I'm trying to figure out how to do something like this in my situation: I'd like to set up the formant to auto engage, but click the toe switch to engage the wah. I've come close, but so far no cigar. There's not a tremendous amount of tutorials on the mixer block.
When you say you want the formant to auto-engage, do you mean you are using the treadle to control the frequency of the formant filter, and you want it to auto-engage when you move the treadle?
If so, you'll need to have 2 wah blocks, one on each of two different rows (for example, formant on row 1 and wah on row 2). Split the input signal into the 2 wah blocks, then add the mixer block. In the mixer block, add the switch as a modifier to 'row 1 gain', and set it to toggle between min and max volume - for example, when the switch is 'on', the gain is at 10, and when the switch is 'off', the gain is at zero. Now do the same for 'row 2 gain', except set it so that when the switch is on the gain is at 0, and when the switch is off the volume is at 10. When you press the switch, the gains for row 1 and 2 should flip flop - one goes from min to max and the other goes from max to min. Set the treadle as a modifier for the frequency of the formant filter, and set it to auto-engage. Also set the treadle as the modifier for the wah frequency.
If your switch is a toggle switch (not momentary), because the Fractal controllers don't detect the state of the switch on start-up the switch state may not match the state of the mixer modifier when you first turn on the device. Accordingly, you may need to toggle it on and off to sync them. I do this every time I startup my FM3, since I have many presets that use this or a similar configuration. That said, after my next gig I plan to swap the switch for a momentary which should solve the issue and also give me the option of having a preset default to one state or the other.
