BMW 328xi Speaker Size

Front Door Panel Speaker

Rear Door Panel Speaker

Rear Deck Lid Speaker

Rear Side Panel Speaker

Center Dash Speaker

Below Seats Speaker

BMW 328xi Speaker FAQ

Which BMW 328xi speakers should I replace first for maximum sound improvement?

Replace the front door panel 4 inch coaxial component speakers first. These handle most of your mid-range frequencies and vocals. The BMW 328xi front components typically run at 4 ohms and can handle 40-60 watts RMS. Since they're component speakers, you're getting separate woofers and the 1 inch tweeters in the door panels. This setup gives you better sound staging than the rear full-range speakers. The front speakers do most of the work anyway - your ears focus on sound coming from ahead of you.

Can I replace the BMW 328xi rear door coaxial speakers with component speakers?

You could swap the 4 inch rear door coaxials for components, but you'd need to figure out tweeter placement. The rear door panels in the BMW 328xi don't have dedicated tweeter locations like the fronts do. Most people just upgrade to better 4 inch coaxials back there. Look for speakers rated around 25-50 watts RMS at 4 ohms. The rear speakers mainly provide fill and ambiance. Component speakers in the rear might actually create imaging issues since you want the soundstage focused forward.

Why does my BMW 328xi have both rear door and rear side panel speakers?

The rear side panel speakers are probably part of a premium audio package. Some BMW 328xi models have additional 4 inch coaxials and 0.75 inch tweeters mounted in the rear side panels for enhanced surround sound. These work with the main rear door speakers to create wider sound coverage. The side panel speakers typically handle higher frequencies while the door speakers focus on mids and lower frequencies. This creates better rear passenger sound quality but can complicate upgrades since you have multiple speakers competing for the same frequency ranges.

What's the difference between the center dash and other 4 inch speakers in the BMW 328xi?

The center dash 4 inch coaxial serves as a center channel speaker. It's designed to anchor vocals and dialogue right in front of you. Most aftermarket replacements should be 4 ohm speakers handling 20-40 watts RMS. The center speaker doesn't need as much power as your main front speakers since it's handling a narrower frequency range. Some people disconnect it entirely when upgrading to avoid muddying the soundstage from the front components. But if your BMW 328xi came with it, the factory amplifier probably expects it to be there.

Should I upgrade the BMW 328xi 8 inch under-seat subwoofer?

That 8 inch under-seat driver is more of a mid-bass woofer than a true subwoofer. It probably handles frequencies from around 80Hz to 200Hz. Upgrading it can improve punch and warmth, but you're limited by the sealed enclosure size under the seat. Look for 8 inch woofers designed for small sealed boxes, rated around 4 ohms and 75-150 watts RMS. The factory unit might be running active with built-in crossover filtering. You'd need to verify the BMW 328xi amplifier specifications before swapping drivers. An actual subwoofer upgrade would mean adding something larger elsewhere.