Vox is a musical equipment manufacturer which is most famous for making the Vox AC30 guitar amplifier, the Vox Continental electric organ, and a series of innovative but commercially unsuccessful electric guitars and bass guitars. Founded in Dartford, Kent, England, Vox has been owned by the Japanese electronics firm Korg since 1992.
The Vox AC30 was originally introduced in 1959 at Hank Marvin's request as the "big brother" of the fifteen watt (15 W) AC15 model, Vox's original flagship amplifier, because the AC15 was not loud enough with the screaming fans at Cliff Richard's concerts. The AC15 was powered by a pair of EL84 tubes, an EF86-driven "Normal" channel, an ECC83-driven "Vib-Trem" channel, and rectified by an EZ81. The original first-generation AC30 used a GZ34 tube rectifier, three ECC83s (12AX7) for the Normal channel and the tremolo/vibrato oscillator/modulator circuits, one ECC81 (12AT7) phase inverter, and EL34 tubes in the power amplifier circuit.
This first generation of AC30s were housed in "TV-front" cabinets, much like the early to mid-50s tweed Fender amps, and had a single 12-inch Goodmans 60-watt speaker, as opposed to the later, conventional twin 12-inch speaker configuration. These early amps sported a thin white covering ("Rexine") with a small printed diamond pattern and larger diamond pattern grill cloth. However, the EL34-powered AC30 was short lived, and a new AC30 version appeared in late 1959. This second generation AC30/4 had two channels with two inputs, hence the "4" in the model name, and a single tone control, and was powered by a quartet of EL84 (6BQ5) power tubes, making it truly a doubling of the AC15 power amp circuit. The AC30/4 also carried over the AC15's preamplifier circuit, which included the EF86 pentode in its "Normal" channel. Vox initially offered a 1×12" version but subsequently introduced the 2×12" AC30 Twin, which solved the volume problem at larger venues. The first AC30 Twins used two Goodmans Audiom 60 15-Watt Speakers, followed by Celestion G12 alnico speakers.
By 1960, Vox had forsaken the more conservative TV-front look for the now legendary cabinet design that has remained largely unchanged since 1960. The new cabinets featured a different covering known as fawn Rexine, which was a sort of beige leathercloth with a subtle printed grain. The front baffle was now divided by a thin gold-toned strip with the upper valence covered in fawn Rexine, and the lower grille covered in brown diamond cloth. Ventilation was provided by three small brass vents on the top of the cabinet, and the TV-front's single suitcase type handle was replaced with three leather straps.
Since the higher output AC30/4 shared its preamplifier design with the lower powered AC15, Vox discovered the high-gain EF86 tube was susceptible to microphonics, or even failure, when exposed to the increased vibration present in this uprated amp. Vox soon tired of the problem so to cure AC30/4 reliability issues caused by the troublesome EF86 preamp tube, in late 1960 Vox redesigned the preamp circuit, replaced the EF86 with an ECC83 (12AX7), and released this new design as the AC30/6. The AC30/6 was now an amp with three channels, each channel having two inputs.
About this time, the "Top Boost" (or "Brilliance") feature became available as Vox's optional addition of a rear panel-mounted circuit that introduced an extra gain stage and tone controls for bass and treble (as opposed to the single "tone" control of earlier AC30s). The unit became so popular that its features were soon incorporated in newer AC30/6 models, and the controls moved from the rear panel to the control panel. Vox AC30/6 amplifiers from around 1963 had already implemented the top boost, and therefore had three tone controls. People began to refer to these amplifiers as AC30TBs. Later on, Vox also offered additional versions of the AC30 unit. In addition to the "Normal" version without the Top Boost, and the Top Boost version (which was a Normal version with the "Brilliance" unit added), Vox, with slight circuit modifications, created two more versions that were "voiced" in Brilliant (Treble), and Bass styles. Of all the different models that came around many consider the AC30 "Super Twin" to be the ultimate AC30, with a "trapezoid" shaped head and separate speaker mounted on a trolley (Vox Story, Peterson & Denny 1993) and Vox showroom web site.
In the late '60s Jennings drifted into financial problems and the company experienced various owner changes. Quality control was also inconsistent.
During the Vox brand's early '70s "Dallas Arbiter" period, the tube rectifiers of AC30s were replaced by silicon rectifiers, which became standard on later AC30TB models. In the late 1970s Vox also introduced a solid-state AC30 (AC30SS), which is the AC30 model that was used by Status Quo. A tube AC30TB with spring reverb feature was reintroduced in 1978.
In spite of at least one AC30 production run titled "Limited Edition" of 100 units with starting serial number 0100 (1991) (no reverb), production of the AC30 has practically never ceased: Newer AC30s are reissues of the various top boost AC30/6 (AC30TB) models. AC30s made between 1989 and 1993 also had spring reverb as a standard feature.The Rose Morris company, who owned the Vox name through the 1980s, sold Vox to Korg in the early 1990s, who then manufactured a reissue of the early '60s AC30 Top Boost, correcting previous inconsistencies ranging from the correct style grille cloth to the GZ34 rectifier tube. These AC30 amps were mostly offered in the traditional black Tolex/brown diamond grille configuration, but were also available in limited numbers with purple, red, or tan tolex. These amplifiers, like all AC30s to this point, were manufactured in Great Britain. These were available with a choice of Celestion "Blue" or Greenback speakers. In the mid 1980s, a company in Marlborough, MA, called Primo, imported and began re-distributing the AC30s in the U.S.