Raspberry Pi i2s DAC: why this sounds so good

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There’s one thing better than a Raspberry PI, and this is an Raspberry Pi i2s DAC!

 

INTRODUCTION: WHY RASPBERRY PI I2S DAC IS THE RIGHT CHOICE

I may be aware there could be also other stuff worth of our joy, but this time I’ll concentrate only on that magic word, which audiophiles should have heard somewhere, sometime… So, what are we talking about?

I2S is a communication protocol specifically designed to carry digital audio data. To quote from Wikipedia

I2S, also known as Inter-IC SoundIntegrated Interchip Sound, or IIS, is an electrical serial bus interface standard used for connecting digital audio devices together. It is used to communicate PCM audio data between integrated circuits in an electronic device. The I2S bus separates clock and serial data signals, resulting in a lower jitter than is typical of communications systems that recover the clock from the data stream.

To better explain, i2s is used in all your fancy CD players, connecting the reading mechanism to the DAC and\or the S\PDIF output. Most important, i2s is used also on every standalone DAC you may encounter. If it’s USB, i2s is the pathway from the USB receiver to the very DAC chip, if it’s S\PDIF the same as above. Starting to smell why we are talking about this?
As straight as we could be: I2S is the protocol of choice when talking about digital audio signal transmission. I could also add that using USB as connection, in the Audio domain, is way far from being an ideal situation. And even if it was, an I2S direct connection has one great advantage: the signal path is shorter. See those examples:

Scenario 1: My little Raspberry Pi (powered by Volumio, of course) is hooked up to a zillion dollar USB DAC, which feds my interstellar amplifier. 

My precious one and zeroes are facing this path:

Raspberry Pi -> USB Bus -> USB Cable -> Zillion Dollar USB receiver -> I2S -> Zillion Dollar DAC -> Interstellar Amplifier

Quite a long way, isn’t it? Add to it all the intrinsic issues affecting connection interfaces, and you got quite a good idea of what is happening here.

 

Scenario 2: My little Raspberry Pi (you know what comes here…) has a tiny DAC hooked on it, via I2S connection, feeding my full-of-common-sense amplifier

The flow of my zeroes and ones?

Raspberry Pi -> I2S -> DAC -> Full-of-common-sense-amplifier

I’m sure now you feel the truth deep in your heart, and the force is with you. But there’s more to come, to sum up and make it shorter, these are the main advantages of having a raspberry pi i2s DAC setup:

  • Ideal signal path: shorter signal path and interfaces (USB, S/PDIF) avoided
  • We’re not using the troublesome USB bus of the Raspberry PI, consider pop and clicks a thing from the past
  • Cheap yet good sounding setup: 80 bucks for a staggering price/quality combo

 


UPDATE

This article was written in 2014, and since then newer and better i2s DACs have emerged. Luckily, we now have a selection of the best among them right here on Volumio shop. So, to save you the fuss of research and comparation, you’ll find listed below my personal choice of the best 4 I2S DACs for Raspberry PI.

And of course the Allo Bundles with the little miracle which is the Kali:


THE OPTIONS

Now that you’re enlighted about raspberry pi i2s DAC wonders, let’s see the options we have:

RPI-DAC : THE DIYER CHOICE

[EasyGallery id=’rpi-dac’]

This is an exquisite work of Audio Engineering. Let’s make it clear, this is a no-compromise solution, even if we are in the DIY domain. What Torsten Jaekel  created is a double layered addon raspberry pi i2s board, which has pretty amazing specs (quoting) :

  • 24bit DAC, Opamp I/V Conversion, Stereo Headphone Amplifier
  • State-of-the-art components on small footprint PCB
  • Single DAC solution with I2S Interface, On-Board Low Noise LDOs
  • Best in class parameters [1]:
    SNR:   > 120dB
    THD+N:   < 0.0006%
    Low Noise:   < 5µV/sqrt(Hz)
    PSRR:   < -82dB
  • No additional Power Supply, just AC transformer required
  • no heat sink needed (PCB used)
  • external filtering possible (connecting a FPGA)
  • Dual DAC (Dual-Mono) available (even higher SNR)
  • Upsampling, Dynamic Range Expansion … in planning (with FPGA)
  • cap-free transmission path

 

Hook it to the PI and you’ll have a fine-tuned Heaphone oriented Digital Music Source. The boards consists of a Audiophile grade PSU paired with PCM1794A DAC. You can also have a dual mono version, which will raise SNR of 3db. What I really like about it? It’s designed with only one goal in mind: Audio Quality. I really wish to congrats with Torsten for what he achieved, and for the fact he published everything you need to build this at home. The culprit of raspberry pi i2s RPI-DAC is the price: it is quite an expensive solution, ranging from 120 to 255 USD. But as you know, quality has its price.

 

HIFIBERRY: THE BANG FOR BUCK KILLER

[EasyGallery id=’hifiberry’]

Here we have the most successful Audio accessory for our little PI: I want to applaude crazyaudio for creating such a simple, good sounding and straight to the point device. What makes the HIFIBERRY special is its price\quality ratio. With 30 euros you have a device which will skyrocket your Raspberry PI’s audio attitude. This means that for a mere 80 euros (50 for the PI in full working order + 30 for raspberry pi i2s Hifiberry) you can have a really good sounding Digital Audio Music Player. What I really like? It’s simplicity: few components, DC taken from Raspberry’s 5v rail. Simplicity is the ultimate sophisticacy, we may say. Culprits? You may want to isolate the 5v rail from the PI’s and use a dedicated PSU, this will raise the bar even more, but you need to mess around a little with the PCB. I would have liked to have that option already prepared, with a switch and a connector.

 

RASPYPLAY3: THE VERSATILE CHOICE

[EasyGallery id=’raspyplay3′]

You know, Raspberry PI can be hooked up to a wide variety of Accessories. I really do like to have a little Display attached to it, to show current title playback (coming soon on Volumio!) and so on. This clever raspberry pi i2s DAC has it capabilities, since it offers a GPIO connector, to easily hook a display on it. Not to mention that this little board offers the same advantages of raspberry pi i2s connected DACS. RaspyPlay3 is developed by a serbian community of DIY and audio lovers, just browse their website to find out they really interesting articles (use google translate and be prepared for some lost in translations…). This raspberry pi i2s dac can be customized with your preferred Capacitors, meaning you can really tailor it to your personal tastes. Plus, you can find all the documentation you need to find out how to build this raspberry i2s cad on your own. Thanks Nebojsa!

Some specs:

  • SNR: 112dB
  • Dynamic Range: 112dB
  • THD+N @ – 1dB FS: –93dB
  • Full Scale Output: 2.1VRMS (GND center)
  • LCD + keyboard connector on board

 

ESS SABRE 9023 + MCLOCK GENERATOR : THE THIRD WAY

raspberry pi i2s sabre 9023raspberry pi i2s clock

 

 

 

As most of us believe, ESS SABRE 9023 is one of the most interesting pieces of silicon around. I always wanted one hooked directly into my little PI. As raspberry pi i2s dac solution however, there is one technical issue preventing us to do that: Raspberry PI cannot deliver a Master Clock, which this DAC needs. So, let’s give it one! What you need is just get a ESS 9023 I2S DAC:

 

And pair it with a Master Clock Generator:

Then, feed both with DC voltage (you can use the same rail if you wish, the range is from 7 to 20 Volts DC). This should be a very effective solution, more pricey and complicated from the ones above, but you’ll be rewared with premium sound quality. And if you really want to get to higher levels, and also higher pricetags, you can choose to hook other fancy semiconductors:

 

CONCLUSIONS

Now you should have a comprehensive idea of why raspberry pi i2s dac is the way to follow if you want to achieve pretty good sonics performances, while  slightly emptying your pockets. I am really reccomending to use this solution if you want a really valuable Audiophile Music Player withouth spending too much, furthermore Volumio + PI + raspberry pi i2s DAC is a solution you can tailor to your very own needs. And as Volumio development will progress, you’ll have also more functionalities available.

 

raspberry pi i2sThe last step is enable raspberry pi i2s DAC support from Volumio’s WEBUI, just go to settings -> I2S DAC -> I2S ON . Then reboot your PI, and enjoy the subtle joy of your one and zeroes flowing via i2s.

 

I’m going to publish soon a complete overview of every raspberry pi i2s DAC mentioned in this article, and hopefully show some measurements of their performances. So, stay tuned and support these amazing engineers, that not only are bringing exciting stuff to us, but they are also sharing their hard work!

 

You can also discuss about raspberry pi i2s DACS on Volumio’s Forum

Enjoy!

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Michelangelo Guarise

Passionate. Heretical. Deeply in love with Technology and Music. I live in Florence, Italy where I teach Interaction Design and Marketing. I'm Volumio's founder and CEO, and I love every second of this great adventure. My audio gear is some strange mix of valve and digital amplifiers, all self built in some cold winter sleepless nights. And I just can't turn that volume knob down.

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