Mu-Tron Tru-Tron 3X by Mu-FX. Super rare. Signed by Mu-Tron Founder Mike Beigel.

Sometimes you get so excited by a pedal that you have a hard time putting that feeling into words. So, I'll just start by presenting the facts. Here is a Mu-Tron 3X, (Yes, a "Mu-Tron," not a "Tru-Tron," which, more about that in a sec) by Mu-FX, and it is signed by Mike Beigel, one of the original Mu-Tron inventors and a co-founder of parent company Musitronics Corp.

This pedal is the modern-day reissue of the storied Mu-Tron III Envelope Filter, produced by Musitronics throughout the 1970s. Used by greats such as Stevie Wonder, Bootsy Collins and Jerry Garcia, the Mu-Tron III set the standard for auto-wah effects, becoming a hallmark of modern funk and a strong influence in the evolution of the Grateful Dead's unique sound. It is known for having a vowel-like voice, which ranges from tortured groans to funky, tight staccato and bubbling, bouncing spheres of tone. I know it might seem like a high price for a pedal but it's outstanding, rare, collectible and signed by the inventor.

Additional background:

Beigel, who re-issued the new pedals through his recent venture, Mu-FX, hand-signed this unit as part of a limited number of commemorative versions that accompanied the launch. It is also notable for the fact that it is labeled "Mu-Tron" instead of "Tru-Tron." The reason, according to what I have been able to glean online, stems from a patent hurdle that prevented Mu-FX from calling the product Mu-Tron in the U.S. Therefore, it was called Tru-Tron domestically and Mu-Tron in the rest of the world. Here is Beigel, in his own words: https://www.youtube.com/watch?v=J6XxOBqQiPg.

When you consider the outstanding sounds of the Mu-Tron/Tru-Tron 3X, which was highly acclaimed upon release, the fact that they are sold out (with no clear indication of future production plans), and the fact that the unit includes Beigel's signature, this pedal (in my opinion) could be destined to only gain in value. But, I say, don't buy it to mount in a glass display case. I feel like it would be a crime not to play it and enjoy it.

The Mu-Tron/Tru-Tron 3X was designed to replicate the original but with additional features, including true bypass, a modern power supply, and a MIX setting that provides an optimized mixture of the dry (unfiltered) signal and the filtered signal. It also has the ability to produce very compelling and authentic overdrive tones. I can't say for sure if it sounds exactly, exactly like the original Mu-Tron in every respect but I could not perceive a meaningful difference between them. They both sound amazing.

From the Mu-FX website, https://mu-fx.com/shop/pedals/tru-tron-3x/:

"Just like the original Musitronics Mu-Tron III™ envelope filter pedal… Only Better!
The Tru-Tron 3X™ is the modern all-analog refinement of the classic Mu-Tron III™ envelope controlled filter. Mike Beigel, inventor/designer of the Mu-Tron III™ and co-founder of Musitronics Corp., has retained all the mojo that made the 1972 unit so popular with Stevie Wonder, Jerry Garcia, Bootsy Collins, Larry Coryell, Frank Zappa, Carlos Santana, Joe Zawinul, George Duke and many more. The Tru-Tron 3X™ is the closest you’ll find to the original Mu-Tron, because at its heart, IT IS.

"The Tru-Tron 3X is bar none the best envelope filter pedal for guitar. Actually, the Tru-Tron 3X is the best envelope filter for bass, keyboards, sax or any instrument that can be plugged in!"

Here are some demo clips from YouTube:

https://www.youtube.com/watch?v=c1WpLoeHku0

https://www.youtube.com/watch?v=QtQ0Z4Ze75s

https://www.youtube.com/watch?v=ppo1RSRO05o

https://www.youtube.com/watch?v=toTcNDBzCZw