Do you love music? I do too! But what actually makes that great music you and I both enjoy listening to?
Speakers are far more simple – and yet complicated – than you might realize. 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 answer your questions in a way that anyone can understand. I’ll also help you learn a lot more about the different kinds of tweeters. I’ll also show you how they’re used, why they’re important, and much more.
Infographic – Tweeter facts
What are tweeters?
Image showing a typical home stereo speaker with a woofer and separate tweeter. Car tweeters are very similar in design and purpose, but are often designed to be installed in a vehicle. In both cases a speaker “crossover” is normally required to block low-frequency sounds they can’t handle.
A tweeter is a type of electromechanical loudspeaker which produces sound and music in the upper (higher frequency) music range. They compliment woofers and other speakers which can’t produce higher-pitched sounds. Tweeters are generally small in size as they produce smaller-wavelength audio and have a small cone.
Most are limited to a specific range of audio production 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.
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 other form of some type of plastic or lightweight metal material. Some tweeters use a combination of materials that are both lightweight and stiff.
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 one of many different materials. 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?
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 field 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.
“Treble” is a word often used to describe the parts of music in this range such as cymbals, synthetic keyboard sounds, drum effects, and the “tssst tsst” (high-pitched) sound from various musical instruments. Tweeters are specialized speakers that produce treble but cannot produce bass or midrange audio unless specially designed. Attempting to do so will causing harsh-sounding audio distortion and can potentially damage them permanently (see more below).
Kilohertz is a term used to describe the frequency of sound produced, or the cycles per second of a signal waveform.
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. For example, music recorded by musicians may have some instruments in the left channel. Others may be on the right. Often, vocal tracks appear to be coming from the center area. Tweeters are important for this too as they reproduce the crisp details in sound production necessary for good imaging.
Music has different sounds over nearly all the range our ears can hear. Additionally, music is normally recorded in stereo in a way that reproduces them in their original positions in the studio. This creates what is called stereo imaging.
Various sound tones & signals are important. They give “cues” to your brain about what you’re hearing as well as where in listening area they’re located.
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 vehicle and more closely pointed to the heads of the listeners. This is because tweeters are “directional.”
As tweeters produce high-frequency sounds, in cars they’re used as part of a speaker system but never alone. They’re always used in addition to other speakers. These usually consist of a woofer (or “midrange”) speaker, one or more passive crossovers, and a separate tweeter.
Woofers produce lower-range frequencies which have larger sound waves which are not as demanding in terms of location. Tweeters, however, are “directional.” This means that the sound produced by them is optimally heard best when they’re pointed at the listener.
Factory-installed tweeters are often placed in a place that’s not ideal. This is because it’s a compromise between space in the vehicle, production costs, and similar factors. 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 use in speaker systems
2-way speaker systems are some of the most common in the world. Shown: a car component speaker 2-way system. Included are 2 woofers, 2 tweeters, and the speaker crossovers designed to match the speakers.
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.
Woofers (often called “midbass” speakers, “midwoofers”, and sometimes mistakenly “midrange”) normally have a poor amount of sound production in the upper range. Therefore tweeters are critical for supplying this missing range of sound.
Why do tweeters need crossovers?
As I mentioned earlier, tweeters need crossovers like those in the image above for a number of 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
2-way speaker (passive) crossovers are extremely common. The tweeter receives sounds that allowed to pass above the crossover point. Below the crossover point. The 2-way crossover shown is made by combing two high-pass and a low-pass sections.
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.
Shown: A typical 2-way home stereo speaker with a tweeter. A single capacitor is used in series as a high-pass crossover to filter out potentially damaging & distorting sounds.
What is tweeter impedance rating?
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 an electrical resistance.
It’s important as crossovers are designed for the impedance rating of your tweeters. Additionally, tweeters need must be matched with woofers and other speakers with a similar rating. If you mismatch speaker impedances 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. This can vary. What’s interesting is that, for example, 8 ohm speakers aren’t exactly 8 ohms. That’s an approximation. They usually fall are a bit below that in practice.
Tweeter power ratings
The average tweeter can’t handle large amounts of power like larger speakers can. Woofers and other larger speakers can dissipate larger amounts of heat and have larger voice coil wiring gauge.
With some exceptions, power rating like 15W (watts) RMS and above are realistic. 25W-50W are 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).
Just like other types of speakers, tweeters have an efficiency rating. That is, for a given amount of power applied with a signal they produce a certain volume of sound. This is normally listed as the “SPL” parameter.
In the case of speakers a higher efficiency is desirable. In the case of average tweeters you might expect to find this at between 89dB to 901dB at 1W of power typically.
Note: dB @ 1W/1m is a standard way of measured speaker efficiency with test equipment with a microphone positioned 1 meter away. However, there are 2 types of tests for this and it is confusing. It’s important when comparing tweeters to be sure that the measurements are for 1W for a given speakers.
The reason for this is that 8 ohm tweeters need a higher voltage applied to create 1W of power as opposed to 4 ohm ones. If the test called “SPL 2.83V @ 1m” is used, it’s not correct for comparing the two different types.
Tweeter types and materials
Examples of some of the most common types of tweeters today. Soft dome tweeters (left) are often made with textiles or silk materials as this one shown. While metal dome tweeters (right) may be typically made from aluminum, titanium, or some hybrid design. Some listeners prefer one over the other, although a well design tweeter of one type may be able to outperform the other type. It’s important to check all of 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 other kinds. Also, it’s important to always check closely as sometimes the specifications aren’t clear and are misleading.
Commonly found materials in tweeters include:
- Silk, textile, or other cloths
- Mylar or other plastics (typically in lower cost tweeters)
- Metal-coated plastics & PEI dome tweeters
- 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 in soft dome tweeters. Titanium and other types of metal like aluminum are also fairly common for mid-to-upper level tweeters as well. These types tend to perform well and because of their extra stiffness in the dome are often associated with a certain “color” of sound.
Other special materials like ceramic and even diamond are found in a few, 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.
“Super tweeters” and horns
Horn tweeters (left) are often driven by a piezo driver instead of a magnet assembly, but not always. Piezo tweeters can be very loud and efficient but not very good in terms of music quality. A “super tweeter” is 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. Super tweeters are larger and harder to mount, too.
Horn tweeters are a special category of speaker. Entry level models like piezo tweeters are inexpensive and not great at producing good musical tones, but they’re inexpensive and very efficient. Their volume is often much higher than standard tweeters (96dB vs. 91dB produced at 1 watt, for example).
Other horn tweeters used in extremely high-quality home stereos systems have very good frequency response as well as sound. These are most often “compression horn” type speakers. Compression horns use a small opening in a horn body which expands from the tweeter dome and magnet to direct the sound more exclusively.
Standard horn tweeters use a lightweight plastic body.
Built for higher power and to produce higher volumes, super tweeters are like a stronger version of standard tweeters. Their power ratings are also higher as well.
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 not ideal.
Ribbon tweeters are a bit different from traditional dome-driven products. 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 off of a voice coil and a magnet, their impedance is much more flat over the audio 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 (sometime 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 are aimed directly at the listeners.
Tweeter frequency response
Tweeters have individual characteristics just like any other speakers. In this image you can see the level of sound produced over different audio frequencies (called the “response”). These graphics show the sound response and different angles. Following the black lines, we can see that Tweeter A has dips and peaks that will cause the sound to be too lacking and too strong (or “harsh”) in certain areas. 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 their average.
This means that it’s important to know that different tweeters behave differently when sound is being produced. For example, some tweeters will have “peaks” (higher volume at certain sound frequencies) than others.
These peaks and valleys (areas where the sound production falls lower) cannot be overcome without and equalizer or other compensation. It’s important to understand that there are limitations between different brands and models.
There’s no such thing as a “perfect” tweeter – they all have good and bad characteristics. However it’s possible to find a good tweeter with good performance if you shop carefully.
Summary – What are tweeters and what do they do?
Tweeters are small, specialized speakers that produce sound in the upper range of human hearing. They come in a variety of styles and materials but most commonly use a dome made of lightweight material and a magnet to drive the cone (dome) and produce sound.
As they’re smaller than other speakers like woofers, they require crossovers to filter out and block sounds that may potentially damage them and will cause unwanted distortion.
If you’re interested in learning more about how to wire speakers, check out my great post here about speaker wiring.
If you have any question or suggestions, be sure to let me know how I can help!