The Moody Sounds Mewtone Envelope Filter is an envelope filter from Swedish maker Moody Sounds, built on the circuit of the Mu-Tron III, the filter that Mike Beigel's Musitronics put out in the 1970s and that many players still treat as the reference for the effect type1. The difference is a Gain control the original never carried, which the reviewer says adds some beef and punch to the overall output sound1.
Where the circuit comes from
The Mu-Tron III that the Mewtone draws on came out of Mike Beigel's work at Musitronics. In a Premier Guitar builder profile, Beigel described deriving it from "the side of the synthesizer we called the 'timbre generator' and one of the four voltage-controlled filters"2. The circuit works by using optocouplers to dynamically control a series of frequency filters based on the level of the input signal, so the filter sweeps in response to how hard you play3. On the original, the gain control doubles as both a volume and sensitivity control4.
Controls
Pedal of the Day's review walks through the panel1:
| Control | What it does |
|---|---|
| Mode | Selects between Hi-Pass, Low-Pass and Band-Pass filters, for a vast array of sonic sounds to choose from |
| Adjust | Acts like a depth or sensitivity control, letting you adjust the filter to fit the instrument or setup you are using |
| Peak | Controls the sharpness of the filter, from subtle and slight to a more biting, less nasal tone |
| Drive | Determines which direction the wah-wah moves, Up or Down |
| Gain | A new control not found on the original Mu-Trons; adds some beef and punch to the overall output sound |
The Mode and Drive arrangement follows the original: the Mu-Tron III carried a low/high Range and down/up Drive rocker switch arrangement alongside its Gain knob5, and the current Mu-Tron III Vintage Silver still lists Up and Down drive among its controls6.
What reviewers said
Pedal of the Day's reviewer, Mike B, found the Mewtone holds to the original while updating it: it "manages to stay true to the original sound while adding in some modern amenities as well"1. His verdict on the character of the pedal:
"this thing is a pure funk machine, with a ton of options allowing for a gigantic spectrum of sounds to choose from"
For context on the circuit it follows, the Mu-Tron III is considered by many to be the end-all, be-all of envelope filters, in the same review's words1. Players comparing the Mewtone against the original or other Mu-Tron III derivatives may also want to read the site's pages on filter pedals generally.
Videos
Pedal of the Day
Questions
Is the Mewtone based on the Mu-Tron III?
Yes. Pedal of the Day's review notes that the controls on the Mewtone line up pretty much with the controls on the Mu-Tron III, and that the pedal manages to stay true to the original sound while adding in some modern amenities. The main addition over the original is a Gain control, which the Mu-Tron III did not have.
What filter modes does the Mewtone have?
The Mode knob selects between Hi-Pass, Low-Pass and Band-Pass filters, which the reviewer describes as offering a vast array of sonic sounds to choose from. The Drive control determines which direction the filter sweep moves, Up or Down.
What does the Drive control do on the Mewtone?
Drive determines which direction the wah-wah moves, Up or Down. That mirrors the down/up Drive rocker switch arrangement of the original Mu-Tron III, which let players choose whether the filter swept upward or downward as you played harder.
Does the Mewtone have a gain control?
Yes. Gain is a new control not found on the original Mu-Trons, and the reviewer says it adds some beef and punch to the overall output sound.
Sources (6)
- Moody Sounds Mewtone Envelope Filter, Pedal of the Day, 2015-06-16
- Builder Profile: The Mu-tron Story, www.premierguitar.com, 2013-09-12
- Lumitron Resonant Filter / Mu-tron® III, Aion FX, 2023-09-08
- The Mu-Tron III: “Without it, there ain't no Bootsy”, Guitar World, 2023-03-17
- How the Mu-Tron III became a vintage pedalboard icon, Guitar World, 2026-02-09
- Mu-Tron III Vintage Silver, Musitronics Mu-Tron (mu-tron.com)
