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Raspberry Pi DAC HAT has dual 24-Bit DACs and a 128dB SNR

Apr 23, 2018 — by Eric Brown — 2235 views

Orchard Audio’s “ApplePi DAC” audio HAT add-on for the Raspberry Pi is available for $175 on Kickstarter, featuring two 24-bit TI PCM1794A monoaural DACs, a 128dB SNR, and both balanced and unbalanced outputs.

Orchard Audio quickly surpassed its $5K Kickstarter goal for its ApplePi DAC HAT board, which it is promoting as “the most advanced and highest performance sound card hat for the Raspberry Pi.” It didn’t hurt that Orchard posted a couple of favorable reviews, including one from Volumio co-founder Michelangelo, who wrote: “This DAC is producing the most detailed sound to ever come out of my Raspberry Pi.”



ApplePi DAC (left) and fully assembled version with Raspberry Pi and Mini XLR connectors

(click images to enlarge)

You can order the add-on board through May 13 starting at $175, with options including a $5 stacking header and a $25 5.25V, 3A power supply. The ApplePi DAC supports the Asus Tinker Board and Allo.com’s Sparky in addition to the Raspberry Pi.

A fully assembled $374 system gives you the HAT board, header, and power supply plus a Raspberry Pi 3 SBC, an acrylic stand, and an SD card with a choice of preconfigured Volumio, Rune Audio, or Raspbian. For $574, you get the assembled system plus a 7-inch touchscreen. All the products ship in July.

The board is driven by dual TI Burr Brown DACs (PCM1794A) configured in monaural mode. The system has a dynamic range of >135dB and a signal-to-noise ratio (SNR) of 128dB, which Michelangelo says can bump up to 132dB.

Total Harmonic Distortion + Noise (THD+N) is listed as an impressively low <0.0005% (-106dB). The board supports both 16- and 24-bit bit rates, as well as sample rates of 44.1, 48, 88.2, 96, 176.4, and 192kHz.



ApplePi DAC detail view (left) and touchscreen kit
(click images to enlarge)

Orchard makes special note of the board’s ultra-low noise linear regulation and low jitter PLL clock generation. The latter derives not from the usual crystal, but rather from a CS2300 IC from Cirrus Logic. This clock chip integrates a crystal, PLL, and clock multiplier into a single device, according to Michelangelo, who says that input jitter is attenuated by 60dB (1/1000).

Michelangelo also praises the “onboard balanced (Mini XLR) and unbalanced (RCA) outputs driven by dual differential output circuit stages.” Orchard says that most competing boards offer only single-ended outputs.

The ApplePi DAC runs at 4.5W, and can be powered by a Raspberry Pi, but Orchard recommends using the optional 5V adapter. In addition to Volumio and Rune Audio, the ApplePi DAC supports moOde Audio, piCorePlayer, and Roon Network Endpoint software.



Crispin amplifier
(click image to enlarge)

Orchard Audio is also prepping a Crispin Class-D power amplifier. The amp outputs at 100W to 250W depending on the configuration, and has an an SNR of 117dB and a THD of less than 0.005 percent. Gold-plated XLR (balanced) or RCA (single ended) inputs are available.

 
Further information

The ApplePi DAC is available on Kickstarter through May 13 starting at $175, with shipments due in July. More information may be found at the ApplePi DAC Kickstarter page and Orchard Audio’s ApplePi DAC product page.
 

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2 responses to “Raspberry Pi DAC HAT has dual 24-Bit DACs and a 128dB SNR”

  1. Orchard Audio (@OrchardAudio) says:

    Thank you very much for doing this write up.

    I will be doing a demo of the ApplePi DAC and CRISPIN Ultra stereo amplifier.

    It will be live streamed on YouTube. 04/28/18 @ 2pm EST

    Check it out:

  2. Orchard Audio (@OrchardAudio) says:

    The ApplePi DAC went on a tour around the country. Here is what people who have tried it, have to say:

    Wayne – Littleton, CO
    “This is a very well engineered and built DAC. I again suggest folks sign up for the tour and listen yourself.”and “I spent a good week listening to it and came away extremely impressed with what Leo has done with this DAC hat.”

    Alan – Harrisburg, OR
    “I have had the Apple Pie for a while and I must say I am really impressed.” and “Any way this is a dammed fine budget setup that punches way above it’s weight.”

    Sharschchandra – Austin, TX
    “The build quality is top notch and I really like the layout.”and “The unit sound great out of box, very organic, almost neutral and full bodied (compared to ES9038PRO based DACs). The vocals were amazing especially on the JBL 4312B monitors.”

    Jerry – Camarillo, CA
    “This is one sweet little Dac, Leo. I actually left work early today just to spend more time getting to listen.”and “You have one helluva nice piece here; I appreciate the gracious demo.”

    The tour continues to this day, and will continue beyond Kickstarter. If you would like to sign up, go here: 
    https://www.audiocircle.com/index.php?topic=155479.msg1665901#msg1665901

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