The Birth of the Vox AC15

Guitarists have heaped bounteous praise on the Vox AC15 since it first hit the scene more than 60 years ago. It has been credited as the first amplifier consciously designed for the electric guitar, the first amp manufactured specifically for the rock 'n' roll market, or simply the sweetest distortion generator ever conceived—but whatever the plaudits, there's near-universal agreement that this unassuming little combo can do magical things when hit with the signal generated by steel wires vibrating over an electromagnetic pickup.

How unlikely, then, that this raging demon of sweet, succulent tone actually came about out of a collaboration between designer Dick Denney and entrepreneur Tom Jennings, who first became acquainted in the early 1940s while working to supply the munitions that would help Great Britain survive World War II?

The image isn't very rock 'n' roll, certainly, but that's where this pair first stepped onto the divergent, winding paths that would eventually bring them back together. A brave new venture on the outskirts of a then freshly swinging London of the 1950s would ultimately launch them to the top of the industry, supplying gear for The Beatles, The Shadows, The Kinks, and other world-straddling artists of the British Invasion.

Rock Rolls Britain

To fully appreciate the scene onto which the newfangled Vox amps would explode in the late '50s, it helps to take a quick look at the cultural and industrial climates in Britain at the time. Musically, late-'50s Britain was partly distinguished from earlier eras by a reopening of the borders, when restrictive Musician's Union regulations previously imposed on American performers in the UK were loosened in 1957, enabling a major influx of touring artists from the US.

American rock 'n' rollers like Buddy Holly and the Crickets, Jerry Lee Lewis, Eddie Cochran, Gene Vincent & His Blue Caps, and others toured the UK in the years that followed, and they often brought their amplifiers with them, giving British audiences—and guitarists—a better look at the near-mythical North American electronics than most had ever had before.

As such, American music continued to have an impact on the British scene, but that scene had itself grown strong enough to withstand a total stylistic overhaul in the wake of this would-be cultural imperialism. Rather than transforming what was happening in the UK, American music was absorbed into it, and a distinctly homegrown style and sound emerged as a result.

Just as the British music scene of the late '50s was developing into its own thing, so the British amp industry was on the verge of busting out in its own right. Such evolutionary leaps are rarely instigated by one person, and certainly there were many significant actors in play at this time, but we might reasonably view the turning point of guitar-amp design and manufacture in the UK as having hinged on one company's hiring of one man.

For a full decade before engineer Dick Denney came to join former wartime colleague Tom Jennings in 1957, however, the legendary proprietor of Jennings Musical Instruments (JMI) was essentially an innovator in search of an instrument to service.

Tube Organs, Accordions, and Acoustic Guitars

In the postwar United States, the guitar was creeping toward center stage in popular music, but it was definitely still a less-popular instrument in the UK at the time, relegated to thumping along in the rhythm section of larger dance orchestras, or accompanying folk singers in coffee shops and other small venues. Meanwhile, horn sections and pianos had been central to the British bands that had both entertained the troops and maintained morale on the homefront, and the accordion had been extremely popular, too, as an instrument that could provide a lot of sound from a portable package.

After serving in the Royal Mechanical and Electrical Engineers Corps during the first two years of the war, Jennings was dismissed in 1942 with what was then called "shell shock" (what we know today as post-traumatic stress), and went to work at the Vickers munitions factory in Crayford, Kent, southeast of London.

Wartime efforts aside, Tom Jennings was also a keen accordionist, and the instrument was the cornerstone of his venture when he opened his repair shop at 119 Dartford Road, Dartford, Kent, just after the end of the war in 1946. Having begun by repairing accordions and other musical instruments, Jennings quickly segued into selling them, while the British music scene began evolving rapidly around him.

Midway through 1950, Jennings placed his business at the heart of the London musical-instrument community by opening a retail shop at 55 Charing Cross Road, which he soon moved to larger premises up the road at number 100 toward the end of the year.

Soon, JMI was marketing a small PA/general-purpose amplifier called the Univox, which was manufactured for them by Henry Weil & Company (later of Fenton-Weil fame, a company that would also make guitar amps). Far more significant to JMI's growth, however, was the Univox J-5 electronic keyboard that soon followed. This monophonic, tube-powered organ became a minor sensation in Britain in the early '50s—and put Jennings' company firmly on the map in the process.

JMI's own guitar amplifier was still several years out, but the venture got the company deep into electronics manufacturing, and the Univox's success also helped to keep it afloat through the early years. As Jennings and company rolled into the mid-'50s, though, it was clear that the cresting wave of the guitar's newfound popularity was going to keep building, and it made total sense for JMI to jump on and ride it.

While expanding its range of console organs in 1956, the company also introduced the first two guitar amplifiers that it manufactured itself, the Jennings G5/6 and G1/10, designed by engineer Derek Underdown. And while they bore no resemblance to what would come in just a few years, and didn't yet carry the Vox logo, they convinced JMI that this was a sector worth doing right.

Born in Bomb Alley

Guitar manufacturer Thomas Walter Jennings at his Dartford factory, Kent, November 16th, 1964.
Photo by: Les Lee / Stringer, Hulton Archive. Getty Images.

If Tom Jennings was the man who founded and propelled JMI as a business, Richard "Dick" Denney was the engineer whose ears, vision, and design talents gave Vox amps their sound. Born in Erith, Kent in 1921, Denney learned to play the guitar at an early age, while also pursuing a hobby in electronics—specifically, amateur radio, which seduced hobbyists by the thousands in the 1930s.

These parallel interests worked in conjunction to enable Denney, in his youth, to secure overseas broadcasts of American popular music, and to build DIY tube amplifiers through which to express his passion for the Hawaiian steel guitar. Years later, the same skills would lay the foundations of a groundbreaking career.

When ill health prevented Denney from entering military service in 1940, he found work at the Vickers munitions factory in Crayford, Kent, where he would eventually meet fellow music lover—and future boss—Tom Jennings.

Legend has it that in addition to meeting and working together, Jennings and Denney played music together while huddling with other employees in Vickers' air-raid shelters, as German bombers flew the skies of "Bomb Alley." This strip of land ran along the industrial corridor that roughly followed the eastern branch of the River Thames from Dartford, Kent, to London's East End (as reported by Jim Elyea in Vox Amplifiers: The JMI Years, History for Hire 2012).

Jennings and Denney had gone their separate ways after the war, but Denney continued his hobby of designing and constructing guitar amplifiers—one of which was gaining some buzz in guitar circles in the mid-'50s—just as the former's business was seeing a very real need for a competitive product in that field. The early Jennings-branded guitar amps designed by Derek Underdown had helped to get the company into the market, but Jennings wanted something that sounded great, something to lead the pack—and word had it that Denney's creation was something of a phenomenon.

Dick's Guitar Amp

Jennings and company put out the call to bring Denney into the fold in the autumn of 1957. Initially courted to help the company develop a commercial rendition of a guitar amplifier that he had built in small numbers for himself and a few other players, he would eventually become the British amp industry's most influential designer. Although the brand name Vox had appeared on organ amplification units prior to Denney's arrival at JMI, the start of his tenure there truly delineates the launch of this seminal name in British guitar amplification.

Perhaps most significantly, Denney's arrival at JMI marks a major pivot away from the use of basic "general-purpose" amplifiers for guitar. These were amps that had been built largely according to general-applications circuits often provided by tube manufacturers to support their products. Instead, Denney forwarded an effort to design and develop amps that were specifically suited to the needs of guitarists, and to the guitar's particular frequency range and sonic characteristics.

While Dick Denney did borrow from many of the standard applications published by tube makers of the day, he appeared to have a better understanding than any British maker before him of how to apply these circuits toward enhancing the sound of the electric guitar—rather than merely harnessing their power to make the instrument louder. In the course of chasing that higher ideal, he established a voice that is arguably more intrinsically linked to a geographical location—the "British sound"—than any other in the history of popular music.

The Vox AC15 Sings

According to research by both Jim Elyea in Vox Amplifiers: The JMI Years and David Petersen in The Vox Story, the original rendition of the AC15, initially dubbed the AC1/15, was created out of a preamp designed by Denney. For ease of production, it had an output stage adapted from JMI's organ amplifiers, with chassis layout and design elements facilitated by Underdown. Upon hitting the market in January 1958, the AC1/15—soon just AC15—grabbed immediate attention, but it would be another year or more before its glories had fully disseminated into the scene.

1960 Vox AC15 TV Front 1x12 Two Tone
1961 Vox Ac-15 Twin Fawn
1964 Vox AC-15 Twin

As a guitarist himself, Denney often carted the AC15 around London clubs for musicians to try out, while Geoff Harris from JMI's organ division also joined in on the promotional effort, as did star guitar instructor Bert Weedon of Play In A Day fame, who was also one of the first customers of the AC1/15. Although they purportedly sounded extremely good, the earliest renditions of the AC1/15 were quite different from the legendary AC15 circuit as it would be known from just a year or two later.

If they could be compared to anything in existence, these early AC15s somewhat resembled the early-'50s, TV-front Fender Deluxe, with top-rear-mounted control panels, individual tone controls (simple treble roll-off networks) for each of their two channels, and EL84 output tubes rather than Fender's 6V6s. Preamp duties were covered by ECC83s (known as 12AX7s in the US), while a 5Z4 was used for the rectifier. A short-lived Vibravox rendition, the first Vox guitar amp with vibrato, added an ECC82 (12AU7).

It wasn't until the very end of 1959 and through the course of the following year that the classic AC15 circuit as we would come to know it would begin to emerge. At this time, Denney redesigned his preamp around an EF86 pentode tube in Channel II, which had a thicker and more powerful sound, while also changing the rectifier to an EZ81, and briefly adopting an ECF82 for the vibrato and the mellower Channel 1 preamp gain stage. Midway through 1960, the circuit dropped the odd ECF82 (which would remain in use in the smaller AC10), returning to an ECC82 (aka 12AU7) for vibrato modulation.

Add all of this to a pair of EL84 output tubes in cathode bias with no negative feedback, and a relatively large output transformer for an amp of this size at the time, then put a Celestion G12 Alnico speaker or two in the cabinet, and the combination is magical—and in fact nothing short of producing one of the finest-sounding guitar amps ever built.

Laden with harmonic overtones even amid edge-of-breakup settings; tight enough for clean pop ballad, jazz, or country playing at reasonable volume levels; and succulently toothsome and dynamic when driven into overdrive, a good AC15 is simply something every guitarist should experience at least once in their playing career.

The AC15 Moves Out, and Moves On

As the AC15 settled into its best self, the square-ish, 18-watt combo also gained a reputation as the hot item with many notable British guitarists. Cliff Richard's band The Drifters took up the new Vox amps, as did its new members Hank Marvin and Bruce Welch, shortly before changing their name to The Shadows and launching an extremely successful parallel recording and touring career in their own right.

Other artists like The Vipers, Wee Willie Harris, Marty Wilde, and Billy Fury were also full-fledged endorsees by late '59, and almost any guitarist who was anyone found an excuse to visit Jennings's Charing Cross Road shop when work brought them to London.

As its popularity grew in the early years, the AC15 also helped to give birth to British rock 'n' roll proper, which had been badly in need of an amp that could get the job done. When the AC15 first hit the scene, manufacturers were still aiming first and foremost at a politer crowd, the jazz and dance-band musicians who constituted the bulk of working professionals.

These players rarely had cause to turn an amplifier up beyond its available headroom; the burgeoning rock 'n' rollers who eventually did, though, were rewarded with the sonic glories of what might be regarded as the AC15's finest characteristics. These amps were outstanding distortion generators, and they still are, in the hands of the fortunate players and collectors who covet them today.

As rock 'n' roll grew more popular, and therefore needed to grow louder to suit the bigger venues that housed the shows, Denney doubled up the AC15's output capabilities to create the AC30 (which itself evolved in design over the first few years of its existence), and Vox amps would continue to propel even more major stars into the spotlight. Denney himself stayed with JMI until Jennings's own departure from the company in 1967.

By this time, an ill-conceived merger with Thomas Organ in California was badly undermining JMI's business and the veracity of English-made Vox amps in general, by allowing the new partner to manufacture its own inferior Vox-branded amps for the US market while kicking back relatively little of value to Jennings and the parent company back home.

The end of the original and golden age of JMI Vox was on the horizon and approaching fast, but Jennings and Denney had already forged a sonic template that would continue to generate stellar guitar tone for decades to come.

Finding "That Tone" in 2019

Even after moving through several successive owners, Vox still often produced an AC15 in one form or another. After the brand was acquired by Korg in 1992, the company released a very reputable version of the AC15 that became a standard of sorts for many guitarists seeking the classic British sound in an 18-watt package, although its circuit used ECC83 (12AX7) preamp tubes rather than the EF86 pentode that had been responsible for the famed early-'60s renditions of the amp.

In the mid-'00s, however, Korg came the closest in years to recreating the seminal circuit with its AC15H1TV, a hand-wired version employing the essential EF86 tube, all housed in a '50-era TV-front cabinet. A descendant of that combo is still offered today, albeit in the even more iconic circa-'60 fawn "split-front" cab, while the more affordable end of the market is met by the AC15 Custom Head and Combo.

Alongside these official offerings, it's not hard to find excellent replications of the authentic AC15 sound in the guises of several boutique amps. The TopHat Supreme 16 pairs an EF86 channel and a Top Boost–inspired 12AX7 channel in front of a very AC15-like output stage, while 65amps's original blue-line London 18, Matchless' Nighthawk, and Morgan AC20 Deluxe all owe a major debt to this early British classic.

About the author: Dave Hunter is the author of The British Amp Invasion: How Marshall, Hiwatt, Vox and More Changed the Sound of Music—which contains further behind-the-scenes tales of the birth of the British guitar-amp industry—as well as The Guitar Amp Handbook, Amped, and more than a dozen other books on guitars, amps, and related gear.

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