BMW 740i xDrive Rear Deck Lid Speaker Size
The BMW 740i xDrive rear deck lid accommodates 1 inch speaker size units and supports 4 inch speakers. Compatible types across both sizes include tweeters and midrange units. The specifications cover a range of 2017 to 2018.
| Year | Type | Size (inch) |
|---|---|---|
| 2018 | Tweeter | 1 |
| 2018 | Midrange | 4 |
| 2017 | Tweeter | 1 |
| 2017 | 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 deck lid of the BMW 740i xDrive accommodates 2 distinct speaker sizes across the listed model years, with both sizes coexisting in the same location to serve separate frequency roles.
- A 1-inch diameter is a standard dimension for tweeters, as the small radiating surface area allows rapid pistonic movement necessary to reproduce high-frequency content, typically spanning from around 2,000 Hz up to 20,000 Hz or beyond.
- The rear deck lid placement of the 1-inch tweeter positions high-frequency sound reproduction toward the rear cabin area, where the lid surface acts as the mounting plane directing treble output into the passenger compartment.
- A tweeter relies on a lightweight diaphragm, often made from materials such as silk, aluminum, or ceramic, to achieve the fast excursion cycles required for upper-frequency audio reproduction.
- The 4-inch midrange driver in the BMW 740i xDrive rear deck lid handles the mid-frequency band, which generally covers the range from approximately 300 Hz to 5,000 Hz, encompassing much of the fundamental tonal content of vocals and instruments.
- A 4-inch cone size produces a focused, relatively directional midrange output, and when mounted in a deck lid panel, the driver fires upward or rearward into the cabin, depending on the baffle angle of the enclosure cutout.
- Midrange drivers reproduce frequencies that carry significant sonic detail, and a dedicated 4-inch unit at the rear deck lid supplements front-stage speakers by adding presence and body to the rear listening zone.
- The deck lid environment typically places speakers within a shallow or semi-enclosed panel cavity, which affects the available rear air volume behind the cone and can influence the lower boundary of effective midrange reproduction.
- Because the 1-inch tweeter and 4-inch midrange occupy the same rear deck lid location, the installation requires a crossover network or head unit processing to divide the audio signal so each driver operates within its appropriate frequency band without overlap or damage.
- Both the 2017 and 2018 model years of the 740i xDrive share identical size and type pairings at the rear deck lid, indicating a consistent mounting cutout dimension and depth across those production years.