BMW 328i Rear Side Panel Speaker Size
The BMW 328i rear side panel accommodates 1 inch speakers, 0.75 inch units, and a 4 inch speaker size across the applicable model years. Compatible types include tweeters and midrange speakers. The specifications cover a range of years from 2007 to 2013.
| Year | Type | Size (inch) |
|---|---|---|
| 2013 | Tweeter | 1 |
| 2013 | Tweeter | 0.75 |
| 2013 | Midrange | 4 |
| 2012 | Tweeter | 0.75 |
| 2012 | Midrange | 4 |
| 2011 | Tweeter | 1 |
| 2011 | Tweeter | 0.75 |
| 2011 | Midrange | 4 |
| 2010 | Tweeter | 1 |
| 2010 | Tweeter | 0.75 |
| 2010 | Midrange | 4 |
| 2007 | Tweeter | 1 |
| 2007 | Tweeter | 0.75 |
| 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 side panel location in the BMW 328i sits within the interior cabin wall behind the rear passenger seating area, a position that places speakers at roughly ear level for rear occupants and at an angle that contributes to the rear soundstage.
- The rear side panel mounting environment typically involves a recessed or flush-fit cavity within the trim panel, meaning speaker depth clearance and diameter are constrained by the thickness of the panel and the structural elements of the vehicle body behind it.
- A 4 inch diameter midrange speaker is among the sizes listed for the BMW 328i rear side panel across all model years in the specifications, and at this diameter the cone surface area is sufficient to reproduce the midrange frequency band, generally considered to span roughly 250 Hz to 5 kHz, which covers the core presence of vocals and most acoustic instruments.
- A 4 inch midrange driver in a rear side panel position reinforces the ambient and spatial qualities of the rear cabin audio field, as midrange frequencies at this location fill the space around rear passengers rather than projecting a focused point-source sound.
- The 1 inch tweeter size listed across multiple model years in the specifications represents a dome or similar small-diaphragm driver, where the compact radiating surface allows reproduction of high frequencies, typically from around 2 kHz to 20 kHz, with reduced mass enabling faster diaphragm movement at those frequencies.
- A 1 inch tweeter mounted in the rear side panel of the BMW 328i directs high-frequency content toward the rear cabin, where treble frequencies are otherwise prone to directional loss due to their short wavelengths and tendency to not diffuse as widely as lower frequencies.
- The 0.75 inch tweeter size also listed in the specifications is smaller in diaphragm diameter than the 1 inch variant, and at 0.75 inch the driver is suited to even higher-frequency reproduction with a very narrow dispersion pattern, which affects how treble content spreads within the rear side panel location.
- The simultaneous listing of both 0.75 inch and 1 inch tweeters as compatible types for the BMW 328i rear side panel indicates the mounting cavity accommodates 2 distinct tweeter footprints, each with different frame and magnet assembly dimensions that must fit within the same panel space.
- The rear side panel location is generally more acoustically enclosed than front door positions due to reduced panel flex and greater structural rigidity in the rear body section, which can affect resonance behavior of the speaker mounting surface.
- Tweeters in a rear side panel placement, whether 0.75 inch or 1 inch, operate in a high-frequency range where off-axis response becomes increasingly narrow, meaning the angle of installation relative to rear passenger ear position is a relevant factor for perceived audio quality in that seating zone.
- The 4 inch midrange driver, compared to the tweeter sizes listed, has a significantly larger cone mass and surround, requiring a correspondingly larger cutout and mounting depth within the rear side panel trim structure of the BMW 328i.
- Across the model years present in the specifications, the rear side panel of the BMW 328i consistently accommodates both a midrange size and at least 1 tweeter size, indicating the location supports a multi-driver configuration within the panel rather than a single full-range installation.