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  • Writer's pictureRicardo Malzyner

Proton Envelope Filter V4, by 3LeafAudio. The best filter to achieve that gritty wah sound.

This highly responsive filter is a must-have for those in the search for the Jerry Garcia "gritty wah" sound.


Though I came to appreciate the Grateful Dead later in life (my fondness grew in my late 20s after attending a Dead & Co. concert), I quickly became enamored with the iconic Jerry Garcia lead tone, much like many other Deadheads. This signature sound can best be described as a gritty, cocked-wah effect with a hint of octave. Naturally, my quest for this tone led me to the Mu-tron IV. And for the octave effect, I turned to the Foxrox Octron 3, which is, in my opinion, one of the finest octave pedals I've ever encountered:

Though I had some great gear, I still felt something was missing. That's when I decided to give the Proton V4 a whirl, and it instantly took the place of the Mu-Tron IV on my board. To this day, it holds its spot there, and it's one of those rare pedals I'd never part with. Given they're produced in limited batches, they're quite the treasure to find.

The genius behind 3leafAudio is Spencer Doren, who is undeniably passionate and meticulous about his work. Operating solo out of Seattle, Washington, he ensures quality at every step. The PCBs in his designs hail from Utah, while the enclosures are crafted in Oregon. Spencer's creations always have a touch of exclusivity, as he's continually experimenting with fresh aesthetics and tweaking circuits.


  • Power: 9V DC, 30mA minimum. 2.1mm center-negative connector.

  • Input Impedance: Very high.

  • Output Impedance: Very low.

  • Bypass: Transparent active bypass system with proprietary electronic switching. No clicks, no pops, will never break.

  • Footprint: 64 mm x 118 mm.

  • Response: Adjusts the envelope detector's sensitivity to playing dynamics. Adjust based on the output of the instrument.

  • Peak: Sets the amplitude of the filter's resonant peak. Higher settings produce a more aggressive sweep.

  • Decay: Sets the time for the filter to close. Adjusts the envelope sound from long and natural to snappy.

  • Tone: Sets the maximum cutoff frequency of the filter. Works like a guitar or bass tone knob.

  • Range: Toggles the frequency range of the filter. High position is similar to the previous Proton version, while the low position is deeper.

  • Sweep: Toggles the direction of the filter sweep. Settings may need to be adjusted based on the sweep direction.

What sets it apart

Its gritty sound character and dynamic response truly distinguish it. This is one of those pedals that functions as an instrument in its own right. The nuanced way each knob interacts with the others is unique and a feature I deeply appreciate about this pedal.

Price Point

In 2021, I managed to get it for $250. I'm uncertain about its current price since 3LeafAudio's website doesn't display that information at the moment. The only purchasing avenue is directly through 3LeafAudio's website.


When considering high sound quality, some comparable pedals include the Analog Man Block Logo Envelope Filter, Mu-Tron IV, and Flower Pedals Hosta Wah Filter.

GPH Final Thoughts

The Proton V4 ranks among my all-time favorite envelope filters. It's always a delight to experiment with, and I absolutely adore its gritty character. If you ever have the opportunity to acquire one, I can assure you, you won't be disappointed.

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