What Speakers Will Work in My Car? The Buying Guide for Car Speakers

You are here:
Estimated reading time: 13 min

The type of speakers used in most BMW’s and MINI’s audio systems are very
similar to each other 90% of the time. It’s the 10% of exceptions that can
ruin your day when you order upgraded speakers online from a company that
isn’t as laser beam focused as we are on exact details. You could be
challenged by incompatible connectors, missing wiring, too deep speakers or
various woofer impedance choices. The devil lies in the details, so how do
you navigate all this on your own?

As mentioned earlier, your exact vehicle specification will profoundly
impact the type of speakers that will be suitable to you.

Here are several things to consider when choosing a car audio
Pro tip: No matter what speakers you choose for your car, be sure to test
them out with these songs.
1 – Car speaker amount: How many speakers are in my car?
Car speaker amount: How many speakers are in my car?

The very first step to start with upgrading your car is to know and
understand what audio system your car came with from the factory. This will
give you a good idea of the foundation on which you’re going to improve.

The easiest way to find out “what speakers fit in my car” and how
many there are is to simply look… But how much fun would it be to take
apart your BMW or MINI just to understand what speakers your car has and
where? When choosing speakers with our Autosvs online store by typing in your
vehicle VIN, you’ll be presented with the exact type and amount of speakers
that we offer for your car. If custom adapters are required we include them
with your speaker order, no questions asked, so you don’t have to reinvent
the wheel all on your own.
As an example we have a detailed blog about the different BMW G20 3-series
audio systems, coming with anything from 6 to 16 car speakers.

2 – Car speaker sizes: What size speakers are in my car?
In most popular BMW’s and MINI’s the shape and size of the respective
woofer, midrange and tweeters used to build the various car audio systems are
almost all the same. Of course the technical specifications and build
materials differ greatly between for example a HiFi midrange with a paper
cone compared to a B&W midrange with an aramid fiber cone.

On the other hand the woofer cone in base stereo BMW’s is much smaller in
diameter than the woofer cone of HiFi equipped BMW’s while the size and shape
of the speaker basket is the same for both.

However, in some rare cases a specific BMW chassis has uncommon size and
shape speakers like oval kick-bass speakers in i3’s or woofers in base stereo
E89 Z4’s that look exactly like every other under seat woofer in any BMW and
MINI but are in fact a scaled down version and you really can’t tell by just
looking at them. In these odd cases we just don’t offer upgraded

Alpha One speaker sizes are as follows:
Speaker Model Speaker Size
A90 Underseat Woofer 229 mm (9)
A45 Midrange Speaker 100 mm (4)
A40 Midrange Speaker 100 mm (4)
A10 Tweeter 25 mm (1)

3 – Car speaker impedance
What do you need to know about speaker impedance in BMW’s? The most
important thing is that you need to use woofers with the correct impedance
for your car.

Practically all BMW and MINI midrange and tweeters have a nominal impedance
of 4 Ohms so it’s hard to get anything wrong here. OEM woofers on the other
hand come in 2,4 and 8 Ohm versions depending on the factory audio system. As
a rule of thumb during the last 10 years base stereo equipped vehicles had 4
Ohm woofers, HiFi 676 and HK 674 had 2 Ohm units and all the higher end
systems starting with 677 HiFi Professional, through Harman Kardon 688,
B&O, B&W, Individual would have 7 or 8 Ohm nominal impedance woofers.
The difference between 7 and 8 ohm woofers is marginal, so they can be used

Once again thanks to the fact that we know everything BMW we programmed our
Alpha One Speakers page to recommend you the correct impedance woofers for
your car.

The only case where we would be recommending woofers of different than OEM
impedance for your car is when you are retrofitting our Alpha One Amp into
your originally base stereo car and upgrading all of the speakers along with
it. In this case our page will recommend 2 Ohm woofers. However, if you
upgraded the speakers in a base stereo car using 4 Ohm A90 woofers before
retrofitting our Alpha One Amp it’s no big deal. Our amp has plenty of power
reserves to drive them just as well as it would 2 Ohm woofers. All it needs
is a different tuning file for 4 Ohm woofers.

What will happen if you get the woofer impedance wrong?
We have heard of many cases where an enthusiast would have a HiFi 676
equipped Bimmer, sourced a full set of speakers removed from a 688 Harman Kardon
vehicle and proceeded to replace as many speakers as possible for seemingly
their more premium counterparts. As soon as they were finished they would
find there was no bass. Perhaps the woofers were broken? Nope. The woofers
were simply playing so quietly, that they were not audible. In this scenario
nothing gets broken. The factory amp is simply not suited to deliver
sufficient power to the woofers as 8 Ohm woofers require an amplifier capable
of delivering a lot higher voltage than the HiFi amp can deliver. 2 Ohm
woofers don’t need as much voltage as they draw a lot of current from the
HiFi amp which it can deliver.

What happens if you install 2 or 4 Ohm woofers into a Harman Kardon
equipped vehicle? We haven’t tried that yet and we don’t recommend checking.
In this case the amplifier is not suited to drive low impedance woofers. They
will be drawing a lot more current from the Harman amplifier than it was
designed for and as a result will sound much louder than the correct (higher)
impedance woofers drowning out the mids and tweeters but only to the point,
where the amp will run out of steam and start getting strained. You could
expect the amp’s overcurrent protection circuitry to kick in. You could even
blow out the woofers. In any case it would sound so bad, that anyone with
common sense would immediately know something is wrong and it would hopefully
turn down the volume and take a break and troubleshoot.

Check how to upgrade Harman Kardon speakers with Autosvs speaker

4 – Car Speaker Power Handling
This topic of speaker power handling should be pretty straightforward
right? It should be just a number expressed in Watts and that’s all folks,
curtains down! For some reason it ends up being more complicated than that.

The main reason for the complications is that quite commonly both big and
small manufacturers of car speakers will puff up their hog with inflated
power handling numbers making it difficult to find out the actual speaker
power handling specs if there still is such a parameter out there.

Power handling should tell you how much power (measured in Watts) a car
audio speaker can receive from audio output and safely transform it into audible
music. Depending on the exact factory audio system the power could be coming
from just a radio head unit in the dash or a big and beefy multichannel beast
of an amp like in B&W equipped BMW’s. Factory audio systems will usually
have speakers that are closely matched to the amplifier’s power output.
Manufacturers don’t want you to be able to blow a speaker when you have the
volume turned all the way up.

RMS Power Handling
RMS (Root mean square) power handling specs are what is most important to
find out as RMS power handling tells you how much power a speaker can handle
continuously safely and without distortion when driven with an impeccably
clean source signal. This is the gold standard of expressing power handling
specs when measured honestly and accurately in a controlled measurement
environment. The world would have been a better place if everyone would have
adhered to this standard. Just like in the civilized world where we use
kilograms and meters instead of measuring in human feet and pounds who still
does that? ūüėČ Oftentimes you will come across speaker power specs that don’t
say whether it’s RMS power or anything at all. In such cases you could be
looking at a max or peak power rating. What are those you may ask?

Max/Peak vs. RMS Speaker Power Handling What’s the difference?
A max/peak power handling rating lets you know how much power a speaker can
handle in a very short period of time without sustaining damage. Shady
manufacturers will often not only inflate their RMS power handling specs or
not publish them at all and instead quote pie in the sky max power ratings
that are 4 times as much as their actual RMS power handling specifications
would be. You shouldn’t consider touching such speakers with a 6 foot pole if
you can avoid doing so.

Full technical specifications for factory speakers used in BMW’s and MINI’s
are not publicly available. You will always find a sticker with the part
number on an OEM speaker, sometimes also including the nominal impedance, but
you won’t find any power ratings printed on them. In technical documents you
can find some information about their power ratings but you won’t find out if
they are for RMS or MAX power. As an example the published power ratings for
a G12 7-Series with a HiFi Audio system is 25W for both the tweeters and
midranges and 40W for the woofers.

Alpha One speaker power handling specs:

Speaker Model RMS Power Max Power
A90 Underseat Woofer 50W 100W
A40 & A45 Midrange 25W 50W
A10 Tweeter 15W 30W
Does a speaker’s power handling tell you how loud the audio system will go?
Not really as that will depend on their power handling, the available power
from the amp driving them and finally their sensitivity.

5 – Car speaker sensitivity
Car speaker sensitivity is a measurement of how much sound pressure level a
speaker can generate with 1W of power. During the measurement a calibrated
microphone is placed 1 meter away from the car speaker. Manufacturers perform
such measurements in anechoic chambers for accurate results. Sensitivity is
expressed in dB or decibels which is the unit used for expressing sound
pressure level (SPL).

How does speaker sensitivity matter in a car audio system? A high
sensitivity car speaker will be able to produce more sound output/volume than
a lower sensitivity car speaker with the same amount of input power.

When you compare a speaker that has 87dB sensitivity to one that has 90dB
sensitivity you might be surprised to find out it takes twice as much power
e.g 2 Watts to drive the 87dB speaker to 90dB of sound pressure while the
90dB speaker will only need one Watt. By principle it takes double the power
to increase the SPL generated by a speaker by 3dB.

If you have a low powered head unit in your BMW without an amplifier it
would be of benefit to have sensitive speakers connected to it so that they
can efficiently convert the limited amount of power that they receive into
actual sound. On the other hand if you have a decently or high powered amp
driving the speakers, it will no longer be as important for the car speakers
to be sensitive but they will need to be able to handle the additional power
needed to get them to a sensible volume level.

It’s quite a balancing act to make a good speaker that is both sensitive,
with a desirable in-car frequency response and able to handle reasonable to
large amounts of power all for the ultimate purpose of achieving high quality
and loud playback volumes. We put a lot of effort into getting the balance
just right in our Alpha One speakers and that is much more important than to
only chase power handling or sensitivity numbers with reckless disregard for
how a complete set of speakers sounds and performs in a variety of cars and
audio systems.

Alpha One Speaker Sensitivity Chart:

Speaker Model Speaker Impedance Sensitivity
A90 Woofer 2 & 7 Ohm 89dB
A90 Woofer 4 Ohm 90dB
A40 & A45 Midrange 4 Ohm 88dB
A10 Tweeter 4 Ohm 85dB
Combining everything together

At this point it would be reasonable to answer the question how important is
a speaker’s power handling and what does it tell you about a speaker’s
potential performance?

When it comes to the volume/loudness in layman’s terms, or more accurately
maximum possible sound pressure level (SPL), that a speaker system will make
in a car this will be a result of a combination of the speakers individual
power handling, their sensitivity and the amount of clean power that it can
be delivered to them from the amplifier or head unit.

There is no point in chasing incredibly high SPL numbers unless you want to
suffer hearing loss. With the combination of our Alpha One speakers and
Amplifier we can achieve SPL levels that get uncomfortable to listen to for
longer than 5 minutes. No detailed calculations are required. Exposure to
sound pressure levels of over 85dB for prolonged periods of time can already
cause hearing loss and our woofers need only 1 watt of power to achieve a
sound pressure level of 90dB. Thanks to this they perform great in BMW’s and
Mini’s equipped with a factory amplifier and can really shine when paired
with our Alpha One Amp thanks to the extra DSP processing that can be done
with it.

There are many different types of car speakers that you can install into
your vehicle.

It’s important to remember that there’s no one single ‘perfect’ setup. You
can have the best car audio speakers, but if they’re not matched to your car
or set up correctly, it won’t sound like it should.

What is a tweeter speaker?
A car tweeter speaker is a speaker that’s designed to recreate high
frequencies, usually over 4KHz. Generally smaller than 2 inches in diameter
when part of a component system, they’re commonly mounted in the A-pillar,
doors, dashboard or even D-pillars and rear shelf.
Not all car audio systems come with tweeters. For example, many BMW models
with base-level systems don’t have them. As always there are further
exceptions here and there with for example F22/23/87 2-Series not having
tweeters despite having the HiFi 676 option.

What is a midrange speaker?
What is a midrange speaker?A midrange speaker, or woofer, recreates the
midrange frequencies, generally between 100Hz and 10KHz. It’s at these
frequencies that most of the music ‘happens.’ The human voice and most
instruments create frequencies in this spectrum. These speakers are usually
mounted in the doors, D-pillars, rear shelf or even the roof in BMW’s.

Subwoofers or woofers speakers?
You can use either term to describe the biggest factory car speakers
mounted in BMW’s and MINI’s used to reproduce the lowest audio frequencies.
Most of the time they’re mounted under the front seats. It seems calling them
car subwoofers seems to roll off everyone’s tongues most easily. By no means
could you compare them to the kind of subwoofer that gets mounted in your
car’s trunk though. Subwoofers or woofers speakers?Typically when you think
of a car subwoofer it would be a 8-18 speaker inside a big and sturdy
enclosure capable of rattling the glassware in your neighbor’s kitchen
cabinets when turned up. You’ve probably seen videos of people terrorizing
fast-food chain drive through employees with such equipment. For that reason
we try to stick to calling them woofers or under-seat woofers in the context
of BMW’s.

Woofers are usually tasked with reproducing frequencies below 200Hz.
They’re the most power hungry car speakers along with subwoofers. A fun fact
about woofers in BMW’s is that they’re usually mounted in a housing not much
bigger than the speaker itself which gets sealed up against an opening in the
unibody chassis to expand the volume of the enclosure in which the speaker
carries out its duties. As a result, on some BMW’s with our Alpha One woofers
installed the side skirt covers start rattling from the additional pressure
and vibration. You can’t hear it on the inside so it’s all good ūüėČ

What should you upgrade first? The amp or speakers? The rules of order by
which we recommend upgrading your system depend on your factory audio system
option and even the iDrive version. It’s fairly difficult to explain all of
the details in a nutshell, but the basic principles by which we make our
upgrade recommendations are easy enough to understand.

Base (Stereo) sound system
If you have a base stereo system vehicle with no tweeters you really need
to retrofit our amp and at least a set of front speakers consisting of
tweeters, midranges and underseat woofers. Needless to say it would be better
to replace all of the speakers including the rear ones if your budget can
handle that. The factory ones are just no good. Just like the audio signal
source without a factory amp.

Could you start off with the speakers and add the amp later? You could and
the sound will be greatly enhanced but only to the point where the factory
audio source will run out of power and that happens quickly. On the factory
speakers the lack of power isn’t that apparent. Good quality speakers like
our Alpha Ones will not be able to perform to their fullest potential without
an amp as a distorted and clipped input signal from the factory audio source
will ruin your listening experience when you try to turn up the volume.
Somewhere above 50% volume, without an amp base stereo equipped cars run out
of steam. Our recommendation is firm: either do it all or don’t do it at all.

HiFi Sound System
bmw amplifierIf you have a HiFi 676 or HK 674 car the factory speakers are
decent enough that we can unlock their hidden potential with just the amp
thanks to the DSP tuning which we pre-load to our amps. (It can be changed
later once you decide to get the speakers replaced ūüėČ ) In these cars you get
a terrific bang for your buck by upgrading just the amp even without Alpha
One speakers. This is much more budget friendly than having to take the
plunge for an amp and speakers like with base stereo BMW’s and MINI’s.

The factory speakers still have limits in the amount of clarity, presence
and bass that they can deliver regardless of our tailor made DSP profiles for
OEM speakers. DSP processing is not magic. Like with engine tuning you can
squeeze much more with a ECU flash from a 3 liter turbo B58 than you can from
a 2 liter B48. We can re-shape the frequency response, increase the volume by
delivering a little more clean power but only within the limits of the
factory speakers power handling specs. Our amp could burn up the HiFi speaker
voice coils in an instant if we were to turn the gain up sending too much
power to the speakers. With our Alpha One speakers we don’t have to push them
around with EQ as much as the OEM speakers, so right from the get go they
sound better with less EQ, and the cherry on top is that they can handle more
power than the OEM HiFi speakers. Of course we have a different DSP profile
for them.

Look at it this way owners of base stereo cars have to do the amp and
speakers in one go anyway, so why not treat yourself with a completely
transformed musical experience instead of only picking the low hanging

Harman Kardon Sound System
If you have a Harman Kardon or other iteration of Hifi Professional 677 or
688 audio system we don’t offer amp upgrades for these yet so your only
option is to upgrade the speakers. The factory amps in these cars are already
pretty powerful and decently tuned. The speakers are pretty good too, but
they do tend to sound over the top harsh in the mid and high frequencies and
the bass, while powerful, lacks some low end extension. Alpha One speakers
come to the rescue here by smoothing out the mids and highs with no loss of
clarity, while our woofers significantly improve the low end response with
extra extension and a cleaner kick-bass punch.

As you’ll find on our Speakers and Amplifier upgrade page we offer a
variety of speaker upgrade packages. A complete set of available speakers for
any given BMW chassis is the best option that we have to offer.

A more budget friendly option is the front & woofer set of speakers,
which while it does not go the full 9 yards like the complete set does this
package still has everything you need for great stereo playback. Similarly to
a set of high end full size floorstanding home stereo speakers.

Lastly if you’re only after improving the bass response with deeper low end
extension and cleaner kick-bass and some more volume than on the factory
woofers this upgrade will be perfect for you.

Was this article helpful?
Dislike 0
Views: 8
Previous: BMW F/G Series NBT Evo ID5/ID6  iDrive Upgrade
Next: BMW B58 Engine Tuning How Can You Improve Your Performance?