Page 365 of the Montage M Operations Doc shows the Filter screen for a drum key.
The screen shows the typical filter graphic and 4 parameters: Cutoff, Cutoff/Vel, Resonance, HPF Cutoff.
Changes to either Cutoff or Resonance are reflected on the screen.
Changes to HPF Cutoff are NOT reflected on the screen for then entire 0-1023 range of values.
HPF Cutoff (HPF Cutoff Frequency)
Sets the cutoff frequency of the high pass filter.
Settings: 0–1023
Is there possibly a parameter on another screen that is taking the HPF Cutoff out of the picture (pun intended)?
Joel has a video for Montage classic demoing drum filters and that video shows the filter graphic doesn't change when HPF Cutoff is swept min to max. This doesn't directly answer any questions. That said, Montage Classic functions the same as M for this.
Current Yamaha Synthesizers: Montage Classic 7, Motif XF6, S90XS, MO6, EX5R