Cabs and user IRs
What an impulse response is, how one gets onto the Axe-Fx II, and the file extension that looks right and does nothing.
What a User Cab is
An impulse response is a recording of what a mic'd speaker cabinet does to a sound. Someone plays a frequency sweep through a real cab, records the result, and mathematically removes the sweep — what remains is the cabinet's fingerprint, which can then be applied to anything. Fractal call these User Cabs when they are yours and Factory Cabs when they shipped with the unit. They are the same kind of thing.
How much room you have
This depends on which Axe-Fx II you have, and the gap is large. The XL and XL+ carry over 150 factory cabs and 1,024 user locations. The Mark II has 130-odd factory cabs and 100 user slots — so a Cab Pack that assumes a thousand slots will not fit. Both support standard 2048-resolution IRs and the higher-detail UltraRes format, which raises resolution without costing more CPU or storage.
Fractal Audio: Axe-Fx II product and support pagesThe slot you chose before sending is the slot it lands in
There is no filename involved anywhere in this. You set the Cab block to a user slot, then send the file, and the unit puts it where the block was pointing. Get that order wrong and the cab goes somewhere you did not intend — and a preset referencing a slot number will happily load whatever now lives there rather than warning you.
Loading a User Cab
IRs transfer as MIDI System Exclusive data. Fractal's own applications are the recommended route, though a third-party SysEx librarian works too.
- 1
Ready the unit to receive
Open a preset containing the CABINET 1 block, select it and press EDIT, make sure MODE is not set to STEREO, and set the CAB parameter to the numbered USER slot you want to load into.
- 2
Then send the file
Axe-Manage Cabs in the editor is the drag-and-drop route and lets you manage what is already in memory. Fractal-Bot sends individual cab files to any memory location.
- 3
Audition before you commit
The four SCRATCHPAD locations at the end of the cab list exist for trying a cab before it takes a permanent slot — particularly useful when user memory is full. They clear every time you restart the unit, which is the point.
Where to get them
Fractal's own shop sells professionally produced Cab Packs, including third-party producers. Axe-Change, their file-sharing site, is a large free library. And the unit has an IR Capture utility if you want to photograph your own cabinet — it needs a mic and a preamp, plus either a flat full-range power amp or a speaker-level DI box.
Cab-Lab is a different tool for a different job
Cab-Lab is an IR mixer — it blends several IRs into one, the way an engineer blends several mics on a real cab. Fractal recommend it for capturing too, because the interface is easier than the on-unit utility. It is not required to load an IR someone else made.
Stereo mode blocks the transfer
The CABINET block's MODE must not be STEREO while you are loading. It is a small thing and it is the reason a transfer that looks fine does nothing.