Let’s take the “Hyper Velocity AF 1” sound example in the synth bass category on the Yamaha Montage. Although this preset is single-element, a secondary trance sound rises when the keys are pressed strongly. From which edit point might this preset be triggering this? In such sets, I can’t fully control and understand the character of the sounds I can’t adjust myself.
I'd have to plug in the keyboard to take a look. Hyper Velocity AF1 was in the Motif XS (two generations earlier than Montage classic).
Velocity can impact lots of things - each of the envelopes (PEG, AEG, FEG) as one example.
However, if this is a matter of the single element using a waveform with multi-sampled velocity layers then what you would need to do is edit the velocity (offset, depth) response to avoid the higher velocities sent to the element. There's a few places where this can be done. The easiest is at the Part level. Assuming Montage Classic: Part Settings->General (Velocity Offset, Velocity Depth). These can be adjusted so that the higher velocities are filtered out.
Current Yamaha Synthesizers: Montage Classic 7, Motif XF6, S90XS, MO6, EX5R