JMI Vox AC-2, AC-6 and AC-4 Amplifier


1959 "TV" Front AC-2 - 8" Speaker Model



AC-4 - 1962
The white box in the amp is a owner installed 120 to 240 volt step up transformer


AC-4 Control Panel - 1962 model



AC-4 Amp - 1964 model


AC-4 Control Panel - 1964 model

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The Vox AC-4 was a guitar a small practice amp that was introduced in 1958 and originally marketed as the AC-2.

While the AC-4 was introduced in 1962, "The Vox Story" by Dick Denney and David Petersen reports that the "TV front" AC-2 was first offered in 1958. In his book, Denney recalls that the earliest design for the AC-2 had a 6.5" speaker. Denney indicated that the speaker size was increased from 6.5" to 8" due to poor sales of the AC-2 with the smaller speaker.

In 1960, without any changes to circuitry or power output, Vox renamed the amp the AC-6 to suggest the peak RMS power of the amp.

In 1961, the TV front cabinet styling of the AC-6 was replaced with what what now be known as "traditional Vox styling" and the amp name went back to AC-2.

The AC-2 electronic circuitry is documented on Jennings Musical Instruments schematic OS/009, dated 9/12/61. The amp is included as the AC-6 in a 1960 JMI Vox double sided sales flyer and as the AC-2 on page eight of a 1961 JMI Vox Amplifier catalog.

The AC-2 (and in 1960, the AC-6) would accompany the AC-10, AC-15 and the AC-30 to form a complete Vox amplifier range.

Cosmetically, the 1961 AC-2 had fawn vinyl, brown diamond grill cloth and brass vents, as seen in the photo at upper left. Electronically, the AC-2 had four tubes: one EZ80 rectifier, one EL84 power tube, one ECC81 (aka 12AX7) and one EF86. The amp had two inputs and three rotary controls: volume, tremolo speed, and a tone control that included an on/off switch. A control panel voltage selector plug also housed the mains fuse. A single button tremolo foot switch was included with the amp.

The 3 ohm 8" speaker in the AC-2 and AC-4 was manufactured by Elac in Germany.

In 1962, the AC-2 was renamed the AC-4. The new name might suggest an increase in output power, but this was not the case. In reality, the AC-4 had the same circuits and power output as the AC-2. The original power output of the AC-2 was about 3.5 watts RMS (6 watts peak), so JMI chose to rename the amp to AC-4 to reflect the actual power output. After a small handful of very minor electronic revisions, a new service schematic, JMI OS/051, dated 9/25/64, was drawn for the AC-4.

The amp shown at lower left is shows the AC-4 in "mid 60's" cosmetics. It was covered in black "basket weave" vinyl and had brown Vox grill, a hinged handle, and two metal cooling vents.




Features - 1962 AC-4
Output Power 3.5 watts RMS, 6 watts peak
Tube Compliment ECC83, EF86, EZ80, EL84
Channel One Two inputs,
one volume,
one tone,
one tremolo
Speaker(s) One Elac 8" speaker
Size 16.5" H x 16" W x 7.5" D
Accessories Cover, Foot pedal.





North Coast Music offers many repair parts amd accessories for the Vox AC-4. Some are shown below.
Exact Replacement JMI "VOX Amplifier" Serial Plates
Exact Replacement Brass Vents for the AC15
VOX Logos (p/n NCM-025 or NCM-026)
Vox Egg Foot Switch - cast aluminum case
Current reissue brown diamond Vox grill cloth
White and gold cabinet piping for the AC30/6




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The VOX Showroom!


Photos and editorial content courtesy Gary Hahlbeck, North Coast Music


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URL: http://www.voxshowroom.com/uk/amp/ac4.html