The Mazda Miata headrest location accommodates a 3.5 inch speaker size across all listed model years. Full-range units are the compatible speaker type for the audio system. These specifications cover the years 1990 through 1997.
A single driver that reproduces bass through treble without a separate crossover network. It is the simplest replacement option and is common in factory audio systems.
Additional Notes
The headrest is an uncommon speaker location, positioning drivers within centimeters of the listener's ears rather than at a distance from a door panel or rear deck.
Proximity to the listener's ears in a headrest installation reduces the acoustic influence of the vehicle cabin's reflective surfaces on the perceived sound.
The Mazda Miata headrest accommodates a 3.5 inch speaker across all listed model years, indicating a physically constrained cavity consistent with the slim profile typical of sports car headrests.
A 3.5 inch driver carries a small cone surface area, which limits low-frequency displacement and places the speaker's effective output range primarily in the midrange and upper-midrange frequencies.
At close listening distances such as a headrest position, the reduced bass output of a 3.5 inch driver is less acoustically significant than it would be in a door or rear deck installation farther from the ear.
Full-range drivers are designed to reproduce a wide span of the audible frequency spectrum within a single driver, covering low-midrange through high-frequency content without a crossover network.
In a headrest location, a full-range driver handles treble reproduction at a very short throw distance, which can produce pronounced high-frequency detail due to minimal air-path absorption between cone and ear.
The sole compatibility with full-range type speakers, as listed for the Mazda Miata headrest, reflects the spatial constraints of the location, where there is insufficient room to mount component tweeters or woofers separately.
A 3.5 inch full-range driver in a headrest enclosure operates in a very small rear air volume, which affects the driver's bass extension and resonant behavior compared to a larger or more open mounting environment.
The consistent 3.5 inch sizing across the 1990 through 1997 model years indicates dimensional uniformity in the headrest cavity across that production span.