HiFiPi – Part 1 – To Amp, To DAC, To DAmp?

Posted: September 22, 2016 in Audio, Hacking and playing, Hardware
Tags: ,

As usual I found myself with more ideas and things to experiment with when building the MooMusic prototype. Seeing all the possible things I could build made me want to move the project on far beyond my original ideas. But that wouldn’t be fair as the use case for MooMusic was very specific – a simple music player for my daughters. So I decided to use one of the various Pis floating around and try to build something more ambitious. I’d seen lots of people restoring antique radios or building small touchscreen enabled devices, so I wanted to do something like that.

First stop is to figure out the best way to get decent quality sound out of the Pi. Do I install something with a headphone style jack, something with phonos (RCA) or something that can take speakers? My initial thoughts were to install a DAC with some phono outs. If I wanted to use headphones I can easily get a phono-headphone adapter (assuming there isn’t one in my cable bin already!).

From the forums related to this kind of project it became apparent that HiFiBerry make some excellent small scale expansion boards that provide all of the connections I can think of and more. The prices aren’t bad either, and are cheaper than some of the true audiophile level DACs that I could try to use.

The problem is, I don’t actually have a real-world use case for this project: I’m not building this for a specific reason, just because I can. I soon realised that because I have no real use case, trying to build something that is suitable suddenly becomes much more complex. If I want speakers, I need an amp. If I want headphones I need a suitable jack. If I want to connect to an external amp, I need phono or maybe SPDif/Optical. Do I need to support Bluetooth? Will I use WiFi or ethernet?

Head-spin.

After taking a step back I decided that I want this to either be my audio source in my office OR to replace the annoying kitchen radio. The actual outcome would depend on how easy to use the final thing was and how pretty it was.

Based on that it became apparent that I needed the ability to drive speakers AND the ability to output via headphone jack. Faced with this, the HiFiBerry boards became a bit too expensive for me to play with. ~£45 for the Amp and ~£23 for the headphone with no indication that I can stack them and use both boards in a single build.

I’m not confident that what I end up making will be good enough to use in the kitchen, so just buying the amp is risky.

While trying to resolve this matter I came across a reference to the X400 board. A bit more digging revealed the X400 board from Suptronics. This board includes phonos, amp (with speaker terminals) AND headphone jack. The downside is that all that requires a separate power supply. Thankfully the power supply also powers the Pi, so there’s no need to use 2 plugs! For ~£20 via eBay (of course) I ordered the board and crossed my fingers.

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