Transformer Originality

We have always considered the AC30 to be a great amp, if not the most versatile when compared to some other well-known names built during the ’60s… like Fender… arguably the most versatile amplifiers ever built.

The ToneQuest Report advisory board member and super player, James Pennebaker, first alerted us to the full potential of the AC30 when, after two decades of loyally playing vintage Fender amps, he switched to the reissue AC30 TBX as his main stage rig. Suddenly, James’ tone seemed to become his own, whether he was playing through his vintage Gretsch Country Gentleman, Cunetto-era Relic Tele or Strat, or Custom Shop Gibson ES295. Last year during the winter NAMM show in Los Angeles the considerable potential of the AC30 came to light again, thanks to west coast swing king Kid Ramos…. The Kid played two long, incredible sets in a cool little dump in Anaheim called the Doll Hut with vintage Strats and Teles through a vintage AC30 with an equally vintage Fender reverb unit, proving beyond any doubt that you can absolutely rule playing the blues and swing with an AC30 rig. The Kid’s tone was unforgettably smooth and musical in the style of an alto saxophone being expertly blown, and for an electric guitar, that’s a mind-blowing experience you won’t soon forget. So you’ll understand our interest in a mysterious and somewhat troubled AC30 that was traded in at Midtown Music. Sick as this amp first sounded, the Kid’s tone was still calling…. The amp seemed to work fine when it first arrived at Midtown, but it soon developed progressively noisy problems that eventually took it down. That’s when we volunteered to deliver the AC30 to Jeff Bakos and make it the subject of this review.

Jeff was able to diagnose and fix the AC30 in a couple of hours (merely a few bad caps and resistors in the vibrato circuit and tone stack), but the amp’s origins remained a mystery. The cabinet was in excellent, original condition and displayed all the classic marks of vintage British Vox construction, but there was no “Jennings Musical Industries” metal serial number tag on the back panel — only the heads of four brass upholstery nails that had once held a missing plastic ID tag. The gray control panel also lacked the typical Vox “JMI” stenciled logo, yet the amp was clearly built with the correct, hand-wired turret board construction, transformers, and Vox circuit. Our attempts to date the amp by the pot codes were unsuccessful because all of the originals had been replaced with CTS pots dating to the early ’90s, so we contacted Mitch Colby at Korg (Vox and Marshall USA) and sent him images of the amp with a request for help in dating it.

Mitch replied that it appeared to be a “Vox Sound Ltd.” AC30 built in England by Dallas Arbiter, the company famous for the original FuzzFace and Sound City amps made in England. Mitch also added that the Dallas Arbiter AC30s were “very nice” amps, having been built in the early ’70s, immediately following the end of the JMI era. Mystery solved. Contrary to information on the AC30s built at the Dallas Arbiter factory that we found at, the cabinet of our amp is built with solid wood throughout — not particle board. And how does it sound? As good as it gets. The Celestion G12 speakers dating to 1979 had been reconed some time ago with the correct Celestion kit, all of the preamp tubes had been updated with JAN GEs, and while not a Jennings, this amp fully earned the vaunted status of vintage AC30 in every regard — punchy, fat, rich in midrange tones where the guitar really lives, with solid bass response and sweet, soaring top end.

Should you decide to explore the full potential of an AC30, you have a number of very good choices. The original vintage amps built by Jennings in England are expensive, so you need to insure originality of the transformers and internal components. A few replaced capacitors or resistors here and there are of no concern, but massive modifications by an overly zealous bench monkey are unacceptable — keep walking. Prices for amps with non-original transformers should be reduced by 30%-50%. Vintage 2×12 combos with original Celestion G12 speakers in excellent condition range from $2,800.00 for a later gray panel to as much as $3,500.00 for a red (candy) panel amp and $5,000.00-$7,000.00 for the earliest tan AC30s. Although increasingly rare, vintage heads alone can sometimes be found for around $1,600.00 and climbing. The limited edition hand-wired AC30 built several years ago by Vox/Korg features reverb and an excellent master volume feature. Outstanding and pricey, expect to pay at least $2,000.00 for this amp in gently used condition. At that price it’s a steal. The discontinued “Korg” AC30 reissue TBX amps like James Pennebaker’s are very good as is, and they can be made to sound even better by replacing the transformers and a few key, tone-shaping components. Don Butler specializes in optimizing reissue Marshall, Vox and Fender amps using premium components and Mercury Magnetics ToneClone transformers (, 661-259-4544).

Early reports on the Chinese AC30 Custom Classic ($1,600.00 with Celestion Alnico G12 speakers, blendable channels, a true bypass FX loop, spring reverb and master volume) are also very good, and Don tells us that his personal Custom Classic also benefited from the same upgrades he makes on the TBX models.

The AC30 is another great amp for players wishing to acquire a sound that sits clearly apart from typical Fender and Marshall tones. AC30s have a unique, compressed character rich in harmonic content and British chime with a versatile amount of clean headroom. More aggressive solos with heavy sustain and gain will require a boost pedal (especially with weaker single coil pickups), but the results will be stellar if you start with a good amp. And don’t buy into the collector hype about Top Boost models being the only desirable version to pursue. Vintage Jennings AC30s stamped “Bass,” “normal,” or “Treble” are equally desirable — in fact, we prefer them. Older AC30s are often a little tattered and may require a tune up and a stout matched quartet of EL84s, but these old amps will reward you with a thicker, richer tone and an intoxicating effluvia of Bitter and Rothmann’s that is lacking in modern AC30 reissues built on printed circuit boards. But oh, how you do pay for the privilege….

The most significant negative regarding all AC30 amps new and old is their considerable weight, which will quickly remind you why they are equipped with not one, but three handles. If you haven’t personally experienced the magical sound of a good AC30, perhaps it’s time. Heave forth….

© Mercury Magnetics
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