AC4 History

“The Vox AC-4 was a small guitar practice amp that was introduced in 1958 and originally marketed as the AC-2”, according to The vox showroom.

The 1960 AC-4 contained a 8 inch speaker and three valves in the signal path: EF86, 12AX7 and EL84 power tube. A fourth valve is used for rectification (an EZ80). The circuit diagram for the original AC-4 amp can be found the KORG UK site).

The AC-4 is a Single Ended Power Output Stage amplifier, using one EL84 pentode power tube.