This I do not understand - it is the hf VCO input
I think you mean the emiter of Q4 don't you?
At emitter of Q4 is the FM(-time)-modulated (high-pass filtered) audio-signal. This signal is also amplitude-modulated by Q5/Q6. To achieve this, the triangle-signal from the LFO is feed via R36 to D1/D2 which are used as something like a sine-converter for the LFO-output. This LFO-signal is fed to the modulation input R31/R32 through C 2x (?). The higher the voltage, the higher the signal.
AND what about the unprocessed signal through the mixing resistor R95??
I would be more inclined to separate the hf and lf outputs and mix the unprocessed signal equally through both branches.
To the mixing section:
It is a virtual-ground summing-amp like it is used in mixing consoles.
So all the signals are mixed together:
1.) the original signal via R95
2.) The bass signal via R97
3.) A part of the treble-signal via R94
4.) And another part of the Treble signal via Q5/Q6
a.) You cannot locate bass frequencies with your ear, so they can be in mono.
b.) Assuming that the (much more complex) leslie-process is a moving between left and right speaker of the treble part, the signal shoulds appear one time in the left speaker and at the other time in the right speaker.
To achieve this we duplicate the mixing-stage including the VCA, BUT we will feed the second (now right) output with an oppposite control voltage than the left (old mono) output. So we need an inverter to invert the control voltage of the LFO which is present at R36/D1/D2/C2x.
After this at one time the left vca gets A high CV and the right a low CV and at the other time the left VCA gets a low CV and the right a high CV.
So the signal-part of (only) the treble part seems to be moving between left and right output .
As the VCA is only used on the hf section , there should be no need to duplicate it
see above.
Here is what I would do for a pseudo stereo output.
1. duplicate C32, R98, IC3 (only one half required - you could use the other half to invert the signal though), R100, and C33.
2. disconnect R97 and connect it to the duplicate C32 instead(this feeds the lows through the new mixer output).
R97 must be feed to both mixing stages, bass is in mono but Frequency-modulated, we need it in both signal paths.
3. double the size of R95 to 300k
4. add another R95 300k resistor to the R95 and R48 junction. connect the other end to the duplicate C32.
Changing the value of R95 will increase /decrease the modulation effect. Without the original signal no modulation, so we need in both signal paths the resistor - R95a and R95b.
This should give an equal unprocessed signal out of both outputs and processed highs out of one socket and processed lows out of the other one.
see above, bass in mono, treble moving left-right is the goal.
Please feel free to help out with any further suggestions - what controls the ramp up and down speeds for example.
So simple questions
- very easy:
C17 and R46, R47 and D3 control the up/down ramp for the treble ("horn") LFO and C31 with R84 control the bass LFO ramp.
D3 is something like a "brake-function" for the horn speaker.
I think if you add a stereo out, you could split the outputs high and low out of phase to get a better Leslie effect.
I understand...you mean to invert the signal at Q4 before mixing with the rest like it is done in stereo-chorus. Yes would be another possibility but can cause problems with out of phase in mono. But this is general a problem of that configuration that the stereo-leslie effect will loose some effect if you would listen to it in a mono-mix.
I think this is worth trying, but I am more interested in implementing the brake function and fine tuning the ramp up and down speeds individually before I commit any more time redesigning this project - a work in progress.
No problem at all..... after this explanations you only have to wait a little bit until the "super-duper-cx-stereo-rotary-effect" will appear on the overprized boutique market... only who and which name... maybe it will get the name "rotary-probe", "rotary-vibe", "cesar of rotary" or simply "Full (spinning wheel) tone" ? But be sure to save at least $500,-- to buy such a unit...
analogguru
There´s a sucker born every minute - and too many of them end up in the bootweak pedal biz.
) - they cost me US$22 approximately for 20 pieces - pretty cheap for a 1024 stage BBD chip that plugs straight in to the MN3004 footprint on the CX3 board(pin 1 to pin 1 
