Jan 042018
 

Vox wasn’t the first player on the British amp scene, but it was the first brand to make a major mark on the history of rock tone, and the AC15 is where it all started.

Vox wasn’t the first player on the British amp scene, but it was the first brand to make a major mark on the history of rock tone, and the AC15 is where it all started. Back before anyone conceived that a band was likely to need more than about 18 watts to get the job done, the AC15 was the market leader in the nation that was incubating the Beatles, the Rolling Stones, the Yardbirds, and other soon-to-be Vox players, and the sound of this amp is virtually etched into the cochlea of any fan of popular music.

Designed in large part by Dick Denney as the first proper guitar amp for Jennings Musical Instruments’ new Vox brand, the AC15 was launched early in 1958, but evolved considerably through its first couple of years of manufacture, hitting its stride—and its archetypal form—by the time our featured amp was made in 1961. By 1959 the new Vox model had picked up endorsements from major British stars like the Vipers, Wee Willie Harris, Marty Wilde, Bert Weedon, and Billy Fury. Heard of them? Probably not, but the AC15’s use by guitarists Hank Marvin and Bruce Welch of the Shadows—who were not only the backing band to hit maker Cliff Richard, but scored dozens of Top 40 instrumental hits in the UK in their own right—was a significant precursor to the coming British Invasion, which would also make Vox amps must-haves for teenagers all across America.

Vox and the AC15 are synonymous with “the class-A sound,” even if that’s something of a misnomer. Rather than being strictly “class-A amps”—a condition proved up on the test bench by measuring very specific performance characteristics—the sound of the AC15 is, in part, typified by its cathode-biased dual-EL84 output stage with no negative feedback. This platform enhances harmonic overtones for that lively jangle when played clean, and segues easily into rich distortion when overdriven. But many other factors contribute to the legendary AC15 sound.

AC15s of the late ’50s and early to mid ’60s stand out for their use of an EF86 pentode preamp tube in channel two, which adds girth and thickness to the output stage’s sweetness. These amps also had unusually large output transformers for their wattage ratings, which helped to maintain a firmer, punchier tone than that delivered by many amps their size. Add to all that the extremely luscious sounding Celestion G12 alnico speakers that these combos carried, later referred to as the “Vox Blue” and reissued as the Celestion Alnico Blue, and the AC15 cruises in as one of the best-sounding sub-20-watt amps of all time. They record beautifully, and still deliver enough oomph to keep up with most drummers on a club stage—or on any stage when miked up through the P. A.

As it goes with so many of the classics, the AC15 is also one of the most emulated amps of all time, and glimmers of its key features continue to be reflected in myriad boutique designs to this day. Matchless, TopHat, 65amps, Morgan, and many others have been inspired to use renditions of an EF86 channel in their amps, and Vox has released several AC15 reissues over the years. One of the more popular, the English-made AC15TB (and “TBX” with Alnico Blue speaker) of the ’90s and early ’00s wasn’t necessarily the most accurate—with an AC30-style Top Boost tone stage and no EF86 preamp tube at all—but was a great sounding 18-watter nonetheless. This crucial element of original AC15 tone first returned to the fold in 2007 with the release of the Heritage Hand-wired AC15H1TV, which did finally carry the magical pentode preamp tube.

ESSENTIAL INGREDIENTS

> Two EL84 output tubes generating around 18 watts RMS
> Long-tailed-pair phase inverter
> 1 x EF86, 3 x 12AX7, 1x 12AU7 preamp tubes
> EZ81 rectifier tube
> Cathode-follower tone stage with Treble, Bass, and Middle controls
> Single Celestion G12 speaker with alnico magnet
> Open-back combo cab with fawn-colored Rexine covering

Classic Gear: The 1961 Vox AC15 1×12 Combo
Source: Guitar Player