> The factory adjustment is ~ 40Hz (+/- 10 Hz) with VCF Frq. and CV Ampl. both
> fully CCW.

Wow, amazing! Last week I took three measurements from my 127 (at 1, 3 & 5V in), noting the frequency giving a signal 26dB down from the input; I then extrapolated the 26dB back up again, to find the nominal 'cut-off' frequency; I took logs and plotted the points, which gave a pretty good straight line; I fitted the points by regression, and then took anti-logs and plotted the resulting exponential curve - the frequency this gave corresponding to 0V CV in 40.3Hz! :-) I'm pretty happy that I'm on the right path now! Many thanks for the info Dieter.

Tim