Changing Glide Rate
Another commonly requested timing change is the glide rate of the 2720-9 Glide circuit. Changing the timing in this circuit is much simpler than in the Envelope Generator and is easily changed to suit individual tastes.
In this particular circuit it is best not to increase the resistance (R3 and R4) of the timing circuit for two reasons. First, a potentiometer is more expensive than a capacitor and secondly, an increase in the value of R4 can, in conjunction with the input impedance of the op-amp IC-1, cause a voltage divider which would cause the keyboard tuning to lower as the glide rate control is advanced. Lower glide times can be most easily obtained by increasing the value of timing capacitor C3. Values above 1 mfd. will require that you use an electrolytic capacitor so be sure that these polarized capacitors are installed with the negative load to ground and the positive lead at the conductor which leads to point (H) on the circuit board.