This was the third version of the Vox AC-50 head. It
combined the single channel, four input version of the AC-50 Mk I chassis with a small box, thick edge" cabinet. It was produced in mid 1964.
The original version of the AC-50 was a single channel amplifier. It had a copper control panel with dual 1/4" instrument inputs, volume, treble and bass controls, indicator lamp, power switch, fuse and a plug style voltage selector. The tube complement included a GZ34 tube rectfier, two fixed biased EL34 power tubes, two ECC83 (12AX7) and one ECC82 (12AU7) preamp tubes.
The second version of the single channel Mk I chassis was used with the AC50 Mk I "small box, thick edge" amplifier. It was identical to the original AC-50 chassis except it had four 1/4" instrument inputs rather than two. These were arranged into the shape of a diamond on the left side of the control panel.
The thickness of the cabinet sides increased from 3/8" on the original AC-50 Mk I amp to 3/4" on the "small box, thick edge." The new cabinet featured eight one pin corners, a Vox handle, a small Vox logo and pancake feet.