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Raspberry Pi's and the Wolfson sound card

Discussion in 'd.i.y.' started by Andrew L Weekes, Mar 31, 2018.

  1. Andrew L Weekes

    Andrew L Weekes Reverse Engineer

    I know there's a few people on here using Pi-based systems with add on sound cards. I've been a bit of a fan of the Wolfson / Cirrus card as it's inexpensive, has a comprehensive set of features and performs pretty well. The drivers for this card are now officially part of the Raspberry Pi kernel and although the newer Cirrus card (which was compatible with the Raspberry Pi 3) is discontinued, it is possible to get the older Wolfson card to work with a Pi3 with a bit of modification.

    Why do this? Well when I last looked there was > 1300 in stock at Farnell and I think they are great value for money. I find it incredible that an HD music player can be built for so little!

    The great thing about the Wolfson card is it has multiple outputs (headphone/line/SPDIF) and it's also an ADC too, so there's line in, SPDIF in and a couple of on-board digital mic's. There's even a very basic, low powered class D amp for driving some speakers, which for £18.76 makes it great value!

    It's very quiet and I mainly use it for headphone listening as a high definition Squeezebox running Squeezelite.

    If anyone is interested I've a few posts about the process, including a simple mod to improve PSU noise rejection and the discovery that out of the box it doesn't make full use of 24 bit sources, although this is easy to fix.

    Hope it's useful, enjoy!

    Connecting the Wolfson card

    PSU noise sensitivity

    Improved PSU filtering

    Increasing dynamic range / making use of 24 bit sources
    Artioneer, John Channing and S-Man like this.
  2. davidsrsb

    davidsrsb pfm Member

    Thanks for the links. It had never occurred to me that a driver might include a noise gate function. This makes me wonder if other badly thought out drivers have gates set at even higher levels, responsible for some loss of detail.
  3. Andrew L Weekes

    Andrew L Weekes Reverse Engineer

    Me too! It does show the value of measurements, here's a video I did today demonstrating the effect.

    John Channing likes this.
  4. davidsrsb

    davidsrsb pfm Member

    I was aware of DACs that muted on digital zero, but thought this was a hardware feature to cheat better dynamic range
  5. JemHayward

    JemHayward pfm Member

    If I connected the Wolfson card to my RPi 3 that is my 'squeezebox' (currently running Moode) could I use it as an ADC to give my 'squeezebox' a selectable analogue input that would then go out via the USB of the Pi and then into my DAC?
  6. Ruairi

    Ruairi pfm Member

    I used a 'pi-top' dac and the sound was class. The interface was great but it was the fact I had to keep imaging the file meant the pi and dac are just laying in a box somewhere.
  7. Andrew L Weekes

    Andrew L Weekes Reverse Engineer

    There is a WaveInput plugin, although this post is quite old, it might be worth looking at: https://forums.slimdevices.com/showthread.php?49584-Announce-WaveInput-for-Linux
    I've also seen solutions using DarkIce and Icecast, the idea being to set up a server to stream audio, then pointing the player at the resultant playlist. Not sure if this can work losslessly though, normally it's an mp3 stream.
  8. JemHayward

    JemHayward pfm Member

    Thanks... looks like an interesting project for a wet Sunday afternoon... If I get it working, I'll post the results here.

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