USB

The information on this page supplements the official manuals.

USB and CPU usage

• Connecting the AX8, FX8 or Axe-Fx II through USB 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. source and source

AX8 and FX8

The AX8 and FX8 have an USB 2.0 type B port (host). It's fully class-compliant. There's no driver required. USB is used to connect the unit to a computer and to run the software editor and Fractal-Bot. USB Audio is not supported.

Axe-Fx II

• To connect the Axe-Fx II through USB a driver must be downloaded to the device first from a computer. USB drivers for Mac and Windows are available for download here. If the USB driver is not installed, utilities such as Axe-Edit, Fractal-Bot and Cab-Lab won't recognize the Axe-Fx II. Also, tablets such as an iPad do not connect to the Axe-Fx II, until the driver has been downloaded to the unit first (without power cycling).
• Fractal Audio:
  • "The driver that we supply for OS-X computers is NOT an audio driver. It is a firmware installer. The Axe-Fx II uses a "soft" USB controller. It gets its code from the host computer. When you turn the Axe-Fx II on it requests firmware from the host. This is superior to a hard-coded controller in that updates merely require a new host image rather than reflashing the controller."
• USB Audio is supported. An external audio interface is required when connecting the analog Axe-Fx II outputs to a computer.
• The USB connection supports USB-to-MIDI, so there's no need to use a MIDI interface in most cases.

USB adapter Mode: using the Axe-Fx II as an USB adapter to update the MFC-101 firmware

• The Axe-Fx II can be used as an USB-to-MIDI interface to update the firmware on the MFC-101, using Fractal-Bot. This is explained in the Fractal-Bot manual.
• Fractal Audio:
  • "The USB Adapter feature was added for simple USB-to-MIDI functionality, specifically firmware updates for the MFC-101. It is a low priority task since audio processing is the Axe-Fx's primary usage. Latency is not guaranteed. It is not intended as anything more than a no-frills, simple MIDI adapter for non-critical tasks." source

USB troubleshooting

• High-pitched noise may be caused by a ground loop.
• Fractal Audio:
  • "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
• The LCD screen may flicker occasionally.
• Fractal Audio:
  • "An occasional flicker when hooked up to USB is not unusual. This is due to the screen redraw being interrupted by the USB thread." source
• When experiencing problems such as dropped connections or an Axe-Fx II which freezes after connecting USB, always replace the USB cable first. Example

Linux

• The Axe-Fx II can work as an audio and MIDI interface just as it does on Windows or OS X, although Linux is not supported officially.
  • Before firmware is loaded the device will be reported as a USB device with Vendor ID 2466 and Product ID 0003.
  • After the USB controller gets loaded with its firmware the Axe-Fx II will be recognized as a USB soundcard device with Vendor ID 2466 and Product ID 8003.
  • For a named output when using lsusb, adequate entries for Fractal Audio Systems and the Axe-Fx II need to be added to "usb.ids" (typically under /usr/share/misc/usb.ids). See source
• Loading the USB firmware
  • Ubuntu 16.04 and above users can use AlbertA's PPA and install the axefx2-usb-firmware package
  • For others, volt created an install script package that is available for download here.
• Since the Axe-Fx II is an Audio Class 2.0 compliant device no additional drivers are needed. The Linux kernel already supports such devices. However, depending on your kernel version, there can be some issues:
  • For systems with a kernel older than 3.10, you will need to patch clock.c in the ALSA's usb-audio kernel module (<linux>/sound/usb/clock.c). See more here.
  • For systems with a kernel older than 4.10, the ALSA usb-audio driver may cause overflows or underflows at the device since there is no proper sync applied. A patch is available here. See more here.
    • Ubuntu 16.04/16.10 users can use AlbertA's PPA and install the snd-usb-audio-dkms package which installs the patched kernel module (DKMS actually builds it for your running kernel and rebuilds any time there's a kernel update).
    • To verify check the “USB” bar graph in Utility->Status which displays the amount of data in the USB FIFO buffer. Ideally the bar should be at around 50%. The number of buffer errors that have occurred since the last buffer reset is indicated above the bar graph - this should be zero when the driver is functioning correctly.
• Threads about using Axe-Fx II with Linux:
  • Linux Again.
  • Linux Support.
  • Linux: USB overflows.