BMW Alpina B7L xDrive Rear Door Panel Speaker Size
The BMW Alpina B7L xDrive rear door panel accommodates 1 inch and 4 inch speaker size units across all listed model years. Compatible types include tweeters and midrange speakers. The specifications cover a range from 2013 to 2015.
| Year | Type | Size (inch) |
|---|---|---|
| 2015 | Tweeter | 1 |
| 2015 | Midrange | 4 |
| 2014 | Tweeter | 1 |
| 2014 | Midrange | 4 |
| 2013 | Tweeter | 1 |
| 2013 | Midrange | 4 |
Speaker Types
| Type | Description |
|---|---|
| Tweeter | A small driver built for high frequencies, typically from about 2,000 Hz to 20,000 Hz. It adds treble detail and clarity and is usually mounted near ear level or aimed at the listener. |
| Midrange | A driver for the middle of the audible range, typically from about 300 Hz to 5,000 Hz, where vocals and most instruments sit. It is often paired with a tweeter and a woofer. |
Additional Notes
- The rear door panel location in the BMW Alpina B7L xDrive houses 2 distinct speaker sizes, 1 inch and 4 inch, each assigned to a separate acoustic role.
- A 1 inch tweeter is a small-diaphragm driver designed to reproduce high-frequency content, typically from around 2,000 Hz up to 20,000 Hz or beyond, where cone mass must be minimal to track rapid air pressure changes accurately.
- Placement of a 1 inch tweeter within a rear door panel positions the high-frequency source at a lateral point in the cabin, contributing to the spatial width of the soundstage experienced by rear-seat passengers.
- A 4 inch midrange driver is sized to handle the vocal and instrumental frequency band, generally spanning approximately 300 Hz to 5,000 Hz, where human speech intelligibility and much of the harmonic content of musical instruments are concentrated.
- The 4 inch cone diameter in a door panel location allows the driver to couple acoustically with the door cavity, which can act as a baffle and influence the low-midrange output of the driver at the rear seating positions.
- Because the rear door panel is a sealed or semi-sealed enclosure formed by the inner door skin and panel, the 4 inch midrange driver operates within a confined air volume that affects its resonant behavior and output efficiency.
- The BMW Alpina B7L xDrive rear door panel configuration pairs a tweeter and a midrange driver together, which reflects a two-way arrangement at the rear door, where the frequency band is divided between the 2 drivers rather than handled by a single full-range unit.
- A 1 inch tweeter is typically mounted at or near ear level or angled toward the listening position; in a door panel, vertical placement relative to the 4 inch midrange affects the time alignment between the 2 drivers as perceived from the rear seats.
- The 4 inch size class of midrange driver is associated with moderate cone excursion capability, meaning the driver handles midband frequencies without the larger displacement required for low-frequency reproduction, which is consistent with a door panel location not designed for bass output.
- The specifications remain consistent across the 2013, 2014, and 2015 model years, indicating no change in the physical mounting dimensions or compatible driver types at the rear door panel location over that period.