The Vahlbruch Chorus Acoustic is an effect pedal specifically designed for acoustic instruments. It features a permanently active buffer/impedance converter to ensure a linear signal transfer through the downstream signal chain, which is particularly beneficial for passive piezo pickups, maintaining a stable and transparent sound. This pedal does not alter the phase of the pickup signal, preventing any cancellations between the direct sound of the instrument and the electronically amplified signal, thus retaining the familiar response and frequency spectrum.