The BMW 735iL rear door panel accommodates a 6x8 inch speaker size, consistent across all applicable years. Full-range units represent the compatible audio system types for the rear door panel location. These specifications cover the 1990 to 1992 model year replacement 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 rear door panel location places speakers within the door cavity, where the mounting surface is typically a vertical panel integrated into the interior trim, requiring speakers to project sound into the cabin at seat level.
A 6x8 inch speaker occupies an oval or rectangular footprint that is larger than a standard 6.5 inch round driver, giving the cone a greater surface area to move air and reproduce lower frequencies with more efficiency in a door-mounted position.
The 6x8 inch format in a rear door panel positions the driver closer to the lower portion of the listening environment, which acoustically reinforces bass and lower midrange frequencies due to boundary loading effects from the door structure and floor proximity.
The BMW 735iL rear door panel accepts a 6x8 inch driver across the 1990, 1991, and 1992 model years, indicating a consistent cutout dimension in the door panel for that production span.
Full-range speakers are designed to reproduce the entire audible frequency spectrum - typically from approximately 50 Hz to 20 kHz - from a single driver, without requiring a separate crossover network to divide frequencies between dedicated components.
In a rear door panel application, a full-range driver handles low-frequency reinforcement and midrange vocal presence simultaneously, functioning as a self-contained acoustic unit within the door cavity.
The oval geometry of a 6x8 inch driver allows the cone to favor low-to-mid frequency reproduction, as the larger physical dimension along the major axis contributes to greater cone excursion for bass output, while the shorter axis helps maintain some directional control in the midrange.
Door panel mounting subjects speakers to road vibration transmitted through the door structure, and the mechanical mass of a 6x8 inch driver must be compatible with the mounting depth available within the rear door cavity of the 735iL.
Full-range drivers in rear door positions serve a supplementary role in stereo imaging by extending the soundstage toward the rear of the cabin, operating across the full frequency band without requiring an external filter or amplifier channel dedicated to a specific frequency range.