In case you don't have this, here is the calibration procedure:
Warm up the SunSyn for at least half an hour. Make sure that all VCOs are tuned before you start the envelope tuning!
Press Menu -> Global -> Tune. Select "Env" so that it reads "Att1 Decay1 Sust1 Voice". Entering this submenu loads a special preset into the edit buffer (the underlying single patch will not be affected). Don't tweak the ADSR1 knobs because this would change the basic parameters - best is to leave them at zero position before you enter the submenu. Exiting and re-entering this submenu will reload the test patch.
Press the button underneath "Voice". This selects the voice to be calibrated. You have to press it once before the actual tuning procedure is entered. It doesn't matter which key you press on the keyboard. When you press a key, an up- and down sweeping tone can be heard. At the peak points the time is measured in 10ms steps and displayed in the attack- and decay value. The correct value is 100 = 1000ms =1sec rise and fall time. If the value is too low, turn the respective encoder knob right to increase the value, left to decrease the value. You have to turn quite a lot since the resolution is fine. After the change of the value, trigger the envelope again to see the result. Repeat it until you get the desired value (100). Do it with the attack and the decay value to obtain almost 100 for each value. Due to the analog tolerances the value may differ from about 95 to 100.
Do this with every voice. If you are finished with the attacks and decays, turn the decay value low at the actual ADSR1 knob up right on the panel.
With the short envelope, select the voice with the highest basic tone (frequency) at sustain level 0. This will be you reference for the others. Remember the tone. Turn the respective encoder knob (3) right to increase the zero sustain level for the other selected voices. Match all voices for the same basic tone. If you have done this, you are finished. Press exit twice to leave the calibration menu.