“Boogie Mod” Dual Showman

What do you do when the humble blackface Bandmaster you acquired sight-unseen turns out to harbor one of rock’s hottest lead circuits? Celebrate! And then go tracing its connection to California’s seminal high-gain guitar amplifier.

Randall Smith’s legendary Boogie lead circuit started as a prank played on an unsuspecting client before he applied it as a modification to smaller Fender amps – mostly Princeton combos. The origins of the circuit were born out of Prune Music in Mill Valley, just north of San Francisco. Co-founded by Smith, who was also its resident amp-repair guy in the late ’60s and early ’70s, Prune was the go-to shop for guitarists in the Bay Area rock scene, and a frequent hang for the likes of Mike Bloomfield, Carlos Santana, Neil Young, Archie Williams, Barry Melton, and others.

Even after his Mesa/Boogie venture took off and Smith had moved into his “doghouse” workshop in Lagunitas, his successor in the amp department at Prune Music continued with the mods that made the shop famous, some of which live on within unsuspecting Fender chassis.

Such was the discovery made by Seattle-based VG reader Ivan Molton, who had been seeking a vintage Fender Dual Showman out of his love of a certain type of California-born music when he slammed headlong into this high-gain throwback.

“I’d always wanted a blackface Fender Showman after reading that they were created by Leo Fender when Dick Dale complained that he couldn’t get enough volume to satisfy his screaming fans at the mid-sized venues of the time,” Molton tells us. “These amps were a surf-rock staple and used by some of my favorite bands, like The Mermen. I learned that Fender made two versions in the blackface era – a Showman and a Dual Showman. The only difference was the output transformer, with one at eight ohms designed to push a single 15″ speaker, and the Dual at four ohms designed to push two 15″ speakers.”

A prolonged search eventually turned up a promising head online, and with some tech chops under his belt, the listing’s “not working” disclaimer didn’t put Molton off.

“The seller said he found it in a storage locker and knew almost nothing about it. Of course, I noticed modifications in the photos and thought I’d just have to gut them. But hey, it was cheap!

“When it arrived, I was surprised to see that the mods included an additional 12AX7 and complete elimination of the Vibrato circuit. I was also surprised by the quality of the modifications, which were done with great attention to detail and a very skilled hand. It came with a rare matched quad of Mesa STR 415 power tubes, but one was shot. I installed a new fuse and a new 6L6, then hooked up the Variac and brought it slowly to life… It worked perfectly!”

Molton set about the routine maintenance and replacement of worn-out components that an old amp inevitably requires, while planning to remove the modifications. Then he noticed a faded silver sticker on the back panel: “Prune Music, 10 Locust Ave, Mill Valley, CA.” Aware of Prune’s connection to Randall Smith, he probed the mods further, only to find that the date codes on several components pointed to the late ’70s, several years after Smith had departed to start Mesa Engineering.

Internet sleuthing led Molton to Larry Cragg, an early employee of Prune Music and, later, guitar tech for Neil Young. Cragg confirmed that Smith had moved on from Prune by the time of these mods, but guessed the work might have been done by his successor, Sal Trentino, a Brooklyn native who had headed west to the fertile Bay Area music scene in 1970. In addition to taking over repairs at Prune after Smith’s departure in ’74, Trentino joined Cragg on Young’s team as an amp tech. For some, he’s best-known as the inventor of the “Whizzer,” the electro-mechanical device that automatically changed the control settings on Young’s tweed Deluxe when he performed live, and later built amps for Pearl Jam and others.

“I then reached out to Mike Bendinelli at Mesa Boogie, who also worked at Prune,” says Molton. “At Mesa, he’s described as the ‘Museum Curator,’ so I thought he might be able to help with the mystery. Mike confirmed that these were indeed Sal Trentino’s modifications and were very similar to a Deluxe Reverb he once owned. Essentially, the mods make the Vibrato channel like a Mark I Boogie, with knobs for Gain, Vol 2, and Master.

“The former Bright switch is effectively a gain boost in that it lifts the ground on the low end of the Middle pot and leaves a 100k resistor to ground, which is like turning all the tone pots to 13. Unfortunately, Sal passed away in 2009, so we can’t get his perspective.”

Having gone in search of a vintage Dual Showman to emulate the surf-rock sound of the ’60s, Molton turned up something very different indeed. But as you might suspect, he’s pleased with the results.

“The amp plays beautifully. It has the usual Fender sparkle on the Normal channel, with tons of chiming high-end and very little sag. I also love the sound of the Normal channel for bass. The Vibrato (high-gain) channel is really flexible and depending on the relative settings of the Bright switch, Gain, Vol 2, and Master, can produce anything from a smooth blues overdrive to a squarish fuzz, going all the way to the kind of endlessly sustaining high-gain tone you’d hear in stoner rock or doom metal. I love the versatility and all the sweet spots you can find in this channel. For me, it’s like having a Bassman and a Mesa Boogie Mark I in the same head.”

All that, and it’s a fascinating piece of Bay Area guitar history wrapped up in a vintage Fender head that reminds us of the true origins of the high-gain revolution – the mod shop.

---

This article originally appeared in VG’s March 2025 issue. All copyrights are by the author and Vintage Guitar magazine. Unauthorized replication or use is strictly prohibited.