dbx AFS224 Quickstart Guide - Manual (Page 8)

14. Disengage the Bypass buttons (LEDs off).
15. Slowly raise the master faders on the mixer. As feedback occurs, Fixed filters
will be set. You may want to push the faders a little past the unity gain point (or
performance level). This way the system will not be right on the verge of
feedback when set to performance level. If you run out of Fixed filters (this will
be indicated by the Mode buttons flashing green) you can go back into the Setup
mode and allocate more filters as “Fixed” (steps 1-5). You can then resume from
where you left off.