The Pontiac Fiero rear door panel accommodates a 4x6 inch speaker size across all listed model years. Full-range units are the compatible audio system replacement types for the rear door panel location. These specifications cover the 1984 to 1988 model year chart range.
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 Pontiac Fiero rear door panel location accepts a 4x6 inch speaker footprint across all listed model years.
A 4x6 inch speaker is an oval-format driver, and the elongated shape allows a larger cone area than a round 4 inch speaker while still fitting within shallow or narrow door panel cavities typical of compact two-seat vehicles.
Door panel mounting positions place the speaker within the lower portion of the cabin, which acoustically favors mid-bass and midrange reproduction due to proximity to the listener's lower body and the reflective surfaces of door trim and glass.
The oval geometry of a 4x6 inch driver produces a directional pattern that is asymmetrical along its two axes, meaning horizontal and vertical dispersion differ from each other, a factor influenced by the orientation of the driver within the door panel cutout.
The full-range type designation indicates a single driver intended to reproduce the entire audible frequency spectrum without a crossover network, covering low, mid, and high frequencies from one cone and dust cap assembly.
Full-range drivers in a door panel location handle both midbass frequencies, which benefit from the door cavity acting as a partial enclosure, and upper midrange frequencies that contribute to vocal clarity and instrument presence.
The Pontiac Fiero rear door panel, across all listed years, is restricted to full-range compatibility, which means component speaker configurations requiring separate tweeters or passive crossovers are not listed as compatible types for the cutout dimensions and depth available at this location.
The rear door panel position in a two-seat sports car places the speaker in close lateral proximity to the occupants, a short listening distance that affects the perceived balance between frequency ranges reproduced by a full-range driver.
A 4x6 inch full-range driver in a door panel cavity relies on the door structure itself to provide some degree of rear-wave isolation, since door panels are not sealed enclosures, which influences the low-frequency output of the driver at this location.