I’m back from Iceland since a week and it was a pleasure to power on my modular analog synth after a 8 weeks travel. I detected then a tuning and scaling problem between my Tiptop Audio Z3000 and my Cwejman VCO-6 oscillators. The Cwejman was OK but it didn’t track on the same way. I tried to calibrate and retuned the Cwejman oscillator, but without knowledge I failed. Some I asked Wowa Cwejman for some helps !
Now my Cwejman oscillators are perfectly calibrated and tuned. Here are his advices: 
You will need a plastic screw driver, an other well tuned and calibrated oscillator (maybe one from a plugin) or a frequency meter (Tiptop Audio Z3000 oscillator is perfect for that).
Hello,
C2 is actually 32.5Hz (as it was calibrated). Please see the pdf (http://cwejman.net/vco-6.pdf).
The calibration, as below:
Mix another oscillator (sawtooth) with VCO-6s sawtooth. Set range to C2 and fine tune to 0. Set anothrer oscillator to the same frequency so you can hear beat freq. Align “freq” for 32.5Hz.
Step up range to C5 (three octaves higher) and align “octave” trimpot to 260Hz. Go back to C2.
If you didn’t touchrd “fm2″ trimpot then it should be calibrated. Use some external CV with 1V/octave and connect to “fm3″ input. Open fully the potentiometer for “fm3″ and calibrater trimpot “fm3″ for for correct tuning for at least 3-4 octaves.
Step up range to C5 and tune the external oscillator so you can hear beat freq. Play every C note (3 octaves or more). Adjust the “hi track” for proper frequency (so you can hear beat freq with the external oscillator). Set range to C2 again and play every C tone for at least 5-6 octaves and correct (v. fine adjustement) FM2 and FM3 for correct frequencies.
Have a nice day!
Wowa
I think that it could be useful for other people. Done stop patching and turning knobs !!!
