Speaker Building 101
Learn how to build your own DIY speakers and the steps required to do it yourself.
Introduction: Why Build Your Own Speakers
Today, more people than ever are building their own custom speaker systems. Whether you enter this hobby to save money or just for the pure enjoyment of DIY, speaker building can be a fun and rewarding exercise. By building your own speakers, you can create designs that will fit your specific needs and tastes.
Designing and building your own speakers can involve several skills such as math, woodworking, and soldering. Fortunately, you can begin with a basic understanding of these skills and still complete a great-sounding speaker design. Thanks to the availability of enclosure and crossover design software, a computer can handle the majority of the math.
You generally don't need to be a master woodworker to build a box. A simple box is usually all that is necessary (some designs don't even require a box). Soldering is sometimes the most intimidating aspect for a beginner, but soldering together a crossover is as easy as it gets, even if you have never held a soldering iron. Finally, there is a large, experienced, and active speaker-building community that can offer advice and assistance in case you ever get stuck.
Parts Express offers several kits where all the design work and most of the woodworking has been done for you. The included knock-down enclosures are completely pre-cut, so you just need to glue them together. All crossover components are included, and most kits include a point-to-point wiring diagram illustrating exactly how to connect everything. A speaker kit is the best way to ensure you end up with a completed project that delivers premium performance, even if you have no experience whatsoever.
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What's In a Speaker
Most speakers are made up of three main components: drivers, crossovers, and enclosures. Here is a general description of each of these components.
Drivers:
Drivers (or transducer) are the electromechanical devices in a speaker that converts electrical signals into mechanical vibration in order to produce sound waves. Drivers are the most recognizable part of a speaker. In fact, a driver by itself is a speaker, but they almost always need help to perform best. Help in the form of other drivers, crossovers, and enclosures. Drivers are usually divided into four primary categories: woofers, midranges, tweeters, and full ranges. There is a large grey area where these categories overlap, but here is a general description of each.
Woofers are drivers designed to play low frequencies, or bass. To produce bass a driver needs to be able to move a significant amount of air. Historically, woofers are larger drivers that are capable of significant displacement. That is not always the case though, thanks to improvements in motor design and improved excursion; some woofers available today can be quite small. Essentially, if you expect a driver to play low frequencies, then it is a woofer. If a woofer is designed to play the absolute lowest frequencies, then is usually called a subwoofer. There are also some woofers that are designed to deliver maximum output in the upper bass range, these are referred to as midbass drivers.
Midranges have the critical job of reproducing the middle frequencies. This frequency range includes the majority of the human voice and most instruments, covering the part of the frequency spectrum that is considered the most important. A woofer or full-range driver can make an excellent midrange in many cases. However, suppose a driver is designed specifically as a midrange. In that case, it usually won't have enough displacement capability to play low frequencies, so most midranges can not be used as woofers.
Tweeters play the highest frequencies, or treble. Higher frequencies require less displacement, so in most cases, tweeters are significantly smaller than woofer and midrange drivers. Due to the small size, tweeters must be protected from midrange and low frequencies, or they can be damaged easily. Also, tweeters need to change direction up to 40,000 times a second, so low mass is required to produce higher frequencies accurately.
Full-range drivers are capable of covering the majority of the audio spectrum. These do-all drivers can deliver a satisfying full-range sound all by themselves but usually sacrifice linearity in the highest frequencies and output capabilities in the lowest frequencies. There are certain cases where full-range drivers can work well as midranges or woofers. Some smaller full-range drivers can even be used as tweeters (or tweeter-midranges).
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Passive Crossovers:
A passive speaker crossover is an electric circuit consisting of capacitors, inductors, and resistors that split the audio signal to the appropriate drivers. Most people consider a crossover as a filter that divides the frequencies and sends them to the appropriate drivers, which in the simplest terms is correct. However, a properly designed crossover can do much more than that. In a well-designed speaker, a crossover filters frequencies while also providing level matching, equalization, phase alignment, and damping. A crossover's job can be as complex as you want to make it (to the point of diminishing returns). Here is a general overview describing filter circuits and other commonly included circuits in a passive crossover network.
Two basic filter circuits are used in a passive crossover: high pass and low pass. As the name implies, these filters allow a specific range of frequencies to pass on to the driver (also referred to as the passband).
A bandpass filter combines high pass and low pass filters, allowing only a specific band of frequencies to pass. The number of times the audio signal is divided describes a crossover's type. For example, a "2-way" crossover includes just a high pass and low pass filter, and a "3-way" contains a high pass, low pass, and bandpass filter.
Filter circuits can also have varying slopes or rates in which the frequencies are filtered out. The rate of the slope is described as the filter's "order." A first-order filter rolls off at a rate of -6 dB per octave, meaning a "first-order 5,000 Hz high pass filter" (starting at -6 dB at 5,000 Hz) will be -12 dB at 2,500 Hz, -18 dB at 1,250 Hz, and so on. Each increase in order increases the slope by another -6 dB per octave, so second-order is -12 dB per octave, third-order is -18 dB per octave, and fourth-order is -24 dB per octave. Due to the number of required components, you usually will not see passive filters higher than fourth-order (possible, but not common).
There are a few other circuits you will find in passive crossovers. The most common is an L-pad, this is a circuit that will lower the overall level of a driver without significantly affecting the impedance of the driver.
Another fairly common circuit is a Zobel network, which is used to counteract the rise in impedance caused by a driver's inductance to make a driver present a more resistive load (vs. a reactive load).
Next is a series notch filter. Most drivers will have an impedance peak centered on the resonant frequency that significantly affects how a filter reacts. A series notch filter will level out this impedance peak to ensure the filter will perform as expected.
Finally, a parallel notch filter is an equalization circuit that lowers the output through a specific bandwidth. Suppose you have a driver with a peak in response at 1,000 Hz (or anywhere). In that case, you can use a parallel notch filter to reduce the peak for a flatter overall response.
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Enclosures:
The enclosure, or speaker cabinet, is the backbone of a speaker system. Of course, the enclosure holds everything together, but there is more to it than that. Since the sound waves radiating from the back of a driver is 180° out of phase with the front of the driver (canceling each other), an enclosure is a simple way to separate (or delay) this "out of phase" rear sound wave. Phase is especially important with lower frequencies, which have longer wavelengths. If the rear radiation is not removed or delayed, then the low-frequency capability of a driver will be significantly reduced. The most common enclosure types are sealed (or acoustic suspension) and ported (or bass reflex).
A sealed enclosure essentially contains and dissipates the rear sound wave while also providing an air spring that helps control the movement of the driver's cone. A ported enclosure uses a vent to tune the enclosure to a specific frequency and actually uses the rear sound wave to augment the low-frequency response. Above the tuning frequency, the rear sound wave is filtered by the port (mechanical high pass filter), but as you approach the tuning frequency, the rear wave is delayed to create a 180° phase shift, so the rear wave is actually combining with the front wave helping improve output at and near the tuning frequency. As you drop below the tuning frequency, the output of the port returns to 180° out of phase, canceling the output from the front of the cone. So, vented enclosures typically produce higher output at a lower frequency than sealed enclosures. However, sealed enclosures have a shallower roll-off, so in some cases, sealed enclosures can deliver more output at extremely low frequencies. There are many more types of enclosures such as passive radiator, bandpass, transmission lines, open baffle (no enclosure), and horn-loaded.
An enclosure can hold everything together and improve low-frequency response, but the enclosure can also affect the overall frequency response. Baffle step is the biggest issue and one that you will need to account for in most designs. Sound waves radiate in a spherical pattern, so the sound waves will actually reflect off of the baffle at higher frequencies.
As the frequency goes down and the sound wavelengths get longer, there is a point where the waves will transition from reflecting off the baffle to wrapping around the baffle. This transition will cause a gradual 6 dB drop in the output below a certain frequency. Another phenomenon that can affect overall response is diffraction. When a sound wave travels across the baffle and encounters any sudden transitions, such as a baffle edge, the sound wave will spread in every direction, creating peaks and dips in the overall response. In most cases, things like flush mounting drivers and rounding the edge of an enclosure will help to minimize this diffraction.
Types of Speakers
Speakers come in various sizes and types like bookshelf, tower, Bluetooth, soundbar, center channel, DJ, etc. However, almost all speakers are described by the number of drivers between which the signal is split.
"Full-range" speakers will use a single driver to cover most of the audio spectrum. A "2-way" speaker splits the audio signal between two drivers and will consist of a woofer and tweeter, or in some cases, two woofers and a tweeter. When the signal is split between three drivers, then the speaker is a "3-way" design. These use a separate woofer, midrange, and tweeter. In some instances, you will see that a speaker is referred to as a "2.5-way". In these designs, the response of one driver overlaps the part of the response of another driver to boost output in that area. A .5-way design is most commonly used to boost the low-frequency output of a system and is a common way to counteract baffle step without sacrificing overall efficiency.
Speaker Design Steps
Learn how to design and build your own custom speakers in 7 simple steps.
1. Plan:
Before starting any speaker project, it is good to start with a solid plan. Without specific goals, it is easy to become overwhelmed by the sheer number of available drivers. Start by deciding what kind of speaker you would like to build. Then consider how much space you have to work with.
2. Select Drivers
Select the woofers, tweeters, or subs that are the best fit for your speakers. In this step you will need to make sure that the specifications and dimensions fit your design.
Woofer Selection Guide3. Model, Design, Build Enclosures
Start to understanding the design and modeling of your enclosures. Modeling, testing, and designing your enclosures is a crucial step to get great sound from your speakers.
Speaker Design Tools4. Measure Drivers
Using measurement and analysis tools measure the drivers that you have selected to ensure that they will meet the needs of your new speaker.
Shop Measurement Tools5. Design Crossover
The crossover design is critical to the final sound of the speaker build. Picking the correct inductors, resistors, and capacitors is important to meet the needs of the the schematic that you designed.
Crossover Design Help6. Assemble and Finish
Put it all together. Don't forget any finish or hardware to give your speaker a professional touch.
Shop Cabinet Hardware7. Enjoy
The best step of the speaker building process is to sit back, relax and enjoy your new speakers.
Speaker Kit Assembly Videos
Parts Express's YouTube channel has a great assortment of videos on how to build speaker kits we offer. Below is a playlist for various speaker kits.
Speaker Builder's Shopping List
You might ask yourself, "what do I need to build speakers?" Below is a list of common items that are needed to build custom speakers.
Test & Measurement
Accurate measurements and specs are essential when designing and building speaker systems. Speed up your speaker design and builds with professional grade test and measurement tools. These tools help measure speaker responses, impedance, and are able to provide measurements and graphs on the fly. Speaker design and crossover software help model your speakers and assist in cabinet design.
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Power Your Speakers
If you would like to add some power to your speaker builds, we recommend that you add an amp board or plate amp.
Amp Boards
The Dayton Audio KAB and KABD lines of Bluetooth amplifier boards give you the ability to quickly and easily add audio to speaker build, kiosk, or any project in which audio enhances the experience. Offering Bluetooth 5.0 both lines of amps provide aptX HD which ensure the best possible wireless sound quality. Multiple feature and power board configurations provide a solution to power most stereo speakers.
The KABD amp boards include powerful digital signal processing capabilities that allow you to fully customize your sound. Complete with a full line of accessories including battery boards, standoff boards, leads, and DSP programmers, the KAB and KABD amp boards are an amazing way to turn any project into an audio experience.
KABD Amp BoardsPlate Amps
For self-contained systems, Dayton Audio offers 3 different full-range plate amplifiers. Our feature packed WF60PA plate amplifier is ideal for creating powered monitors with a variety of inputs, including Bluetooth and wireless streaming. Specifically for sound bars, the SBA302BT includes all the modern features you expect, such as remote control, HDMI ARC input, Bluetooth, and more. To drive high output PA speakers, the powerful PPA800DSP is a feature packed 800 watt 2-channel amplifier that includes customizable DSP with presets.
Designed to optimize your subwoofer's performance, Dayton Audio's comprehensive line of subwoofer plate amps offer power and versatility to fit in any design. Select models feature fully customizable and integrated DSP. The DSP feature allows you to achieve incredible low end no matter the size of the cabinet. Dayton Audio's high-output, and robust sub plate amps are a great solution for any powered subwoofer.
Recommended Reading
This primer was intended to show you the steps required to build a two-way system without the need for expensive measurement equipment. We tried to be as in-depth as possible without getting into too much complex theory. To gain much more valuable information on the subject of loudspeaker drivers, cabinet construction, and crossover design, we highly recommend the following books and publications:
What's The Next Step?
To take the next step in your speaker building journey, be sure to check out the speaker kits that are available from Parts Express. There are a variety of speaker types which are a great starting point to discover a new passion.
Additional Resources
Driver Resources
Crossover Design Help
Learn From The Best
Parts Express is a leading supplier in raw drivers, speaker components, and resources for speaker builders. Whether you are a seasoned vet or someone looking to find a new hobby, Parts Express has the gear and resources you need to complete your next project. The large community of speaker builders on our Tech Talk forum allow you to learn from some of the best in the business. For more inspiration, check out the Project Gallery which showcases a variety of designs from the speaker building community.
Want a second or third opinion about your speaker cabinet design or other audio related problem? Post your question or comment on TechTalk, our Technical Discussion Board. Hundreds of technicians, engineers, and hobbyists, nationwide read and discuss electronics related questions each week. We welcome your participation!
