Types of loudspeakers

Loudspeakers can be classified by their transduction method, radiation method, frequency range, or physical arrangement.

Moving-coil drivers

The moving-coil driver is the most common design. A voice coil moves in a permanent magnetic field and drives a cone or dome.

Advantages:

• Mature and widely available
• Suitable for almost every frequency range
• Compact and relatively economical
• Can provide high excursion

Challenges:

• Usually modest efficiency as a direct radiator
• Suspension and motor nonlinearities
• Diaphragm breakup at higher frequencies
• Directivity narrows as the radiator becomes large relative to wavelength

Compression drivers and horns

A compression driver feeds a horn through a small throat, often using a phase plug to organize the wavefront.

Advantages:

• High efficiency
• High maximum output
• Controlled directivity

Challenges:

• Horn resonances and diffraction must be controlled
• Directivity must be matched through the crossover region

A horn is an acoustic loading device; it is not a separate electrical transduction principle.

Coaxial and dual-concentric drivers

A coaxial system places the high-frequency driver on the acoustic axis of the low-frequency driver.

This can reduce variations caused by driver spacing, although the cone, waveguide, and crossover still require careful design.

Full-range drivers

A full-range driver attempts to cover most of the audible range without a conventional crossover.

It offers simplicity and a compact acoustic source, but one diaphragm must satisfy conflicting requirements for bass displacement, midrange behavior, and high-frequency dispersion.

Driver roles

• Subwoofer: Lowest frequencies
• Woofer: Bass and lower midrange
• Midrange: Middle frequencies
• Tweeter: High frequencies
• Super-tweeter: Upper treble
• Full-range: Attempts to cover most of the spectrum

No driver type is automatically superior. Implementation matters more than labels.