USB

Manual

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Diagram: USB features

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User contributions

Driver for USB connectivity

• Drivers for Mac and PC which add USB connectivity are available for download here.
• It's not an USB driver in the conventional sense. It's a daemon that waits for the Axe-Fx USB port to appear and then downloads software to the port to make it USB class-compliant. The plist-file is located here: /Library/LaunchDaemons/com.fractalaudio.axefx2load.plist.
• The USB driver control panel should not be used for configuration. Ignore error messages when clicking on the controls. Source1 Source3
• The names of the Axe-Fx channels on the computer are assigned by the computer, not by the Axe-Fx. Source
• If using AxeEdit, you will need to go to Settings > MIDI Settings and select the Midi In and Out ports for it to use. They are named something like "AXE-FX II MIDI In" and "AXE-FX II MIDI Out". The Axe-II must be connected via USB and powered up for the MIDI ports to appear in the settings list.

No MIDI interface or audio interface required

• When using the USB interface, there's no need for an additional audio interface. An audio interface is still required when connecting the analog Axe-Fx II outputs to a computer instead of through USB.
• A MIDI interface is not required to connect the Axe-Fx II to a computer. USB suffices (MIDI-over-USB). The Axe-Fx II itself operates as an USB-to-MIDI adapter. MIDI interfaces can still be used and editing with the help of a MIDI interface is also still possible.

Using the Axe-Fx II to update the MFC-101 firmware

The Axe-Fx II can be used as a USB-to-MIDI interface to update the firmware on the MFC-101. Here's a walkthrough

USB connection increases CPU utilization

Creating an USB connection increases CPU utilization. This is by design. If a preset uses much CPU, you may run into CPU overload problems when connecting the Axe-Fx II to a computer through USB. Source1 Source2

Latency

When monitoring audio via the Axe-Fx II, latency is none. When monitoring the audio signal via the computer's output, the latency depends on the computer.

Solving USB noise

High-pitched noise may be caused by a ground loop. Cliff: "The USB spec calls for grounding the cable at both ends (mistake). This can create an USB ground loop. Make sure everything is plugged into the same outlet strip." Source

Disabling the Axe-Fx output signal when monitoring through a DAW

When the Axe-Fx is connected to a DAW through USB, you're using monitors connected to the Axe-Fx, and you're recording, you may want to monitor just the DAW signal, not the signal from the Axe-Fx. To accomplish this, turn down the preset level in Axe-Edit. Or set USB/Digi Out Source to Out 2, then route guitar to FXL only. Source

USB storage media

The Axe-Fx II cannot connect to an USB stick. Source

Linux

Linux is not officially supported by FAS. Nevertheless all USB features can be obtained under Linux, too.

The Axe-Fx II is fitted with a Cypress USB chip (FX-LP2) which needs to be loaded with firmware (this is not the Axe-Fx II firmware but a dedicated bootloader) to achieve its functionality.

The firmware hex file can be extracted from the Mac OSX driver package (Axe-Fx_II_USB_Driver_Setup.dmg from [1]).

With fxload ([2]) you could upload the USB firmware manually, which would be pretty inconvenient. But with a proper udev rule executing fxload, it is also possible to upload the USB firmware file automatically to the Axe-Fx II.

You may write your own udev rule or use the already existing bash script ([3]) to setup a Linux system to recognize the Axe-Fx II each time it is connected to a USB port and then upload the USB firmware.

After executing the script or applying your own udev rule and then switching on or rebooting the connected Axe-Fx II lsusb will report a new USB device with VID 2466 for Fractal Audio Systems and PID 8003 for the Axe-Fx II. If you like to have a named output you can add adequate entries to the file called usb.ids which is usually located under /usr/share.

Linux recognizes the Axe-Fx II as a generic USB audio and midi device. As such it is handled by the snd-usb-audio respectively the snd-usbmidi-lib module. Unfortunately only MIDI over USB works out of the box but not the USB audio interface. The latter needs some handwork:

Since the Axe-Fx II (at the moment) neither responds to set sample rate requests nor get sample rate requests, it is necessary to patch the files clock.c and format.c (located under /usr/src/linux-kernelversion/sound/usb/) as described here [4]. After applying the patch the snd-usb-audio module has to be recompiled. Once the previous version of this module has been removed from the kernel (rmmod) and the newly built module has been added to the kernel (modprobe), playback and capturing devices of the Axe-Fx II appear and are functional.