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The Skeleton-Tron III Envelope Filter is a faithful recreation of the vintage Mu-Tron III used by Jerry Garcia, Bootsy Collins, Stevie Wonder, 311, Edie Brickell & New Bohemians, and many others. If you’re attempting to capture the most authentic Grateful Dead tones, this envelope filter is for you.


Vintage Mu-Trons, like the one used by Jerry, have been out of production for decades (since 1979).  They're scarcely found, and very hard to find in good condition.  Additionally they’re very expensive, have an unusual power supply, and are a really big stomp box.  The Skel-Tron III comes in a 125B sized enclosure (JHS sized) with ultra-reliable components that were sourced for quality, durability, and authenticity. The vintage tone of the Skel-Tron III is immediately recognizable.


We’ve tried many different envelope filters from big brands such as the DOD, Boss, Line 6, and Ibanez. We also tried pedals by high-line boutique brands like EQD, Mojo Hand, 3 Leaf, and others. We found some great sounds out there, and in the case of the boutique brands, some really quality pedals.  However, they all seemed to fall short of Jerry’s tone.  The Skel-Tron III is the only envelope filter on the market purpose built for fans of the Grateful Dead.


Volume controls the output level of the effect. Peak controls the filter response (intensity). Gain boosts the input signal and can increase envelope detection. Drive controls the sweep direction UP or DN (down). Filter allows for low-pass (LP), high-pass (HP), and boost-peak (BP). Range "LO" provides better response to bass signal and "HI" responds better with guitar.  The blue LED light indicates when the effect is on or off. The red LED eyes of Bertha light up and pulse when the effect is triggered.


The enclosure has glow-in-the-dark powder coating and the graphic is UV printed. The Skeleton “Bertha” as she’s known to Deadheads, was adopted by the Grateful Dead in early artwork and posters around 1966. However, she was actually painted many years earlier by artist Edmund J. Sullivan circa 1900 in a work called “A Skeleton Amid Roses”. 

Skel-Tron III Envelope Filter (Auto Wah)

Excluding Sales Tax
    • Enclosure dimensions: 122mm x 66mm x 39.5mm
    • Tough die-cast aluminum enclosure
    • Glow-in-the-dark powder coating with durable UV printed graphics.
    • Soft footswitch (no click) is true bypass and rated for 50,000 stomps!
    • Heavy 22 gauge stranded wire.  The thicker stranded wire makes for solid electrical connections that are much harder to break through vibration and shock.
    • Nutrik 1/4" I/O mono jacks.  These hi-quality jacks maintain great contact and grip on your guitar cable.
    • Lead-free solder helps protect environment and human health.  
    • LEDs powered by 9vDC center-negative jack
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