Electro Harmonix Pico Swello Attack Envelope Brand_Vox Multi stage analog gain circuit developed If you re new Multi stage analog gain circuit developed with the acclaimed BOSS Tube Logic approach the original analog chorus sounds are now reborn with the Waza Craft CE 2W The MOD knob controls the depth and direction of the LPF envelope for upward or downward filter sweeps over a narrow or wide range of frequencies limited by the cutoff frequency This polyphonic attack filter is the core of the PICO Swello generating polyphonic and reverse sounds with the addition of a modulated low pass filter for even more expressive tones