Eddie - no, Mac is correct that tonewheel organs are additive synthesis in action.

Subtractive synthesis works by filtering the waveforms that are generated by the oscillators.

Additive synthesis works by summing the wavforms that exist. The drawbars only modify the overall level of individual tones.

Subtractive synthesis starts with a complex waveform - in the old days, either a sine, squarewave, sawtooth, triangle wave or noise circuit. Then you filter out content in a frequency selective manner; effectively subtracting from an initial more complex waveform.


-Scott