What Is John Mayer's MYSTERY Pedal?

John Mayer's pedal choices have shaped the tastes of generations of guitarists, however there's one device, based on a Dumble effects loop buffer, that's lived on his pedalboard for years, which is rarely discussed by even his die-hard fans. In collaboration with guitarist ‪@GabrielBergman95‬, we'll attempt to unpack this mysterious Dumble effects loop buffer by using a similar Dumble-style circuit (called a Kleinulator) and demonstrate the sonic benefits using such a device and why you might consider adding it to your pedalboard rig. ⬇ BUY A Klein-ulator ⬇ Ceriatone - https://ceriatone.com/klein-ulator Reverb - https://reverb.com/marketplace?query=... Ebay - https://www.ebay.com/sch/i.html?_nkw=... ⬇ SHOUT OUT To The Tone Geek (Ryan Colgan) ⬇ Box It Later Deep Dive -https://www.thetonegeek.com/single-po... BUY Ryan's Box-A-Later Replica - https://www.thetonegeek.com/product-p... ⬇ BUY My Masterclass ⬇ Signal Paths - https://vertex-effects.teachable.com/... ⬇ JOIN My Patreon ⬇   / vertexeffectsinc   ⬇ Buy My PEDALS ⬇ Sweetwater - https://bit.ly/vertex-sweetwater Amazon - https://amzn.to/40HcRg6 Reverb - https://bit.ly/vertex-reverb ⬇ Listen To My PODCAST ⬇    / @chairmenoftheboards   ⬇ APPROVED Pedalboard Materials ⬇ Zip Ties: https://amzn.to/45pZxPr Tie-down Mounts: https://amzn.to/3IPpjUJ 3M Dual Lock Velcro: https://amzn.to/40Gyo8r Patch Cables: https://amzn.to/4mgH3GG Instrument Cables: https://amzn.to/4mcQEhS Pedalboards: https://amzn.to/3GXqQaF ⬇ APPROVED Buffers ⬇ Vertex Buffer Interface: https://amzn.to/41l9Uld Vertex Buffer Module: https://amzn.to/3IKQ7p8 ⬇ APPROVED Power Supplies ⬇ CIOKS DC7, 8, 4, SOL, Crux - https://amzn.to/40JzRe6 Strymon Zuma, R300, Ojai - https://amzn.to/4l3W4e7 Walrus Audio Canvas 5, 8, 15, 22, HP - https://amzn.to/3IT52O8 Truetone CS Series - https://amzn.to/4mmrGgc Voodoo Lab 3, 3+, X4, X8 - https://amzn.to/3UBwRNf IEC Plug Covers - https://bit.ly/34fpGl3 ⬇ APPROVED DIY DC Cable Supplies ⬇ 2.1mm DC Power Plugs (right angle) - https://amzn.to/4miVTfR 2.1mm DC Power Plugs (straight) - https://amzn.to/4l5jobt Pre-Made Power Cables (pre made) - https://amzn.to/4oaV5eU ⬇ APPROVED Rig Building Tools ⬇ Soldering Iron - https://amzn.to/2TTdMI4 Solder (60/40) - https://amzn.to/2U7XhsD Solder Dispenser - https://amzn.to/4m2hBFl Octopus Arms - https://amzn.to/2V3O8OD Wire Strippers (30-20 AWG) - https://amzn.to/2BBMI6n Wire Strippers (20-10 AWG) - https://amzn.to/2EbhBR3 Wire Snips - https://amzn.to/2EazwqU Vise - https://amzn.to/4m2hBFl Heat Gun - https://amzn.to/2BwGdlm Label Maker - https://amzn.to/4lUlfkE Label Maker Tape (black) - https://amzn.to/3J8sFSB Label Maker Tape (clear) - https://amzn.to/3GXsSaN DeOxit D5 Contact Cleaner - https://amzn.to/2GEm4gu Tone Brush - https://amzn.to/2HIfze3 Upholstery Crow Bar - https://amzn.to/4fhccI7 Multimeter - https://amzn.to/4fdPuAg ⬇ TABLE OF CONTENTS ⬇ 00:00 Mayer’s Secret Pedal 01:43 How John Uses His Box-It-Later 02:44 A Widely Available Alternative 03:12 Recreating John’s Box-It-Later Sound 03:57 Signal Path Walkthrough 05:27 John’s First Theorized Use of the Box-It-Later 08:25 John’s Second Theorized Use of the Box-It-Later 11:53 Which Method Sounds the Best? 13:16 Why This Matters to You! 14:58 Thanks for Watching! CREDITS Host/Producer: Mason Marangella Co-Host/Guest: Gabriel Bergman Videographer: Nico Sotomayor Video Editing: Mason Mejia Co-Production/Design: Mason Mejia Audio Editing: Hunter Harrison Engineer: Mason Marangella LOCATION Oakland, California DISCLAIMER This video was originally posted on August 11, 2025 but was electively taken down within 24-hours of posting due to a mixing error in post production that put the stereo amplifiers audibly out of phase when summed to mono, to the point that the guitar was practically muted under certain listening conditions. It goes without saying that when demonstrating audio equipment the quality of the sound and the nuances of the tone are key parts of the video and having any compromise to that end undermines the entire presentation. Thank you to those of you who brought this to our attention on YouTube and Instagram! #johnmayer #guitarpedals #vertexeffects