Effects pedal expert Josh Scott, owner of JHS Pedals, has uncovered the long-lost prototype of the Electro-Harmonix Holy Grail reverb pedal. This iconic stompbox has shaped the sounds of artists like John Frusciante and Jim Root, influencing countless musicians worldwide.
The Hunt for a Legendary Pedal
Scott, a renowned historian of guitar effects, pursued this elusive artifact for years while researching his upcoming book, Made on Earth for Rising Stars. Co-authored with illustrator Daniel Danger after six years of work, the book delves into Electro-Harmonix’s history through interviews, creative insights, and in-depth explorations of pedal innovation.
The Holy Grail stands out as a pinnacle of pedal design from one of America’s most innovative companies, according to Scott. During his archival visit to Electro-Harmonix’s Queens facility, the breakthrough occurred.
A Surprise Find in the Depths
“We were digging in the basement at Electro-Harmonix,” Scott shared during a January 26 live stream. “We’d always ask, but we were always met with, ‘Nah, there are no prototypes.’ At some point, you’re like, ‘There has to be prototypes.'”
As the team wrapped up interviews with engineers, Owen Matthews—son of EHX founder Mike Matthews and artist relations specialist—suggested exploring further. “To my memory, we were packing up one day,” Scott recalled. “Then all of a sudden Owen goes, ‘Have you been down to the basement?’ This building is massive, it’s in Queens, and it’s like half a city block. The basement is for R&D and tube storage, but he means the basement basement.”
There, they discovered the prototype: a unit with a stainless steel front plate marked “Holy Grail 1, handle with care” in Sharpie, featuring complex internal wiring. At its core lies the Crystal CS4811 chip, a game-changer in pedal technology.
Revolutionizing Reverb Technology
In 2000, Mike Matthews spotted the CS4811 chipset at a trade show, Scott explained. “With it, you can essentially load in their pre-programmed algorithms, and you can mess around with it and tweak it. This is a big deal; it’s the beginning of simple DSP (Digital Signal Processing) for guitar players. This unit, to my knowledge, is the world’s first digital spring reverb unit. Mike Matthews saw the opportunity, had it in the hands of an engineer, and produced a product before anyone else.”
Early Holy Grail models offered three reverb modes via an external switch, but enthusiasts discovered hidden options. “Now, what’s funny is that the original units shipped with three reverb sounds on the outside, but some people figured out that you could hack it and have eight total sounds via the dip-switches,” Scott noted. Inside, eight dip-switches allowed access to varied reverb characters beyond the standard three-way selector.
What’s Next for the Prototype and Book
The prototype’s future remains open, but Scott’s book is now open for pre-orders through Third Man Books, published by Jack White’s company. White previously collaborated with JHS on the innovative Troika Delay pedal. For more details, visit Third Man Records.

