tweeter

A tweeter is a specialized loudspeaker driver engineered to reproduce sound frequencies typically between 2,000 Hz and 20,000 Hz, the upper range of human hearing. Where a woofer handles bass and a midrange driver covers the middle frequencies, the tweeter's job is to deliver clarity, detail, and presence in the treble band. This division of labor across multiple drivers is called a crossover system, and it exists because no single cone can move fast enough to handle both deep lows and crisp highs efficiently.

Tweeters come in several designs. The most common is the dome tweeter, which uses a small hemispherical or inverted dome made of materials like polypropylene, silk, or aluminum, typically 0.75 to 1.5 inches in diameter. Above that sits the horn tweeter, which uses a flared waveguide to direct sound and improve efficiency and directivity. Ribbon tweeters employ a thin metal ribbon suspended in a magnetic field and excel at producing very smooth, detailed response. Piezo tweeters use crystalline materials that vibrate when voltage is applied, and they are cheap but rarely used in professional audio because of their narrow frequency response and poor off-axis performance.

Where tweeters live and fail

In a multi-driver loudspeaker enclosure, the tweeter sits physically separate from the woofer, often mounted in its own baffle section or horn. A passive crossover network (built from capacitors, inductors, and resistors) divides the incoming signal and routes high frequencies to the tweeter while blocking low frequencies. Active crossovers using electronic circuits instead of passive components allow more precise control but require amplification and more real estate. The tweeter's impedance, usually 4 or 8 ohms, must match the crossover design and amplifier output.

The main failure modes are mechanical rather than electrical. The dome or ribbon can tear from physical impact or thermal stress if driven too hard at high volume. The surround, a flexible ring of material that allows the cone or dome to move, degrades from age, heat, and UV exposure, eventually tearing or stiffening and preventing motion. The voice coil (the wire wrapped around the core that sits in the magnetic field) can burn out if impedance drops or if the amplifier clips and sends unfiltered DC current. Dust and moisture can accumulate in the gap and stiffen the mechanism.

The term tweeter comes from the high-pitched chirping sound of a bird's call, an onomatopoeia that stuck because these drivers quite literally tweet. In the 1920s and 1930s, as radio and recording moved beyond tinny single-speaker systems, engineers realized that bass and treble needed separate mechanical solutions. The tweeter became essential to home audio, car audio, and professional sound reinforcement. Today, you will find them in everything from bookshelf speakers at 40 Hz crossover point to three or five-way speaker systems in concert venues, where multiple tweeters might be arrayed together to achieve wider coverage angles than a single driver can provide.