The One Control Butter Yellow Auto Quack is an envelope filter pedal, the auto wah family of effects: instead of a rocking treadle, a circuit watches how hard you pick and sweeps a resonant filter up from each note's attack. One Control describes it as an envelope controlled filter whose center frequency moves upward as you strike a note harder, taking the initial transient of a plucked note and then following the note's decay1. Paolo De Gregorio, writing at Delicious Audio, describes it as an analog resonant filter on that same principle2.
It is part of One Control's BJF series of mini-pedals2, and it is adapted to the range of electric guitar and electric bass, with a more narrow range than keyboard envelope filters1.
One Control's product page listed the pedal as sold out as of 26 October 20261.
The controls
The Auto Quack keeps its faceplate simple: two knobs and a range switch. The SENSITIVITY control sets the level where transients trigger the filter to move, the DECAY control sets the rate it takes from the transient moving the filter to return, and the MELLOW/BRIGHT switch sets the filter range from low and narrow to high and wide1.
| Control | What it does |
|---|---|
| SENSITIVITY | Sets the level where transients trigger the filter to move1 |
| DECAY | Sets the rate it takes from the transient moving the filter to return1 |
| BIAS | Sets the starting point of the filter and can be used to sweep through the filter's entire range12 |
| MELLOW/BRIGHT switch | Sets the filter range from low and narrow to high and wide1 |
The Bias control is the one that shapes the character of the sweep most directly. One Control notes that the starting frequency can be set with the Bias control so that even small movements, which the maker calls mini-wahs, can be created on each plucked note1.
How it sits in a signal chain
Most envelope filters are played on clean tones, but One Control points out a second use: the Butter Yellow Auto Quack can also be used ahead of distortion to make a hand controlled wah effect, with your picking strength doing the work a treadle would1. That places it before distortion or overdrive pedals in the chain, in the usual spot for filter pedals.
One design detail separates it from many envelope filters: where filters often rest at a very low frequency, the BYAQ is made to rest at about transparent level. One Control says this allows having the BYAQ stay on as a see-through effect until a transient triggers the filter1. In practice, that means the pedal can remain engaged without coloring your clean tone between attacks.
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Questions
What does the Bias knob do on the Auto Quack?
The BIAS control sets the starting point of the filter and can be used to sweep through the filter's entire range. One Control notes that setting the starting frequency with the Bias control lets even small filter movements, which the maker calls mini-wahs, be created on each plucked note. Together with Sensitivity and Decay, it shapes how each note's attack opens the filter and where the sweep begins.
Is the One Control Auto Quack analog?
Yes. Delicious Audio's Paolo De Gregorio describes the Butter Yellow Auto Quack as an analog resonant filter whose center frequency moves upward as you strike a note harder. The maker describes it as an envelope controlled filter that takes the initial transient of a plucked note and follows the note's decay.
Can the Auto Quack go in front of a distortion pedal?
Yes. One Control says that though envelope filters are often used on clean sounds, the Butter Yellow Auto Quack can also be used ahead of distortion to make a hand controlled wah effect. Placing it before a distortion or overdrive pedal means your picking strength drives the filter sweep that the distortion then clips.
What does the Mellow/Bright switch do?
The MELLOW/BRIGHT switch sets the filter's range, from low and narrow in the Mellow position to high and wide in the Bright position. It works alongside the Bias control, which sets the filter's starting point, so the two together determine both where the sweep begins and how far it can travel.
Sources (2)
- BUTTER YELLOW AUTO QUACK (OC-BYAQn), One Control USA
- New Pedals: One Control Butter Yellow Auto Quack, Delicious Audio, 2020-12-03