Pro-One Modifications Page

Title link takes you to a page on some nice mods for the SCI Pro-One. There are more shots, details and some pretty impressive samples. Make sure to check them out.



Modification Summary:

• Replaced the white noise source with a new circuit that provides white, pink, red, and infra-red noise. A rotary switch selects the noise colour.


• The new noise source can act as a modulation source in addition to its role as an audio signal. A pot sets the noise level fed to the buses. A rotary switch selects whether the noise signal feeds the Direct or Wheel modulation buses.


• Added a Sample & Hold circuit. The new noise source is the signal input to the Sample & Hold. The LFO square wave is the clock. The Sample & Hold output can be used as a modulation source.


• The pulse width of the LFO signal can be adjusted from 0% to 100% with a pot.


• The LFO signal can be inverted. A rotary switch selects LFO non-inverted, LFO inverted, or Sample & Hold as a modulation source.


• Added a triangle wave for oscillator A. A pot allows manually mixing between the triangle and sawtooth waves.


• Filter resonance can now be used as a modulation destination. A rotary switch selects from either the Direct or Wheel modulation buses as a source.


• The filter envelope can be inverted. Inverted and non-inverted envelopes can be applied to filter frequency and the Direct or Wheel modulation buses via two slide switches.


• The filter frequency signal from the Kenton MIDI interface can be assigned to the Direct modulation bus. A pot sets the signal level fed to the bus.

The circuitry fits on one tiny Rat Shack board. The pots, rotary switches, and slide switches are mounted on the plastic casing between the main panel and the keyboard.