Danelectro U1, some Telecasters) H (Gibson ES-165 Herb Ellis, Kramer Baretta, later Les Paul Juniors) H-S (Hamer Californian Deluxe, Les Paul BFG, Squier '51) H-H-H (some Gibson Les Paul Goldtop and Custom models, Gibson SG-3, Gibson ES-5 Switchmaster (after 1957), Kramer Jersey Star, Ibanez Destroyer, Ibanez PGM200) Examples of rare configurations that only a few particular models use include: H-S, but with single coil in the middle (one model of Fender Jazzmaster, Ibanez RG2011SC, Fender Player Jaguar) H-S-S, but with no space between the middle single coil and the bridge humbucker (Hamer Phantom with angled neck pickup) H-H-S (Mayones Legend “22” Anders Nyström signature, some ESP Stephen Carpenter Models, and Alembic Jerry Garcia Models) H-S-S-H (Music Man Steve Morse Signature) S-H (some Telecasters, Music Man “Valentine” James Valentine signature) S-H-H (some early seven-string ESP Horizons) S-H-S (Fender Wayne Kramer Signature) Piezoelectric pickups Sensors The piezoelectric pickup contains a piezo crystal, which converts the vibrations directly to a changing voltage. Many semi-acoustic and acoustic guitars, and some electric guitars and basses, have been fitted with piezoelectric pickups instead of, or in addition to, magnetic pickups. These have a very different sound, and also have the advantage of not picking up any other magnetic fields, such as mains hum and feedback from monitoring loops. In hybrid guitars, this system allows switching between magnetic pickup and piezo sounds, or simultaneously blending the output. Solid bodied guitars with only a piezo pickup are known as silent guitars, which are usually used for practicing by acoustic guitarists. Piezo pickups can also be built into electric guitar bridges for conversion of existing instruments. Most pickups for bowed string instruments, such as cello, violin, and double bass, are piezoelectric. These may be inlaid into the bridge, laid between the bridge feet and the top of the instrument, or, less frequently, wedged under a wing of the bridge. Some pickups are fastened to the top of the instrument with removable putty. Preamps Piezoelectric pickups have a very high output impedance and appear as a capacitance in series with a voltage source. They therefore often have an instrument-mounted buffer amplifier fitted to maximize frequency response. The piezo pickup gives a very wide frequency range output compared to the magnetic types and can give large amplitude signals from the strings. For this reason, the buffer amplifier is often powered from relatively high voltage rails (about ±9 V) to avoid distortion