BMW Alpina B7 Rear Door Panel Speaker Size
The BMW Alpina B7 rear door panel accommodates a 1 inch speaker size and 4 inch speakers. Compatible types for these locations include tweeters and midrange units. These specifications cover the 2007 to 2017 model years.
| Year | Type | Size (inch) |
|---|---|---|
| 2017 | Tweeter | 1 |
| 2017 | Midrange | 4 |
| 2015 | Tweeter | 1 |
| 2015 | Midrange | 4 |
| 2014 | Tweeter | 1 |
| 2014 | Midrange | 4 |
| 2013 | Tweeter | 1 |
| 2013 | Midrange | 4 |
| 2008 | Midrange | 4 |
| 2007 | 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 of the BMW Alpina B7 accommodates 2 distinct speaker sizes across the listed model years: 1 inch and 4 inch.
- A 4-inch midrange driver operates within the vocal and upper-bass frequency band, roughly 300 Hz to 5 kHz, making placement within the rear door panel acoustically significant for passengers seated in the rear cabin, as door-mounted positioning directs sound laterally toward occupants at ear or shoulder level.
- The 1-inch tweeter handles high-frequency content, typically above 2 kHz to 3 kHz, and at rear door panel locations, the compact diameter allows for placement that reduces high-frequency dispersion loss experienced by rear-seat occupants.
- Door panel mounting generally places drivers within a constrained cavity behind the panel surface, which can introduce boundary reinforcement at lower frequencies and affect rear-wave cancellation depending on enclosure depth behind the mounting surface.
- The BMW Alpina B7 rear door panel lists compatible speaker types of tweeter and midrange across multiple model years, indicating a 2-way speaker configuration at the rear door location rather than a full-range or 3-way arrangement.
- A 4-inch cone driver in a midrange role within a door panel operates with a relatively narrow physical aperture, which at higher frequencies within the midrange band begins to narrow the horizontal dispersion angle, relevant given the lateral orientation of door-mounted speakers.
- The 1-inch tweeter size is consistent with dome tweeter formats standard in automotive applications, where the small radiating surface produces wide high-frequency dispersion suited to the varied listening positions within a rear passenger compartment.
- In 2007 and 2008, the rear door panel of the BMW Alpina B7 lists only the 4-inch midrange, without a corresponding 1-inch tweeter entry, as is present in the 2013 through 2017 model year listings.
- Door panel speaker cutouts impose fixed dimensional constraints on cone diameter and magnet depth, and the 4-inch specification defines the maximum cone diameter fitting the rear door panel mounting location across all listed model years.
- The pairing of a 1-inch tweeter and a 4-inch midrange at the rear door panel location places both high-frequency and mid-frequency reproduction within the same door surface, concentrating the acoustic output of both drivers from a single lateral plane relative to rear-seat occupants.