The Cadillac Eldorado rear door panel accommodates a 6x9 inch speaker size. Compatible types for the location include full-range units. These specifications cover the years 1998 to 1999.
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 in the Cadillac Eldorado positions speakers within the door cavity, where mounting depth and baffle dimensions are constrained by the door's internal framework and window mechanisms.
A 6x9 inch speaker footprint requires an oval-shaped cutout and mounting surface that accommodates the elongated frame, meaning the rear door panel must provide sufficient flat baffle area to seat the speaker without interference from door hardware.
The 6x9 inch cone surface area is larger than a standard round speaker of comparable nominal diameter, which increases low-frequency displacement and extends bass response - a characteristic relevant to rear door placement, where mid-bass reinforcement from the listening position is typical.
Rear door panels are subject to vibration from road noise and door operation, and the mass of a 6x9 inch driver makes secure mounting critical to prevent resonance between the speaker frame and the door panel material.
The Cadillac Eldorado rear door panel accepts 6x9 inch drivers across the 1998 and 1999 model years, indicating dimensional consistency in the door cavity between those 2 model years.
Full-range speakers reproduce the entire audible frequency spectrum - typically from around 50 Hz to 20 kHz - from a single driver, making them suited for door locations where a single mounting point must handle both mid-bass and high-frequency content without a separate tweeter.
In a rear door panel position, a full-range driver's high-frequency dispersion is directed toward the cabin interior at an angle influenced by door panel geometry, which affects the treble energy reaching rear passengers.
The full-range type designation for the Cadillac Eldorado rear door panel means no crossover network is required at the speaker level, as the driver is designed to operate across the full spectrum without frequency filtering.