The Expert window shows model parameters that provide precise control over your organ sound. These include not only basic level and tonal balance controls, but a number of parameters that emulate the sonic characteristics—and technical “flaws” or limitations—of the original Hammond B3. You can even emulate the quirks of the B3 by aging the virtual components. See Vintage B3 Pitch controls, Vintage B3 Sustain controls, Vintage B3 Condition controls, and Vintage B3 Organ Model controls.
See Choose a Vintage B3 MIDI control mode for information on the Hardware Controller parameter shown in the Misc section of the Expert window.
For more information about the technical aspects of the Hammond B3 and the concepts behind tonewheel sound generation, see A brief Hammond history and Tonewheel sound generation.