1. Low-frequency Speaker
For various speakers, the requirements for the quality factor of the low-frequency drivers—Q0—differ. For sealed and ported boxes, a Q0 value between 0.3 and 0.6 is generally preferable. Generally speaking, the larger the diameter of the low-frequency driver's diaphragm, magnet, and voice coil, the better the low-frequency reproduction performance, transient characteristics, and sensitivity. The structural form of the low-frequency unit is mostly cone-shaped, with a few being flat. The low-frequency unit membranes come in a variety of types, including aluminum alloy, aluminum-magnesium alloy, ceramic, carbon fiber, bulletproof cloth, glass fiber, acrylate, and paper membranes. Low-frequency units with aluminum alloy and glass fiber membranes typically have a smaller diameter but can handle higher power. Units with reinforced paper cones and glass fiber membranes reproduce music with more accurate sound quality and good overall balance.
2. Mid-frequency Speaker
In general, a mid-range speaker is sufficient as long as its frequency response curve is flat, its effective frequency range exceeds the width of the sound band it carries in the system, and its impedance and sensitivity match that of the low-frequency unit. Sometimes, if the power capacity of the mid-range is insufficient, one can opt for a mid-range with higher sensitivity and an impedance higher than the low-frequency unit, thereby reducing the actual input power to the mid-range unit. Mid-range units typically come in two types: cone and dome. Their size and power handling are simply larger than those of tweeters, making them suitable for mid-frequency reproduction. The diaphragms of mid-range units are mainly made of soft materials like paper and silk, with occasional use of a small amount of alloy dome diaphragms.
3. High-frequency Speaker
The high-frequency unit, as the name suggests, is a loudspeaker component designed for reproducing high-frequency sounds. Its structural forms mainly include horn, cone, dome, and aluminum ribbon types, among others.
