The Tremolo circuit was modified from the opto-coupled or photo-cell tremolo circuit in the blackface amps and moved to a bias modulated circuit. This change provides a more pleasing and warmer sound to the ear.
The Normal and Vibrato channels of the Evertone has volume, treble, bass, reverb, speed, and intensity. The Vibrato channel has an additional middle control. The original blackface deluxe amp did not have a middle control. The middle control is a great addition as it provides more control for the player’s midrange sound.