Our goal is not to be overly technical here in terms of the exact circuit employed, but more to outline some of the more interesting points of its history and, where necessary, use other known Dumble circuits to try and create a timeline of sorts. As the current owner of these amps is a long time friend and client, I have had the opportunity to play, study, feed, and care for these amps many times over the years. It was fun, interesting, and challenging for me to be charged with trying to find out just what it was that we had here as far as history is concerned. There are few amplifiers that have shared the same shroud of mystery as the Dumbles.
At this juncture, I would like to take a moment to point out that Dumble amplifiers are handmade and are often “tuned” to the prospective player’s needs and desires. This is not unique to Dumble amps, and should be typical for any custom builder worth his or her salt. This is important to keep in mind because this results in many variations between amps. Variations can also be attributed to the natural development of a builder’s circuits and abilities—basically, it can be hard to pin down.
With that said, this is what we believe to be true.
Alexander Dumble was living on Jackson Browne’s property during the time that this amp was constructed for Browne (In fact, the original wooden channel switching footswitch still bears his name). The amp was originally constructed as an OD-100WR and it has most certainly been modified and updated over the years. The current owner speculates that these updates were made because it was close by and a convenient “guinea pig” for Mr. Dumble to try out new circuit design ideas.
The preamp circuit most likely began as (what’s known in internet circles) the “classic” preamp. This is based on other OD circuits built around the same time period. What we do know is that it does not have the classic pre in it now. Poring over my own notes and schematics as well as speaking with colleagues that have had experience with these circuits over the years, we decided that it probably has a very early version of the “skyline” pre, though the tone stack more closely resembles one of earlier examples. Could this be the first incarnation of this now famous design? The plate load resistors are not the earlier “low plate classic” design but a surprisingly current array. Some pretty interesting stuff going on in here.
The overall signal path is as follows:
Clean gain (Volume) > tone controls > the other gain stage > clean master Ratio (located on back) > two OD stages’ Gain and Level on front > OD Ratio (on back, tones are mostly bypassed in OD mode) > Reverb > Clean/Wet summing stage before the phase inverter, which is different from Fender circuits.
The current owner rightly brings up the fact that much of the magic seems to come from how you set and balance the “Ratio” controls on the back of the chassis.
This is all a gross simplification, of course! To go into great deal on this amp would require me to write a short novel on the topic. We could dedicate several articles on the choice of plate load resistors alone!
Another thing we discovered was that the combo cabinet and chassis were not necessarily intended to be used together. The story goes that the purple suede-covered 1x12 cabinet, complete with EVM-12L speaker and oval ported back panel, was offered to Bonnie Raitt to be used as a combo (with a head/chassis which is unknown to us) but was rejected as being too heavy. It then resided beside Mr. Dumble’s workbench serving as a coffee table of sorts until it was sold to Greg Bayles in 1989 (former owner of Make’n Music in Chicago) where it was mated with the OD-100WR chassis and sold to its current owner.
I will say that amongst all of the Dumble amps (and Dumble inspired clones) that I have spent time with, this definitely takes the cake! It has headroom, power, incredible touch sensitivity where one can go from clean cords to blistering single note runs with the energy of your picking hand. Truly superb! I’m a lucky man to have a job like this!
[Updated 2/15/22]
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PRS Standard 24 Satin Electric Guitar - Satin Red Apple Metallic
The exquisite BilT Brothers collaborative guitar: a Frank Brothers Ultra Light in BilT eggplant sparkleburst with Arcane 3x3 Gold Foil Humbuckers and loaded with a Caroline Custom Cannonball Distortion.
It was like any other random day at work: We had customers coming in, items shipping out, services on the bench. I was simultaneously working on a pedalboard for a customer and making plans with some vendors. I was on the phone with Brandon Darner of BilT Guitars when DHL dropped off our latest Frank Brothers guitar. Now, I’m never shy about talking up builds from any of our vendors. Spec’ing guitars for our shop, seeing their execution exceed my expectations, and then getting it into the hands of its new owner is one of my absolute favorite parts of my job. So, naturally I mentioned that we just got a new Frank Brothers in. Brandon told me how much he loved their stuff—sort of a “game recognizing game” kind of thing.
After we unboxed the guitar, I called Tim Frank to let him know how we continue to be impressed with their work and how much we loved the new arrival. I also mentioned Brandon had some very nice things to say about their work. Tim’s response was something like, “Oh wow! That’s really cool. Their stuff is amazing and we have a lot of respect for those guys.” At first, I thought he was just being polite, but I’ve gotten to know him pretty well. I knew that the compliment and sentiment was genuine and past the point of his wonderful Canadian pleasantness. One thing led to another, and I started a group text. Very quickly, they became friends. In fact, Brandon even ordered a Frank Brothers shortly after the introduction.
The Frank Brothers and BilT team, left to right: Tim Frank, Tim Thelen (BilT), Nick Frank, and Brandon Darner (BilT).
My last call of the day was to Philippe Herndon from Caroline Guitar Company. As we talked, he was glowing about the pedal building community and how friendly and collaborative it is, and obvious questions popped into my head: “Why aren’t guitar companies like that?” “Why can’t we do a collab guitar?”
Long story extremely short, with tons of excitement, I got Brandon and Tim on the phone and proposed the idea of doing a guitar together. Without hesitation, the response from both was “Hell yeah, let’s do it!” and it was time for us to spec it. We decided on a Frank Brothers Ultra Light. BilT would apply their world-class fit/finish as well as their signature effects treatment. I picked my favorite finish in the BilT repertoire called eggplant sparkleburst, selected Arcane 3x3 Gold Foil Humbuckers, and tapped Philippe on the shoulder to ask if he had any Custom Cannonball Distortions—the first pedal I bought from Caroline in 2013—that he could provide for the build, to which he happily obliged.
A year or so later, the BilT Brothers was born. Of course, it is exceptional beyond words and is a true testament to the results of these incredible companies working together to produce something truly remarkable. We decided, with custom shirts and all, to proudly debut our creation at Fretboard Summit in Chicago. The reaction from everyone exceeded our expectations and showed me that the level of mutual respect and admiration in this business can lead to phenomenal results.
This project has opened a lot of doors that I’m not sure anyone knew existed. For me, the most exciting part of all of this is the fact that, like the smaller pedal companies, there is an actual community here filled with like-minded, pure enthusiasts who also happen to be master craftsmen—and who truly geek out over each other’s work.
Never was this more evident than at the Wood Wire Volts show this January, where not only did the BilT and Frank Brothers crews travel and stay together, they were also often in deep chats with fellow luminaries Sacha Dunable (Dunable Guitars) and Carlos Lopez (Castedosa Guitars), discussing the trade, the work, and ideas for the future. If the vibe is any indicator, we can safely assume that while the BilT Brothers was, by all accounts, the first ever collab guitar of its kind, it will not be the last.
This entire experience is reminiscent of the DIY community ethos that I’ve clung to and has inspired me for most of my life. There is a cliché about the journey being greater than the destination, and while the destination in this case is one of the finest guitars I’ve ever laid my hands on, I’d have to say it holds true
