What is the difference to the classic Piezo Stompbox? The P-Bass Stompbox is equipped with E-Bass pickups. Why Bass Pickups? Tones of about 50 - 100Hz we take as deep tones, tones with frequencies of 2000Hz or 5000Hz we perceive as high tones. Normally it is the vibrating strings that make the pickup respond. How is that supposed to work? Good question. The pickups are mounted under the License Plate. The vibrating metal plate generates the magnetic field and makes the pickup respond. But beware, not all Americans number plates are suitable for this. Most signs are made of aluminium and are therefore not magnetically conductive. So a fero-metallic number plate has to be used or something made of ferrite has to be mounted under the number plate. Metal can lids like those used for sweets are suitable for this.