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Raspberry Pi gains Wolfson HD audio card

Mar 14, 2014 — by Eric Brown 9,335 views

Newark Element14 and Wolfson have launched an HD-ready Wolfson Audio Card for the Raspberry Pi with 192kHz sampling, MEMS mics, and I/O including S/PDIF.

The Wolfson Audio Card extends and enhances the Linux-ready Raspberry Pi’s audio features beyond its native HDMI output with onboard HD audio and a variety of interfaces. Raspberry Pi manufacturer Premier Farnell has the exclusive contract for the add-on, and is distributing it through its subsidiaries, including Newark Element14 in North America, Farnell Element14 in Europe, CPC in the UK, and Element14 in Asia Pacific. The Wolfson Audio Card sells for $33.62 and works with Raspberry Pi Rev2 Model A or B single board computers that include P5 pads for connecting the daughtercard.

Wolfson Audio Card

The Wolfson Audio Card incorporates Wolfson’s WM5102 audio hub chip, which offers a 192kHz sample rate, 8-channel input, and other HD audio components. Together with the audio I/O and digital MEMs microphones, the chip enables a voice controlled wireless home media network capable of running 24-bit “better than CD quality” playback, says Wolfson Microelectronics.

Wolfson Audio Card detail

The Wolfson Audio Card adds the following key hardware components:


  • 3.5mm stereo line-in (for digital audio players and mobile phones)
  • 3.5mm stereo line-out (for connecting external stereo amplifiers or powered speakers)
  • 3.5mm 4-pole jack (for a headset/boom mic combination for gaming or VoIP)
  • 3.5mm mic input (for microphones)
  • S/PDIF input
  • S/PDIF output
  • Speaker outputs (left and right) with Wolfson WM8804 transceiver
  • 2x WM7220 Wolfson digital MEMS microphones
  • Small pin header for extra function expansion (if they are low cost, already on-chip, and don’t require further components)
  • Class D power amplifier for external speakers (with connection to external power source if needed)
  • Pins to connect card to RaspPi via P5 pad

Pi with Wolfson card attached

The WM5102 chip is available in a wide variety of smartphones, tablets, and other portable audio devices, and is already supported by hundreds of applications, says Wolfson. The company is said to have shipped more than two billion audio chips, which are featured in devices such as the Samsung Galaxy line of mobile devices.

With the widespread use of Wolfson’s WM5102 chip, numerous applications are said to support four key features that are now enabled on the Raspberry Pi:

  • Play — Play back HD audio files on the Raspberry Pi
  • Talk — Build a VoIP conference phone for the PI by hooking up a boom microphone and headset to make hands-free calls
  • Record — Record HD audio using any of the microphones or line-in ports, and voice activate projects
  • Share — Connect the Pi to the cloud services to stream music around the house, and develop and play multiplayer online games that allow in-game audio via a gaming headset

Wolfson WM5102 audio hub block diagram
(click image to enlarge)

“With the Audio Card, Wolfson is delighted to provide a new accessory that opens up a whole new world of applications to the Pi community,” stated Alistair Banham, Senior VP & GM of Custom Solutions at Wolfson Microelectronics. “Working with Newark element14 has given Wolfson the opportunity to bring more high quality audio to the Raspberry Pi and enable developers, students and hobbyists to experience great audio quality when developing applications.”

Further information

The Wolfson Audio Card is available for $33.62 exclusively from Newark Element14 in North America, Farnell Element14 in Europe, CPC in the UK, and Element14 in Asia Pacific. Through the end of the year, Wolfson Microelectronics and Newark Element14 are also providing five “studio master quality music downloads” from HDtracks, offering 96kHz/24-bit quality. More information may be found at Newark Element14’s Wolfson Audio Card order page and Wolfson Audio Card datasheet (PDF), as well as at Element14’s Wolfson Audio Card community page. More on the WM5102 may be found at Wolfson’s WM5102 page.

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2 responses to “Raspberry Pi gains Wolfson HD audio card”

  1. CFWhitman says:

    When you understand how digital audio works, you realize that so-called “HD” audio is basically a scam. There is no advantage to sampling rates higher than 48kHz (unless you have ultrasonic hearing).* There is an advantage to 24 bit recording because it gives you “headroom” during production to not have volume levels perfect to begin with. There is no advantage to it over 16 bit for playback of a properly mastered recording, however.**

    This is not to say that this will not be a great audio card for the Pi because I’m sure the quality will be superior to the built-in equipment of the Pi, but it will not be because of a higher sampling rate or greater bit depth of playback.

    *For anyone who is unfamiliar with the principles involved, a higher sampling rate allows you to increase the frequency of sounds recorded and played back, if you have equipment that can capture and playback those high frequencies (research equipment, not stereo equipment; you can’t hear those frequencies). There are no other practical benefits to increasing the sampling rate.

    **A greater bit depth allows you to increase the difference in volume level between the quietest and the loudest sounds you can capture or play back; that is, it’s not that it allows you to increase the volume; it’s that it allows you to increase the volume range. Since 16 bit depth is enough to capture the difference between the quietest sound any person can hear and the loudest sound that will not cause pain or damage hearing, there is no real advantage to higher than 16 bit playback. If all recordings were made perfectly, you wouldn’t have a use for greater than 16 bit depth with audio files at all. However, 24 bit capture allows you to have set the capture volume incorrectly and still have the full range of bearable volume available for remixing. There is no other practical advantage to greater bit depth.

  2. IVO GELOV says:

    This in essense is equivalent to the opinion that 600 dpi is more than enough for laser printers. Most people who have seen the pages printed by a 1200 dpi printer will tell you that there is a visible difference between 600 and 1200 dpi. A large amount of the above people will tell you there is a visible difference between any 1200 dpi page compared to a 2400 dpi page – once they see both pages right in front of their eyes.
    I can tell you from my own experience that there was a time (1995) when most of the people who have had sound cards in their PCs (and by “soundcard” I mean anything other than the built-in PC speaker) were actually Covox devices. These devices were a simple R-2R resistor matrices placed on the LPT port. They were only 8 bit and the sample rate was directly dependant on the PC timer, which works as a frequency divider. The clock frequency was 1,19318 MHz – so the usable sampling rates were 44191, 33143 and 22096 Hz.
    And people were happy with those Covoxes (I still have one under by bed – but I do not have an LPT port to plug it). Nevertheless, people do hear a noticeable difference between the sound of a Covox, 16-bit sound card and 192KHz 24-bit sound card. There are simply much more distinct digital values by which to represent the contiguous analog signal. You can say there is no point in using 55-megapixel photo camera – but there are too many people who will notice the difference between a photo from 3-megapixel sensor and a 55-megapixel photo which was downscaled to 3-megapixel size. Probably not so many people will notice the difference between 25-megapixel and 55-megapixel images, downscaled to 3-megapixel size – but there will be at least a dozen of people who WILL notice. And those people will prefer the 50-megapixel camera, 2400 dpi printer, 24-bit sound …..

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