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Khadas Tone Board

Discussion in 'd.i.y.' started by tomek, Jan 31, 2020.

  1. tomek

    tomek pfm Member

    Hi,
    after reading some nice reviews about Khadas Tone Board

    https://www.khadas.com/tone

    i will order one and try as a usb dac with Pi 4. GPIO connection with Pi is not possible, only usb.
    I would like to power the "Tone Board" separately at GPIO pins, not with usb 3 connection from Pi 4.

    it is very well documented

    https://docs.khadas.com/toneboard/HardwareDocs.html

    My question to pfm diyers - what will be the best way to disable the dac usb power from Pi ? I need only usb data from pi. Just cut the "+5V" cable inside the usb cable ?

    Tomek :)
     
  2. James Evans

    James Evans Bedroom Bodger

    You can put a small piece of insulation tape over the power pin in each end of the usb cable as a non-invasive test. Fiddly, but I've done it here ok.
     
  3. sq225917

    sq225917 Bit of this, bit of that

    Maybe Ian's pi conditioner might do the job, it's a hatboard that feeds the pi rails from above. Detail on diy audio,com in the power supply section.
     
  4. tomek

    tomek pfm Member

  5. sq225917

    sq225917 Bit of this, bit of that

  6. diamonddust

    diamonddust New Member

    You can check soundcheck blog. He's got the same setup as yours and he know it inside out ;-)
     
  7. tomek

    tomek pfm Member

    So i have one Tone Board. Already connected with usb to PI4 running picoreplyer sounds very good. With one linear ps based on lt1083 sounds better.
    The sound quality for this price is incredible.
     
  8. tomek

    tomek pfm Member

    I tried different ps with Tone Board:

    1. Official raspbery pi 4 ps connected to pins 1 and 21 - better sound, than getting usb power only from pi 4
    2. Standard LM317 built with good parts - much better sound, than with 1.
    3. Absolutely phantastic sound with ps based on TPS7A4700 set at 5.2V

    https://www.ldovr.com/product-p/tps7a4700-spsu.htm

    Also tried different ps for pi. Impact on the sound is very small, but noticable - official raspberry pi 4 ps with shortened cable and buffered with bigger caps just before Pi (1x 10000uF/25V+ small oscon) sounds better, than big linear ps build around LT1083CP. I have to try ifi power for pi.
     
  9. sq225917

    sq225917 Bit of this, bit of that

    Get a mezzanine.
     
  10. tomek

    tomek pfm Member

    I checked mezzanine. It looks very interesting, thank you :)
    If i want to power only pi, than i need just mezzanine with module A and B and one external ps with 6V ?

    https://www.ldovr.com/product-p/mpower.htm
     
  11. sq225917

    sq225917 Bit of this, bit of that

  12. Dowser

    Dowser Learning to bodge again..

    Let me know your thoughts Tomek please, also interested in one for a streamer I plan. Thanks :)
     
  13. tomek

    tomek pfm Member

    I ordered mezzanine, when it will be delivered, than i will report :)
     
  14. tomek

    tomek pfm Member

    Last edited: Feb 21, 2020
  15. brumjam

    brumjam pfm Member

    The mezzanine board is a nice upgrade...I killed a Pi trying to remove the DC/DC converter though. Second attempt was successful.
     
  16. Dowser

    Dowser Learning to bodge again..

    More detail please :) Was converter removal to allow the use of a mezzanine provided 3.3v line?
     
  17. brumjam

    brumjam pfm Member

    Hi Dowser. The DC converter must be removed to use the 3.3v and 1.8v rails from the Mezzanine board.
     
  18. sq225917

    sq225917 Bit of this, bit of that

    But you dont need to do it that way, you can choose to settle for just a main 5v feed.
     
  19. Dowser

    Dowser Learning to bodge again..

    Thanks both - law of diminishing returns?
     
  20. sq225917

    sq225917 Bit of this, bit of that

    A nice clean 5v feed is good especially if otherwise youd be introducing a smps into a system without one. If your dac doesnt take power from the pi then its unlikely to affect the sound. I think Allo showed a 1.5db Improvement in thd+n for their best psu,
     

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