I always find the high-end solutions of streaming audio not really interesting. As developer and part-time designer,
I knew the systems could be created better. Often, devices from high-end audio manufacturers are lacking in one area or another. Updates stay out, interface or connectivity is terrible, or always a compromise. I feel this can be done better by doing some DIY and profit from access to the software & interface
When the raspberry pi came on the market, the amounts of different projects from it where skyrocketing last year. You can only wait until someone will create a distro for the PI. And that indeed happened. RaspyFy was one of those projects. It later split up between Runeaudio and Volumio. I was amazed by the ease of the MPD software on linux and the community support. Also by just adding an MPD-app to the phone and use it as remote control, or use any other software to send commands to the MPD-service, is kind of a no-brainer where you can just hack away with anything you want to do!
I picked Volumio as my main distro because of the more open nature of the project and the more approachable lead, Michaelangelo. I decided to help Volumio with the interface and some design decisions. Unfortunately, I didn’t got the time to contribute really, so had to abandon that
While the quality of the raspberry pi output is not that high-end, you can definitely make it so. There are many start on a better player. I started off with using a Hifiberry digi+, and send it using BNC-connector to my Schiit Gungnir multibit DAC. I was happy with the result, but I wanted to see how far I could go. I’ve heard some upgrade stories about the pi-clock.
As we know in studio-land, that clocks are the driving force behind AD/DA convertors, and knowing that the PI-clock is generated and not by a crystal, it was time for something to do about it.
On Google, I ended up the DIYAudio forums, to be precise at Ian’s project. Ian is a medical engineer with a passion for audio. He knows about precise engineering. It took me a long time to invest to see how this is working. He created a fifo-buffer, so all bits line up well, and can be fed to the DA-converter with a better clock. I also read that using a battery on the clock would get a much cleaner output than using a great voltage regulator. So, I thought… let’s get all the boards, and see exactly what it does
The order placed at Ian
- FiFo II-board
- Dual XO-board with standard clocks
- S/PDIF interface board
- I2S-backdoor kit
- Finished TPS7A4700
- Finished FiFo-isolator board
- Battery management kit
- Some accessories to and wire mount everything together
The first set-up
To see what a difference it made, I decided to start listening to one song and know it well. I chose Michael Jackson’s Black and White. The song got so many elements in to listen to all crucial high-end parts. Sound stage, sound effects, dynamics, clarity, etc.
The basic set-up
- A raspberry pi, being powered by a lineair power supply
- Schiit Gungnir multibit DAC
- Exposure 2010s integrated amp
- Exposure 2010s power amp
- Kef Reference 1 (bi-amped)
The first iteration: Hooking up the S/PDIF board, FiFo, and Dual XO-board.
After listening well, I added the pi-hat for the fifo-board, and connected it with the dual-clock-board with very basic clocks. then using the i2s output to digital-out board
I couldn’t hear anything, and after many times spoken to Ian, it appeared to be one of the clocks being broken. I’ve decided to use the upsample function of Volumio to get to use the working clock.
When it started to playing again. I was listening with my mouth dropped open. So much improvement. (And I know, this is always exaggerated, but even the people I invited that do not have trained ears, could definitely tell the difference, and also preferred it.
The second iteration: Adding the isolator board
After already such a big difference, I started on the second iteration. This was adding the isolator board. Because the clock-board is now not being powered anymore by the PI, I had to use the voltage regulator board. Since it’s isolated, I decided to power it from the PI’s usb-port.
Even better sound-stage and clarity. It brought so much rest in the music. Isolating the PI’s power and regulating the analog clocks seem to really work its magic. You can definitely tell that isolating the PI’s noise and use a regulated power source has a lot of effect.
The third iteration: Replacing voltage regulator with a LiFePo-4 battery
From many recommendations on the forum, is to add a LiFePo-4 Battery to the clock board. This battery seems to regulate the power the near-best it can get. The battery is long lasting and has no diminishing charging cycles. To do this, I had to solder some jumpers and take off the power regulator board.
Wow, wow, wow. I did not see this coming. This was perhaps the best improvement to make to the whole system. I have the feeling that the rod was paved with my setup, but replacing the battery at the clock, was the biggest step in the chain.
I remembered when I got my DAC returned with the Multibit upgrade, I was a little disappointed. It didn’t sound too much better and had to get used to the sound. It was more precise, but at the cost of the “thump” in the low end.
With the battery powered clock, this came back, and it resulted in improvement on all facets of the sound. It was -this- exact thing I was looking for in a stereo set-up. I remembered listening to Avalon Acoustics speakers during an audio-show in Maastricht a long time ago. I did not see the set-up then, and I honestly thought there was a band playing live, and realised only after the music stopped, when people moved away and saw two not-too-large speakers. Though, priced at 25.000 euros per set. Which was far and far out of my price range. So back to my set.. I closed my eyes.. and there it was. I was inside Michael Jackson’s music. I actually looked around me when I heard the bonking, but it was just the intro. Mission accomplished! And…that from a Raspberry Pi! Wow wow wow!
The fourth and final iteration: Installing new clocks
I got the recommended Crystek CCHD-957 audio clocks, they supposed to be a big upgrade from the standard supplied clocks with the dual-xo-board. I soldered the clocks on the pins I’ve ordered with the kit. And time to take it for a listen again.
Frankly, I’ve hardly heard much difference. It sounded as awesome as before, but not more than it already was.
I had to get a replacement for one of the clocks anyways, but other than that, I thought it was a bit waste of money.
I have to say that the Schiit Gungnir can re-clock the signal as well. And it said to have a really good clock-system. So I think the clocks itself did not do the trick for me, but just isolating the digital signal and removing its noise was the best thing happened to the PI-player.
Putting all together in a box
I was, and am, never good putting things in a case and making it into a great polished item, so with the knowledge of drilling into steel and thick aluminium with a strong-hand drill was just asking for issues. Luckily, a not-so-good looking back is not the worst that can happen. I put everything together, and got some nice buttons and connectors to ensure proper connection. Added some shielding and damping to the equation for my ease-of-mind (but still wondering if I did this correct). I had to overcome one problem… I needed to get a battery charger meant for LiFePo-4 batteries, and I am no electronics engineer. I know well enough how the idea works in the big lines, but no where near enough to create my own electronics. I found a guy with a nickname “Xorbit” on Tindie, from the USA that sells usb-chargers for LifePo batteries that I could include in my project. Checking with him (seems he is also Dutch), this could work out great. Switching the “power on” for the clock board, instead of the charging, but also using the proper way of adding an LED to when it’s actually on, I had to order some logical IC to get this done. Luckily as programmer, I do understand this ;-). Yes! Finally, all done!
I am satisfied with the result, visually but more even, the sound quality!
i think I would’ve heard more difference when upgrading the clocks when I would feed the i2s signal directly into the DAC, or add the DAC into the PI. Having the Schiit DAC already, I did not feel the need to do go into this direction, as I am already really happy with my sound now.