I wanted to post a quick update about my development of an audio “daughter board” for raspberry pi.

I have a working prototype – and it is sounding good! Its a pretty basic implementation to begin with – I just wanted to get something working before trying anything too silly. It has unbalanced stereo in for recording, and stereo out balanced or unbalanced. No measurements so far – just got rid of the hissing background noise that was bugging me, dead silent now.

I intend to develop this as an open-source project, so follow along if you want to build one yourself. The smallest parts are 0805 so no problem for hand soldering. Version 1, using this WM8731 CODEC chip will be ready soon for public consumption. 9V DC supply (guitar pedal type) will power the whole board including the pi itself. You will spot some bodge-wires (how could I get the DC connector pins wrong???) and dirty hacks in the photo: this is definitely a work-in-progress!

It has a few cool features which I will explain in a later post, just wanted to share this success so far. Any suggestions for preferred DAC/ADC chip to use in the future? Leave a comment…. but no audiophile-phoolery please :-P


A working prototype of my raspberry pi audio board. Stereo in unbalanced, stereo out balanced or single-ended.
A pretty basic circuit for now, but sounding good already!









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23 Responses to Working Stereo Audio Board for Raspberry Pi

  1. Szymon says:

    I hope you get time to make it real product. Maybe a kit with SMD parts presoldered? I would buy one for sure. I’d like to use it in a guitar digital multi fx pedal instead of USB dongle type sound card.

  2. Serge says:

    Very interesting project!
    I am wondering if you had any success with recording (capture).
    And also do you have both DACLRC and ADCLRC connected to PCM_FS/GPIO29 (P5, pin 4)?


    • pasdesignal says:

      Hi, thanks for the comment!
      Yes, recording is fine.
      Yes, I do have both DACLRC and ADCLRC connected to P5, pin 4.

      I wish I had a finished product available for you to play with but my job keeps getting in the way of life!

  3. Daniel says:

    I want one!!!

  4. Daniel says:

    I also got my card running. It is a pure DAC. Parts are 0603, but even this size is still good to solder by hand.
    Check it out at: http://www.crazy-audio.com/projects/hifiberry-mini/
    More measurements and listening test coming soon.

  5. Jean-Pierre says:

    I will be very interested to buy a ready made board at the price of the RP +- 20%.
    Could you use a well known DAC like the one used in this product :http://www.audiophonics.fr/audiophonics-usabre-mini-usb-dac-24bit96khz-sa9023es9023-p-5807.html
    What would be the impact on the price ?
    Alternatively, I would also be interested by a daughter board with a S/PDIF output to feed my existing DAC.
    How would you compare sound quality wise, your solution vs a HDMI audio extractor ?
    Cheers Jean-Pierre

    • pasdesignal says:

      Hello Jean Pierre,

      Thanks for the thoughts and comments.
      I have noticed a lot of people mentioning the ES9023. My only problem with ESS products is the secretive nature of their website. Why on earth can one not download a datasheet without speaking to a representative? It seems ridiculous to me, and quite against the ‘open’ nature of technology that I love. For this reason I think I would like to stick to other high-end DAC chips, where the data is readily available and not hidden behind smokescreens and mirrors.

  6. […] Mckenna un Néo Zélandais a posté sur son blog le texte suivant (traduction) […]

  7. Daniel says:

    Cool design. I will do some tests with other DAC chips in the next time. Many need external clock, but this should not be a big deal. I see, that you use normal sockets to connect the Raspberry and the card. Unfortunately my DSP board is bigger than this card and I need a connector that is higher than the normal connectors. Adafruit has them for the 2×13 connector, but not for the 2×4 I2S header. Any idea how to do this? A female/female connector might be an option, but I couldn’t find something like this :-( Any idea?

    P.S. I will do some tests with the PCM510x, but this is a pure DAC chip.

    • pasdesignal says:

      Hi Daniel, I considered using the Adafruit header as well. I was going to cut down one with a blade to fit the 2×4 pins, as I also coudn’t find a 2×4 version. Or maybe just keep it full size and use the extra pins for jumper settings? Good luck and keep me posted on your progress :-) Shannon.

  8. William says:

    I’d definitely pay at least $35.00 for something like this. The people who would complain about it being as much as the Pi itself really have lost sight of why the Pi is so cheap(ie it use in education).

    • pasdesignal says:

      Thanks for the feedback William. Yes, not to mention the fact that it has sold over 1 million units!

  9. William says:

    Hey, pretty awesome project. I would love to get my hands on one. I was thinking if you don’t want to hassle with manufacturing and listing on Tindie and all that, I could help. I am setup for reflowing at home and shipping and all that. I am friedcircuits on Tindie if you want to check that out. If you want to do something send me an email and we can chat.

    Either way I will keep an eye on your blog.

    Now that I think about it, what would it take for some kinda of digital audio out? Either optical or coaxial output?

    • pasdesignal says:

      Hey, great suggestion! Thanks for considering getting involved. I’ll defo be in touch, that could work out really well.
      In regards to digital out, that shouldn’t be a problem technically.. just a matter of thinking about where that fits in conceptually and if it would be an optional extra or different board version etc.
      One of my main objectives with this board development is to get involved working with people such as yourself…I’ll be in touch friedcircuits!

  10. Nice work Shannon, I recently paired a Schitt Modi DAC with my Pi and it sounds way better than I expected, I think it uses this DAC chip http://www.cmedia.com.tw/ProductsDetail/page-p/C1Serno-25/C2Serno-27/C3Serno-0/PSerno-43.html.
    I like your approach though, also check out Raspify.

    • pasdesignal says:

      Thanks for the feedback Dave, yes Raspify is a great initiative and I am keeping an eye on its development. Hopefully the Raspify people will find this board, or a higher spec version, perfect for their playback needs…

  11. […] pasdesignal’s developed an audio “daughter board” for raspberry pi: […]

  12. AnonDog says:

    Could you kickstart that? I would really like to have one without the hassle of builiding it myself. ;o)
    Are you using P5 to connect it? Last, it would be nice to have it powered just by the raspi itself.


    • pasdesignal says:

      Hi thanks for the interest, and suggestions.
      I will happily supply built boards if there is sufficient interest, maybe do a listing on Tindie or something. I don’t want to go through the hassle of a kickstarter campaign to be honest. One thing I would have to work out is the pricing. This isn’t a cheap board to make at the moment – and I’m not keen for it to be the cheapest option out there at the cost of audio quality. How much would you be willing to pay for a board with these features? I can see it being similar price to the Pi itself – which seems a little crazy but it would reflect the true cost!

      I know what you mean about powering via the pi itself, the problem is if you want any decent output level and especially balanced out – you need a split rail and 9v is really the minimum value for achieving this with any decent output level. I think I could implement a jumperable option where you could power the whole thing off the 5v usb supply and only use headphone output of the DAc chip, or power it using external 9v supply and have greater audio peeformance including balanced out etc. Thanks for the idea! I’ll include this in the next PCB design.

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