audiosciencereview.com/...gital-audio-shield-for-the-raspberry-pi.7136/
     
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  15. bigbear1997

    bigbear1997 Acquaintance

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    The 502DAC you are referring to is the 502DAC Pro started from Indegogo?
     
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  16. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    No, it is referring to the original 502DAC. The one that has the PCM5102 dac. The pro version never reach the performance levels that we wanted and so we decided to not go forward with it.

    Cheers,
    Michael
     
  17. bigbear1997

    bigbear1997 Acquaintance

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    You are right. I look at the board it says 502DAC no pro.
    I reinstall volumio recently and noticed there are drivers for pro & non-pro. I thought I have the pro version 8)
     
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  18. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    Update on PI2AES final revision testing. I had four boards built up and have tested all of them. Results are excellent, though to be honest I personally can’t tell if they have improved dramatically from the previous revision. Three of these units will be sent out to reviewers and hopefully they will agree or at least tell me that the results are as good as or better than the previous rev.

    Sometime this week we will be turning on pre-ordering for the unit. We first have to work out a delivery schedule just so we know what to tell people for delivery time. My guess at this point is 3 to 4 weeks max from tomorrow we will start delivering. It might be a bit sooner, but some of the parts we have to order will take a week or two to get in hand.

    As soon as possible I will post a reply here to tell you guys that you can order a board. As always I am extremely grateful and humbled by the support and feedback that I get from this community and I am happy that I can provide something to bring some joy to my fellow audio-fools.

    Cheers,
    Michael
     
  19. Yethal

    Yethal Rando

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    Do preorders also include the case? Also, is the clear acryllic the only available option?
     
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  20. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    Yes we have the case, but clear is all we are offering at this time.

    Cheers,
    Michael
     

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