The Legend and Legacy of Dumble Guitar Amps
With a background in music and electronics, combined with a somewhat entrepreneurial streak, Howard Alexander Dumble (who later claimed to be known as Alexander) had a future in amplifier design that was almost predetermined. Growing up in Bakersfield, California, Dumble sold homemade transistor radios to his school friends and built a 200-watt sound system for the local junior baseball team.
As an epicenter of progressive rock and electric guitar development, California – particularly Los Angeles and the San Francisco Bay Area – was driven by local bands such as Jefferson Airplane, The Grateful Dead, The Byrds , Little Feat and Santana.
After leaving school, Dumble was introduced to luthier Semie Moseley in Santa Cruz, who was looking for someone to design an amplifier to complement his line of Mosrite guitars. Dumble built 10 or 11 Mosrite amps, but things turned sour, with Dumble returning to build amps for himself, one at a time.
His first “real” amp – often considered a prototype for the Overdrive Special – was called the Explosion. According to legend, Dumble’s inspiration for the Overdrive Special came from seeing Robben Ford playing through a stacked ’60s Fender Bassman head and cab.
Its circuitry was loosely based on ’60s Fender “black panel” designs, with a boosted power stage and clean channel followed by a tone network, followed by a footswitchable overdrive section in which the cascaded clean preamp section.
The concept of cascading gain had already been popularized by Mesa Engineering. But Dumble – who was an accomplished guitarist and bassist – didn’t mind Mesa’s approach and changed the position of the overdrive section, placing it after the tone controls. This resulted in a fatter, rounder overdrive tone that was further tweaked with toggle switches for Bright and Deep functions, as well as a Jazz/Rock switch that shifted the character of the amp to a flatter EQ with less gain.
One by one
Dumble wasn’t interested in mass production; he was happy to build his amps one by one, each individually tailored to the needs of the artist he was working with. As a result, they are all different, with subtle (or not-so-subtle) changes to component values and positioning to bring out the desired characteristics.
The nature of the preamp means there is an inherent trade-off between clean and overdriven sounds, as one drives the other with a shared EQ. So this is an area that Dumble would have varied depending on the client’s needs – we know that some ODS models have clean channels that warp sooner, while others stay clean up to 10.
The circuit has been constantly updated and improved. Following early Fender-influenced designs of the 70s, a different “Skyline” EQ was added in the 80s. This was another modification that added a separate internal “set and forget” EQ for the dash section. overdrive – called the “HRM” (“Hot Rod Marshall” or “Hot Rubber Monkey”, depending on which books you read) – to address the EQ trade-off split.
For the Overdrive Specials, Dumble built everything from the aluminum chassis to the hand-drilled grommet boards, giving him complete control over where components should be placed.
It’s a fundamental part of the Dumble’s unique tone and dynamic character. In more than one interview, Dumble himself has said that it’s not just the schematic, and that parts and layout are equally important, which is why he started coating his preamp boards with epoxy resin as its reputation grew.
Dumble was notoriously protective of his job, and there are many examples of the infamous contracts he made potential clients sign. These documents meant that people were prohibited from opening the chassis, photographing the internal layout or even selling the amplifier without its permission, although it is unlikely that such stipulations were ever tested in court. .
Nonetheless, several examples have been ‘de-gooped’ and component values and layouts recorded for posterity, one of the most well documented being serial number 124.
This writer had the chance to take a look inside an example gooped several years ago, revealing a layout and construction typical of many unique handmade amplifiers, with a mix of components mostly New Old Stock sitting on a hand drilled formica grommet board. It was clear that every visible component and wire had been individually selected and placed with precision.
The ODS was a product of its time – built to last, intended for professional use on large stages and calibrated to enter the sonic tune at high volume. Dumble has also built its own speakers, mostly using semi-enclosed designs with carefully tuned oval ports to enhance the mids and upper-mids, paired with high-sensitivity speakers, such as the JBL D140s or Dumble’s favorite , the Electro-Voice EVM12.
Dumbles didn’t have a proper effects loop; there was a pair of insert jacks between the preamp and power amp sections intended for use with a self-contained buffered effects loop circuit with variable send and return level controls, called the Dumbletor. Some later amps had the Dumbleator circuit built in. Most Overdrive Specials did not include reverb, but a few were made and called Overdrive Reverbs.
Dumble used the 6L6 power valve for most of their amps, although later there was a series of EL34 powered ODSs, including serial number 183, which is another frequently copied design.
Other famous Dumblers include Larry Carlton’s 6V6-powered model, one of two owned by the LA session legend and commissioned for use in smaller clubs – and, of course, the famous serial number 102 by Robben Ford, perhaps the most coveted of all the Dumbles.
Slightly less well known perhaps, serial number 75 belonged to session guitarist Steve Farris of Mr Mister fame and is responsible for some of the best recorded examples of higher gain Dumble sounds, as heard on the 1985 album Welcome To The Real World.
Of course, Dumble didn’t just create Overdrive Specials. Besides previous models including the Dumbleland and Winterland, his other best-known model is the Steel String Singer, a high-headroom, 100-watt single-channel head used by Stevie Ray Vaughan, John Mayer, Eric Johnson, Jackson Browne, and David Lindley. . , to name a few.
To our knowledge, SSS serial number 1 was commissioned and still owned by pioneering experimenter Henry Kaiser, who owns several other Dumblers. SSS number 2 was commissioned by Jackson Browne and we believe he currently lives with John Mayer, who also owns several other Dumblers.
In addition to creating his own designs from scratch, Dumble has also modified several Fender and Marshall amps for various artists, including Eric Clapton and Kenny Wayne Shepherd. There were custom tweed Deluxes which he renamed “Tweedle Dees” and, as far as we know, a unique model based on a tweed bassist called “Manzamp”, which was commissioned and is presumably still owned by Bonnie Raitt .
With less than 300 real Dumble amps in circulation, supply will always be far outstripped by demand, so it’s no surprise that many amp manufacturers have tapped into this market. Some are similar to Dumble: small one- or two-person operations building high-quality replicas, often of specific serial-numbered ODS or SSS amps.
Bludotone’s Brandon Montgomery is one such builder whose products have found their way into the platforms of users like Carlos Santana, Jon Herington and Larry Carlton. Other well-known names in this category include Amplified Nation, Louis Electric and Jelle Welagen.
Meanwhile, amp builders such as Fuchs Audio Technology, Two-Rock and 633 Amplification have taken inspiration from the Dumble and extended its capabilities, producing new designs that are perhaps more suited to today’s demands. .
For those of us on a budget looking for that Dumble tone, there are plenty of pedals out there that can get you in the ballpark. Standout mentions would include the Ethos Overdrive, Van Weelden’s Royal Overdrive and Wampler’s Euphoria, while there are various kits available on the booming DIY market, the best known being the Ceriatone from Malaysia.
With Dumble’s departure, the opportunities to see and hear the real thing may become even more limited as they are likely to spend more time in bank vaults than on stages. Fortunately, there are plenty of alternatives at all price points. While Alexander Dumble may have taken a lot of irreplaceable knowledge about guitar amps with him, he left behind a sonic legacy that will likely last forever.
- Those looking to indulge more in the work of the master amp builder will do well to seek out the rare and definitive Jesse Schwarz. A stupid bookpublished in 2009.