A view of a JMI AC-30 hand wired tag strip
Vox "Crystal Phono Cartridge" Reverb Pan
The original cartridge shown above is an ACOS Stereo GR71
Later Vox crystal phono cartridge reverb pans used a Sonotone 2T stereo cartridge
Neither is commonly available anymore
UK JMI Vox (upper) and US Thomas Vox "Super Reverb Twin" badges
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In the 1993 book, "The Vox Story," written by David Petersen and Dick Denney, the authors picture and mention the slope sided AC30 on page 39. They call it "the ultimate in AC-30 development." Electronically and cosmetically, I could not agree more with this assessment. As you will discover as you read onward, Thomas Organ in America must have felt the same way.
The amp shown at left is the AC-30SRT version, from the North Coast Music collection. It features the AC-30/6 chassis with the Top Boost controls in the upper main control panel. It also included the infamous Vox "crystal phono cartridge reverb" system.
Two reverb controls were mounted in the rear panel in the same chassis location formerly used for an "add-on" Top Boost unit. The upper control had a chicken head knob mounted to a three position rotary switch. This switch assigned the reverb circuit to either the Brilliant or Normal channels. The lower control had a small round knob that adjusted the "dwell" or loudness of the reverb.
Tom Jennings, the president of Vox, resented having to pay the $1 per amp licensing fee charged by Hammond Accutronics fee for the use of their patented reverb pan. Instead, he designed his own reverb pan, just barely skirting the patents on the Accutronics unit.
The reverb pan designed by JMI used two 1 volt output crystal phono cartridges for drive and receive transducers. A single delay spring was connected to the needle saddles of each cartridge.
About all one could say about the JMI reverb pan is it worked to a degree, but the tone and depth of the reverb was certainly lacking when compared to Fender amps of this era.
The AC-30SRT speaker cabinet included a chrome swivel trolley. The amp head had a badge in the lower right hand corner that said "Super Twin Reverb."
Let's jump over to American Vox for a second. Thomas Organ hired a brilliant engineer and former Fender employee, Sava Jacobson, to develop a transistorized version of the AC-30 for the US market. I suspect that Sava took a long look at the AC30SRT when he was working on his design. Comparing the AC30SRT with the US equivalent Buckingham amp, one can notice many obvious similarities. Each amp had three channels. Each had reverb, and each had a reverb selector switch that toggled between the Normal and Brilliant channels on the rear control panel. Each head had a trapeziodal head cabinet. A "Super Twin Reverb" badge was in the lower right hand corner of each amp. Both amps had a nearly identical swivel trolley and 2x12 speaker enclosure. Both amps used locking XLR jacks for speaker connection.
North Coast Music offers many repair parts amd accessories for the Vox AC30SRT. Some are shown below.
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