What exactly are car tweeter speakers, and what do they do?

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are tweeters in a car?

Car door tweeter speakers are the smallest type of speaker used to emit the
highest frequencies of the audio spectrum.

Tweeters create sounds that are often described as crisp or sharp.
Technically speaking, tweeters usually produce frequencies between about 3
kHz and 20 kHz. For reference, human hearing goes up to and not beyond 20

Fun fact: 20kHz is that sound you can’t hear super well, or likely not at
all once you hit 30. Especially if you frequented more than a handful of loud
concerts as high frequencies at high volumes can cause irreversible damage to
your ears. If you remember hearing quieter and ringing in your ears after
leaving an event your hearing probably suffered some damage that day.

What are tweeters in a car?

You would think that all BMW’s these days would leave the factory with a
decent audio system that is equipped with at least a pair of tweeters in the
front but that is not the case. We don’t know why but in 2022 BMW’s most
basic audio system is still not equipped with even a pair of tweeters and the
base audio system is not even that rare.

For example the current 3-Series BMWs even in the M340i version were
occasionally made with the base audio system. It would have been
understandable to see the base level audio system installed in a no frills
manual 318d used in a fleet in Europe but in a M340i? Come on BMW.

If you have the most basic audio system in your BMW/MINI it will comprise
of only four mid-range speakers in the doors and two small under-seat woofers
to cover the whole audio spectrum. No tweeters to be seen on the horizon.
Such an audio system is easily beat with a $200 Bluetooth speaker and you
could take the latter to the beach too.

On the other side of the spectrum of BMW audio systems, you have the fairly
decent Harman Kardon audio system in BMWs which has a total of seven tweeters
to create a significant audio experience. Perhaps that’s where all the
tweeters went ūüėČ The HK system has been fairly difficult to come by in
2021-2022 due to chip shortages.

Can you imagine a chocolate chip cookie without chocolate chips? That’s
exactly what an audio system without tweeters is. Tweeters are required for
any audio system to produce high frequencies all the way to the limit of our
human hearing range. Without them any audio system is simply deficient and
limited. By installing tweeters you’ll get better sound quality overall and
they will help give the music a sense of space and presence.

Female voices, cymbals, synthesizers, and distorted guitars will sound much
better but also be heard how they were intended to sound which is what you
should be aiming for with any audio system.

Tweeter speaker build/constructionYou can say tweeters are built just like
any other standard speaker. As you read earlier, tweeters emit sounds
generally between 3 kHz to 20 kHz. 20 kHz translates to 20,000 cycles per
second. Frequency, after all, is a measurement of cycles (or vibrations) per

In other words, to recreate very high-frequency sounds, tweeter cones must
vibrate insanely fast. This is also why tweeter speakers are small, to move
more quickly!

There will of course be differences between how a specific tweeter from a
specific manufacturer is built but many elements of a tweeter are

The biggest difference, aside from the size, is that tweeter cones usually
point outwards, toward the listener, compared to falling inward, away from
the viewer, like a normal’ speaker. As a result, most tweeter cones are
called domes’. At the end of the day a speaker cone or dome regardless of the
exact shape is intended to move like a piston.

Attached to the dome is a cylinder called a former which is wrapped around
with a wire called a voice coil. The tweeter dome also has a suspension
around the outer edge. These elements are what moves in a tweeter making the
sound and are joined into one assembly. Alpha One vs. Harman Kardon

The other essential parts of any tweeter get combined into a second
assembly consisting of a magnet sandwiched between two metal plates (called a
top plate and a back plate). These plates create a cylindrical magnetic gap
in which the tweeter’s voice coil will move according to the audio signal
being fed to it.

These two assemblies then get precisely glued to each other and voila you
have a tweeter. Of course it’s not as simple as that. In the process of
putting the two together you have to attach the tiny voice coil wires to a
set of terminals and maybe even fill up the magnetic gap with a special
fluid. Our Alpha One Tweeters have the voice coil gap filled with a
ferrofluid to enhance and maximize their performance. The presence of a
ferrofluid increases power handling via enhanced heat dissipation from the
voice coil and also reduces resonances so why not.

Tweeter domes can be made out of many different types of materials, each
having its own influence on the sound. There are often commonalities in the way
aluminum domes from different manufacturers sound like, but the fact that the
dome is made from a certain material doesn’t determine what a specific
tweeter sounds like.

Alpha One vs. Harman Kardon Tweeters
For example if you look at an Alpha One tweeter from the front next to a
Harman Kardon tweeter taken from a BMW you might think they’re actually one
and the same. Furthermore you will find the Harman Kardon tweeter has all of
the negative acoustic characteristics stereotypically assigned to tweeters
with aluminum domes. They’re harsh, screamy and just over the top compared to
our Alpha One tweeters that have a detailed yet smooth response without any
such harshness. Just clean and precise sound. Why is that?

To use another culinary analogy a cook and a chef can be tasked with
sourcing the same ingredients to make the same kind of salad. The cook will
get run of the mill industrial farmed and processed ingredients from the
nearest supermarket and toss them together in a flurry. The chef on the other
hand will visit his local farmers market to get produce straight from the
farmer he knows doesn’t use any pesticides or herbicides on his lovingly
grown produce. Once in the kitchen the chef will proceed to masterfully put
together a salad with just the right amount of fresh and tasty ingredients to
make a mouth watering feast. The saying don’t judge a book by its cover
applies to tweeters too.

As you read earlier, car tweeter speakers create the high frequencies of
the audio spectrum. High frequencies have a short wavelength, so they’re
crucial for creating clarity and stereo imaging. 

Tweeters in sound reproduction stereo imaging
Tweeters are very directional, especially in the highest frequencies
compared to lets say a subwoofer. If you listen to a tweeter off axis (from
the side) you’ll observe a significant drop in output when you’re standing
next to it compared to directly in front of it. Furthermore high frequencies
are easily damped with curtains at your house or the carpet and headliner in
your car.

On the other hand low frequencies can travel through concrete walls and can’t
be damped out as easily nor can you tell exactly where they are coming from.
When you compare these two behaviors you’ll understand why tweeters are
essential for stereo imaging: that is, creating the perception of space and
three dimensionality in music. Tweeters are vital for building the stereo
separation in your car’s audio system. An audio system with good stereo
separation will make a well recorded female vocal seem as if the artist is in
a specific location on the dash or windshield (if you can imagine that with
closed eyes) rather than coming directly from the car doors next to you.

Tweeters and sound balancing
Believe it or not, aside from the size and power required, there’s not a
lot of difference between a giant subwoofer and the smallest car door
tweeter. They’re speakers dedicated to recreating a specific part of the
audio spectrum.

And because they’re each dedicated speakers they’re essential for sound

Tweeters and sound balancingWhen you compare a compromised base stereo
system in a BMW (only 4 midrange speakers and two small woofers) with a 676
HiFi system consisting of 5 mids, 3 tweeters and two decent sized underseat
woofers in both cases the designers tried to balance the sound as best as
possible. It’s much easier to do when you have a set of 3 different types of
speakers compared to just a midrange and woofer.

That’s why for base stereo equipped BMW’s we recommend replacing the mids,
adding tweeters and replacing the woofers all with Alpha Ones. You just can’t
add tweeters and expect them to blend well with the existing mids and woofers
as the balance will be off. The lack of tweeters is just the tip of the

On HiFi and Harman Kardon equipped BMW’s on the other hand you can easily
replace just the woofers with Alpha One A90’s without touching anything else
and you’ll be golden as our woofers alone are a great upgrade on their own.
Of course they would sound even better when paired with our mids and tweeters
for a fully balanced and full sound.

Tweeters make it easier for mid-range speakers to focus on midrange
frequencies; the woofers mean mid-range speakers don’t have to reproduce
low-end frequencies.

As a result of having car speakers dedicated for both the high and low-end,
mid-range speakers are free to create a better quality of mid-range sound
rather than struggle to create high and/or low-end sounds.

With the correct tweeters, your mid-range speakers will distort less, and
the sound will be significantly better balanced.

Not all car tweeters are created the same. Different types of magnets, cone
materials, and crossover points mean that there’s a lot on the market. But
finding the best tweeters for your car isn’t too challenging.

What size tweeters are in my BMW or MINI?
Most dedicated tweeters in the car audio space are approximately 1 inch or
25mm in diameter, and some are 0.75 inches (19.05mm). A slightly larger
tweeter will be able to reproduce 3kHz more easily while a smaller one will
have more difficulty with that. We believe 1 tweeters are the way to go for
any BMW or MINI.

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