Yesterday, we discussed the tremolo effect found on the 1959 Fender Vibrasonic. Today, we'll look at the change Fender made to this circuit sometime during 1961. Basically, an extra 12AX7 was added - so, there are now six rather than five of these small tubes. Actually, only half of the additional tube is used in this upgraded circuit, and it functions as a split-load inverter. So, the two sides of the twin triode previously used as both an oscillator and an inverter now function as a direct-coupled cathode follower.