The Mu-Tron Super-Freq is a dual state variable filter with multiple routing and actuating options, made by Musitronics Mu-Tron. Either of its two filters can be run as an envelope filter, a wah-wah pedal, or a parametric EQ with resonance control, which puts envelope-triggered filtering, manual wah-style sweeps and surgical EQ in one box1. It lists at $479.00 USD and is made in the US1.
What it does and where it comes from
A state variable filter, as the maker explains it, is a type of active filter in electronic circuits which can produce simultaneous lowpass, highpass and bandpass outputs from a single input. The Super-Freq carries two of them, each with its own actuating options, so one channel can follow your playing dynamics while the other is swept by hand or set as a fixed EQ notch or peak1.
The design leans on two lines of filter history. For manual control of frequency, the maker points to dual potentiometers as used in the Tychobrahe Parapedal, the Alembic SF-2 and the Anderton Super Tone Control. For the automatic side, it uses optically controlled state variable filters like those in the Mu-Tron III and the Mu-Tron Vol-Wah1. The maker also highlights a modular optical design which allows for consistency across units1. Players who want the optical envelope approach in a smaller footprint may also look at the Mu-Tron Mini-Freq.
Controls
| Control | What it does |
|---|---|
| Frequency | Controls the range of frequency manipulation |
| Peak | Can be used as resonance or damper control |
| Direct gain | Allows the dry signal to be blended with the filtered signal |
| Up and Down drive | For either envelope, can be fine tuned internally |
The Direct gain blend is worth noting for players who want to keep low end and attack under a swept filter: the dry signal is mixed back in alongside the filtered one rather than replaced1.
Routing and stereo use
The two input and two output jacks back up the pedal's three routing modes1:
- STEREO: the two filters run as independent channels.
- MONO IN-DUAL OUT: one input is split to two filtered outputs.
- MONO-SERIES: the filters run in series for deeper filtering.
The maker says these options allow for limitless applications1.
Power, size and specifications
The maker's page gives the supply as 9V-12V DC, and separately describes it as operating on standard 9V with a negative center tip and a 100mA power port. The specifications list states the pedal draws 110 mA. The two current figures differ and the maker's page gives both1.
The stated 110 mA draw is high for a 9V pedal, so a standard low-current daisy-chain output may not be adequate; the maker specifies a 100mA power port1.
For size, the specifications list gives 4.75" x 2.5" x 7.25" and a weight of 1 lbs, while the product data table on the same page lists 8 x 6 x 3 in and 24 oz. The two sets of figures disagree, and both are given here as the maker states them1. The pedal carries a 1 Year Limited Warranty, and the maker's page carries a California Prop 65 warning that the product can expose you to chemicals including lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm1.
What reviewers say
The maker's product page states "There are no reviews yet" as of 26 October 2026, so no published reviewer verdicts on the Super-Freq are available1.
Questions
Does the Mu-Tron Super-Freq work in stereo?
Yes. The maker says the Super-Freq can be used in STEREO, in MONO IN-DUAL OUT, or in MONO-SERIES, which it says allows for limitless applications. The pedal carries two 1/4-inch input jacks and two 1/4-inch output jacks, so both channels can be fed and taken separately.
What power supply does the Mu-Tron Super-Freq need?
The maker's page gives the supply as 9V-12V DC, and also describes it as operating on standard 9V with a negative center tip and a 100mA power port. The specifications list separately states the pedal draws 110 mA. The two current figures differ, and the maker's page gives both.
Is the Mu-Tron Super-Freq made in the USA?
Yes. The maker's product page states the Super-Freq is made in the US, and it carries a 1 Year Limited Warranty.
What is a state variable filter?
As the maker describes it, a state variable filter is a type of active filter in electronic circuits which can produce simultaneous lowpass, highpass and bandpass outputs from a single input. The Super-Freq uses two of them, and each can be actuated by an envelope, set up as a wah, or run as a parametric EQ with resonance control.
What are the Super-Freq's three routing modes?
STEREO, MONO IN-DUAL OUT, and MONO-SERIES. In STEREO the two filters run as separate channels; in MONO IN-DUAL OUT one input feeds two filtered outputs; in MONO-SERIES the filters run one after the other. The maker says the routing options allow for limitless applications.
Sources (1)
- Super-Freq Vintage Silver, Musitronics Mu-Tron (mu-tron.com)
