Recently, I became the proud owner of a Behringer X-Air XR18. This became the key to opening a new business, which I’ll announce at a later date. I’m working on acquiring more equipment to make this work.
As many people know, the XR18 is a stagebox-style mixer in which the mixer is physically on the stage with no controls but controlled with an iPad or Android tablet. However, as the owner of a Behringer X-Touch, which integrates seamlessly with an X-Air mixer via either MIDI or Network connections. In my situation, this gives the ability to have a physical front-of-house setup, with a computer showing the X-Air Edit application.
However, what if I want to multi-track record or add custom effects via Ubuntu Studio? This is where it would get complicated as I would then have to run a prohibitively-long USB cable from my computer to the XR18 on the stage. This would not be ideal.
As many people know, MIDI can be routed via network, which is the way the X-Touch, XR18, and X-Air app work together. A simple WiFi router and ethernet cable wouild be a great solution to this problem, but that also leaves an Ethernet cable prone to being tripped-over by audience members (unless one were to gaff it down). So, since we’ve already got WiFi, let’s take advantage of that.
To expose the audio ports to the WiFi, we’re going to have to bridge it. But… how? Most people would tell me just to use Dante but, unfortunately, Audinate refuses to support Linux, and AES67 support in PipeWire is very young. However, it turns out, JackTrip is in the Ubuntu repositories and, as its name would imply, integrates seamlessly with JACK and, therefore, PipeWire.
Setting this up is rather simple, and I’m documenting the process here.
Prerequisites
- A Raspberry Pi 4 or higher (I have a late 2023 Raspberry Pi 5)
- A micro SD card (16GB or larger)
- Ubuntu Server for Raspberry Pi (I used 24.04, linked here).
- Optional: Ubuntu Pro (for the RealTime Ubuntu Raspberry Pi Kernel)
Here we go…
The first thing I did was install the downloaded preinstalled server image to a micro SD card. This is accomplished using Raspberry Pi Imager. I used the Snap version maintained by Dave Jones of Canonical, part of Canonical’s Raspberry Pi team. If you’ve never met Dave, he does all of his computing via Raspberry Pi, and it’s a sight to behold!
To get that, it’s as easy as sudo snap install rpi-imager.
I made sure to set the server to automatically detect my WiFi, but if you plan to use a hard Ethernet connection, this isn’t necessary. Just be sure you can SSH into the machine as this is key (pre-set a user and set the machine name).
Once the SD card is imaged, I SSH’d into the machine (ssh erich@{computer-name}.local). The first thing I did was install jackd2 and jacktrip:
sudo apt install --no-install-recommends jackd2 jacktrip
One must use the --no-install-recommends option to avoid installing unecessary graphical tools as jackd2 will want to install qjackctl which is the GUI application to control JACK. We don’t need it here. JackTrip has an option to automatically connect to all inputs and outputs, so we’ll use that here.
To automatically start JACK upon boot, I modified this systemd unit file to be custom for my setup. You’ll notice I made the buffer 256 (-p 256) with 3 periods per buffer (-n 3) as gives the highest reliablility on a USB connection. Additionally, the highest frequency an XR18 runs at is 48000 Hz, so I made sure to set the frequency there (-r 48000). Also, we want the process to run in realtime and directly to ALSA (--realtime -dalsa):
[Unit]
Description=JACK server using %i user profile
Documentation=man:jackd(1)
After=sound.target local-fs.target
[Service]
User=%i
Group=%i
#Type=notify
EnvironmentFile=-/etc/jack/alsa.conf
#EnvironmentFile=-%h/.config/jack/%i.conf
ExecStart=/usr/bin/jackd --realtime -dalsa -p 256 -n 3 -r 48000
# -d $DEVICE $DRIVER_SETTINGS
LimitRTPRIO=95
LimitRTTIME=infinity
LimitMEMLOCK=infinity
# Caution: use on memory-limited devices only
# OOMScoreAdjust=-1000
[Install]
WantedBy=multi-user.target
I installed this to /usr/lib/systemd/system/jackd@.service.
Next, I created a systemd unit file to start JackTrip. I needed this to be a server (-s), with 18 inputs and outputs (for an XR18, -n 18) and automatically connect upon start (-q auto):
[Unit]
Description=JackTrip Audio Network Service
After=network.target sound.target jackd@%i.service
Wants=network-online.target
[Service]
# Run as a specific user who has JACK permissions
User=%i
Group=%i
ExecStart=jacktrip -s -n 18 -q auto --udprt
Restart=always
RestartSec=5
# Optional: environment for JACK if needed
#Environment=JACK_NO_AUDIO_RESERVATION=1
# Give JACK/JackTrip real-time priority
LimitRTPRIO=infinity
LimitMEMLOCK=infinity
[Install]
WantedBy=multi-user.target
I installed this to /usr/lib/systemd/system/jacktrip@.service.
Next, to make sure this runs as my user, I did the following:
sudo systemctl enable jackd@erich.service
sudo systemctl enable jacktrip@erich.service
Optionally, since this will be used as a headless appliance, one can use Ubuntu Pro to get the RealTime Kernel. This is accomplished by the following with an Ubuntu One account:
pro attach
pro enable realtime-kernel
To make sure everything worked, check pro status.
You can have up to 5 machines running Ubuntu Pro for free. In my case, as an Ubuntu Member, I can have up to 50 machines for free, and this is only my third one!
Once this is done, reboot. On your other machine, install jacktrip-gui. (This will be in Ubuntu Studio 25.10 and higher by default!): sudo apt install jacktrip-gui.
Opening it, it will ask you if you want to sign in with a Virtual Studio account. This is because JackTrip allows you to collaborate across the entire internet with fellow musicians with very low latency! It’s pretty cool! However, we don’t need that for this purpose. Instead, we’re going to say “No” and simply connect to the server as a P2P client:
Enter the computer name with .local afterwards, and it should find it as long as your desktop or laptop is connected to the same network as the Raspberry Pi.
After you click “Connect”, you should see this:
As you can see, this has audio coming in from a microphone already.
Back in X-Air Edit, already connected to the mixer, I changed my routing so channels 1 and 2 were being sent to the aux, so I can then use my computer’s audio there for music from e.g. Spotify:
Next I started a Dummy Audio Device from Ubuntu Studio Audio Configuration and made it the main output for the computer. I then connected the monitor of the dummy output to channels 1 and 2 of JackTrip using Patchance:
…and VIOLA! Even testing my microphone, there was so little latency it was imperceivable.
I’m envisioning a setup like this:
STAGE:
_________ USB _______
| X-Air |--------------| RasPi |
|_________|--- ETH ---|_______|
_|______|_ __________
| WiFi | | WiFi |
| Router | )))) (((( | Repeater |
|__________| |__________|
ETH |
FOH: ------------
__________ _____|_____ _________
| Computer | ETH | Ethernet | ETH | X-Touch |
|__________|------| Switch |------|_________|
|___________|
I’m excited to test this further! Overall, I feel like I’ve found a way to do a Dante-less audio-over-ethernet setup that cost me nothing!