The bass traps are the key to an excellent sounding studio. Step one is to make sure your material gives off the sound you want. If it doesn’t, step two is to experiment with different materials until you find what you’re looking for.
Bass trap material is one of those things that just isn’t always easy to get at your local building supply store or online these days because there’s so many choices that it can be overwhelming for both professionals and amateurs alike. The choices can include foam, fiberglass, batting and rubber.
I’ve provided the step-by-step procedure to retool your bass trap material in this article:
- MATERIAL SELECTION: Choose a material that is durable and easy to work with so you don’t ruin it when you put it up in your studio. Finding a material that has good sound absorption and good projection is important. I’m using Royal Crown Fast Action Foam (ROF) because it’s very soft, relatively inexpensive and it sounds great when used as a bass trap. (See my ROF article here.)
- CONSTRUCTION: As much as I’d love you to use the standard 4′ x 4’x 1/2″ Open Cell Foam, which is lightweight, easy to handle and very fast set-up and tear-down for bass traps, you’re much better off using closed cell. It’s more expensive but it’s also a lot more versatile when it comes to sound absorption and diffusion. Closed cell products tend to be heavier but they last a lot longer.
You can find closed cell products from companies such as Acousta-Tek where they include a wealth of information on how they work and what their various materials are used for in a studio. Best of all, you can get the exact material you need for your studio.
- TRIMMING: When choosing closed cell product, you need to be careful not to cut the fiberglass off the batting cloths leaving too few fibers in the cloths. It becomes less effective as a bass trap (sound absorption) if it doesn’t have enough fiber in it to act as effective diffusion of low-frequency sound waves. You want enough material to act as diffusion between your sub-division traps and your main bass trap systems.
- CAPACITY: Here are the types of fiberglass fiber you need for your bass traps. The more the better. One word of advice. If you’re using multiple bass trap systems, don’t use the same type of material on each trap because it’s more difficult to keep them all clean after multiple uses, especially if they’re rubber coated.
I suggest using 2′ x 4′ sheets for smaller areas and 3′ x 5′ sheets for larger areas or when you want to cover more than one wall with bass traps because it’s less costly than buying two different materials for each wall.
Use 8 oz. Fiberglass (Open Cell Foam): It has a little more weight than other weights and can be slightly harder to use but it’s still very easy to handle. You want the weight because that gives your bass trap system better absorption capabilities for frequencies around 300 Hz and below. If you’re using multiple bass trap systems, it’s best to mix and match this type of material with various different weights to get optimum absorption for each system.
Use 12 oz. Fiberglass (Closed Cell Foam): It’s heavier but it costs more. A little easier to handle because of it’s weight, you can still cut this heavy material with normal household scissors.
Use 14 oz. Fiberglass (Closed Cell Foam): This is the same 14 oz. fiber I use for my main bass trap systems for about the same price, only you get slightly more material out of each sheet of insulation.
Use 20 oz. Fiberglass (Closed Cell Foam): Not only is this the heaviest of the three foam types described above, it’s also the most expensive but at least you get twice as much material in each sheet when compared with 12 oz. fiberglass.
Here are the different types of foam that I suggest you use for your bass traps:
- 3″ Open Cell, 8 oz. Fiberglass: Best for low-frequency absorption and diffusion. This is what I use in all my studios.
- 3″ Closed Cell, 8 oz. Fiberglass: Not as effective as the Open Cell but still a very good product for bass traps since it’s very soft and easy to handle, even with a finish on it.
- 4″ Closed Cell, 8 oz. Fiberglass: The cheapest closed cell material you can buy because it’s less than half cost of the fiberglass but then cut into smaller pieces that are easier to handle than the 3″ closed cell material described above that weighs more than twice as much at 12 oz. (See my article on his product here.)
- 4″ Closed Cell, 12 oz. Fiberglass: This type of material is sometimes sold as 1/2″ or 5/8″ thick and you can even find an acoustic foam that’s 30% open cell and 70% closed cell that you can use (see my article on this product here.) So far, none of these products have shown to be as effective as the standard 8 oz. fiberglass but they’re still a good choice, especially if you want to add mass to your bass trap system without having such a heavy material such as 12 oz. fiberglass or leather.
- ADHESION: No matter what type of material you use, I strongly recommend that you add a very little bit of polyurethane (commonly known as rubber cement) to each sheet to ensure the material sticks well together. This protects both sides of the fiberglass from sticking to itself and it keeps air from leaking in and stale air from coming out when it’s put up. Use a small piece and apply it carefully and sparingly around all edges and around any openings (like windows).
- CLEANING: It’s very important for your bass trap material to be clean, especially after multiple uses. Use a soft washcloth with water to clean up the excess dust around the fiberglass fiber before applying the rubber cement on the fiberglass sheet.
- STAPLES: I highly recommend using staples instead of ductape to hold my material up on all 4 corners but you only need two staples per sheet on each side of your project. All you do is slide one staple into each hole then run a small amount of rubber cement over the end of each staple then twist it back or forth until they’re secure inside their holes inside your fiberglass sheet material. After you have one staple per sheet, switch sides and repeat the process.
- PREPARATION: If you’re using a large bass trap system that includes a 4-way or up to a 5-way bass trap, it’s important to have at least one extra sheet of fiberglass. That way you have enough fiberglass to spread out around the entire project which is essential if you want it to work as well as possible.
If you’re covering all of your walls with your new bass traps, make sure each of your bass traps has enough space on all sides or at least 2 inches on each side for air flow between the wall and the main surface of the bass trap material.
- INSTALLATION: Make sure you cut your material into 4 panels that are each 2 feet wide by 5 feet tall to make installation easier. If you’re using multiple panels, make sure to overlap the material slightly on all sides for an even look and feel.
- MOUNTING: I always use heavy-duty industrial strength staples to mount my bass trap material on my walls or partitions, but be careful when installing it because you want the material to stay where it’s supposed to be for optimal sound absorption performance.
- AFTERWARDS: After you’ve completely installed your bass trap system, all you have to do is plug in an air freshener machine to the wall and it will remove all stale air from your room so you can get rid of at least 70% of any smelly odors in your room. Yes, it works but the process can take several days or even weeks depending on how much stale air is in there. It’s not that expensive if you already own an air freshener machine and honestly, it will keep away any bad smells for months or even years depending on how much you use your studio.
- WARRANTY: After installing a bass trap system, I always recommend that you purchase a material warranty plan from a company that manufactures their own fiberglass bass trap materials. I personally use an American made company for this purpose.
- PRICE: The price difference between the different characteristics of fiberglass bass traps is not very much at all and if you get a good deal on your material, you’ll get more value for your money by purchasing more fiberglass sheets of the same quality of the one you got for less than buying individual sheets in any other type or weight of fiberglass.
- MULTIPLE USES: I explain the reason why I buy multiple sheets in my article about bass trapping in a home theater room design.
- AIR SEALING: Once your room is completely sealed from air leakage from any source, you won’t have to worry about any sound leaking into or out of your space unless you intentionally open a door or window to listen to music in a different room.
- CONTACT CEMENT: Don’t use adhesives because the fibers will not be able to hold together and will not perform as well because of it, but make sure your material is clean by using a soft washcloth with water before installing it on your walls.
- INSTALLATIONS: In my experience, it’s best to install multiple bass traps on all 4 corners of the room including the corners above any ceiling areas to make sure you have enough material to use as a wall for your bass traps to absorb sound. I’ve used different types of fiberglass materials for a whole year before finishing a DIY home theater installation before selling it and it worked great! I’ve sold dozens of projects over the past 20 years and they’ve all performed great too. And if you’re worried about any sound leaking into neighboring rooms through walls or floors, you can just paint or putty over any holes in your walls and ceilings with painter’s tape.
What makes a good bass trap?
A good bass trap is the one that performs well, is easy to install, inexpensive, and is built for DIY installation no matter what level you’re at. Your room will need to be completely sealed from both the inside and outside of your space for this treatment to work properly.
The goal of a bass trap is not only to absorb high frequency sound but also low frequency sound in your room as well which helps achieve a more accurate mix and recording. A basic bass trap setup consists of multiple panels inside a 4-way or 5-way system and multiple panels along all or part of your walls and ceiling (if applicable).
I hope I’ve given you the knowledge and confidence that you need to install your own bass trap system in your studio or home theater room without any help. If you’re concerned about the expense of all the tools, materials, and labor involved in this DIY project, I suggest looking for secondhand tools on Craigslist. You can sometimes find great deals there or even borrow them from a friend if you wish.