2008 BMW 128i Speaker Sizes
The 2008 BMW 128i factory audio system features locations where the front door panel and rear side panel accept 0.75 inch speakers. Front door panel and rear deck lid and rear side panel accommodate 4 inch units, while below seats accepts an 8 inch speaker size. Compatible speaker types for a replacement and upgrade include tweeter, midrange, and subwoofer.
Specific details regarding locations, speaker sizes, and types are outlined in the compatibility chart.
| Location | Size | Type | Notes |
|---|---|---|---|
| Below Seats | 8 | Subwoofer |
|
| Front Door Panel | 0.75 | Tweeter |
|
| Front Door Panel | 4 | Midrange |
|
| Rear Deck Lid | 4 | Midrange |
|
| Rear Side Panel | 0.75 | Tweeter |
|
| Rear Side Panel | 4 | Midrange |
|
2008 BMW 128i Speaker Replacement Summary
6
total positions
3
easy to replace
2
high priority
0
professional only
Replacement difficulty:
Low: 3 Medium: 3 High: 0Replacement priority:
High: 2 Medium: 2 Low: 22008 BMW 128i Radio Slot Size (DIN)
| DIN Type | Size (inch) | Size (mm) | Notes |
|---|---|---|---|
| Single DIN or Double DIN | 7"×2" or 7"×4" | 180×50 or 180×100 | Vehicle supports both radio sizes |
- Always measure the slot before purchasing a new radio
- Check slot depth - it may vary
Additional Notes
- The 2008 BMW 128i utilizes a component speaker system with separated tweeters and midrange drivers rather than full-range coaxial units, which typically allows for better soundstage imaging and frequency separation.
- Factory tweeters measure 0.75 inch and are positioned in both front door panels and rear side panels, handling the upper frequency range independently from other drivers.
- Midrange speakers at 4 inches are distributed across three locations: front door panels, rear side panels, and rear deck lid, providing mid-frequency coverage throughout the cabin.
- An 8-inch subwoofer location exists below the seats for low-frequency reproduction, which is relatively compact compared to aftermarket subwoofer options that often range from 10 to 12 inches.
- The component configuration in the 2008 BMW 128i suggests that replacing individual speaker types separately may be necessary rather than using single full-range replacements, potentially increasing installation complexity.
- Aftermarket component speaker sets with matching tweeter and midrange sizes could maintain the factory separation design while potentially offering improved materials like silk dome tweeters or polypropylene cones.
- The 0.75-inch tweeter size is less common than the standard 1-inch aftermarket tweeter format, which might limit direct replacement options without modifications or adapters.
- Sound improvement would likely come from upgrading the 4-inch midrange drivers first, as these handle the majority of vocal and instrumental frequencies where audio quality differences become most noticeable.
- The radio accepts both Single DIN and Double DIN head units, providing flexibility for aftermarket stereo installations that could power upgraded speakers more effectively than factory amplification.
- Under-seat subwoofer placement at 8 inches conserves trunk space but may produce less output than trunk-mounted alternatives due to spatial constraints and potential obstruction from seat frames.