BMW 640i Rear Side Panel Speaker Size
The BMW 640i rear side panel accommodates 1 inch speaker size and 4 inch speakers across all model years covered. Compatible types for the audio positions include tweeters and midrange units. The system specifications span the 2012 to 2018 model year range.
| Year | Type | Size (inch) |
|---|---|---|
| 2018 | Tweeter | 1 |
| 2018 | Midrange | 4 |
| 2017 | Tweeter | 1 |
| 2017 | Midrange | 4 |
| 2016 | Tweeter | 1 |
| 2016 | Midrange | 4 |
| 2015 | Tweeter | 1 |
| 2015 | Midrange | 4 |
| 2014 | Tweeter | 1 |
| 2014 | Midrange | 4 |
| 2013 | Tweeter | 1 |
| 2013 | Midrange | 4 |
| 2012 | Tweeter | 1 |
| 2012 | 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 640i accommodates 2 distinct speaker sizes simultaneously, indicating a multi-driver configuration built into the panel housing.
- A 1-inch tweeter in the rear side panel handles high-frequency reproduction, typically covering the range above 2,000 Hz, where directional dispersion from a compact dome or cone element contributes to high-frequency presence in the rear cabin zone.
- The small physical diameter of a 1-inch tweeter limits low-frequency excursion, making the rear side panel placement acoustically appropriate for high-frequency reinforcement rather than full-range output.
- A 4-inch midrange driver in the rear side panel operates across the vocal and upper-instrumental frequency band, generally spanning roughly 300 Hz to 5,000 Hz, filling the acoustic space between subwoofer-range reproduction and the tweeter's upper register.
- The 4-inch cone diameter produces sufficient surface area for midrange frequencies while remaining compact enough to fit within the constrained depth and width of a side panel enclosure typical of a coupe body style.
- The BMW 640i rear side panel pairing of a 1-inch tweeter with a 4-inch midrange reflects a divided frequency responsibility between the 2 drivers, where crossover filtering directs the appropriate frequency bands to each unit.
- Rear side panel installations are typically recessed into the trim structure of the vehicle's C-pillar or quarter panel region, which affects the baffle depth and mounting orientation available to each driver.
- The 4-inch midrange driver's enclosure conditions within a sealed or semi-open side panel cavity influence resonance behavior, particularly in the lower portion of the midrange band where cabinet volume plays a role in low-end rolloff.
- The 1-inch tweeter's wide horizontal dispersion at high frequencies is relevant in the rear side panel position, where the driver radiates toward occupants seated in the rear rather than projecting forward along the vehicle's primary listening axis.
- The specifications apply consistently across model years 2012 through 2018, indicating a stable rear side panel cavity dimension across the full production span covered.