Driver Size
Driver size is the nominal diameter assigned to a sound-producing transducer.
It is commonly expressed in millimetres or inches. Nominal size need not equal the effective radiating diameter or the dimension of every visible part.
Driver Size — Subwoofer
For a subwoofer, driver size identifies the nominal woofer diameter. It is one construction detail alongside driver count, excursion, enclosure loading and amplifier capability.
Compare sizes on the same stated basis, and keep multiple-driver arrangements distinct from one larger driver. Diameter alone does not establish maximum output or bass extension. A passive-radiator size should not be mistaken for the powered woofer size.
Driver Size — Loudspeaker
For a loudspeaker, sizes can be listed separately for bass, midrange and high-frequency drivers. Their different roles make a single largest diameter an incomplete description of the system.
Compare the size and role together, preserving whether a number describes a cone, dome or another driver dimension. Do not treat cabinet diameter or a mounting cutout as the nominal transducer size. Driver diameter alone does not describe crossover behaviour or the complete response.
Driver Size — Headphone
For headphones, driver size describes the nominal transducer dimension within an earpiece. This is separate from earcup size and from the number of drivers fitted.
Compare the stated measurement basis, particularly across different driver shapes and technologies. A larger nominal diameter does not automatically provide stronger bass or better sound. Fit, acoustic loading and the complete driver design also affect the result.