BMW X1 and X2 Speaker Upgrade: The Complete Guide for F48, F39, and U11 Owners

TLDR: The BMW X1 and X2 use the S674A Harman Kardon system, not the S688A system found in larger BMW platforms. It's a less powerful configuration than most owners expect from the Harman Kardon name.

Stage One replaces the factory drivers with OEM-matched components and no coding required. The Ghost Subwoofer fits the F48 X1 and F39 X2.

Both together turn one of BMW's weakest factory audio setups into one of its most improved. Build your kit here.

The X1 and X2 sit at the entry point of BMW's SUV lineup. Compact, practical, well-priced relative to larger X models. The audio system reflects that positioning in a way that surprises a lot of buyers who expected more.

The base system is what you'd expect from a budget configuration: six speakers, no external amplifier, no tweeters.

What surprises people is the Harman Kardon option. The X1 and X2 cannot be equipped with the S688A Harman Kardon system available on the X3, X5, 3 Series, and 5 Series. BMW reserves that system for its more premium platforms.

Instead, the X1 and X2 get the S674A system. Same Harman Kardon badge. Different amplifier. Fewer speakers than the S688A on comparable platforms.

The S674A setup's specifications are very similar to the regular Hi-Fi option but with more speakers. It lacks the fiber optic signal transmission and more capable amplifier of the full S688A system.

That's the starting point. Stage One and the Ghost are the finish line.

F48 X1 (2016 to 2022) and F39 X2 (2018 to 2023)

These two platforms share the same audio architecture and the same upgrade path.

Audio configurations: Base and Harman Kardon S674A. Standard Hi-Fi (S676A) was not widely available on US-spec F48 and F39 models. Most US cars have either base or the S674A HK option.

Base system: Six speakers powered entirely by the head unit. No external amplifier. No tweeters. Two front door midranges, two rear door midranges, two underseat woofers. The underseat woofers are often mistaken for subwoofers. They are not. They're standard woofers that happen to be positioned under the front seats.

S674A Harman Kardon: More speakers than base with a dedicated amplifier, but not the amplifier found in the S688A system on larger BMW platforms. The X2's HK system is described on Harman Kardon's own site as having "two central bass woofers underneath the front seats" as a feature.

Those are the same woofer positions the base system has, just better driven. The system sounds noticeably better than base. It does not sound like the HK system in an X3 or 5 Series.

How to confirm your system: iDrive, Settings, Vehicle Information, Vehicle Data. S674A is Harman Kardon. No code is base.

U11 X1 (2023 to Present)

The third-generation X1 is a complete redesign on a new platform with updated audio configurations.

Audio configurations: Base and Harman Kardon. The U11 generation moved to a larger, more practical body with a more upright interior. Audio option availability on the U11 has expanded compared to the F48 generation.

What to know: The U11 is a newer platform, and Stage One fitment continues to be developed. Use the Build Your Kit tool to confirm Stage One and Ghost availability for your specific U11 model year before ordering.

Why the S674A Disappoints X1 and X2 HK Owners

The pattern is consistent across BMW audio communities. X1 and X2 owners who optioned HK expected the system to deliver something close to what a premium aftermarket brand implies.

What they got is a system that's meaningfully better than base but still falls short of what the Harman Kardon brand suggests.

The amplifier is the main reason. The S674A runs less power than the S688A. The cabin in an X1 is smaller than an X5, which means the power differential matters less in absolute terms. But the speaker quality limitation applies regardless of cabin size.

Paper and polymer cone drivers in a dedicated HK amplifier setup still compress at volume and lose midrange definition under pressure.

Stage One addresses the speaker quality limitation directly. The amplifier stays in place. The factory wiring stays in place. What changes is what the amplifier has to work with: woven fiberglass cone woofers and silk composite tweeters instead of the factory drivers.

Diego, who upgraded his 2021 X3 M, described the result after his Stage One install: "Quality is way better than stock. Sound is amazing. I even had to turn down the bass." The X3 M shares a similar HK architecture. The X1 and X2 Stage One improvement follows the same pattern.

Stage One and Ghost: The Complete X1 and X2 Upgrade

This is the post where giving Stage One and Ghost equal billing matters most. Here's why.

The base X1 system has no tweeters and no dedicated amplification. The S674A system has tweeters and an amplifier, but no meaningful low-end output from a dedicated subwoofer.

Neither configuration produces bass that feels present and physical in the cabin. The underseat woofers do what they can. It's not enough.

The Ghost Subwoofer fits the F48 X1 and F39 X2. It installs in the underseat space that already exists in the car, connects to factory wiring, and adds the dedicated low-frequency output that neither factory configuration provides. No drilling. No trunk space. No coding.

For X1 and X2 owners, the combination of Stage One and Ghost is a more complete transformation than on almost any other BMW platform. The starting point is lower. The gain from both products together is proportionally larger.

Steve, a Bavsound customer who upgraded with both Stage One and Ghost, described the experience: "The plug and play install was a breeze. Take your time, watch the videos and anyone can install these speakers and subwoofers. The bass is clear and tighter. I am so impressed with Bavsound's speakers and subwoofers."

That's the X1 and X2 upgrade story. Two products, one afternoon, a system that sounds like it belongs in a more expensive car.

Build your complete X1 or X2 kit here.

Base / S674A / Stage One + Ghost Comparison

The X1 and X2 Install: What to Expect

The F48 and F39 share a similar door panel removal process. Compact SUV panels are smaller than X5 doors and come off faster. The underseat positions for both Stage One woofers and the Ghost require sliding the front seat to access the mounting hardware.

Tools you need: Trim panel removal tool, T20 Torx bit, Phillips head screwdriver.

Time estimate: Front doors take 45 to 60 minutes each on a first install. Rear doors are faster. Adding the Ghost runs about 30 to 45 additional minutes. Plan on two and a half to three hours for Stage One and Ghost together.

Doing both at once: This is the post where it makes the most sense. Stage One and Ghost together in a single session means one afternoon instead of two. The Ghost underseat install happens at the same time you're accessing the underseat woofer positions for Stage One. The overlap is significant.

Watch the chassis-specific install video at bavsound.com/pages/bavsound-install-tutorials before starting. The F48 has a specific clip sequence on the rear door panels that the video covers in detail.

Frequently Asked Questions

Why can't I get the S688A Harman Kardon system on my X1? BMW reserves the S688A system for its more premium platforms. The X1 and X2 are entry-level SUVs in BMW's lineup, and the audio configuration reflects that positioning. The S674A is a genuine improvement over base, but it's a different system from the HK available on larger BMW models.

Is Stage One worth it on a base X1 without any audio upgrade? Especially worth it. Base X1 owners start from six speakers with no amplification and no tweeters. The improvement from Stage One is larger in proportional terms than on almost any other BMW platform. Adding the Ghost completes the picture.

Does the Ghost fit the F39 X2 as well as the F48 X1? Yes. Both platforms share compatible underseat dimensions. Confirm fitment for your specific model year using the Build Your Kit tool before ordering.

I have a 2023 or newer U11 X1. Does Stage One fit? The U11 is a newer platform. Use the Build Your Kit tool to confirm current fitment for your specific model year. Stage One development for newer platforms is ongoing.

Can I do Stage One and Ghost in the same install session? Yes, and that's the recommended approach for X1 and X2 owners. The underseat access for Stage One woofer positions and Ghost installation overlaps significantly. One session is more efficient than two.

Key Takeaways

The X1 and X2 cannot be equipped with the S688A Harman Kardon system available on larger BMW platforms. The S674A system is a genuine upgrade over base but uses less powerful amplification and fewer speakers than the full HK system.

Stage One replaces the factory drivers with woven fiberglass cone woofers and silk composite tweeters matched to the S674A amplifier. The improvement is immediate and significant on both base and HK X1 and X2 cars.

The Ghost Subwoofer fits the F48 X1 and F39 X2. No factory X1 or X2 configuration includes a dedicated subwoofer. The Ghost fills that gap without drilling, coding, or permanent modification.

Stage One and Ghost together in a single afternoon session is the most efficient upgrade path for X1 and X2 owners. The combined improvement is proportionally larger than on most BMW platforms because the factory starting point is lower.

Everything is reversible. CPO and lease owners do this regularly.

Build your complete X1 and X2 kit here.

About the Author Bavsound Engineering Team The Bavsound engineering team has spent over two decades reverse-engineering BMW factory audio systems to build direct-replacement upgrades that work without modification.

Every Stage One kit, Ghost Subwoofer, and Revenant Pro amplifier is developed from hands-on analysis of factory speaker specs, impedance curves, and OEM connector configurations across hundreds of BMW chassis codes.

They have done this install more times than they can count.

Not sure which kit fits your X1 or X2? Use the Build Your Kit tool or email support@bavsound.com with your VIN and model year.

We will confirm fitment before you order.