A 6×9 speaker can fit into a 6×8 opening, but the installation requires modification because the larger speaker frame does not align with the factory mounting points. Both sizes are common oval shapes used in automotive audio systems, typically in door panels or rear decks. Modifications range from simple hardware adjustments to physical alteration of the vehicle’s speaker location. This upgrade is often sought to leverage the larger speaker’s superior audio performance, particularly in the lower frequency range.
Comparing 6×9 and 6×8 Speaker Dimensions
The physical difference between the two speakers necessitates the installation adjustment. The 6×9 speaker is larger in both dimensions, with a frame approximately one inch longer than the 6×8 model. Although the “6” measurement is similar, the 6×9 speaker’s full dimensions offer a wider cone area compared to its counterpart.
This added surface area allows the 6×9 speaker to move more air, resulting in a richer bass response and fuller sound. Factory 6×8 openings often share a mounting hole pattern similar to 5×7 speakers, which is incompatible with the larger 6×9 frame. The modification must accommodate the larger frame and ensure the speaker cone can vibrate freely.
Adapters and Mounting Modifications
Successfully fitting the 6×9 speaker into the 6×8 opening involves two methods: using pre-fabricated adapters or performing custom modification. Adapter plates offer the most straightforward solution, bridging the gap between the two distinct mounting patterns. These brackets secure the 6×9 speaker while utilizing the vehicle’s original 6×8 screw holes.
Using Adapter Plates
Commercially available adapter plates are typically constructed from rigid ABS plastic or PVC, which are preferred for durability and resistance to moisture within car doors. Avoid using materials like wood or MDF for door applications, as they can swell and degrade when exposed to water, compromising the speaker’s seal and stability.
Custom Modification
The alternative is physically altering the opening by trimming the edges of the speaker hole or drilling new mounting holes. This custom approach requires careful measurement to ensure the larger speaker frame sits flush and the speaker cone remains clear of obstructions.
Physical and Electrical Installation Constraints
Even after resolving the mounting pattern issue, installation can be complicated by physical and electrical constraints within the vehicle. Speaker depth is the most common physical limitation, as the larger 6×9 speaker often features a deeper magnet structure than the factory 6×8 speaker. The magnet must not interfere with internal components, such as window tracks or door mechanisms, when the window is fully rolled down.
A spacer ring, often made of plastic or composite material, can push the speaker outward to gain necessary clearance behind the mounting surface. However, this introduces the problem of grille and panel clearance, potentially preventing the interior door panel from reattaching properly.
Proper electrical connection is necessary for optimal performance, requiring attention to the standard four-ohm impedance of most aftermarket speakers. The wiring connections must maintain correct polarity to ensure the speaker cone moves in phase. Correct phasing prevents the cancellation of bass frequencies and preserves the integrity of the sound.