The information on this page supplements the official manuals.

Fractal Audio products firmware downloads

Firmware release notes

Axe-Fx II: Firmware update guide for Axe-Fx II. Including troubleshooting tips.

Always disconnect the MFC-101 when updating the firmware on the Axe-Fx II.

The firmware for the AX8 and FX8 includes a firmware update guide.

MFC-101: go to the MFC-101 page.

Built-in backup firmware in the Axe-Fx II XL and XL+, FX8 and AX8 allows recovery in the event of complications during update.

Axe-Fx II XL/XL+: hold down Page Left and Page Right while cycling power.
FX8: hold down SETUP and power the unit on. Hold the button for about 1 second beyond the power up, then release. The unit will now allow you to install firmware using Fractal-Bot.
AX8: hold down SHIFT and power the unit on. Hold the button for about 1 second beyond the power up, then release. The unit will now allow you to install firmware using Fractal-Bot.

If the Axe-Fx II or AX8 sounds bad after an update, try reinstalling the firmware, or perform a system reset.

Updated firmware may cause changes in your presets. Read the firmware release notes and verify your presets.

The Axe-Fx firmware is coded in C and assembly. source

Fractal Audio:

"The Axe-Fx II can be reprogrammed at least 100,000 times." source
"Most DSP compilers include library functions for common signal processing functions. However every library I've seen makes the same mistakes in several important and oft-used functions. I can't disclose what functions and what those mistakes are but because of this we use our own hand-coded assembly functions for our own libraries. The results are measurable and audible especially when dealing with the special requirements of amp modeling. I should add that these libraries are low-level functions like FFT() and such. You're not going to find a library that implements a Tube Screamer or even something more granular like a diode clipping circuit. That all has to be developed in-house." source