In 1960, Vox replaced the AC-30/4 with the AC-30/6. The fawn vinyl covered 1962 AC30/6 "Bass" model amp shown at left belongs to my good friend, Brian Mahacek of Northfield MN.
History: The AC30/6 chassis was produced in four different versions, as documented by Vox service schematics for the amp. JMI Vox schematic OS-056 depicted the "Treble" version of this amp. Schematic OS-057 was the "Bass" version, and OS-065 was the "Normal" version. The final version was the "Top Boost " version, which added separate bass and treble controls to the "Brilliant" channel. This model was depicted by a combination of JMI Vox schematics OS-065 and OS-010.
Early "Top Boost" models had these controls mounted to a recessed plate in the upper back of the cabinet. Later versions moved the treble and bass controls to the main control panel.
The electronic differences between the AC-30 Treble, Bass and Normal amps are extremely minor. The values of only two tone voicing capacitors, C3 and C10, are affected.
AC-30/6 Bass Amp - With an open back and two 12" 15 watt speakers, an AC-30 leaves a lot to be desired in today's world as a bass amp. Vox recognized this as well. By 1963, Vox was developing several amps built particularly for bass, the T.60 and the Foundation Bass.
However, the AC-30/6 "Bass" amp works great for guitar. It had three channels, Normal, Brilliant, and Vib/Trem. A single tone control rolled off the treble response of the amp. A single button "JMI" foot switch engaged the Vib/Trem effect.
The fawn Vox AC-30 Bass amplifier pictured on this web page has the early "thin edge" cabinet. While the top and speaker baffle of the amp are 3/4" baltic birch plywood, the sides and bottom are 1/2" baltic birch. The back panels are 3/8" thick. The back edges of the cabinet were not rounded (see photo, lower left).
The amp was covered in fawn (tan) vinyl that was no thicker or more durable than wallpaper. It had three leather handles, three brass vents and no corner protectors.
The amp is sitting in a recreation of the early Vox "tray" style rigid stand.
A small "BASS" model flag was affixed to the lower right corner of the grill.
Two 12" 15 watt Celestion/Vox Alnico Blue speakers were installed in AC-30s from this period. The wire lugs for these speakers were mounted in holes drilled through the frame. Later Celestion Alnicos would have the connecting lugs mounted to a cardboard tag strip riveted to the frame.