Aftertouch Slew Rate

I’m running into a problem where aftertouch information is really jumpy.

What I’m after is those smooth aftertouch swells to the filter cutoff that you hear on a CS80 or other big old synth.

I suspect part of the issue is that resolution coming from my controller (Arturia Keylab MKII) is coarse, but from poking around in other forums this seems to be pretty common across controllers. I’ve tried tinkering with mod curve, which helps a little, but mostly it just moves around the point at which the movement gets jumpy.

Fundamentally, I’d love to be able to define a slew rate for aftertouch—a minimum amount of time it would take to move from one point on the AT curve to another. It seems like there might be a way to use the mod matrix to achieve this, but I can’t quite wrap my head around the logic problem.

Has anyone had any success solving for this, or should I move this question to a feature request?


sounds like a job for a “glide” algorithm, or a simple dezip/interpolator no?

Is that something you’d have to apply to incoming midi via some sort of script?

If it is a problem that is gear-specific then maybe it’s an Arturia question. maybe there’s something in their software control setup program that could set that?

But in my initial response I meant it could be a possible option in the advanced settings of Vital, possibly a bugfix or a feature request. It all depends on what the maximum possible frequency of aftertouch should realistically be. what I’m talking about is basically putting a low passed envelope follower somewhere in the code somewhere to prevent jumps that are happening at an extremely high frequency, resulting in stepping. Aftertouch should be smooth but not sluggish either. So someone has to bite the bullet to do the finesse. Maybe this is on Arturia’s side or their configuration software?

do you have any arturia soft synths to test the aftertouch on?

Yeah, it’s jumpy in their software too, unfortunately. They just released a firmware update with a big improvement in the resolution of the Velocity information, but the AT is still finicky.

well then i think it could be left up to the synth developers if they can afford to put an envelope follower in their aftertouch algorithms. On the other hand i think the accuracy of the pressure sensors in the keyboard themselves might be a factor.

I’ve never found a keyboard that puts out really smooth aftertouch. In most patches AT is used for an accent to something within a patch more than exact values. It’s a player’s parameter. If I want to assign aftertouch to something and want smooth, precise changes, I’ll automate in the DAW. However, if I’m going to do that, then I’m probably writing automation to an assigned MIDI CC with a control on my Akai controller or drawing in by hand.

Vital seems to respond to AT without issue. If I assign AT to a patch element, it does what I expect it will when I play a key and send some AT to the note.

I’d check your hardware AT output with MIDI OX or etc.