Mu-Tron III

New, sophisticated, versatile… utilizing the latest in music synthesis techniques. Small enough to be a ‘mini-synthesizer’. Mu-tron III translates the envelope or “volume picture” of every note automatically… into an easily-controlled, articulated, vowel-like sound – as fast or slow as you play. Use Mu-tron III to create a variety of synthesizer sounds through most electrified instruments – guitar, keyboards, drums, flute, saxophone, brasses, bass, mandolin… even microphone. The sharper your attack and the more percussive your instrument, the wilder your sounds. Mu-tron III can be used with an octave divider or other devices – or in pairs for cascading effects. Besides providing inverted vowel trajectory (‘staccato snap’), Mu-tron III also functions as an automatic ‘wah’ pedal.”

– From original Musitronics Mu-Tron III ad circa 1970s


  • Mode (LP/BP/LP) selects the type of filter: Lowpass, Bandpass, Highpass
  • Peak Controls volume of the cutoff frequency
  • Gain adjusts the filter’s sensitivity to the signal of your 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


  • Gain: variable from 0.1 to 40, when driven from a low impedance source
  • Input Impedance: 1 megohm at lowest setting of GAIN control, variable to 3.3K ohms at maximum gain setting
  • Output Impedance: 600 ohms
  • Minimum Input Signal For Full Mu-Tron Effect: 1.5 mV from 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)


Alexis Grimaldo’s Mu-Tron III Demo

Original Owner’s Manual:


  • Good-Very Good Condition: $400-$600
  • Excellent Condition: $600-$750

Mike Beigel on the Mu-Tron III pedals made by ARP:

By the time ARP was making Mu-Tron III’s, I was already out in my own (Beigel Sound Lab) consulting and product design business again, and I never paid much attention to the ARP Mu-Tron products. They are the Mu-Tron III products WITH the AC line cords, and labeled as produced by Mu-Tron INC. (not Musitronics Corp. which made them from 1972 to 1978).

On January 17, 2014, while working with my colleague Richard Lingenberg on some new product design work, we got to talking about the ARP (Mu-Tron INC.) units, and I got a BIG and DISAPPOINTING surprise. I had always figured that they were competent enough to make the product the way I had originally designed it, but that was WRONG.

Apparently they changed the inside POWER SUPPLY VOLTAGE but in doing so they apparently DID NOT UNDERSTAND to change some component values that were designed for the ORIGINAL power supply voltage.

To make this brief, Richard (who gets all of my vintage Mu-Tron repair work and his own repair work from other sources) has fixed up and calibrated a lot of these ARP units. What Richard noticed about (ALL?) the ARP units coming in for repair, was that the FREQUENCY SWEEP was WAY TOO HIGH and also that the DOWN DRIVE never really worked to drive the filter down “all the way” as it was supposed to. Both of these symptoms had to do with changing the power supply voltage but not compensating for the change by ALSO changing some very critical component values.

So Richard, who knows what a Musitronics Mu-Tron III unit SHOULD sound like, changed the offending parts values and re-calibrated the SWEEP range and DOWN DRIVE to what they were designed to be.

I never knew about this before, and am sharing it now.

If you have an ARP Mu-Tron III and don’t like the way it sounds or works, now you know why. If you want it to be fixed (even though it’s not officially “broken”) and re-calibrated, please send me a note at <info at mu-tron dot ORG> (NOT .com), and I will forward the information to Richard, who will contact you and give you a quotation on fixing the parts values and re-calibrating it to the frequency sweep range of the original factory Musitronics Mu-Tron calibration.

(But if you are perfectly happy with your ARP Mu-Tron unit, then by all means USE IT AS IS. Richard also noticed enough variation in the calibration of the ARP units that it’s just possible that YOUR vintage ARP Mu-Tron III unit is accidentally calibrated “just fine”.)

There weren’t all that many ARP unites made, but I thought it appropriate to inform the owners of these vintage (and AUTHORIZED by Musitronics Corp.) i.e. LEGITIMATE reisssues, that there might be issues with the units that (I) didn’t know about until recently.

“Patent Search: Michael Biegel’s (sic) Mu-Tron III” – Guitar Player Magazine (May 1982)

[Best_Wordpress_Gallery id=”36″ gal_title=”Patent Search: Michael Biegels Mu-Tron III” – Guitar Player Magazine (May 1982)”]

Get in touch

"Modern Vintage Analog" Effects Pedals