A tweeter is a loudspeaker that produces high frequencies. The range of frequencies is typically from around 5,000 hertz to 22,000 hertz (20,000 Hz is generally considered to be the upper limit of human hearing). However, piezoelectric tweeters reach up to frequencies of 30,000 hertz, and one exotic example is claimed to reach up to 100,000 hertz.
In home stereo systems, most tweeters are dynamic (voice coil driven) small domes or cones of 1.5 inches (38 mm) or less in diameter. More exotic designs can use electrostatically driven diaphrams, or metallic ribbons suspended in a magnetic field.
Tweeters for sound reinforcement and public address applications are often horn-loaded piezoelectric speakers. The horn increases the efficiency and directivity of the speaker.
Tweeter output is highly directional. Due to the short wavelengths reproduced, it tends to beam in a single direction. This renders correct placement of cabinets containing tweeters a critical part of both home applications and sound reinforcement design.
Because tweeter voice coil wire must be small diameter to reduce weight, they are the most sensitive of any speaker type to overpowering and burnout. Overdriving an amplifier to distortion is a common reason for tweeter failure.
A new type of tweeter is appearing on the market today, with "Niobium Rare Earth Ferroelectric Transducer Magnet".
See also