my favorite Rapture lead preset "Kreamed Lead". I begin doing some basic tweaks such as killing the decay envelopes in amp modulators so that when I let off a note it stops immediately
Here's something that you can try out in that particular preset (repeat the process for both E1 and E2):
In the Amp EG, press 'S' while hovering over the sustain point, to remove it.
Right-click on Node#1/3 [at 7.5 ms] to remove it, then bring the default Node#0 up to maximum level.
The Amp EG will now only play for less than half a second at a
maximum.
You can bring up the EG Sync 'multiplier' to 4 or 8 to lengthen this out to a measure or two.
That preset is in mono/legato mode [Polyphony 0]. To hear multiple 'palm mute' attacks, set the Polyphony to 1.
You'll lose the portamento glide. A compromise is to change Polyphony to 1 in in E1, and leave it at 0 in E2.
Now, on to the Modulation Matrix.
Source: your desired controller message Destination: Volume EG Attack All
Depth: -300
Smooth: 0.0
The choice of 'desired controller message' is unimportant, but the method by which it's delivered is very important. You mentioned the mod wheel in your question. Not only is that currently 'occupied' by the Pitch LFOs, but it doesn't have instant on-off capability (characteristic of palm muting). If you have programmable switches on your keyboard controller, I'd use them.
One switch state sends a zero value, and the other sends a full value of 127, without any kind of intermediate sweeping of values. If you're going to use a sustain pedal for this, remember to change Sust to Off in both E1 and E2. The Depth value in this Matrix routing is a general starting point. Adjust the -300 ms. value upward or downward for variable amounts of 'palm muting'.
I tried to use a low pass filter tied to the wheel but that does not give me the heavy percussive sound that I'm after.
I think you were on the right track for one way to accomplish this. For the reasons stated above, I wouldn't have used the mod wheel. As for filter choice, I'd select something on the shallower side for the second filter, such as LP 2. The DSP routing is already in series (which is good). Leave the LP2 Cutoff knob up full. and the Reso fully down.
This trick to percussive output here would be to lower the F2 Cutoff frequency while you raise the F2 Resonance simultaneously.
As a
very rough guide, the additional Modulation Matrix slots would look something like this:
Source: CC
X Destination: F2 Cutoff All
Depth: -6650
Smooth: 0.0
Source: CC
X Destination: F2 Resonance All
Depth: 40.0
Smooth: 0.0
That's going to 'tune' your palm mute to an approximate 'pitch' of C. Adjust the Matrix Depth value of the F2 Cutoffs to tune the resonant filters to other apparent pitches. If you've feeling some reckless abandonment, you can add a 'maximizing' slot to the matrix. Remember: You're essentially adding feedback to the filters at the cutoff frequencies, so at some point,
you're going to hit runaway feedback conditions.
Source: CC127
Destination: F2 Resonance All
Depth: 40.0
Smooth: 0.0