Dumble Amplifiers
In 2012, Vintage Guitar magazine said the Dumble Overdrive Special is the most valuable in the product line, with used amplifiers fetching between $70,000 and $150,000.
[9] Before he was 21, Mosrite, a guitar manufacturer in Santa Cruz, hired Dumble to build a special line of amplifiers for The Ventures.
Dumble, however, was not interested in selling amplifiers in greater numbers, but focused solely on getting the best possible sound.
Dumble became known as a tube electronics master, and his high end clientele gained him a reputation as a reclusive amplifier tech to the stars.
Carlos Santana, for instance, had only heard of Dumble in reference to Stevie Ray Vaughan in the late 90s.
[10] Beginning in the 1980s, Dumble covered the preamp circuitry of his amps with a thick layer of usually opaque epoxy, presumably protecting his circuit's exact design from prying eyes.
Known famous players owning either an Ultraphonix or Rockphonix Amp are Eric Clapton, Robben Ford, Peter Frampton, Kenny Wayne Shepherd, Lenny Kravitz, Chris Cobb, and Don Felder.
On May 13, 2021, guitarist Don Felder published an Instagram story with a photo of Dumble servicing his ‘65 Fender Deluxe Reverb.
Robben Ford shared a video statement on his social media, and said that Dumble had been in poor health for a long time.
After his passing, another recent picture of Dumble emerged of him playing the guitar, allegedly through the very first amplifier he ever built.
Fender CEO Larry Thomas and CPO Richard McDonald interacted with Dumble for several months in 2013 to create a joint Fender-Dumble product.
In a letter of authenticity for one of the amps, McDonald said, "[Dumble] lived 'off the grid' in the truest sense and so it was virtually impossible to create a sound, legitimate partnership.
[16] Robben Ford describes the tone of the ODS as having "a perfect sonic curve, the lows are deep and rich but not unclear, it doesn't mush out like some amps will.
[16] Earlier versions also had more complicated phase inversion techniques that had been pioneered in vintage high fidelity amplifiers, and Fender style transformers.
Starting with #4, Dumble simplified the phase inversion and gave the amp more negative feedback, which further cleaned up the signal.
Guitarists often characterize its sound as extremely clean and compressed, with dynamic response and a lush reverb circuit.
There are reportedly "higher highs" and "lower lows" that are not often heard through other amplifiers, and a significant amount of harmonic response to the strength of the input signal.
Notable owners and users of the Steel String Singer include Stevie Ray Vaughan, Eric Johnson, David Lindley, Jackson Browne, John Mayer, Kirk Hammett, and Henry Kaiser.
[20] One of the earliest Dumble amplifiers, it was also the model which Stevie Ray Vaughan and Double Trouble used for 80% of the guitar tracks on their debut album, Texas Flood, which was recorded at Jackson Browne's studio.
Browne was a long time friend of Dumble, and owns some of his earliest amplifiers (including the first Overdrive Specials).
