BMW 135is Rear Side Panel Speaker Size
The BMW 135is rear side panel location accommodates a 1 inch speaker size and 4 inch speakers. Compatible types for the rear side panel include tweeter and midrange audio units. These specifications cover the 2013 model year system.
| Year | Type | Size (inch) |
|---|---|---|
| 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 side panel location in the 2013 BMW 135is accommodates 2 distinct speaker sizes, a 1 inch and a 4 inch, each assigned to a specific acoustic type.
- A 1 inch tweeter in the rear side panel handles high-frequency reproduction, typically covering the range above 2,000 Hz, where directional clarity and detail in upper harmonics are most critical.
- The small physical diameter of a 1 inch driver is acoustically suited to high-frequency work because shorter wavelengths require smaller diaphragm surface areas to reproduce accurately without distortion.
- The BMW 135is rear side panel pairs the 1 inch tweeter with a 4 inch midrange driver, placing both frequency-specialized speakers within the same panel zone.
- A 4 inch midrange driver is sized to cover the vocal and instrumental frequency band, generally spanning approximately 300 Hz to 5,000 Hz, where much of the perceived tonal presence of audio content resides.
- Placement in the rear side panel positions the midrange driver at a lateral angle relative to the primary listening area, influencing the spatial distribution of mid-frequency sound within the cabin.
- A midrange driver, as a speaker type, is designed to handle only a defined middle portion of the audible spectrum and is not intended to reproduce the lowest bass frequencies or the highest treble frequencies.
- The rear side panel mounting environment is typically a confined enclosure within the vehicle's interior trim, which affects the rear acoustic loading on a midrange driver and can influence its low-frequency rolloff behavior.
- The tweeter type, by design, produces minimal low-frequency output and relies on crossover filtering to receive only the high-frequency signal content appropriate to a 1 inch driver at the rear side panel position.