Great-sounding speaker systems are made up of several types of speakers including tweeters. But what are tweeters? And what do tweeters do?
In this comprehensive post, I’ll show you what tweeter speakers do, the different speaker driver materials, which sound the best, and more!
Infographic – Tweeter facts
What are tweeter speakers?
Tweeters are speakers that produce the upper range of sound you hear in music. Because higher sound frequencies have smaller sound waves their size is smaller than the other speakers they work alongside.
A tweeter is a type of electromechanical loudspeaker that produces sound and music in the upper (higher frequency) music range. They compliment woofers and other speakers that can’t produce higher-pitched sounds, like those used in a 2-way bookshelf speaker pair design.
Tweeters are small in size as they produce smaller soundwaves and have a small cone. Generally speaking, they’re best used when pointed toward the listener.
Most are limited to a specific range such as 3 kilohertz to 20 kilohertz (kHz) maximum, although it depends on the specific speaker’s limitations. The typical range of human hearing is around 20 Hz to 20kHz.
Kilohertz is a term used to describe the frequency of the sound produced or the cycles per second of an audio signal waveform.
Basic tweeter parts
Image of a disassembled car tweeter. Shown is the magnet assembly (left) and the dome/grill/wiring terminal assembly (right). The voice coil is attached to the rear of the dome. In this image, the dome is made of silver material – most likely mylar or some other type of plastic or other lightweight material.
The typical tweeter design (although various other types exist) consists of a small magnet with a circular gap inside of it. A wound copper wire voice coil, called a voice coil, is attached to a speaker dome made of one of many different materials. They’re different in that most use a curved dome shape curved outwards unlike other speakers that use a cone angled downward.
This assembly is inserted into and suspended inside the magnet’s gap. The dome is supported on its sides, like other loudspeakers, by a flexible but stiff material.
What do tweeters do?
Enjoy good music? Tweeters make good music possible in a sound system you see everywhere. Home stereo speakers like these Dayton B652 bookshelf speakers use an inexpensive but effective tweeter to fill in the sound range a midrange speaker or woofer can’t produce. Together they can produce the entire range of audio to create a good-sounding audio system.
Tweeters are used to produce high frequency sound (treble) and complement other speakers that aren’t suited for this. When part of even a moderately-priced audio system with a subwoofer and 2-way speakers they can sound fantastic.
“Treble” is a word used to describe parts of the music in the upper range such as cymbals, synthetic keyboard sounds, drum effects, and the “tssst tsst” (high-pitched) sound from various musical instruments.
When an amplified musical signal is applied to the tweeter via the positive (+) and negative (-) wiring connections the voice coil creates a magnetic field inside the magnet’s permanent magnetic gap area.
This varying field causes the tweeter coil and dome to move forward and in reverse, moving air very rapidly following the signal. As this happens sound is produced.
Tweeters in music reproduction – why they’re important
Music is made up of much more than a limited range of sounds. It’s a very complex combination of different tones, frequencies, and other characteristics. These are made by different instruments, the voice of singers, and items added when music is recorded.
Tweeters are critical in a sound system for producing the full range of sounds you can hear. Music is much more enjoyable and sounds much more natural because of this.
Stereo imaging is the term used to describe how music is recorded and played back to give spatial cues that tell your brain where the sounds are coming from. For example, music recorded by musicians may have some instruments in the left channel, center, and right channel. Tweeters help to reproduce the higher-range audio cues and create the stereo “image”.
Music has different sounds over nearly all the ranges our ears can hear. Additionally, it is normally recorded in stereo in such a way that allows the original studio instrument and sound placement (left, right, center, etc) to be reproduced.
This creates what is called stereo imaging when listening to good quality music with your sound system.
An image showing 3 of the most typical factory-installed tweeter mounts. Left: dashboard. Center: pillar mounted. Right: upper door mounted. Just like home stereo speakers, they’re used along with other speakers like woofers. In cars, they’re often mounted higher in the because tweeters are directional and it reduces volume lost.
As tweeters produce high-frequency sounds, in cars they’re used as part of a speaker system in cars but not alone. They’re used alongside others like component speakers or to compliment and improve what’s already there.
A better-sounding car audio system will use a woofer speaker, one or more passive crossovers, and a separate tweeter. (Note that car tweeters often have a speaker grille permanently attached for protection).
A midrange driver produces mid to lower-range frequencies which have larger sound waves and are not as demanding in terms of location. Tweeters, however, are directional as the sound produced by them is optimally heard best when they’re pointed towards your ears.
Factory tweeters are often located in a less than ideal location. This is because it’s a compromise between space in the vehicle and assembly line production costs.
Tweeter location isn’t considered very important by car manufacturers except for luxury vehicles and other premium sound systems.
Custom car stereo systems often get the best sound by using custom mounting to overcome the limitations of space and mounting locations. Additionally, aftermarket (non-factory) tweeters are available in a wide array of quality levels which I’ll discuss further.
How are tweeters used?
Common uses in speaker systems
For high-quality sound, a set like this CT Sounds Strato car component system can be used. Component speaker systems typically use woofers and tweeters connected to speaker crossovers via speaker wire.
They’re designed to match the drivers and separate sound production, sending it to the one best suited for it.
Tweeters are used in speaker systems for a limited number of reasons (they’re never used alone):
- In a 2-way or 3-way speaker system to produce sound the other speakers cannot
- To add more high-frequency sound (treble) for added effect
Most speakers systems in use today are called “2-way”, as they use a combination of 2 speakers which are supplied a limited range of sound to produce. This is because almost no speakers sold today with a single cone can produce the full range of sound you can hear.
The main reason for this is that large speakers cannot produce higher (treble) frequencies well and small speakers cannot produce larger (bass) frequencies.
Speakers, in general, are specialized and are best suited for a range of sound.
A mid range speaker like woofers (also sometimes called “midbass” speakers or “mid woofers”) normally have terrible performance in the higher range of sound.
Therefore tweeters are critical for supplying this missing range of sound.
Why do tweeters need crossovers?
Car speaker crossovers (left) and home stereo speaker crossovers (right) are responsible for directing bass to the correct speakers. They protect the tweeter and block distortion and potentially damaging bass power from overdriving it.
As I mentioned earlier, tweeters need crossovers like those in the image above for several reasons:
- Tweeters cannot play low frequency sounds – they distort heavily
- They may be damaged if a large enough low-frequency signal or signals drives them
- It reduces the power applied and helps protect it
Understanding speaker crossovers
2-way speaker (passive) crossovers are extremely common. The tweeter receives sounds that are allowed to pass above the crossover point. The 2-way crossover shown is made by combing a high-pass and a low-pass section. In this diagram, an inductor (wire coil) is shown as “L” and the capacitor as “C.”
In many cases, tweeters come with a simple capacitor connected in series with one of the wiring terminals. This is normally the positive (+) terminal by convention.
Capacitors act as a single order (single stage) audio crossover. That is, they have a crossover slope that works at a rate of -6 decibels per octave (dB). An octave is a term used for audio and represents a doubling or halving of a frequency. For example, 400 Hz is one octave above 200 Hz.
Higher order crossovers filter out even more bass that would be reaching the tweeters and are even more effective. -12dB/octave (2nd order) is one of the most common and is effective without being too costly.
As you can see in the image above a 2nd order (-12dB) crossover requires an additional component called an inductor. These are coils of wire which react to music and reduce the output to the speaker at certain frequencies.
Shown: A typical 2-way home stereo speaker with a tweeter. In this low-cost design, a single capacitor is used in series as a high-pass crossover to filter out bass. This prevents distortion and potential damage to it as well.
What does a tweeter impedance rating mean?
Impedance, rated in Ohms, is a term used to describe the total electrical resistance to current for a speaker. A tweeter’s voice coil is made of a long amount of wire wound into a coil. This wire has electrical resistance.
Impedance is important as crossovers are designed for the rating of your tweeters. Additionally, tweeters should be matched with woofers and other speakers with a similar rating.
If you mismatch speaker impedance one will play at a higher volume than the other as more power drives them. This is because the power developed by a speaker is directly rated to its Ohms rating.
Traditionally, home stereo speakers are rated at 8 ohms while car speakers are typically 4 ohms. What’s interesting is that, for example, 8 ohm speakers aren’t exactly 8 ohms. That’s an approximation as they’re usually somewhat below that (say 6 to 7Ω for example).
Tweeter power ratings
The average tweeter can’t handle large amounts of power as larger speakers can. Woofers and other larger speakers can dissipate larger amounts of heat and have a larger voice coil wiring gauge.
With some exceptions, power ratings like 15W (watts) RMS and above are realistic. 25W-50W is fairly common for mid-priced models sold today.
Tweeters must match the rated impedance expected from an amplifier. Amplifiers can overheat if used with speakers that are too low for their design. (For example: using 4 ohm tweeters with a stereo rated at 8 ohms minimum is not acceptable).
Tweeter efficiency (SPL rating)
Just like other types of speakers, tweeters have an efficiency rating. This tells you how much volume, in decibels (dB) a tweeter produces for a specific amount of power. This is normally listed as the “SPL” parameter.
In the case of speakers, higher efficiency is better. For average tweeters, you might expect to find this at between 89dB to 91dB at 1W. It’s not unusual for them to sound “harsh” or too “bright” due to having a higher output than the midrange or woofer speakers they’re used with. Hence the need to reduce the tweeter volume using an L-pad or attenuation network.
Common tweeter types and materials
Examples of some of the most common types of tweeters today. A soft dome tweeter (left) is often made with textiles or silk materials as shown. A metal dome tweeter (right) is typically made from aluminum, titanium, or some hybrid design. Some listeners prefer one over the other, although a well-designed tweeter of one type may be able to outperform the other. It’s important to check all the specifications and the frequency response if provided.
There are simply far too many materials used to list here, but I’ll cover some of the most common. Don’t forget that some sold today are made of a variety of less common materials.
Also, it’s important to always check closely as sometimes the specifications aren’t clear and are misleading.
Some of the most common materials used for tweeters include:
- Silk, textile, or other cloth
- Mylar or other plastics
- Metal-coated plastics & PEI materials
- Metals: aluminum, titanium, and alloys
- Ceramics and ceramic-coated domes
- Kapton (in ribbon tweeters)
Silk and textile are some of the most common materials used. Titanium and other types of metals like aluminum are also fairly common for mid-to-upper price range tweeters as well.
A silk dome tweeter is one of the most popular types and often a good compromise between cost, performance, and sound quality. A great example is this pair of Polk Audio DB1001 car tweeters.
These types tend to perform well and because of their extra stiffness are often associated with a certain “color” of sound. Other special materials like ceramic and even diamond are used in others too.
However, it’s very important to understand that the type of material used for the tweeter dome alone doesn’t determine its quality. You need to always check the specifications such as the frequency response chart if provided.
If none is provided, it’s best to consider seeking out more information and buy a model that provides that information.
Otherwise, you’re taking a gamble with buying a tweeter that’s too “bright” or “harsh” in that it may have certain ranges of sound it emphasizes too much or not enough.
Mylar, PEI, and others
Mylar and PEI types use plastics for the dome. They’re often found in budget component sets or coaxial speakers. While they’re lower cost, they usually aren’t very good for accurate, crisp sound. You can often hear the difference when comparing them directly against a silk dome tweeter pair.
Some models are hybrid and use a type of metal coating that may or may not offer better performance. All of the types listed are usually cone tweeters in how they’re shaped.
Horn and compression horn tweeters
A horn tweeter (left) can driven by a magnet assembly or piezo driver. Piezo tweeters are very loud and efficient but aren’t very good in terms of music quality. A “super tweeter” is usually magnet driven and produces more volume and has a higher power rating than average products. Both are often used for outdoor music events and gatherings.
Horn tweeters are a special class of speakers. Entry-level models like piezo tweeters are inexpensive and not great at producing good musical tones, but they’re cheap and very efficient. Their volume is often much higher than standard tweeters (96dB vs. 91dB produced at 1 watt, for example).
Unlike models that use a magnet, a piezo tweeter uses a piezoelectric crystal coupled to a mechanical diaphragm like a digital watch or electronic clock uses for sound. They usually have a very high impedance and may not even need a crossover. A piezo tweeter is low-cost, efficient (good dB output per watt) but not good for sound quality.
Other horn tweeters used in extremely high-quality home stereos systems have a very good frequency response as well as sound. These are most often “compression horn” type speakers with a magnet and dome that attach to a horn body that expands outward.
This helps to direct the sound more effectively and can radiate sound more evenly than others.
Super tweeter and bullet tweeter models
These are similar to others but may have a “bullet” shape attached to the dome to help produce high sound levels. They’re great for volume and more power handling.
You can use tweeters like these for situations where high power handling and loud volume are the main requirements. For critical listening and enjoyment indoors, they’re normally not very practical.
A ribbon tweeter is a bit different from the others. They use a unique design with a very thin “ribbon” diaphragm which moves back and forth in a linear fashion to produce sound.
Tweeters of this type are some of the best and most musical available today, but it depends greatly on the design & quality. Prices range from in about $25 to $600 or so.
One reason they’re so unique is that unlike tweeters based on a voice coil and a magnet, their impedance is much more flat over the frequency response range.
This means there’s less interaction with your crossover due to fluctuations that occur when the audio signal frequency changes.
Ring radiator (concentric) tweeters
Dual-ring radiator (sometimes called “concentric” ring) tweeters are a unique type of tweeter with a moving surface consisting of several rings and a center plug. These types are more sonically accurate and musically detailed tweeters.
Tweeters of this kind are less common, however.
A downside is that unlike other types they produce far less sound at angles (called the off-axis response ). This means that they’re best suited for speaker systems where they’re aimed directly at the listener.
Tweeter frequency response basics
Tweeters have unique characteristics just like any other speaker. In this image, you can see the level of sound produced over different frequencies (called the “response”). These graphics show the sound response at different angles.
In the graphs above we can see that Tweeter A has dips and peaks that will cause the sound to be lacking in some ranges and is too “harsh” (too high) in others. Tweeter B has a much more flat and ideal response, as it’s almost consistently the same over the range of sound produced.
Tweeters, just like any other type of speaker, have limitations. For a given range, they have frequencies at which their response (volume level for a given power applied) is higher or lower than an average decibel (dB) volume produced.
These peaks and valleys (areas where the sound production is higher or falls lower) cannot be overcome without an equalizer or other compensation. Frequencies at the bottom end of the response range are best left to midrange speakers
There’s no such thing as a “perfect” tweeter speaker – they all have good and bad characteristics along with price, mounting, and performance factors to consider.