3Leaf Audio is a boutique effects pedal company based in Washington state, founded by Spencer Doren in 2008. What began as modifications and tweaks of existing pedals evolved into a full line of original designs, with a strong focus on bass effects. The company operates as a one-person shop, with Doren handling design, assembly, and photography, and pedals are produced in limited-edition runs — typically batches of 111 units — announced monthly via newsletter.

3Leaf Audio is best known for its envelope filters and octave pedals for bass. The Proton envelope filter, a modern take on classic funk and psychedelic filter tones, has gone through multiple iterations up to the Proton MK4. The Wonderlove is another acclaimed envelope filter offering deeper, more expressive tones. The Chromatron is an optically-controlled analog filter that can switch between envelope and expression pedal control. The Octabvre line delivers analog octave effects and has been refined across several generations. Other notable designs include the Doom and You're Doom fuzz pedals, The Enabler bass DI/EQ, and the Groove Regulator, which was the company's original 2008 release.

The brand's pedals have found their way to prominent bassists including Bootsy Collins, Meshell Ndegeocello, Tim Lefebvre, and Paul Turner. Circuit boards are fabricated in California, while assembly, metalwork using American stainless steel, and screen printing are done in Washington and Oregon.

3Leaf Audio has 20 products cataloged on Equipboard, including Filter Effects Pedals, Harmonizer & Octave Effects Pedals, and Fuzz Effects Pedals. Their gear is featured by 19 artists, with the strongest followings in Rock, Jazz, and Funk / Soul. Notable users include Paul Turner, Paul Bander, and Victor Wooten. Most 3Leaf Audio products sit firmly in the high-end, boutique range.