Having bought a Chord Mojo recently at a bargain price and then realising it’s actually the best sounding digital source I own, I wanted to be able to drop it in and out of the main system easily and take full advantage of its capabilities.
Most of my listening is streamed using Slim Devices / Logitech Squeezebox type devices as a front end to Logitech Media Server, or Qobuz. It’s a system I’ve been running for many years now and it works perfectly. Unfortunately, many of these Squeezeboxes are showing their age, in terms of resolution limitations or just hardware ageing.
The best sounding device is the SB+ a two-box modified SB2 with external PSU, better PSU regulation and upgraded audio circuitry, but it’s limited to 24/48kHz as per the SB2 / SB3 it’s based on.
I also have a Slim Devices transporter, but even that is limited to 24/96, which is fine 99% of the time and works great with the Mojo via optical out, but I don’t like the idea of resampling 192k material to 96k if I can avoid it and since Qobuz has a fair bit of 192k material it would be nice to listen to it at it’s best.
The obvious choice was to use a Raspberry Pi, as I’ve done before and whilst I could use USB to connect to the Mojo, for a really inexpensive solution, the risk of induced noise from the non-galvanically isolated USB, made it sensible to look at a Digital out HAT for the Pi, with optical capability, to achieve the electrical isolation I wanted.
I also wanted it to be touch screen device, like the well-regarded Squeezebox Touch, that many use as it can be made to play 24/192 with an app.
The official Raspberry Pi 7″ touchscreen seemed like a good choice, as the newer versions of these support backlight dimming another feature I wanted. Looking around for suitable enclosure that everything would just drop into and that didn’t look too ugly lead me to the SmartiPi Touch case. In my case the Touch 1, as I’m using a Pi3 B+ I had lurking in a dusty drawer. This case has a couple of different depth rear covers you can buy, to give a more professional finish to the completed project, I bought the deeper one, not knowing if the shallow one was sufficiently deep.
The other feature I wanted was full IR remote control, as I have on the Squeezeboxes. Looking at Digi HAT’s lead me to the Justboom Digi which is supplied with an IR sensor and has the necessary electrical connections on the Digi HAT for it to be fitted.
piCorePlayer was the final piece of the puzzle, offering a lightweight Pi distro, with Squeezelite (a software Squeezebox) and Jivelite (a touchscreen interface with different skins). piCorePlayer even supports IR remote control when enabled from within it’s web interface. Even more impressive was that when enabled, it just worked with any of the existing squeezebox remotes (or the Logitech Harmony I mostly use), without any configuration or fiddling!
The result is great, I wanted the IR sensor out of sight so made a small window in the touchscreen’s black surround (using a bit of abrasive glued to a screwhead, in a pillar drill!), behind which I’ve fitted the IR sensor.
The final result is domestically acceptable and for the most part the amount of work was minimal, just assembling parts like a Lego kit!
All current versions of the official Raspberry Pi touchscreen support backlight controls for dimming the screen, which is something else I wanted on the final design, I often listen to music with the lights dimmed and it’s very annoying if a screen across the room is excessively bright. piCorePlayer and Jivelite make that available through the touch interface, a future project is to automate screen dimming, using a suitable light sensor.
The only real work was the screen mod above for the IR window and a cutout in the rear cover for the SPDIF connections.
At some point a nicer base for the SmartiPi case will be on the list, it’s the only part I don’t really like, maybe something with a defined location for the Mojo to sit in.
Even when the Mojo isn’t connected, I can sync it with the transporter and it acts as a remote touch screen controller, that displays album artwork whilst playing.