Yesterday afternoon, I had great fun setting up the JustBoom AmpHAT. JustBoom is a new player in the Raspberry Pi audio market, but comes from well-known company Pi Supply. I was sent the full family of JustBoom boards for review by Aaron, but I’m free to say what I want about them.

Here are the specs:

• Full high quality audio – 192kHz / 32bit
• 2 x 55 Watt peak output at 8 ohms (2 x 30 Watt RMS)
• Includes both a DAC and power amplifier – just connect to your passive speakers
• Back-powers the Raspberry Pi over the GPIO (with full HAT compliant protection) at 2.5A so only one power supply required for the whole system.
• Plug and play compatibility for ease of use
• Hardware and software volume control from your Raspberry Pi
• Onboard, hardware jumpers for configuring mute and gain settings (jumpers could optionally be changed with switches)
• Mute/enable with GPIO22 (this can be overridden by using jumper J4)
• No soldering required
• Compatible with all 40-pin Raspberry Pis: Zero, A+, B+, 2B and 3B
• Mounting hardware included
• Optional IR receiver included in package
• Unused GPIO pins still accessible via unpopulated extension header
• Fully HAT compliant
• Full driver support in Raspbian / NOOBS
• Compatible with OSMC / Max2Play /RuneAudio / Volumio / Moode / PiCorePlayer / PiMusicBox / OpenELEC and others

This is the top-of-the-line combination DAC/amplifier board, costing £60, so I thought I’d see if it was worth it.

Equipment

To use the board, I bought a couple of speakers and a power supply. In comparison to what I could have bought, the speakers were fairly cheap (£80). I also grabbed some speaker wire so I could connect the speakers up.

I pretty much didn’t know what I was doing connecting the speakers to the AmpHAT. I knew enough, however, to make sure that the positive and negative terminals matched and the instructions provided with the speakers were clear enough.

Operating system

I installed OSMC onto an SD card and plugged it into a Raspberry Pi 3. I assumed that there was some automated set-up that would happen on first boot and, sure enough, the file system expanded and some software installed itself. I plugged in a USB pen-drive that contained some music in FLAC format (a format I knew to be of the highest quality) and selected a track to play.

Nothing happened.

Documentation

I looked on the JustBoom website for some help, but unfortunately the guides are yet to be written. I hope they get them done soon as at the moment it really is difficult to know what to do. I contacted Alex Eames (who I knew had got one of the boards working) to find out what he did, but it was a Raspbian-only solution to do with editing the Pi’s config.txt file: not an option with OSMC. So, I did a little exploring in the OSMC settings and discovered that you needed to get OSMC to load up the JustBoom DAC overlay file. I enabled this. Still nothing happened. I eventually found the setting to control where the audio was output to and selected the ALSA option. Suddenly, music blared out of the speakers, scaring the hell out of me! It worked! It worked! My first choice for music? Transformers: The Movie. For two reasons: first of all, I’ve always loved the music; secondly, I knew that it was a synthesised soundtrack with a lot of treble and a lot of bass, so I knew it would be a good workout for the system. Here is a video of the results. Please note, the sound is so much better than this – this is just on my mobile.

Opinion

So what did I think? Well, I thought that the audio result was simply tremendous. The complete sonic range of the music came through and it sounded brilliant. I appreciate this is a purely subjective opinion, but I don’t think I’ve ever heard Vince DiCola’s music with such a level of detail before.

So, in conclusion: the JustBoom AmpHAT delivers quality results once you get it working. The components on board are clearly of high quality and they’ve been put together very well. The documentation, however, is a problem – those guides need to be written as soon as possible to give a fully plug-and-play experience as it is currently not clear how to make it all work. My experience with OSMC was a bit of educated guesswork, and that’s not great for a £60 product. However, the results you get when you do get it working are… wow.

I’ve also got an IQaudIO board to test out, so I’ll let you know once I’ve got that working and can compare the two.

More information and buying

More information about the board can be found here.

The JustBoom AmpHAT is available from several different retailers including Pi Supply and The Pi Hut.