Dummies Guide to Pi2AES! Throw away your PC or laptop.

Discussion in 'Digital: DACs, USB converters, decrapifiers' started by purr1n, Jan 29, 2020.

  1. earnmyturns

    earnmyturns Smartest friend

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    Could there be some kind of subtle clocking artifact between successive write() system call executions in the driver that is hidden by the buffering and reclocking in the Kali?
    Update: Oh, @androxylo just saw that suggested the same.
     
  2. Dandou

    Dandou Acquaintance

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    There's something more to say.

    According to my contact at Audiophonics, the advantage of the €100 KALI board over the €1,050 Audio-GD digital interface is that KALI clocks the sound correctly in the RBI from the start, and it is transferred directly by the PI2AES to the I2S port of the DAC.

    The Audio-GD does not have an I2S input. It has only a SPDIF and a USB inputs.
    So when you use it with a PI2AES, the sound is converted twice. From I2S to SPDIF by the PI2AES. And then from SPDIF to I2S again by the AudioGD.
     
  3. Dandou

    Dandou Acquaintance

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    As far as I understood, the clock of the RBI is not set at a frequency that is suited to match the frequencies of the PCM sound.
    In addition, it is possible that the clock of the RBI is of a poor quality, and not a high precision clock, because it is a cheap component inside a very cheap computer (RBI).
     
    Last edited: Jul 8, 2022
  4. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    You are correct about the clocks from the raspberry pie. However, those clocks are not used by the pi2aes. Instead we create the clocks and feed them to the pie which acts in slave mode. My confusion with the Kali is that I can’t understand who is the master? Our board wants to be the master of the clocks it seems that the Kali does as well.

    it’s possible that somehow the software is recognizing the Kali and changing our board into slave mode? I’m stretching for ideas here, so if anybody knows for sure that would be great. Perhaps Allo themselves could weigh in on this.

    One last point, the start of this discussion was predicated on a statement that everyone, whoever they are, knew that the audio GD DDC improves the sound coming out of the pi2aes. Perhaps it’s simply that you’re calling my baby ugly, but I do take exception to that because I don’t believe that to be true.
     
  5. Dandou

    Dandou Acquaintance

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    @Michael Kelly ,

    My technical understanding is limited.
    I will submit your questions after the week-end to my contact at Audiophonics, and will ask him to explain me.
    Then I will tell you his answer.
    BTW, they told me that what KALi does, can also be done with another I2S reclocker, from Ian Canada. But because of global storage of components, this product is not available at the moment.

    I did not want to be offensive at all.
    English is a very difficult language, and it's not easy for a Frenchman like me to post a comprehensive message that remains very well nuanced.
    I did not mean that EVERYBODY knows that the DI-20HE can improve the sound of the PI2AES. But I know two very demanding audiophiles who use PI2AES this way.

    Your product is not ugly, it's great and that's why I use it. And I complement it often.
    It's a very good streamer, at an affordable price, that is superior in quality to much more expensive streamers. But it's impossible to expect it to be the best product for all the tasks at the same time. Such device does not exist, even among the very pricey high end products.
    The makers of Audio-GD are also competent. It's a very good brand, and their device is a dedicated digital interface designed for specific tasks.
     
    Last edited: Jul 9, 2022
  6. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    Sorry, my snark and sarcasm did not come across correctly! I did wanna understand the statement about improving our board, but I used non translatable humor! It’s all good.
     
  7. Dandou

    Dandou Acquaintance

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    An update:

    Audiophonics were not sure that Allo KALI + PI2AES will remain stable over time.

    I made them playing together non-stop during 48 hours. When I was not listening to music, I streamed web radio to them.
    There were no issues at all, nor crushes of the RBI… but suddenly, it stopped working.

    When I remove KALI, the PI2AES works as usual.
    When I put KALI back, I get no sound…
    I tried everything to no avail.

    So, there may be some kind of incompatibility between these boards.
    I will send KALI back to Audiophonics.
     
    Last edited: Jul 10, 2022
  8. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    My best guess is the output circuit of the Kali may be damaged by the output circuit of the PI2AES. If they are both trying to drive the same signals that causes one or both of them to draw excessive current. Hopefully no one else will try this again!
    Sorry you had to be the one to find it out for the rest of us. :(
     
  9. Dandou

    Dandou Acquaintance

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    Yes, it's very possible that KALi is damaged. I don't have a way to check what happened to it.
    And merrily my PI2AES continues to work fine. This model is discontinued, so it would have been impossible for me to replace it.

    Otherwise, it was an interesting experience.
     
  10. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    The PI2AES does not “improve” the clocks from the pi, instead it puts the pi into slave mode and supplies all the clocks to the pi from the low jitter NDK oscillators. The pi only supplies the data.
     
  11. Dandou

    Dandou Acquaintance

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    I want to add something, because I think that I may have created a wrong impression.

    An I2S Reclocker is beneficial to all the RBI based network players. In this regard, PI2AES is not a special case with a special weakness that needs to be repaired. People use the Audio-GD DI-20HE with many other RPI based network players. For instance, a friend of mine uses it with Rosana, a RBI based streamer from After Dark, that is 4-5 times more expensive than PI2AES.
     
    Last edited: Jul 10, 2022
  12. androxylo

    androxylo Acquaintance

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    I'm using RPi 4B with Tidal connect on stock Raspbian OS for several months with no major issues. Tidal + Pi = Love. Note, without active cooling Pi gets really hot, throttles and Tidal starts glitching badly because I think thermal throttling doesn't give it enough resources. I doubt Tidal will work on Pi3 because it's much slower, however someone who tried should know better.
     
  13. earnmyturns

    earnmyturns Smartest friend

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    I think you are still missing the key difference between Pi2AES and some other (all?) other Pi-based sources: the Pi2AES is the clock master, so the Pi will deliver I2S to Pi2AES following the more accurate Pi2AES clock, not the less accurate Pi clock.
     
  14. Dandou

    Dandou Acquaintance

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    You mess between two different things.
    Being the clock master reduces jitter during the transfer of the data. PI2AES does it very well.
    But the data (the I2S converted sound) is processed by the RPI whose clock is ill suited for the task, because it works at a frequency that does not match the basic frequencies of the PCM sound (44.1 KHz and 48 KHz), and because the precision of this clock is poor.
    I tried to explain it in previous posts.
     
    Last edited: Jul 10, 2022
  15. earnmyturns

    earnmyturns Smartest friend

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    You tried to explain, but what you say makes no sense. For a synchronous data transfer like I2S what matters is the transfer clock, not whatever clock(s) are used upstream to prepare the data to be transferred.
     
  16. Dandou

    Dandou Acquaintance

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    I never said that the synchronous data transfer does not matter. Low jitter does matter of course.
    But it's not the only factor that matters, if you wish to improve further the sound of your system. And a propre clocking of the I2S sound matters as well.
    I already miss the sound that was getting from the PI2AES + KALI.
     
    Last edited: Jul 10, 2022
  17. earnmyturns

    earnmyturns Smartest friend

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    I give up. The Pi2AES manual is quite clear about the flow of clock signals between Pi2AES and Pi. There's nothing else that is relevant to the timing of the I2S signal from Pi2AES. Sure there are other factors, but they mainly have to do with electrical noise leakage into DACs from connected hardware. Additional external devices may help with that, or not.
     
  18. Dandou

    Dandou Acquaintance

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    I do not argue about anything that you say nor about electrical noise.

    I point to the clocking of the PCM sound during its conversion to I2S. This task is not executed by the high precision clocks of the PI2AES. The sound is processed by the RPI with its poor quality clock.
     
    Last edited: Jul 10, 2022
  19. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    Maybe this will help. Internal to the PI is a buffer that holds the audio data. The PI places that data into the buffer using the PI clock. The data is sent out from the PI using the clock from the PI2AES. The end result behaves much like the Kali does, i.e. crappy PI clock is used to fill the Kali FIFO, but a low jitter clock is used to send the data out from the FIFO.
     
  20. LetMeBeFrank

    LetMeBeFrank Won't tell anyone my name is actually Francis

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    Are we sure the Kali was even doing anything? If the same driver is being used for the PI2AES, and the pins are pass-through, its likely the Kali was just sitting there doing nothing.
     
    • Agreed, ditto, +1 Agreed, ditto, +1 x 2
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