Like the original Wurly electric piano, Wurlybird's controls are extremely simple and straightforward. In this section we'll cover the controls contained on the instrument itself.
Left-Side Controls
Volume- Adjusts overall instrument level. Thank goodness for this informative document, right?
Vibrato Amount- Wurlybird includes a highly accurate emulation of the 140B's optical tremolo, and the Vibrato knob controls the effect depth. As was common in those days, the "vibrato" name is totally incorrect, there's no pitch variation happening; it's strictly a fluctuation in volume (but you can use the chorus pedal if you want something more like the pitch fluctuation of true vibrato).
Vib Rate- The vibrato rate was fixed on original Wurlys, but some instruments out in the wild have been modified to allow adjustable modulation rate. The Vib Rate control can be set from 1 to 15 Hz. The default rate when the New button at the upper left is clicked is 5 Hz, which is about the rate of the original (they varied).
FX- When in the down position, stomp box effects are disabled. Clicking the switch to the up position enables stomp box effects and displays them on Wurlybird's music stand.
The FX switch has no effect on the Vibrato effect and controls on the end cheek.
Right-Side Controls
Velocity Curve- This alters how keyboard velocity affects the loudness and brightness of notes. Lower settings result in a quieter curve, requiring more force to play loudly, whereas higher settings require less force to play loudly. (and bright-er-ly? Note that Cherry Audio only hires the best writers!)
Hum- The output signal of all of the original Wurly electric pianos contained 60 Hz hum to some degree, dependent on model, and the age of its electrical components. Though your first instinct might be to avoid hum wherever possible, it is a part of the tone, so we've included a Hum amount knob.
The interesting thing about the hum is that when the vibrato circuit is used (actually tremolo), the hum level rises and falls with the tremolo amplitude modulation, and this is accurately emulated in Wurlybird.
Tune- Sets the master tuning of Wurlybird down or up one semitone.