How to easily improve your sound system with a BMW under-seat subwoofer upgrade?


  • What speakers does BMW use? What size speakers are in a BMW? Where are the speakers in a BMW?
  • What do BMW under-seat subwoofers do to your sound?
  • What are the best speakers for BMW?
  • How to change speakers on a BMW How to disconnect the under-seat subwoofer BMW
  • How can I improve the sound system in my BMW even further?

We all know that BMWs are great driver’s cars, but how are they for a music fan?

The lucky few have vehicles that came fitted from the factory with a great amp and impressive speakers, most importantly pounding BMW under-seat subwoofers.

The rest of us have to make do with the sometimes lackluster sound systems BMW bundles with many of its cars, which all too often offer a weak sound that only gets worse as you turn the volume up.

Or do we…?

With top-quality aftermarket speakers and BMW subwoofers on the market, it’s easy to step up your BMW’s audio game. But before we start picking out hardware for our new stereo, it’s worth getting to know the factory BMW car speakers. Just so we know what we’re about to tear out so we can put something better in its place.


There are several BMW speakers brands, it all comes down to how much you want to pay…

The BMW HiFi sound system (S676A) and low-tier base stereo both feature OEM speakers from BMW’s partners, but don’t carry any overt branding from a known audio name. Those two stereo options are found in more than half of all BMWs, but the situation changes as you move up through the stereo options.

Harman Kardon BMW speakers are available in many vehicles, with the BMW/HK partnership already well-established at this point. Whether you’re looking for a 3 Series or an X5, you shouldn’t have any problem finding a vehicle with HK speakers. Just keep in mind that when it comes to the full Harman Kardon Surround Sound System, BMW limits its availability to higher-end models.

Those models may also be able to choose speakers from a more prestigious audio house, like Bang & Olufsen or Bowers & Wilkins, and as can be expected you’d be looking at dropping some serious coin to pick up one of those systems.

Learn more in our BMW Harman Kardon sound system review.

When it comes to the subwoofers, each stereo system includes woofers with a resistance (ranging from 2 Ohm to 8 Ohm) that will perform well with that system’s factory amplifier. That means you won’t get ideal performance from swapping out your subwoofers for those from another BMW OEM system — unless you’re changing the rest of your audio hardware, too.

What size speakers are in a BMW?

Don’t believe us? You could always try that swap out; almost all modern BMWs use standardized speaker sizes, so the speakers from all stereo options can fit neatly in the same cavity in the interior trim.

That means each speaker type is going to have the same diameter:

  • Subwoofers: 255mm
  • Midranges: 100mm
  • Tweeters: 25mm

Dedicated BMW replacement speakers, like those in the Alpha One BMW sound system upgrade, will be made to the same size with the same mounting points, so they easily bolt in in place of the factory speakers.

Where are the speakers in a BMW?

Where you’ll find your BMW’s speakers depends on both on which model you have, and which stereo system it’s kitted out with. That shouldn’t come as any surprise – the X5 has places to put a speaker that doesn’t even exist in a Z4.

A more premium sound system also comes with more speakers in more places, for a more immersive sound experience.

The BMW G20 audio system is representative of a typical kit, where a full set of speakers may consist of:

  • A tweeter and midrange in the dashboard.
  • A tweeter and midrange in the front doors.
  • A midrange in the rear doors/panels/shelf possibly with tweeters.
  • A BMW under-seat subwoofer under each front seat.
  • A pair of tweeters and midranges on the real shelf.

Larger vehicles may have speakers in the D pillars, to make sure the whole vehicle is filled with sound. The exact location can also be a little different; some two-seaters fit the subwoofers behind the seats, rather than under them.

This only applies to vehicles with a higher-end stereo system. In lower-spec vehicles, the BMW door speakers are probably going to stay, but you’ll likely have to do without any (or as many) speakers in the dashboard and rear shelf / D pillar positions.

That said, when buying BMW replacement speakers or getting a BMW amplifier upgrade, you may choose to add those missing speakers, particularly if your vehicle’s interior trim has open mounting positions for the speakers in higher-spec vehicles.


So why so many speaker types? Of course, each speaker is dedicated to a particular frequency. For the best sound experience, you’re going to want to make sure your woofers, mids, and tweeters are all performing at their best.

It’s the subwoofers that are responsible for the most visceral sound, though, so for many, high-quality subwoofers are the most important thing. Particularly if you listen to bass-heavy music, you’ll want to do everything you can to get crisp, powerful bass.

With the factory woofers, the sound can start to break down at higher volumes, giving either distortion or an overly compressed, muddy sound. BMW under-seat subwoofer issues like that definitely aren’t what you want, which explains why the woofers are the most popular speakers to replace first.

With the right BMW under-seat subwoofer upgrade, you’ll get great bass on all styles of music.


You’ll want to make sure you’re choosing the right BMW under-seat subwoofer replacement, then. That’s where the Alpha One woofers stand out, with their careful design, great performance, and a perfect match for your BMW. Crafted from premium materials and with greater power handling than the stock BMW speakers, they’re a marked step up from the factory HiFi and Harman/Kardon systems, and can even replace the individual audio (S752A or S6F2A) woofers in vehicles with BMW’s top stereo offerings.

Depending on your factory-original BMW sound system or aftermarket amplifier retrofit, you’ll want speakers with the right specifications to match the rest of your stereo. In some cases, the best speakers are low-resistance 2 Ohm woofers, but with some setups, you’ll get better performance from a higher-resistance speaker.

Autosvs makes it easy, with the Alpha One subwoofers available in 2, 4, or 7 Ohm versions to match your factory amplifier or the partner Alpha One BMW amplifier upgrade. Just select your factory stereo — or even easier, your VIN — and Autosvs will offer the perfect subwoofer for you. That way, you can be sure you’re getting the best bass response from your setup.

Learn what to upgrade first – BMW speakers or an amplifier?


As they are made specifically for BMWs and MINIs, and use the same dimensions and mounting positions, switching out your factory BMW speakers is simple. In most cases, you only need to…

  • Gain access to the speaker (you might need to pry off a few interior trim pieces).
  • Unscrew the factory speaker.
  • Unplug the audio in/out cables (no cable-cutting required).
  • Plug your BMW replacement speakers into the same wires (the Alpha One speakers come with matching plugs).
  • Screw your new speakers back in place, using the same holes the original was mounted to.

That makes for an easy, DIY installation process, and it’s completely reversible if you ever want to move your aftermarket speakers over to a new vehicle. Just do the same in reverse, and your OEM speakers will be back like nothing ever happened. Or if you know there’s no going back, your stock speakers will come out in mint condition, so you can even sell them to help fund your new and improved audio setup 😉

How to disconnect the under-seat subwoofer BMW
When swapping out your BMW under-seat subwoofers, there may be one extra step compared to the standard process outlined above.

In some BMWs, the factory subwoofers are glued in place, rather than screwed. In that case, after moving your front seats to get to the woofers, you’ll need to pry them loose from the enclosures.

With that done, you can easily unplug them, slip the replacements into place and screw them in. The Alpha One A90 subwoofers come with the required mounting fixtures, so you’ll have everything you need to get your new woofers set up.

If you aren’t sure whether your subs will need ungluing (for something like the BMW F30 under-seat subwoofer, it can depend on your vehicle configuration), get in touch with our team for help.


Of course, the story doesn’t end with great BMW replacement speakers. You might get better, clearer bass after a BMW under-seat subwoofer upgrade, but your sound is still likely to be limited by what your BMW’s amplifier is capable of putting out, which is just one of the reasons why it’s worth upgrading your BMW amplifier.

With the right amplifier, you can go further fine-tuning your audio, to produce stronger bass along with better performance in the higher frequencies.

The Alpha One amplifier by Autosvs is made to match either the stock BMW speakers or the Alpha One replacement speakers for BMW. With its 64-bit DSP that comes custom tuned for your BMW model and musical preferences, you’re guaranteed amazing sound out of the box.

Like the Alpha One speakers, it’s BMW-specific, so installation is quick and easy. And with Autosvs’s expert team ready to help, you know you’re going to get the sound you’ve been dreaming about.

Find out about the Alpha One range of BMW audio upgrades.

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