If there ever was a mystery Vox amp, it would have to be the 1964 JMI AC-10SRT. Have you ever seen this amp before?
The AC10SRT is mentioned, but not pictured in a September 1964 JMI Vox amplifier flyer and the 1964/65 JMI Vox catalog.
The amp pictured at left is from the North Coast Music collection.
The AC10SRT was an all tube, 10 watt amp head. The tube complement was one ECC83, three ECC82, two EL-84, and one EZ81 rectifier.
The "SRT" designation was an abbreviation for "Super Reverb Twin." Vox used the term "Super" to describe amps that had separate heads and speaker cabs. The term "Twin" indicated that the amp had two speakers.
Aside from Reverb, Tremolo Depth and Tremolo Speed, the only other controls were a Volume and a "Tone" cut control. A single button "egg" foot pedal was included to actuate the tremolo.
The matching speaker enclosure had two Celestion 10" speakers. The speakers in the cabinet shown at left are not original.
Tonally, the AC10SRT is one of my favorite Vox amps. It has a great clean tone with a sparkly top end. It can also be overdriven into a harmoncally rich yet smooth distortion.
The AC10SRT used the infamous Vox crystal phono cartridge based reverb pan. 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 ACOS GR71 or two Sonotone 2T 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. Furthermore, this phono cartridge based reverb pan would easily slip into a howling acoustic feedback if the amp was played too loudly.