A keyboard amplifier is a powered electronic amplifier and loudspeaker in a wooden speaker cabinet used for amplification of electronic keyboard instruments. Keyboard amplifiers are distinct from other types of amplification systems such as guitar amplifiers due to the particular challenges associated with making keyboards sound louder on stage; namely, to provide solid low-frequency sound reproduction for the deep basslines which keyboards can play and crisp high-frequency sound for the high-register notes. Another difference between keyboard amplifiers and guitar/bass amplifiers is that keyboard amps are usually designed with a relatively flat frequency response and low distortion. In contrast, many guitar and bass amp designers purposely make their amplifiers modify the frequency response, typically to "roll off" very high frequencies, and most rock and blues guitar amps, and since the 1980s and 1990s, even many bass amps are designed to add distortion or overdrive to the instrument tone (for bass, this is called "fuzz bass").