Behringer B-Tron III

The Behringer B-Tron III is an envelope filter pedal, the effect type that opens and closes a filter automatically as you play, producing an automatic "wah" or vowel-like sound with no rocking pedal under your foot. Behringer describes it as "a vintage envelope filter that creates a 'Wah' or 'vowel' sound every time you play a note," and says it "works great for bringing the funk with either guitar, bass or keyboards"¹. It is a budget take on one of the most storied pedals in the category: Guitar World called it "a not-so-subtle $69 replica of its Mu-Tron III envelope filter," referring to the original Mu-Tron III made by Musitronics².

What it does and how it is controlled

An envelope filter listens to the dynamics of your playing and sweeps a filter in response: pick harder and the filter opens further. The B-Tron III gives you two switches to shape that response.

MusicRadar's Jonathan Horsley, covering the launch, described the same layout: "the B-Tron III has three different filter modes - Low Pass, Band Pass and High Pass, selectable via a three-way rotary dial," and "The Rate switch can be set up to emphasise low vocal sounds or to tease out some more high-end overtones"³.

The original Mu-Tron III used a Gain control that "adjusts the filter's sensitivity to the signal of your instrument," and its Low-High switch, in the words of the Guitar FX Layouts technical analysis, "does not create distortion, just focuses the envelope detector on bass or treble tones"⁵⁶. That detector focus is what the B-Tron III's Range switch carries over.

Where it came from

The pedal the B-Tron III copies dates to the Musitronics era. The original Mu-Tron III's maker notes that its "original bi-polar internal voltage insures high headroom and low noise," and that it "can be used with an octave divider or other devices, or in pairs for cascading effects"⁷⁵. On That Pedal Show's introduction to auto-wah and envelope filters, Dan and Mick highlighted the Mu-Tron III's "sensitivity at the input" as a defining feature of the design⁸.

Behringer officially launched the B-Tron III Envelope Filter in February 2025, with pre-orders opening at $69 in the US². Guitar World reported that it "is being distributed, sight unseen, six month pre-order," and that "The pedal is most likely entirely made in China and will sell for less than the cost of what it takes us to produce here," the last part quoting Musitronics².

The response from Musitronics

The launch did not go unnoticed by the company behind the original. In February 2025, Musitronics posted publicly accusing Behringer of copying its products, trade dress and history with the $69 B-Tron III². Guitar World noted the episode "led to a social post from Musitronics last year after its hallmark stompbox was copied"⁹. The dispute is worth knowing about if you are weighing the B-Tron III against the reissue Mu-Tron III Vintage Silver or an original Musitronics Mu-Tron III: the Behringer sells for a fraction of the price, while the Musitronics-made versions carry the original circuit lineage.

For more on how this kind of effect works and what else is available, see the site's guide to filter pedals. Behringer has since expanded its filter line with the Behringer Meatball, a take on the Lovetone Meatball, and the BM-15M Murf Box, a budget version of the Moog MuRF.

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