The Infiniti M30 rear deck lid accommodates a 6x9 inch speaker size across all listed model years. Full-range units represent the compatible audio system type for the rear deck lid 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 deck lid is a horizontal surface located at the top of the trunk compartment, beneath the rear window. Speakers mounted in a rear deck lid fire upward toward the cabin, with sound reflecting off the rear glass before reaching the listening area.
A 6x9 inch oval speaker footprint requires a mounting cutout and baffle area large enough to accommodate the elongated frame, which spans a greater surface area than a circular 6-inch or 6.5-inch driver.
The oval geometry of a 6x9 inch driver allows for a larger cone surface area than a round speaker of comparable width, which increases low-frequency displacement capability without requiring a perfectly square or circular mounting cavity.
In a rear deck lid position, the physical distance between the drivers and the front seating area creates a delay in direct sound arrival, which is a spatial characteristic inherent to this mounting location.
Full-range speakers are designed to reproduce the entire audible frequency spectrum-typically from around 50 Hz to 20 kHz-from a single driver, making a dedicated crossover network unnecessary for basic installations.
In a rear deck lid context, a full-range 6x9 inch driver handles both midrange vocals and upper bass frequencies from a single mounting point, without requiring additional enclosure depth below the deck surface.
The Infiniti M30 rear deck lid position, in combination with a 6x9 inch full-range speaker, reflects a configuration where the driver must operate without a sealed rear enclosure, relying instead on the trunk cavity as an informal acoustic space behind the cone.
The cone area of a 6x9 inch driver is larger than that of most round midrange speakers, which influences how low-frequency waves develop at the mounting location relative to the enclosed trunk volume beneath the deck.
Full-range drivers at the rear deck lid position reproduce high frequencies as well as low-midrange content, meaning the tweeter element within the speaker cone or whizzer cone operates in a rearward-facing, upward-firing orientation relative to the passenger cabin.