Musitronics III Envelope Filter by Mu-Tron

The Musitronics III Envelope Filter, also known as the Mu-Tron III, is an analog envelope-controlled filter designed and manufactured by Musitronics Corporation. It was first introduced in 1972 and has since become an essential effect for many funk musicians. The pedal is capable of translating the envelope or "volume picture" of every note automatically into an easily- controlled, articulated, vowel-like sound, as fast or slow as the user plays. It can be used with various electrified instruments such as guitar, keyboards, drums, flute, saxophone, brasses, bass, mandolin, and even microphone.

Key Technical Specifications:
- Gain: Variable from 0.1 to 40 when driven from a low impedance source
- Input Impedance: 1 megohm at the lowest setting of the GAIN control, variable to 3.3K ohms at the maximum gain setting
- Output Impedance: 600 ohms
- Minimum Input Signal for Full Mu-Tron Effect: 1.5 mV from a 600-ohm source
- Maximum Undistorted Output Signal: 3.6 volts RMS
- Power Supply: ±9 Volts from 2 NEDA 1604 batteries or Musitronics Model PS-1 Battery Eliminator
- Dimensions: 8¾” l. X 5″ w. X 3⅛” h.
- Weight: 3¼ pounds (without batteries)

Controls:
- Mode (LP/BP/HP): Selects the type of filter - Lowpass, Bandpass, Highpass
- Peak: Controls the volume of the cutoff frequency
- Gain: Adjusts the filter’s sensitivity to the signal of the instrument
- Range (Low/High): Selects the frequency range covered by the filter envelope
- Down/Up: Selects the direction of the filter sweep - down or upwards
- Power (Off/On): Switches the power on or off

Use Cases:
The Musitronics III Envelope Filter is widely used by musicians across various genres, including rock, jazz, funk, soul, art rock, psychedelic rock, alternative rock, experimental rock, electronic, jazz fusion, and folk rock. It has been favored by renowned artists such as Flea, Steve Vai, Trent Reznor, Andy Summers, Jerry Garcia, and Squarepusher.

The pedal's functionality as an automatic 'wah' pedal and its ability to provide inverted vowel trajectory (‘staccato snap’) make it a versatile tool for creating a variety of synthesizer sounds and cascading effects.

The Musitronics III Envelope Filter remains a sought-after vintage effect pedal due to its unique sound and its historical significance as the world's first envelope-controlled filter.