Intro: How to Build Custom Speakers
Building your own custom speakers has got to be one of the most rewarding, straightforward and cost-effective DIY activities I've come across. I'm absolutely shocked that it hasn't had a larger presence on Instructables and in the community...well, until now of course.
Some speaker projects can be complete in a weekend, while others can go on for years. Budget speaker kits start around $100, while top-of-the-line kits and components can add up to several thousands of dollars. Regardless of how much you choose to spend on your speakers, you'll likely be building something that will sound as good as commercial product that off the shelf would cost as much as 10 times more.
So, if you've got access to a table saw, a jig saw, a drill, some wood glue, clamps, and a place to make some sawdust, then you've got the opportunity to build your own custom speakers.
This Instructable will cover the entire process, from sourcing components, to tips and tricks, to exotic and inspiring finishing options.
The images below show just a few of the speakers that I've built over the last 10 years.
Step 1: Why?
Back in 1997 I attended the Home Entertainment Show with my father. We had the intent to build the best speakers that we possibly could. We listened to just about every manufacturers flagship model. I recognized all of the drivers from the DIY catalogs, wondering which one would reign supreme.
At the end of the day, after the votes were in, we both selected the JM Labs Grande Utopia's as our favorite model, hands down. Since then, it's been widely agreed that the Grande Utopia are among the best sounding home audio speakers in the world. The only catch is that back in those days, the speaker sold for $40,000, and now the updated model, equipped with a Beryllium tweeter, costs even more.
JM Labs uses affiliate company Focal brand drivers. Now here's where it gets interesting...the same line of drivers used in the JM Labs loudspeakers, can also be purchased from Zalytron. My father and I purchased an extremely similar set of drivers, from the same product lines that JM Labs uses, including "W" cone woofers and audiom inverted metal dome tweeters, and built our own "DIY Grande Utopias" for only $3,000. I would never claim that they are an exact copy of the Grande Utopias, but they do sound absolutely amazing, and at less than 1/10th the cost, it's hard to argue. That, my fellow Instructables users, is why I think everyone should build their own speakers.
Step 2: Speaker Theory
Yes, they do sound better, and no you don't have to be an audiophile to hear the difference
- Sound quality has been steadily declining as heavily compressed digital audio, iPod docks, and bottom dollar stereos have proliferated around the world over the last 10-15 years. Listening to music on a great set of speakers is the single biggest change you can make to your stereo to get better sound quality. If you want to blow $200 a foot on oxygen free speaker wire made from precious metals, great, go for it, just make sure you've already invested a lot of time and energy in making the best possible speakers your finances and skill level allow.
- If you're about to build your own custom speakers, you'll likely be spending at least 40 hours on the project if you've got experience with woodworking, electronics, finishing techniques, or have built your own speakers before, and even longer if it's your first pair. Depending on how you value your time, you'll have thousands of dollars of free labor (your own) invested in the speakers. If you happen to find yourself deciding between a $5 paper cone, no name woofer, and a $25 poly cone made by some brand name, please, get the more expensive one. Like tools, speaker components are an investment that you'll have for the rest of the your life, so reach a little and get the best stuff for your project that you can afford.
- Get started by ordering a kit from a supplier. It takes a significant amount of knowledge and work to design your own crossovers and calculate your own box dimensions. It's much easier to tackle your first speaker project by standing on the shoulders of experienced audio engineers. So, get a kit from one of the retailers listed in the next step and get started on your project today.
Step 3: Resources
Before embarking on a DIY speaker building journey, take some time to familiarize yourself with the process (this Instructable should cover that), and also poke around sites that showcase DIY speaker builders work, designs, and the companies that distribute the best components in the U.S. There's a wide range of designs, driver options and technologies to learn about and choose from.
Great print resources include:
The Loudspeaker Design Cookbook
Introduction to Loudspeaker Design
Designing, Building and Testing your own Speaker System
There are numerous web resources for DIY speaker builders:
DIY Loudspeaker Designer's Selection Guide (the LDSG)
The Subwoofer DIY Page
DIY Audio Projects
Wayne's Speaker Building Page
Parts Express is great for entry level drivers and is also a great supplier of all kinds of speaker building accessories.
Madisound has a wide range of products, from hi-fi components to complete kits that even include pre-assembled cabinets.
Zalytron is the primary US dealer for the world renowned Focal brand drivers and offers everything from budget kits for the money conscious builder, to top-of-the-line audiophile kits that rival the industry's best speakers.
Step 4: Select Your Kit or Components
Some factors to consider when selecting drivers are:
- the kit designer
- design specs and requirements
- sensitivity db
Take your time in learning about what technologies and speaker components you'd like to use. When making your selection about tweeters alone you can choose from, horn tweeters, soft dome tweeters, inverted metal dome tweeters, coaxial drivers, ribbon tweeters, bullet tweeters, flared tweeters, and piezo tweeters.
Check out Madisound's drivers page to get an idea of what the different technologies look like.
Some of the most well-known producers of speaker drivers are:
The speakers that are being given away feature the following drivers from Zalytron and plate amp from Parts Express:
2.5 way MTM Towers:
(2) JM Labs 6VE3251B woofers
(1) Focal TC 90 TD5B tweeter
2 way TM Bookshelf Speakers:
(1) JM Labs 6VE3251B woofer
(1) Focal TC 90 TD5B tweeter
12" Sealed Subwoofer:
Dayton SA100 100W Subwoofer Amplifier
Step 5: Choose a Cabinet Design
Once you've selected your drivers it's time to begin planning out the cabinet. Work with your component provider to choose a box design that best matches your specific components. If you're building a kit, a box design should have come along with your drivers and crossover plans.
Box design can make a $5 driver sound like a speaker that costs $500 retail, but if it's not designed and built correctly, it can also make a $500 driver sound like it was ripped out of an old transistor radio. DIY speaker builders can't make their own drivers very easily, but we do build our own speaker cabinets, so that's where we tinker, innovate, build with care, and shine. As a result, it's the cabinet design and execution that we spend the most time on.
Cabinet design decisions start at the basics, like the volume of the cabinet, whether it will be sealed or ported, how much bracing the cabinet needs, what thickness material it should be made out of and what height the tweeter should be mounted at so that it's in line with the listeners ears.
From there, it progresses to more complex and acoustic decisions like rounding over the corners to reduce interference, building elaborate horn structures to amplify the sound, using exotic materials to further dampen resonant frequencies, line arrays to gain efficiency, mounting drivers at different distances from the listener to accommodate for the fact that high frequencies travel slightly faster than low frequencies, and eliminating parallel faces - the surfaces that create resonant frequencies, by building poly-faceted cabinets, or better, spheres, rather than the standard rectangular cabinet.
That being said, the vast majority of DIY speaker builders start with a straightforward, rectangular cabinet design that even though lacks the bells and whistles, and highly engineered elements listed above, still sounds fantastic.
An example of a MTM bookshelf speaker speaker design appears below from Zalytron.
Step 6: Cut the Speaker Panels
I build all of my speakers from a type of fiber board called MEDEX. It's a LEED certified formaldehyde free material that's similar to MDF, but far heavier, denser, and moisture resistant. Many contractors use it as a building material in humid climates, and it's widely used to make counter tops.
It's not stocked in every lumberyard, but it can be special ordered. If your local lumber yard can't find a source for it, or if you don't want to pay the higher price for it, MDF is the next building material of choice. Avoid plywood, hardwoods, OSB, strand board, and light density fiber boards if possible.
The speaker cabinets should be as sonically dead as possible. That means heavy, thick-walled, and well constructed. Ideally the entire cabinet should be built out of 1.5" material. In reality, I've only done a handful of speakers that were that thick due to the cost and weight. The industry standard is a 1.5" front baffle, and then 3/4" for the rest of the cabinets. Zalytron builds their cabinets to these same specifications. Many other companies do not. Look closely to see what's included in your specific kit if your ordering one that has the cabinet included.
Plan out your speakers on paper and create a cutting diagram based upon the raw 4' x 8' sheets. Head to the lumberyard and pick up as many sheets of MDF or MEDEX as you need for your projects.
Transfer your cutting diagram onto the sheets themselves and then begin to break them down, making the biggest cuts first. Work the large sheets down into small manageable panels and cut things to their exact size. When cutting like-sized speaker panels make all of your same-sized-passes on the table saw at the same time, without moving the fence, to ensure that parallel panels will be exactly the same size.
Once all of your panels are cut, check and then recheck your measurements. If the speaker cabinets are going to be square, they've got to start with perfectly cut panels, otherwise they just won't ever line up correctly.
Step 7: Mark and Cut Support Panels
As shown in the cabinet design in step 5, the basic speaker cabinet contains supports on the inside to further strengthen and sonically dampen the exterior walls. These supports are usually cut from scrap 3/4 material and are cut with a swiss cheese like pattern to allow air to pass through them so that they don't divide the cabinet and impede air flow inside.
Internal support panels should be located in parts of the speaker that are closest to the woofers, and anywhere that the cabinet may need reinforcement, like the midpoint of the sides.
The tower speakers have two internal supports, while the bookshelf speakers have only one.
Trace a simple pattern of circles or squares onto the support panels and use a drill with a large drill bit to create a starter hole for your jig saw. Then, use the jig saw to connect the drill holes and trace the path of your cutout.
The picture set below ends with the brace for the subwoofer, so it's a bit bigger and has a larger cutout for the larger subwoofer driver.
Step 8: Mark and Cut Biscuit Joints
Like most professional kitchen cabinet makers, I use biscuit joints to hold my speaker cabinets together. They easily and perfectly align adjacent faces, are quick to cut and install, and are super strong.
First, mark adjacent surfaces with a pattern or code of your choosing. I simply assemble the speaker panels into the correct formation and mark adjacent sides with an "a", "b", "c", or "circle", "square", "triangle" code and so on. I then give them a little tick mark crossing onto both sides where I'll alight the biscuit joiner to make the plunge, and draw a long line on the face that will get a groove cut into it, so that I don't get lost and cut into the wrong face. See the secondary photos below to see what I mean.
With the faces all marked up, I clamp the boards down to the table and begin cutting slots with the biscuit joiner.
I generally install two biscuits per joint on the speaker cabinets. This part is a bit tedious, because there are many joints and adjoining faces, but it's worth it when you go to glue because things will line up really well. I find messing around with screws while trying to glue and clamp the cabinets together is just a bit clumsy and certainly more difficult to square up.
Step 9: Glue the Cabinet Sides Together
The first part of the cabinet to be assembled are the sides, top and bottom. The front and back go on later.
Before gluing up the cabinets I lay everything that I'm going to need out on a large flat level surface. Once the glue bead gets laid down, the clocks ticking, so you'll want to move with some speed and efficiency. Having an extra set of hands for the step really helps, but it's not a necessity.
Lay a thin bead of high quality wood glue (I like Titebond myself) along the edges of all adjacent sides. Be sure to spread extra glue inside the holes for the biscuits. I use a chip brush to paint the glue into position and spread the bead evenly into a 3/4" strip.
Insert the biscuits into the slots, being sure to push them all the way down. Any biscuits that don't easily fit into the slot should be discarded and swapped for a new biscuit--sometimes the biscuits swell slightly due to moisture and humidity.
With the biscuits in place and glue on all of the adjoining surfaces, it's time to assemble. Join edges to faces and construct the cabinet.
I use many many clamps to pull the cabinet tightly together and apply uniform even pressure to the joints.
With the edges glued and the clamps loosely in place, now's the time to square everything up. Using a tape measure and the clamps, measure the diagonal from corner to corner of the square you've just created and adjust the clamps until they are equal. This means that the box is perfectly square. See the photos below.
Before the glue sets up, it's also a good time to make all of the panels flush with each other. Use a dead blow hammer and a block of wood to knock all edges flush.
Apply a sufficient amount of clamps and wait for the exterior walls of the cabinet to dry. As you can see from the pictures below, pipe clamps are great for this purpose, and if you've been needing an excuse (or two) to buy some, 42" tall tower speakers are good ones.
Step 10: Cut Out Holes and Recesses for the Drivers
With the sides, top and bottom of the cabinets drying, it's a good time to start work on the front and back panels. First time builders may choose to simplify this step and simply cut a large circle opening for the speaker driver to mount in. In that case, the speaker drivers' frame will rest on the surface of the speaker, protruding an 1/8" or so. For a truly professional look, however, you'll want to recess the drivers so that they mount flush with the front face.
In either case, the first step is to cut out a circle that accommodates your driver. I use a plunge router fitted with a Jasper Circle Jig. This Jasper Jig allows be to cut a circle of just about any size up between 2" and 18". If you don't happen to have this handy router and circle jig set up, the old drawing a circle using a piece of string tied around a nail works pretty darn well too. Then, simply cut carefully along your line with a jig saw and you're in business.
If you are using a router, use a 1/8" or 1/4" straight bit to cut out the circle so you end up removing as little material as possible. The wider the bit, the more material you have to eat through, the more dust you create, and the slower the process goes. Make multiple passes, incrementally plunging deeper and deeper through the front face.
Once the circles are cut, it's time to tackle the optional recess.
To do this you need to create a pattern template. Carefully trace, draw, plot, copy, CNC cut, or laser cut the outer pattern of your driver onto a thin piece of material creating a template. Technical drawings for speaker components can usually be found on the manufacturers or resellers website. Recreate a pattern in a drafting program of your choice from the drawings and produce the actual pattern piece. Remember, this step is totally optional!
Once the patterns have been created, center and mount it into place on the front face. I'm using some simple wood screws in the photos below.
Then, using a good router and a sharp straight bit fit with a pattern bushing collar on it, simply trace the pattern at the proper depth to create the recess.
Elliot from Zalytron has been kind enough to use his vast library of patterns to route the driver recesses for me when they're too complex for me to generate on my own - so if you're sourcing components from him, see if he can help you out.
Step 11: Cut Holes for the Terminal Cups, Ports and Any Other Additions to the Cabinet
There are some more holes that need to be cut in the front/and or back cabinet faces. Using the same drill and jig saw method described in step 7, cut out properly sized holes for the terminal cups or binding posts depending on what kind of connection point you've decided to use.
For the port, each situation will be unique. Different port designs require different holes. Slotted ports are built right into the cabinet, while PVC tubes (the kind I'm using below) require a properly-sized circle. Some ports go on the front face, others on the back, and other speaker designs require no port at all. Consult your cabinet plans to see what kind your kit requires.
The circle jig makes quick work of the port hole on the back panel in the photos below.
In the final few pictures in the sequence below you can see the back panel of the subwoofer. I'm using the jig saw to cut out the hole for the plate amplifier that will get mounted back there. Writing myself plenty of notes about the location and sizes of the holes and cuts is really useful for me so I can keep track of everything I'm doing, especially when building 5 cabinets simultaneously like I am here.
Step 12: Glue in the Support Braces
If the initial glue-up of the cabinets is dry, it's time to glue in the support braces. As before, apply a thin bead of glue to both surfaces and slide them into position.
The support braces can be glued in position when the top, bottom and sides are glued. It adds a bit more work to an already busy process, but it allow you cut slots and insert biscuits on the supports to join them to the sides, something that can't be done if they're glued in on their own like I'm doing here. Since their position isn't absolutely crucial like the other parts of the cabinet are, it's not a problem do wait for for the initial glue-up to dry, and do them on their own.
The subwoofer supports are shown below first, followed by the rest of the speaker cabinets.
Step 13: Glue on the Back Panel
With the supports in place you can glue on the back panel. By this point we've all gotten really good at gluing and sensing just how much glue to apply before excess starts to drip out. Paint the glue on both surfaces, apply the back, and clamp thoroughly.
Step 14: Install Dappening Material
Once the glue has dried it's time to install dampening material. Some people use polyester fill, others use acoustic foam, and others use pre-made adhesive backed foam products (pictured below). Different designs call for different types of dampening, in different quantities.
Follow your kit guidelines or contact the system designer to find out how much dampening you should use.
Black Hole 5 is the top-of-the-line name out there. It's a multi-layered dampening material, however from what I've found acoustical foam works equally as well and is a whole lot cheaper.
If your dampening material does not have an adhesive backing, use hot glue, or a construction adhesive to apply it to the walls of the speaker cabinet. The rule of thumb for dampening is that you'll want to dampen most of the inner surfaces of the cabinet, leaving room for your crossovers, drivers, ports and terminal cups.
For subwoofers I use standard polyester that's found in fabric stores.
Step 15: Wire Up the Crossovers
With the cabinets ready to go (minus the fronts), the next step is to wire up the crossovers. As described in the beginning of this Instructable, the crossover makes sure that high frequencies, like cymbal crashes, get sent to the tweeter, while lower frequencies, like bass guitars, get sent to the woofers and subwoofers. While some drivers don't require crossovers at all because they are equipped to reproduce all of the different frequencies, the vast majority of speaker designs and drivers require one for the tweeter, and another for the woofer.
I've built speakers for 10 years now and have never designed my own crossovers. It's a right of passage for sure, but an easy thing to get around by following someone elses design. In this case, I'm following Joe D'Appolito's design (legendary speaker designer and the man who invented the midrange, tweeter, midrange (MTM) driver configuration), since he's the guy who developed this speaker system.
Crossover plans look exactly like wiring diagrams and should come along with your speaker kit. They consist of resistors, capacitors and inductors. Audiophile quality components are a treat to work with since they're about 10x the size of standard electronics components.
Solder all connections together and hot glue components into place on a panel. Inductor coils should already have bare copper on it's ends, but, if there's any doubt, do a little sanding to remove the paint-on layer of insulation.
Each crossover will need high quality speaker wire running to, and coming from it. You'll need positive and negate leads going to the start of the circuit from the terminal cup, and positive and negative leads that run from the crossover to the speaker driver. For woofers that share the same crossover, which commonly occurs anytime you've got more than one woofer in a 2-way (woofer & tweeter) system, you'll need to solder on two sets of leads coming from the crossover. If you're building a 2.5 way system, like I am in the tower set in this Instructable, where one woofer plays lower then the other, you'll need to make three different crossovers the three different drivers.
I label the tails of all of my leads so I know where they are coming from and going to when it comes time to assemble. Nothing worse then gluing everything up only to find that you put the leads from the tweeter crossover into the woofers and vice a versa.
Step 16: Install the Crossovers Inside the Cabinet
Use hot glue, screws, or construction adhesive to install the crossovers inside the speaker cabinet. Put the heaviest crossover on the bottom and try to orient inductor coils at 90 degrees to each other to limit electromagnetic interference.
Pull leads into position through the terminal cup and into the area where the drivers will be mounted. I tie the speaker wire leads around the holes in the mounting bracket to reduce/eliminate wire tension that would be transmitted to the drivers and the crossovers in the event of a tug or snag.
Step 17: Glue the Front Panels Onto the Cabinets
With the crossovers and dampening material in position it's time to glue the front panels into position. Apply a thin bead of glue, use a brush to spread it out along the edge, and clamp the front face into place. Before sealing up the cabinet, do one more visual check that you've got all your wire leads in a place that's easy to reach, that you've followed all of the previous steps, and that everything is set to go, because once that front face gets glued on, there's no getting it off.
The photos below show this process occurring on the bookshelf speakers first, then the towers, and finally on the subwoofer.
Step 18: Sand the Edges Smooth
After all the glue has dried, there will likely be a small amount of hardened glue that was squeezed out by the clamps. Use a power sander to take this off and sand all edges flush. Try not to sand off too much, since the more that you do, the more out of true and square your cabinet becomes. Also, be careful to sand only one surface at a time and never round over the corners. You'll want those crisp lines when you apply our finishing material.
Step 19: Explore Finishing Options and Finish the Cabinet
Before any of the actual components get installed, you've got to do all of the finishing work.
Most speaker cabinets are finished with a wood veneer that's got some kind of lacquer, varnish, or polyurethane product applied to it, but don't let that limit your imagination. These are you speakers and you can make them look however you like! It won't affect the sound quality really at all, as that's all in the cabinet construction, so go nuts and make them look beautiful!
Some creative ideas I've seen around the web are linked to below. Since the speakers I made were built as the prize for the Art of Sound contest, we went with something unique, bold and festive...in other words, bright orange and white upholstered vinyl with black edge piping for the towers, spray on pickup truck bed liner, 3" chrome plates spikes and waterjet cut steel flames for the subwoofer, and fur covered, eye patch toting, horned and toothed monster treatment for the bookshelf speakers.
Rubiks Cube Subwoofer
The process of veneering requires an entire Instructable on it's own. The basic concept can be described as taking a very thin layer of a good looking hard wood, like maple, cherry, oak etc., and adhering it onto a less beautiful substance, in this case MDF or MEDEX.
For the basic concept check out Rockler's Veneering page.
For more info you can also read Veneering: A Foundation Course on Google Books.
Step 20: Install Cabinet Spikes
Cabinet feet and spikes come in all different shapes and sizes but generally get installed in the same way.
Pre-drill the proper size hole for the gnarled nut and hammer it into position using a block of wood for protection. Then, simply screw in the spike and lock it into position with the lock nut. The spike sleeves in the photos below are threaded, so they get screwed into position using an allen wrench, rather than hammered into place.
Step 21: Install Terminal Cups, Ports and Port Flanges
It's getting close to the end - time to get excited!
Drill pilot holes for the terminal cups and screw them into position.
The port tube can be hammered into place and covered with a port flange or cap. These aren't necessary, but make everything back there look really nice.
Step 22: Install Drivers (tower Speakers)
Mark and drill pilot holes for all for all of the mounting holes on the speaker drivers. Then, grab the leads coming from the crossovers and solder them onto the metal tabs coming from the driver. Use your labels to match the positive lead to the bigger tab, usually stamped with a red dot and "+" sign, and the negative lead to the other tab, usually a bit smaller, not marked with a red dot, and stamped with a "-" sign.
Once the drivers are soldered into place, stuff excess speaker wire back into the cabinet and screw the drivers into position using some nice, pan-head, black finish, coarse thread screws.
Step 23: Install Driver and Plate Amp (subwoofer)
The process of finishing up the subwoofer is relatively similar to finishing up the other speakers. Instead of acoustical foam or Black Hole 5, I use polyester fill. Subwoofers are generally filled with a larger amount of acoustical dampening material, and as a result, I generally opt for the cheaper, more compressible option of poly fill.
The subwoofer has no independent crossover, only an active variable crossover built into Dayton 100W plate amp from Parts Express, so there's nothing to do there.
Connect the speaker wire to the binding posts on the back side of the plate amp and install the amp into position in the hole that was previously cut out of the back.
Route the wires through the speaker cabinet, tying them around a support bracket to reduce wire tension in the event of a snag, and then twist them around the leads coming from the sub woofer driver.
Solder all connections.
Finally, install the subwoofer driver into position on the front of the speaker by drilling pilot holes and then screwing it into position using pan head black finish screws.
Step 24: Test
With all the driver mounted and all components in position, it's time for the big moment, the first real test run of the speakers.
Assuming that you can bare the suspense, carefully carry them to a good quality amplifier in a well dampened room, or wherever you plan on keeping them. Hook up speaker wire, power up your amp, and reach for your best mastered, best sounding CD, record, or dare I say, iPod.
There's virtually endless debate on what to play to "break speakers in" or test them with, but I've found that it's just best to play what you like, and what you've listened to most. You ears will remember what it has sounded like in the past, and hopefully, if all has gone to plan, will notice the huge improvement that you're now hearing.
I've found that Pink Floyd The Wall Disk 1, and more specifically "Mother" is an excellent track to test with. It starts off slow and low, so you're inclined to crank the volume up higher than you should at the beginning (this is a good thing), and then, around a minute or so into the track, it explodes in a rich sound stage, excellently mastered, and beautifully balanced, giving your speakers a real chance to shine. While the list of well mastered and arranged music is constantly growing, many DIY enthusiasts can agree that even though it's a bit dated at this point, Pink Floyd just sounds bigger and better then a lot of what's out there.
Speakers need a break-in period of time, or at least the industry big wigs claim that they do. I've found that the sound does tend to break in a bit, but for the most part, how the sound for the first time is a pretty good indicator of how they'll sound in 5 years.
Once the test is complete you should be grinning ear to ear, proud of your achievement and excited to re-listen to all of your music, knowing that it's not only sounding better then it ever has before, but that you made the whole thing possible, from start to finish.
Step 25: Enjoy
Once you discover how simple and rewarding custom speaker building can be, you may want to build more of them...I certainly did at least.
Here's to many great speaker projects, thick strong cabinets, the latest and greatest speaker drivers, and doughy-eyed grins at the end of our favorite songs.