The Kuassa Efektor WF3607 emulates a must-have classic with a rich history. In the 1920s, guitar players were fascinated by the wa wa wa sound made by trumpet players by opening and closing their mutes. Its filtering effect alters the resonance of the instrument, and it feels to increase the expressiveness of playing.More than 40 years later, an accidental invention resulted in a device that forever changes the sound of guitar. This pedal eventually known as the Cry Baby. Next, in the 1970s, an aborted synthesizer project resulted in a similar wah wah effect, which later known as Mu-Tron III envelope filter. These two devices revolutionized almost every genre of music as we know it today.