The story behind one of guitar pedal world's most infamous engineering mix-ups reads like a comedy of errors — except the consequences were very real.
In 2019, Josh Scott left a John Mayer rehearsal in Los Angeles with two extremely rare Dumble units. His job was to reverse engineer them for a new product: the NOTADÜMBLË. What he didn't know was that these two units — the BBC1 and the Box It Later — would take him on a years-long journey of forgotten schematics, lost documentation, and a mistake that wouldn't surface until after the pedal had already shipped to thousands of customers.
The Two Units
Scott received both rare Dumble pieces from John Mayer. The first was the BBC1, which became the basis for what he described as "the basic boost" — an overdrive section. The second was the Box It Later, which was supposed to form the clean channel of the NOTADÜMBLË.
What Scott didn't realize is that these two units performed essentially the same function. Both were clean circuits with similar controls: input and output gain knobs. Howard Dumble's design philosophy meant both circuits shared similar tuning philosophies, making them nearly indistinguishable by ear.
But there was a critical problem hidden in the documentation chaos.
The Documentation Disaster
The timing made everything worse. In 2019 when Scott brought these home, and through 2020-2021 when they were reversed and replicated for John Mayer's signature pedals, JHS was in crisis mode. The company was dealing with the pandemic, massive operational upheaval, and the tragic passing of Cliff Smith — Scott's former head of R&D who died a few months after shipping the final units to Mayer.
"These are what I refer to as friends and family tasks," Scott explained. "It's when a friend hands off something cool. I'm interested in it. So I reverse it to have a schematic. I make a one-off and we move on. The documentation doesn't necessarily go into the main R&D documentation because I wasn't planning on ever making this product."
The problem: none of the Box It Later project was digitized properly or put into any R&D system. But for some reason, the BBC1 — which Scott had found in his database — did have proper Eagle-documented schematics.
"I don't know why this is," Scott said. "I will never know why Cliff never digitized this one. My guess is we're super busy. This is a side project."
The Discovery
In late 2023, early 2024, Scott was working on the NOTADÜMBLË and began investigating what exactly sat inside the clean channel. When he sent an email to his current head of engineering Josh M, the subject line simply read "Dumble" — containing only the schematic to the BBC1.
Scott couldn't find that schematic in their R&D database. He couldn't locate it on any computer system. The email had gone out with the wrong circuit entirely: he was thinking the BBC1 was actually the Box It Later because he had completely forgotten about this whole side of it.
"It's super important to reiterate here that Josh M had never seen this or this 3 years prior," Scott said. "He didn't know this existed."
The real tragedy: some of Cliff Smith's very last work was misplaced and not documented properly — lost in the chaos of moving offices during the pandemic lockdown.
The Mistake Revealed
When Scott finally connected both units side-by-side for comparison, he discovered what he already suspected. The clean channel in the NOTADÜMBLË wasn't based on the Box It Later at all. It was built from the BBC1 circuit — the one he had mistakenly used because he thought it was the same as the Box It Later.
The labels were identical: both said input and output, similar knobs for gain and recovery. When looking at the schematic of the BBC1 or the clean section of the NOTADÜMBLË, it read "input output" just like John's Box It Later.
"I think there's also a lesson here in engineering," Scott reflected, "which is just like me, I tune things a certain way. Howard Dumble's tuning the same frequencies no matter the method."
The two circuits are extremely similar — one FET-based and one op-amp-based — but they do have subtle differences that most players would never notice without comparing them side-by-side.
The Lesson
This wasn't a case of poor R&D testing. JHS runs rigorous approval processes with groups of employees who reject any issues. They tested on tons of rigs and backtracked to control units. But there weren't really any controls or anything to compare against — the original units had been shipped back to John Mayer because they're extremely valuable.
"The next thing that's really puzzling and realized in hindsight," Scott said, "is that when we replicated these... you're going to notice something. They share the exact same knob labels."
Howard used things like depth and gain on one, and drive and recovery on the other — but those labels were changed to match John's Box It Later exactly.
Critics might note that this explanation raises questions about JHS's quality control processes. How does a company sell thousands of pedals without knowing what's actually inside them? The answer lies in how similar these two circuits sound: to most people, you're not really going to notice the difference.
"These are extremely similar. The recover is the gain. The drive would be the input. So that's your inputs, that's your outputs."
The bigger concern isn't whether there are audible differences — it's that the company's documentation practices failed catastrophically at exactly the wrong moment.
Bottom Line
This story is less about a single engineering mistake and more about how documentation systems fail under pressure. The clean channel in the NOTADÜMBLË works perfectly fine — it sounds nearly identical to what John Mayer uses. But the real lesson here is about the fragility of institutional memory: when key team members leave, when documentation isn't digitized properly, and when pandemic-era chaos upends everything, even the most rigorous companies can lose track of what's actually inside their products.
The good news? Both circuits sound excellent. The bad news? Josh Scott still doesn't fully know what happened — and neither does anyone else.