[sdiy] suggestions for extra modules in DIY EMS VCS3

[ganesha]

Hi,

I'm in the middle of building a synthesizer based on the EMS VCS3. I already made most of the modules but recently I was was able to buy a second Ghielmetti patchmatrix at a low costprice. So now I'm going to redesign everything in order to use 2 20x20 matrixes in the synth. This also gives me the opportunity to add a lot of extra modules. 

I've never used a VCS3 so I would like to ask to everyone who has more experience with this synthesizer what extra modules they whish were available on the VCS3? Please only modules for which schematics are available on the internet since I can't design modules myself.

Also I was thinking about using 1 matrix for audio signals and the other for control signals but use 2 patchpoints of each matrix to connect the matrixes together.I would also make all the oscillators outputs available on both matrixes. Do you think this is a good idea? 

Modules I've planned so far:
VCS3 VCO1
VCS3 VCO2
VCS3 VCO3
JH MatrixFX VCO3
EMS Filter with JHmatrixFX mod to have also High pass
Korg MS20 35ic HPF+LPF
Steiner Parker synthacon filter
Sample & hold
2 trapezoid env. generators
VCS3 inputs
VCS3 outputs
VCS3 ringmodulator
VCS3 noise generator
VCS3 joystick
JH Wavefolder
Korg ms03 pitch to cv convertor
Yusynth saw animator

All suggestions and comments are welcome.
Best regards,
K.