Background:

"Solo 1st Violin AF1" contains two Parts. The 1st Part is one violin sound and 2nd Part is a slightly different violin sound. The superknob morphs between the two sounds. With the superknob full counter-clockwise, Part 1 is fully on and Part 2 is fully off (squelched). With superknob full clockwise, Part 1 is fully off (squelched) and Part 2 is at full volume.
When you first recall "Solo 1st Violin AF1" - the default of superknob is at full counter-clockwise. Therefore, you would only hear Part 1 unless you moved superknob.

Are you moving the superknob? If not, you can get rid of the 2nd Part altogether.

Also, modwheel in "Solo 1st Violin AF1" already controls a couple parameters. Reverb Send and Insertion B Dry/Wet. Is there any position of the modwheel you favor? With the modwheel rolled all the way "down" - there is zero offset to either of these parameters. Deleting these assignments will give you the same sound as having the modwheel rolled all the way "down".

1) Press [PERFORMANCE] (HOME) button
2) Touch the first of 2 Parts of "Solo 1st violin AF1"
3) Touch "Edit" when the left-side menu pops up
4) Navigate to menu "Part Settings" -> "General"
5) Touch the "Volume" parameter to select it. You should notice now a [CONTROL ASSIGN] button (physical amber button) is lit. First, edit the volume value from 100 down to 0
6) Press the [CONTROL ASSIGN] button.
7) Move the mod wheel
8) Press [+] to add a destination and pick the "Volume" destination.
9) Change the curve as you see see fit to create the volume change relationship you're after. Ratio can be changed. Curve parameter(s) and type. Keep the curve as uni-polar. Ratio of +32 and Param1 of 9 can work.
10) Make sure "auto select" in upper-left is turned on
11) Turn assignable knob 6 - you will see it has a destination of volume
12) Press "delete" (lower-right) to remove this destination.

That should demonstrate something. I would remove the superknob control and delete the 2nd Part as well. If you don't want to do that, then you'll need to edit the 2nd Part in a similar way then touch-up the superknob morphing settings (Part 1 and Part 2 Assignable Knob #6 as source and volume as destination). I'll assume you're OK with deleting the 2nd Part for now (which makes the steps easier).

Jason,

thank you very much! There was a wealth of new information for me in your post. e.g. I hadn't thought to use the Superknob on that particular patch, yet .....

I will work through your steps as soon as I find the time and give feedback how it works out.

As a starting point, I would prefer if MW rolled down means 0 velocity and rolled all the way up 127. After writing this, I wonder is it volume or velocity?

Thanks again!

I would really prefer to control volume with the mod wheel for this instrument.

What I was giving you was a replacement for using FC7 which previously modulated volume and transferred this to the modwheel. Volume was requested as above.

There is, depending on the samples' number of velocity zones, potentially a big difference between volume and velocity. Although higher velocities can (and would normally) increase the volume - it's more the timbre of the instrument that one would notice as you "dig in". Volume modulation is NOT going to do this. If you want velocity digging-in-ness, then you have to supply a higher velocity to the element.

I've wished before that velocity could be set (to a particular value by a controller) or offset (by a certain amount by a controller) using the modulation matrix. There were a few things I was trying to do with instrument control/"emulation" that would have been served by being able to dial/knob/ribbon/wheel/pedal/switch in by a controller. Even just having access to velocity offset and velocity depth as a destination would help. However - neither of these are destinations. There are no velocity parameters you can use as destinations. Therefore, adjusting velocity "on the fly" using a controller isn't going to happen.

The closest you can get with the existing system is to have two or more sets of sounds that you can "switch" between (if 2-3 - you can use XA control which are buttons or "muting" as follows, if more than 3 you can use Part levels and "mute" by squelching all but one at a time and/or use keyboard control although keyboard control would force you to use scenes as a control mechanism and not modwheel).

So the idea of using modwheel would be to assign regions of the modwheel where one Part is volumed "up" while the rest of the associated Parts are squelched. As you move through the modwheel from rolled down "down" to "up", you "unmute" a different Part which itself is a different velocity layer of the same instrument (or copy of the Part with the velocity offset turned up or down). It's not the same as XA Control or Keyboard Control because you "morph" the sound as you roll instead of using it to setup your next note. So notes that start with a gentle velocity will be real-time changed to higher velocity by rolling up. This may be OK.

It's going to take more bricks and mortar to build up something related to velocity because the engine wasn't built to modulate velocity. You have to cheat. A velocity offset, BTW, would always affect the next note played and would not swell up any current notes playing. If the "BTW" is what you want - you may need to back away from the modwheel requirement and move to either A.SW1, A.SW2 or move to scene #1-#8 as a control mechanism. Using scenes you get 8 different possible velocity "levels". On MODX it's not so easy to get to all 8 buttons at once. Using A.SW1/2 you get less possible velocity levels but may be easier to control.