Raspberry Pi I2S to SPDIF Hat

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

  1. Poleepkwa

    Poleepkwa Friend

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    Better to get these things during prototype stage! So better not to try and fix the dac outouts then? I assume the digital side performance remains unchanged?
     
  2. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    The Digital side remains unchanged, other than swapping the XLR for a quarter inch jack. But as I mentioned we are including the adapter.

    The problem with the analog side is that the noise is being injected via the internal ground plane. This cannot be fixed without a PCB respin.

    Believe me, if I could I would! I spent the weekend tacking on various filtering solutions, but as mentioned, they were less than satisfactory.

    Cheers,
    Michael
     
  3. Poleepkwa

    Poleepkwa Friend

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    I think most people are more interested in the digital side and see the DAC as a nice bonus. Hope you get it finalised in the new batch.
     
  4. Merrick

    Merrick A lidless ear

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    Hi Michael,

    Can you repost your email? I sent a PM but I see you want an email.

    Thanks!
     
  5. Clemmaster

    Clemmaster Friend

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    You replaced the XLR with a quarter inch jack? What about the impedance?
     
  6. haywood

    haywood Friend

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    For personal use definitely, but the dac side seems like it could be part of a good replacement for the eventually dead squeezebox I got my parents to use for internet radio.
     
  7. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    The small discontinuity from the jack does not impact the signal. Remember, this is digital, not analog. As long as all our bits get where they are going it's all good! The dScope reports the same very accurate clock from 1/4" to XLR as with the BNC.

    Cheers,
    Michael

    P.S my email is [email protected]
     
    Last edited: Jan 31, 2017
  8. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    Well that did not take long! I have all 9 units spoken for. Once we have the next revision with analog we'll put another 10 or so out there for final testing.

    Cheers and many thanks for the great support!
    Michael
     
  9. hifiandrun

    hifiandrun Almost "Made"

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    Hi Michael,
    Would there still be a chance to switch back to the "through hole" design instead of the SMT? I understand that the connectors are tall and won't be able to stack anything on top. It would be more flexible for DIYers. For example, I'd like to stack a small 3.5 inch touch screen on top by desoldering the tall connectors. Sorry for being selfish, but the through hole solution would be better for me.
    By the way, how would you officially call your DAC board? SPD2 or 502DAC?
    Cheers!
     
  10. hifiandrun

    hifiandrun Almost "Made"

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    You are right. Thanks. Have been slow over the last week. I will post on slimdevices forum right away.
     
  11. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    Name is 502DAC. As for the header I will give it some thought. The main issue for us is cost of assembly. Someone has to sit and solder all 40-pins versus loading it into a reflow oven that is already needed. Very little extra work.

    Cheers,
    Michael
     
  12. hifiandrun

    hifiandrun Almost "Made"

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    Thanks. I revised my reports, replaced SPD2 with 502DAC.
     
  13. Merrick

    Merrick A lidless ear

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    Man, I seem to have missed every opportunity to test this.
     
  14. hifiandrun

    hifiandrun Almost "Made"

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    Nice review. I also had this big question. But now I am very clear in that the SOC plus I2S DAC is the way to go. It is really hard to get the usb souce sounding right.
     
  15. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    Go ahead and send me an email. Maybe I can scrounge up something. I know you have been participating in this discussion, pretty much from the beginning.

    Cheers,
    Michael
     
  16. Kattefjaes

    Kattefjaes Mostly Harmless

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    For those of us who have been silently stalking the thread, is it worth hanging on for a production unit or looking elsewhere for a stopgap for now? I'm quite keen to pull the trigger on some sort of SPDIF hat for a second MPD box.

    A transformer coupled coax appeals a lot- you seem to be building something very relevant to my interests...
     
  17. Merrick

    Merrick A lidless ear

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    Thanks! I sent you an email yesterday when you were offering the boards. Did you not get it? I sent a PM too.
     
  18. darkstar>eyesoftheworld

    darkstar>eyesoftheworld New

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    So what do I need? Should I go for a pi 2 over a pi 3? Do I need to provide my own power supply for the 502? What specs should I look for in a power supply? As far as the pi goes, do I need a powered USB hub for my 1 and 2 GB HDs? If I get a power supply with a high enough amperage, can I forget about the USB hub? What software do I need to get the pi and 502 running? That's all I can think of for now.
     
  19. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    I would be happy to build up the other 10 that we have, leaving off the analog output. See how many more think like you do, and will see about building them up.

    I don't feel I can sell them, but if people covered the shipping cost I would be happy to send them. Go ahead and send an email to me, with the subject matter "502DAC digital only". First 10 get one. Make sure To include a PayPal email. US, Mexico and Canada mailing cost is $10 and international is $25.

    Cheers,
    Michael
     
  20. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    The reviews so far seem to indicate an external low noise supply has some benefit, but even with the standard pi USB power it seems to work very well. Maybe some of the reviewer's can chime in here?

    Cheers,
    Michael

    PS when I tested the recovered clock accuracy with the dScope I was using the USB power supply. I have a low noise bench supply that I also tested with, no difference. But that supply is not the lowest you could get.
     

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