In 1956, Jennings was shown a prototype guitar amplifier made by Dick Denney, a big band guitarist and workmate from World War II.

Features simplified from the AC15 included a tremolo effect (mislabeled as "vibrato"), a single, shared Tone control, and smaller output transformer.

The AC30, fitted with alnico magnet-equipped Celestion "blue" loudspeakers and later Vox's special "Top Boost" circuitry, and like the AC15 using valves (known in the US as vacuum tubes), helped to produce the sound of the British Invasion, being used by The Beatles, The Rolling Stones, The Kinks and the Yardbirds, among others.

The Vox AC30 has been used by many other artists including Mark Knopfler, Hank Marvin who was instrumental in getting the AC30 made, Ritchie Blackmore, John Scofield, Snowy White, Will Sergeant, Tom Petty, The Echoes, Mike Campbell, Peter Buck, Justin Hayward, Tom DeLonge, Mike Nesmith, Peter Tork, Noel Gallagher, Matthew Bellamy, Omar Rodriguez-Lopez, Dustin Kensrue, Tame Impala, Jimmy Page, Tony Iommi[2] and many others.Once The Beatles became tied to Vox amplifiers (a deal was struck early in their recording career whereby they would be provided Vox equipment for exclusive stage use), the quest for more power began.

John Lennon's first Vox was a fawn-coloured twin-speaker AC15, while George Harrison's was a fawn AC30 with a top boost unit installed in the rear panel.

Joe Benaron, CEO of Warwick Electronics Inc. / Thomas Organ Company, the United States distributor of Vox, along with Bernard Stockly (London), importer of Challenge pianos to the United States, arranged for the boys to have full use of the tall Super AC 100 Vox amps (4×12" speakers).

The solid-state version of this amp (known in the US as the "Super Beatle") was produced to cash in on the Beatles-Vox affiliation, but was not nearly as successful as the valve AC30 and AC15 models.

A modern popular rock artist known for use of the Super Beatle is Tom Petty and the Heartbreakers, although in the April 2008 issue of Premier Guitar, lead guitarist Mike Campbell revealed that the Super Beatle backline was, on their thirtieth anniversary tour at least, primarily used only as a stage prop, though Petty used his "on a couple of songs."

Phil "Fang" Volk of Paul Revere & the Raiders played a Phantom IV bass (which was eventually retrofitted with a Fender neck).

It was followed a year later by the teardrop-shaped Mark VI, the prototype of which had only two pick-ups (rather than three) and was made specifically for Brian Jones of The Rolling Stones, again using a Bigsby-like "Hank Marvin" bridge.

The Stereo Phantom XII had split pick-ups resembling the Fender Precision bass, each half of which could be sent to a separate amplifier using an onboard mix control.

Notable characteristics include a 3D contoured ergonomic design which not only had an arch top, but also bent back from the neck toward the base of the guitar hugging the player's body.

In May 2013, a Vox guitar used by George Harrison and John Lennon on the Magical Mystery Tour album sold at a New York auction for 408,000 USD.

[6] John Lennon played one onstage with The Beatles during "I'm Down", including at their 1965 concert at Shea Stadium, and the instrument was used by British Invasion musicians such as the Dave Clark Five's Mike Smith and the Animals' Alan Price.

[14][15] Jennings formed a deal with the Thomas Organ Company in 1966 to manufacture Continentals in the US, with production moving to Italy the following year.

The V251 is somewhat awkward to play as the neck is wider at the nut end than at the body, and a player's natural tendency to bend a string results in it slipping off the divided fret.

Ian Curtis of Joy Division is sometimes believed to have used a GuitarOrgan, but he actually owned two white Phantom VI special with onboard effects.

[20] In 1964, Tom Jennings developed a relationship with Sepulveda, California-based Thomas Organ Company, which began importing English Vox product lines to the United States.

A shift in focus to transistors came with Jennings' decision to sell controlling interest in JMI to the Royston Group, a British holding company, and move some manufacturing to Erith, Kent.

[21] With assistance from Dick Denney, Thomas Organ began to produce a line of mostly solid-state amplifiers in the United States that carried the Vox brand and cosmetic stylings.

First marketed in 1965, these amps effectively paralleled JMI's own transistor-based amplifiers, but differed from British and Italian made Vox in sound and reliability.

In 2010, Vox released a Hand-Wired version of the AC30 and AC15 with turret board construction, valve rectification and a choice of Celestion Greenback or Alnico Blue speakers.

However, Vox did not retain the pentode/triode output section modes from the "G1" version that allowed for full or half power operation as well as a broader tonal palette.

Gone is the bright chrome look of the "G1" models as both heads received new cosmetics in the form of a black mirror finish on the tube cage and a new suitcase-type handle.

For the Lil' Night Train NT2H-GD-SET, Vox supplied the NT2H head with a matte gold coloured tube cage and black control knobs, and then covered its V110NT cab with a retro-traditional "Brown Diamond" grille cloth and basket weave covering (since there was no "G2" version of the Lil Night Train, this limited edition NT2H seems to mark the end of the line for this model as Vox makes no further reference to it).

Utilizing Korg's REMS modelling software, the blue-colored Valvetronix amps were driven via the "Valve Reactor" low-power tube preamp stage and a solid-state power amp, emulating 11 classic amplifier sounds with a variety of built-in effects[24] (Notably, Korg did not specifically cite in the product manual which non-Vox amplifiers were modelled.

): The Valvetronix XL series (2007-2009) built on the concept, focused on high gain sounds designed to span the entire range of heavy rock music.

With four variations, the Valvetronix XL renamed its control labels with rock-inspired descriptors: The entire line was refreshed in 2008 with the chrome-tinged Valvetronix VT series, including three programmable memory banks and 22 total amplifier models (in order from green to red mode): Korg/Vox evolved the Valvetronix line from 2010 to 2019, pushed the emulation capacity to 33 different models in the VT+ Series, added a premium VTX 150 variant with professional-grade features, and revised the modeling engine called Virtual Element Technology (VET) engineered to more accurately represent classic sounds.

[25] The MV50 series of compact, hybrid amplifier heads released in 2015 were first to feature the Nutube 6P1, a long-life, dual-triode vacuum tube developed by Korg and Noritake Itron Corp.[26] Each variant in the MV50 series emulated an individual style of classic amplifier, including Clean, AC, Rock, Boutique, and High Gain, with basic controls for Gain, Tone, and Volume.

Two of the Cooltron pedals, the Big Ben Overdrive and the Bulldog Distortion, won the Guitar World magazine Platinum Award.