There is a recent thread on the gearslutz forums started by a guy who completely restored one of the few remaining Yamaha GX-1's (Benny Andersson's in Stockholm) to its full glory and actually posted some high quality, no-FX demos. This is something I have been waiting for for a long time.
https://www.gearslutz.com/board/electronic-music-instruments-electronic-music-production/1042036-yamaha-gx-1-alive.htmlI fired a bunch of questions at him and finally was able to get a complete picture of how the GX-1 produces its rich sound. Using this detailed information produced a breakthrough for me with the Origin. I will try to do the same with the CS-80V but it will require using two instances of CS-80V, panned left and right, with the PWM LFOs synchronized.
No FX on the poly GX1 programs, to show how rich (and stereo!) the synth really sounded.
Almost all of the programs use the joystick to increase, slightly, the PWM amount (Y axis) and vibrato amount (X axis)
Also for an authentic GX1 experience, when changing filter or envelope settings use them in Macro mode (via the white Select knob).