The 5F11 Vibrolux was the companion and essentially identical to the Harvard, but with an added tremolo circuit driven by one side of a dual-triode 12AX7 which replaced the Harvard's single-triode 6AV6/6AT6, and was built into a Deluxe cabinet.
The Fender Vibrolux is a 10 watts amp with Tremolo effect using as preamp a 12AX7 an for the power stage 2 x 6V6GT. Also featured are a rectifier 5Y3GT, a phase inverter ½ 12AX7 (split load) and Tremolo ½ 12AX7 (bias vary). The preamp used half of the phase inverter 12AX7 and half of the tremolo 12AX7. The selenium rectifier is used in the bias circuit.
The amp is fitted with a Jensen P10R.
A speaker and tremolo foot-switch jack are located on the bottom of the chassis.
A perfect working condition amp with a very distinctive sound