The Musitronics Mu-Tron Mini Mu is an envelope filter pedal, the newest reincarnation of the classic Mu-Tron III envelope filter, in a pedalboard-friendly size1. An envelope filter, sometimes called an auto-wah, listens to the volume of your playing and sweeps a filter in response: play harder and the filter opens up, play softer and it closes down. Musitronics Mu-Tron describes the Mini Mu as a simple but effective and versatile envelope filter that provides all the classic Jerry tone and Bootsy funk in a smaller box1.
Controls and how it works
The Mini Mu has four controls, and each one maps to a job a player will recognize from the original Mu-Tron III1:
| Control | What it does |
|---|---|
| Gain | Controls the envelope of the filter's audio drive, setting how hard your signal pushes the sweep1 |
| Peak | Controls the filter audio response, or notch shape of the filter1 |
| Range | Tunes the pedal for low and high frequency instruments, so bass and guitar both track well1 |
| Mode | Switches between low-pass and band-pass filter operation1 |
The Mode switch is the biggest tonal decision. Low-pass mode sweeps the filter downward from the top of the spectrum, the more vocal, wah-like sound. Band-pass mode emphasizes a moving band of frequencies, which tends toward the tighter, funkier quack associated with the Mu-Tron sound. An LED indicator shows the bypass status of the effect1.
Where it goes in the signal chain
Musitronics recommends placing the Mini Mu after clean boost and octave effects, and before modulation, delay, and reverb1. That ordering matters for any envelope filter: the effect's envelope detector reads the level of whatever feeds it, so a clean, strong signal before it and time-based effects after it give the filter the clearest picture of your attack.
Size, power, and build
The Mini Mu measures 4.75 by 2.5 by 2.25 inches and weighs 1 pound, housed in a rugged Mu-Tron enclosure1. It runs on 9V DC and is designed for low current consumption, so it works with any standard power brick or adapter1.
The Mini Mu is a 9V DC pedal, not a battery-and-daisy-chain-free design like the original 1970s Mu-Tron III, which drew its own power internally. Plan a spot on your power supply for it.
The Mu-Tron III lineage
The Mini Mu's circuit descends from the Mu-Tron III, which Vintage Guitar notes arrived in 1972 as the first envelope-controlled filter on the market12. On That Pedal Show, Dan and Mick cover the Mu-Tron III's history and its status as a discontinued original that later builders have reissued and reinterpreted3.
Musitronics Mu-Tron today offers the Mini Mu alongside other pedals in the family, including the Mu-Tron III Vintage Silver and the Micro-Tron IV, so a player comparing envelope filters can look at the full current range before deciding which size and control set fits their board.
Videos
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Questions
Is the Mini Mu made in the USA?
Yes. Musitronics Mu-Tron states the Mini Mu is made in the USA, and it carries a 1 year limited warranty from the maker.
What do the Mode and Peak controls do on the Mini Mu?
Mode switches the filter between low-pass and band-pass operation. Peak shapes the filter's audio response, adjusting the notch shape of the filter. The other two controls are Gain, which sets the envelope of the filter's audio drive, and Range, which tunes the pedal for low or high frequency instruments.
Where does an envelope filter go in the signal chain?
Musitronics recommends placing the Mini Mu after clean boost and octave effects, and before modulation, delay, and reverb. That lets the filter track the cleanest, strongest signal available for its envelope detection.
How big is the Mu-Tron Mini Mu?
The Mini Mu measures 4.75 by 2.5 by 2.25 inches and weighs 1 pound, small enough to fit on a crowded pedalboard while keeping the Mu-Tron sound.
Is the original Mu-Tron III still made?
The original Musitronics Corporation Mu-Tron III is discontinued. Musitronics Mu-Tron now builds the Mini Mu true to the original Mu-Tron III gain circuit and otto-coupler design, alongside other reissues in its current lineup.
Sources (3)
- Mini Mu - Musitronics Mu-Tron, Musitronics Mu-Tron
- VFE_MiniMu.pdf, madbeanpedals.com, 2020
- That Pedal Show, That Pedal Show, 2017-11-17
