How to Make Your Own Audio Diffusers with Concrete Forming Tubes
How to Make Your Own Audio Diffusers with Concrete Forming Tubes GA S REGULAR Menu Lifewire Tech for Humans Newsletter! Search Close GO Home Theater & Entertainment > Audio 99 99 people found this article helpful
The diffusers are made with concrete form tubes, cardboard tubes with walls typically about 3/8-inch thick. Home Depot sells them in sizes up to 14 inches in diameter and 4 feet in length. Construction supply stores sell them in sizes up to 2 or 3 feet in diameter, in lengths up to about 20 feet, but they'll be happy to cut them to your preferred length. To make the diffusers, you'll need to split the tubes in half, then attach supports to mount the diffusers on the wall.
To make your cuts, measure the actual diameter of the tube. In this tutorial, the diameter is 14-1/4 inches. Next, measure half of the diameter of the tube, and mark that height on each tube. Mark the halfway point on the tube on both sides, on each end. Before you make height marks, put something heavy inside the tube to ensure it won't roll. We used an anvil—you know, like the one Wile E. Coyote used to try to drop on the Road Runner.
Go nice and slow, and you'll be rewarded with a straighter and smoother cut. With one side done, unclamp the 1x2 and move it over to the other side of the tube. Now clamp it along the other marks you made, making sure to clamp it so you'll get two even halves when you cut. If you cut the wrong side, you'll end up with one diffuser that's thicker than the other. To make sure your line is straight, mark the distance on both sides of the half-tube, then stretch a wide strip of something like a wide fabric belt around the tube to serve as a guide to make your cut line. Then make a slow, steady, and precise cut along the mark with the jigsaw, or a hand saw. This tutorial assumes that you want to make your diffusers 4 feet high, but if your room design or existing wall decor requires a shorter diffuser, no problem—cut them to whatever length you want.
We also used 1-1/2-inch wire brads (nails) with flat heads of 1/8-inch diameter, with two brads per side, per bracket. Be gentle with the hammer because the cardboard tubes can dent easily. Just make sure the brad heads are flush with the tube. Now mark the center point in one of the brackets and drill a 3/8-inch hole there. You need to put a hole in only one of the brackets.
If you're using a video projector, wrap your diffusers in black or dark gray felt to absorb light—the less light bouncing around your room, the better the contrast on your screen.
Spray the surfaces of the tubes and give the adhesive half an hour to set.
Trim the fabric, leaving about 2-1/2 inches excess all around.
Spray the insides of the tubes on their long sides. Fold the fabric in, making a couple of quick cuts with scissors to accommodate the mounting brackets.
Let the adhesive set for another half hour, then blast the inside ends of the tubes with a generous amount of adhesive.
Fold in the rest of the fabric.
How to Make Your Own Audio Diffusers
A tutorial for creating and mounting diffusers for acoustics
By Brent Butterworth Brent Butterworth Writer University of North Texas A former Lifewire writer, Brent Butterworth's lifelong passion for audio and music has taken him from building DIY speakers to searching for the hottest new audio technologies. lifewire's editorial guidelines Updated on June 3, 2022 Tweet Share Email Tweet Share Email Audio Speakers Soundbars Stereos & ReceiversWhat to Know
Use concrete form tubes from a hardware or construction supply store, cut in half, place around room.Diameter matters: 24-inch diameter = more effective 1-foot thick diffuser; 14-inch = more affordable 7-inch diffuser.Choose diffuser positioning, measure and mark tubes, cut in half, nail in mounting brackets, set up against wall. This article explains how to build audio diffusers for your room acoustics, based on Dr. Floyd Toole's book, Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms. Diffusers reflect sound in many different directions in a room to give your home audio system's sound a greater sense of spaciousness. The materials you need to build diffusers are available in stores like Home Depot, Lowe's, and other construction and craft supply stores.The Plan
The image below shows a simplified room layout according to Dr. Toole's principles. The blue areas represent diffusers. The red areas represent foam absorbers. The diffusers and absorbers are all mounted on the wall, about 18 inches off the floor and 4 feet high. These sizes are only examples and not critical measurements for creating diffusers.The diffusers are made with concrete form tubes, cardboard tubes with walls typically about 3/8-inch thick. Home Depot sells them in sizes up to 14 inches in diameter and 4 feet in length. Construction supply stores sell them in sizes up to 2 or 3 feet in diameter, in lengths up to about 20 feet, but they'll be happy to cut them to your preferred length. To make the diffusers, you'll need to split the tubes in half, then attach supports to mount the diffusers on the wall.
Choosing the Diffuser' s Diameter
The diameter you choose for your diffusers is important. The thicker the diffusers and the farther they stand away from the wall, the lower the frequencies they can affect. According to Toole, a geometric diffuser like the ones in this article must be 1-foot thick to be effective through the entire midrange and treble frequency range. However, 1-foot thick diffusers are bulky, and the 24-inch diameter concrete forming tubes required to make 1-foot thick diffusers are expensive. If you want to make your listening room great, build 1-foot thick diffusers. If you want your room nice-looking and more affordable, use 14-inch diameter tubes available at Home Depot. The 14-inch tubes will give you 7-inch thick diffusers, still better than many of the too-thin commercially available diffusers sold by pro-audio stores. This tutorial builds 8-inch thick diffusers for a back wall and 7-inch thick diffusers for sidewalls.Diffuser Positioning
It's a good idea to place a couple of diffusers at the "point of first reflection" on each sidewall. The point of first reflection is the place where, if you put a mirror flat on the wall, you can see the reflection of the speaker nearest that wall while you're sitting in your favorite listening chair. You can also place a couple more diffusers farther back along the sidewall. Definitely put a few along the back wall, which will minimize flutter echo. The size, shape, and layout of your room will influence your diffuser count and positioning.Measuring for the Cut
Once you have your tubes, you'll need to split them in half. Make the cuts straight and precise so your diffusers will be flush against the wall and appear professionally made. We used a jigsaw with a fine-tooth blade consisting of 24 teeth per inch—the finer the teeth, the smoother the cut. You can split the tube in half with a hand saw, but your cut probably won't be as smooth or precise as with a powered jigsaw. Do not use a jigsaw unless you have experience using one. Instead, ask a more skilled person to make the cuts for you. Or study the proper operation and safety practices, then practice cutting junk wood. Also, wear safety glasses and ensure other people and pets are a safe distance away when using a jigsaw.To make your cuts, measure the actual diameter of the tube. In this tutorial, the diameter is 14-1/4 inches. Next, measure half of the diameter of the tube, and mark that height on each tube. Mark the halfway point on the tube on both sides, on each end. Before you make height marks, put something heavy inside the tube to ensure it won't roll. We used an anvil—you know, like the one Wile E. Coyote used to try to drop on the Road Runner.
Making the Cut
To make a smooth, straight cut, clamp a 1x2 stripboard on the side of the tube. Make sure to align the 1x2 stripboard with the marks you just made. Use high-quality 1x2 stripboards because they're straight and almost always defect-free. In addition, it'll be worth the extra few bucks because you'll be cutting these up later to make your mounting brackets. Now, carefully cut the tube by using the 1x2 stripboard as a guide for the jigsaw. The blade is in the center of the saw, so your cut will be offset from your marks, but this is fine because you'll have a matching offset on the other side of the tube. In this tutorial, the offset is 1-1/2 inches.Go nice and slow, and you'll be rewarded with a straighter and smoother cut. With one side done, unclamp the 1x2 and move it over to the other side of the tube. Now clamp it along the other marks you made, making sure to clamp it so you'll get two even halves when you cut. If you cut the wrong side, you'll end up with one diffuser that's thicker than the other. To make sure your line is straight, mark the distance on both sides of the half-tube, then stretch a wide strip of something like a wide fabric belt around the tube to serve as a guide to make your cut line. Then make a slow, steady, and precise cut along the mark with the jigsaw, or a hand saw. This tutorial assumes that you want to make your diffusers 4 feet high, but if your room design or existing wall decor requires a shorter diffuser, no problem—cut them to whatever length you want.
Nailing in the Brackets
The mounting brackets are part of the 1x2 strip boards you used for measuring. To make the mounting brackets, cut the boards to the same measurement as the original inside diameter of the tube. Use a miter box to ensure a straight, square cut. Nail the mounting brackets as shown below. You can use two brackets on each diffuser to make the diffusers less likely to warp. Then place one bracket about one foot from each end of each diffuser.We also used 1-1/2-inch wire brads (nails) with flat heads of 1/8-inch diameter, with two brads per side, per bracket. Be gentle with the hammer because the cardboard tubes can dent easily. Just make sure the brad heads are flush with the tube. Now mark the center point in one of the brackets and drill a 3/8-inch hole there. You need to put a hole in only one of the brackets.
Finishing Touches
Here's where you bring your creativity to the process: decorating your diffusers. You could paint the diffusers, but keep in mind they're made like giant toilet paper tubes, with a continuous seam wrapping around the tube. You're better off covering the tubes with some fabric, wallpaper, or almost whatever you want. Perhaps whimsical paisley fabric? Or a favorite cartoon character? It's up to you. Just make sure the store has enough of it because you'll be using several yards' worth.If you're using a video projector, wrap your diffusers in black or dark gray felt to absorb light—the less light bouncing around your room, the better the contrast on your screen.
Adding Fabric to Diffusers
To apply fabric, use a spray adhesive like Loctite 200, then: Cut the fabric with about 6 inches to spare on every side.Spray the surfaces of the tubes and give the adhesive half an hour to set.
Trim the fabric, leaving about 2-1/2 inches excess all around.
Spray the insides of the tubes on their long sides. Fold the fabric in, making a couple of quick cuts with scissors to accommodate the mounting brackets.
Let the adhesive set for another half hour, then blast the inside ends of the tubes with a generous amount of adhesive.
Fold in the rest of the fabric.