Note: To use the new USB MIDI features, you need both UAFX firmware 2.0 or newer (available in the UA Connect app) and the UAFX Control mobile app 3.0 or newer. Get these apps here.
Troubleshooting the USB Host MIDI Interface
UAFX pedals are controlled by other MIDI devices through the USB port.
In order to do this, UAFX pedals need to be connected to a USB host-capable port. We list common configurations in our Getting Started with UAFX 2.0 USB MIDI article.
Each USB MIDI host interface has its own manual with instructions. It is good practice to update the firmware on all the devices you are using, and to pay particular attention to any included editor for the device.
As an example, when using the CME H2MIDI Pro or CME H4MIDI WC, you need to use their provided UX MIDI Tools or HX MIDI tools applications to route MIDI within the device. Once you’ve assigned the routing, the device is configured, and you shouldn’t need to adjust this again unless you change how you are using the device.
Here is an example of an eight UAFX pedal configuration with the H4MIDI WC; handily, the UAFX pedal names are detected automatically. This unit has the WIDI Core installed, so it’s possible to use Bluetooth MIDI to connect to this USB Host MIDI interface and to control the UAFX pedals connected by USB.
Bear in mind that the number of UAFX pedals you can connect to a USB MIDI host-capable device is limited by the number of virtual MIDI ports it supports. Typically, you will find this specification listed by the manufacturer.
Troubleshooting USB cables and hubs
While UAFX pedals have USB-C ports, the data protocol used is USB 2.0, for the simplest possible connectivity and easiest compatibility. Unpowered and simple USB 2 or USB 3 hubs are recommended, with up to eight ports. It does not matter if the cables or hubs are type C, type A, or a combination of connector types.
Look out for ‘charging cables,' and verify in their specifications that they support at least the USB 2.0 data protocol. USB 3, 4, or even Thunderbolt 3, 4, or 5 cables will work, but are unnecessarily costly.
There can only be one USB host connection to UAFX pedals. This means that you can connect the USB port either to use MIDI with a USB host-capable MIDI interface or to a mobile device for use with the UAFX Control mobile app. Connecting both simultaneously does not work.
See our UAFX cable guide for further information.
Troubleshooting Noise
If you experience unusual noise on audio outputs after connecting USB MIDI to your UAFX pedal, first, disconnect the USB cable from the USB MIDI host port to see if noise is being introduced here. As any kind of device can be connected over USB, it is possible that another device can introduce noise to the guitar signal. We would expect this when a UAFX pedal is connected to a computer over USB, but not when connected to a simple USB MIDI Host Interface.
If this is the case, there are a number of options. A simple standalone USB MIDI host like the CME H2MIDI Pro has simpler electronics and the least chance of introducing noise. When connected to something like a computer or a device with a display, there is more potential for noise to be introduced over USB.
In testing, we have found USB isolators (filters) to work extremely well, and it is possible to connect one of these to a MIDI host port to prevent noise from entering UAFX pedals via the USB port(s). The DSD TECH SH-G01C USB-C 480M High Speed Isolator has been tested and found to work effectively. This would mean the UAFX pedals are connected to a USB hub, then to the isolator, then to the USB MIDI interface host output port.
Troubleshooting MIDI behavior
MIDI can appear complex, and the best first step in troubleshooting is to simplify.
- Connect only one pedal to your USB MIDI host interface to reduce the chance of errors.
- Verify your USB MIDI host interface and pedal firmware are up to date.
- Verify in your USB MIDI Host interface routing software that you can see the UAFX pedal, and that the MIDI ports are correctly routed to the pedal.
- If you have multiple UAFX pedals, make sure they are all connected to the same USB MIDI host interface using a USB hub. MIDI is a serial protocol, and you want your MIDI to arrive at pedals as close to the same time as possible.
- Verify in the UAFX Control mobile app that you have enabled both program change and MIDI CC. By default, MIDI control of pedals is disabled. From the same page, you also need to set the MIDI channel you intend to use.
- Verify the device you are sending MIDI from is sending to the same MIDI channel as the UAFX pedal.
- If you are trying to change presets with program change messages, make sure that you have assigned your presets to a program change slot in UAFX Control, and that the program change number you are sending is the same as your assignment, on the same MIDI channel.
- If you have more than one UAFX pedal or other MIDI devices connected, make sure you have assigned them their own separate MIDI channel unless it is your explicit intention not to.
- If the MIDI configuration you are trying to achieve is complex, test one MIDI signal at a time to verify the pedal responds in the way you expect it to. Start out with a simple MIDI CC bypass by sending CC 19 value 0, and then CC value 19 and value 2, one at a time, to alternate between active and bypassed states.
- Use a MIDI monitoring tool to verify what MIDI data is being sent to the UAFX pedal. Snoize MIDI Monitor is a free application, and many MIDI editors included with MIDI controllers include a MIDI monitoring tool.
Working With Presets (on UAFX pedals, which feature presets)
When you have configured a program change to swap presets, you can use the pedal to adjust your preset to taste and press the store button. This replaces the assigned program change preset with your new preset. Your original, unchanged preset is still available in UAFX Control should you wish to undo the change, or to rename your new preset.