The USB subsystem of the Axe-Fx III and the onboard firmware of the FC controllers can be updated separately from the main firmware. The current USB firmware version is displayed in Home > Setup > Utilities > Version. The FC's firmware version is shown on the main display when powering on.
Release notes, guides, FAQ
Read ALL release notes for present and previous firmware versions:
The firmware file contains a guide. The Owner's Manuals also explain the update process.
Axe-Fx III FAQ (from the Axe-FX III Owner's Manual):
Q: How do I know the upgrade worked?
A: Check your firmware version anytime by pressing the SETUP button (Push-knob E) on the Home page. The version is displayed at the top of the Setup menu.
Q: Can I skip versions to go from a very old firmware version to a much newer one?
A: You can upgrade from any version to any other version. When you skip versions it is recommended that you also read the Release Notes for all interim versions, all of which are included with every firmware release.
Q: Will updating my Axe-Fx II firmware upgrade my factory presets?
A: Updating firmware does not upgrade Factory Presets. Updated Factory Presets, when offered, are released as a separate update on our web site support page. Fractal-Bot can be used to transmit this update in the same way it is used to update firmware.
Q: Will updating my Axe-Fx II firmware erase my customized presets?
A: Firmware updates do not erase customized presets. However, firmware updates may alter the sound of existing presets. Always read the Release Notes included with a given version before updating. Saving presets after a firmware update can render them incompatible with previous versions. It is always wise to back up your Axe-Fx II using Fractal-Bot before a major update.
Q: The firmware update failed mysteriously. What should I do?
A: If the Axe-Fx still boots normally, just try the update again. If successive failures occur, please delete and re-download the update file before trying again. Trying a different USB port or cable can also solve issues.
Q: After updating, my Axe-Fx will no longer boot normally.
A: See “Recovery” below.
Checking the firmware version
Go to the Utility menu to see the installed firmware version. The Axe-Fx III also displays it on the Home page.
Fractal-Bot displays the current version upon connecting.
Axe-Fx III – Firmware Update Guide. You can actually keep playing while the DSP firmware is loading!
Axe-Fx II – Firmware update guide for the Axe-Fx II, including troubleshooting tips. Always disconnect the MFC-101 when updating the firmware on the Axe-Fx II!
AX8 and FX8 – The firmware includes an update guide.
MFC-101 – MFC-101.
Auditioning presets after updating
Updated firmware may cause changes in your presets. Read the firmware release notes and verify your presets.
Built-in backup firmware in the Axe-Fx III, Axe-Fx II XL and XL+, FX8 and AX8 allows recovery in the event of complications during update.
Axe-Fx III — Hold down PAGE LEFT and PAGE RIGHT while cycling power.
Axe-Fx II XL/XL+ — Hold down Page Left and Page Right while cycling power until the Emergency Utility menu appears.
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 unit sounds bad after an update, try this: Reset hardware settings.
The Axe-Fx firmware is coded in C and assembly. source
"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