12 extra ideas on the Raspberry Pi as Spotify Join endpoint

Earlier this week, I laid out a range of ways in which one could turn a Raspberry Pi into a network audio streamer that runs – amongst different issues – Spotify Connect. What follows are 12 extra ideas on Raspberry Pi audio streaming that construct on the newcomer goal of the video to additionally apply to Roon or UPnP endpoint roles.

1. Which Pi ought to I take advantage of to feed a DAC over USB? Go together with the Pi4 and never the Pi3. Why? The Pi3’s USB knowledge bus is shared with Ethernet, which might result in pops and clicks when the USB knowledge buffer underruns. The Pi4’s USB knowledge bus is shared with nothing else.

2. There is no dedicated DAC chip on the Pi board. Neither does the D/A conversion happen on the Pi’s Broadcomm SoC. Simon Lengthy, a software program engineer from the Raspberry Pi Basis, explains the way it’s completed:

“We use pulse width modulation to place the audio sign on a few GPIO traces which drive a easy exterior passive filter community; it’s not in contrast to the previous bitstream strategies used for D/A conversion again within the early days of CD. One tip – at all times use it at most quantity for the very best quality – at something lower than max quantity, the noise ground rises considerably. The motive force is optimised to be used at 100% output solely, so flip the software program quantity management up as excessive as it would go, and use an exterior preamp to set the listening degree.”

3. There aren't any USB HATs obtainable for the Raspberry Pi (that I'm conscious of), solely DACs or S/PDIF DDCs. Utilizing one of many extra rigorously engineered S/PDIF DDC HATs will ship superior sound high quality to the Pi4’s USB port when feeding the identical DAC, all different issues being equal.

4. All different issues are not often equal. Have a look at your digital interconnects: is your USB cable the identical make/mannequin as your coaxial? In all probability not.

5. That mentioned, even with probably the most fundamental of digital interconnects in play, the prospect stays excessive {that a} HAT’s S/PDIF coaxial output will present a extra expansive, easeful sound than the Pi4’s USB.

6. Many newcomers will ask: absolutely TOSLINK will sound finest as a result of it isolates the DAC from the Pi’s electrical noise? While it's true {that a} TOSLINK cable will isolate the DAC from the upstream digital transport’s electrical noise, a TOSLINK connection can introduce more jitter into the signal, with what we hear decided by the DAC’s capability to reject or cut back that jitter. Very, only a few DAC are fool-proof on this respect.

7. Why doesn’t a DAC’s knowledge arrival buffer get rid of that jitter? As a result of, in response to this article by Madrona Digital’s Amir Majidimehr, “the DAC should output the samples utilizing the timing previous to that buffer seize.”

8. Pi customers usually ask if they will use its HDMI port as a digital audio supply. It’s potential, sure, however HDMI introduces a substantial amount of jitter into the sign. Far more than S/PDIF. Why? HDMI communicates no clock info of its personal; it should be derived from the video clock as a substitute, which runs at 74.25MHz and isn't an integer a number of of the 44.1kHz or 48kHz clock households wanted by digital audio.

9. Will you hear this jitter? That relies upon upon its nature. Here’s PS Audio DirectStream DAC designer Ted Smith on the topic. And here’s Hans Beekhuyzen take. Like these two gents, I hear variations between digital transports. You'll be able to take heed to jitter’s impression on an audio sign over at this excellent post from Serene Audio.

10. What in regards to the Bluesound Node 2i? Will a Raspberry Pi4 + AudioQuest DragonFly DAC sound higher? In a phrase, sure: the Pi4 + AQ offers a livelier sound with extra cleanly outlined p/layer separation. Per my video, the HELM Bolt offers us a way of ease that additionally makes its addition to the Raspberry Pi4 sound extra satisfying than a Node 2i.

11. What in regards to the Node 2i’s digital outputs? In response to recent coverage from Twittering Machines’ Michael Lavorgna, the Bluesound offers us one thing {that a} Pi4’s USB output can not: “Is the RPi a large killer? If we think about the Bluesound Node 2i a large, the reply isn't any. It’s extra like a large’s cousin’s child brother.” However…

12. The Node 2i is conquered as soon as the ALLO DigiOne HAT is added to the Pi4 (or Pi3). This HATted answer smacks down the Bluesound on sound high quality. Nonetheless, the Pi’s streaming software program choices can’t match BluOS’ spit, polish and ease of use — usually essential to newcomers.

Additional info: Raspberry Pi

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