Typically, you'll build four separate 4 inch thick panels of denser rigid fiberglass in the shape of a rectangle, because this is the shape the insulation is manufactured in.
You'd hang them so they straddle the corners like pictured above. This creates a gap behind the panel where the bass wave has a chance to bounce against the wall and pass back through your trap a second time! It's the most efficient way to use these traps, especially when you're on a budget. We hang all panels with a gap behind them for this reason.
But stay tuned, because below I'm going to show you the elite way of building these, called a Superchunk , if you have the budget for it. You'll need a lot more insulation to pull it off, but you'll get an exponentially better result and it looks better. There's four easy steps that take a lot of time and space to do-it-yourself, but you'll save a lot of money if you can make it happen.
First, you'll first need to find a place to order some Owens-Corning rigid fiberglass panels there's a link to their panels on Amazon below so you can get an idea of the price. For bass traps you want their panels denser!
So I recommend going to a local Lowes or Home Depot and letting them order it for you. I recommend ordering 2 inch thick panels if available.
You can get the 1 inch thick ones but you'll need to stack four of them together instead of two because you want a total thickness of 4 inches. It's easiest to keep them in the exact shape they come in, though you'll find they're easy to cut. I literally used a dull butterknife to cut some of these in half when I did my entire DIY build.
You can use a marker to draw lines across them so you have a guide. Your next step is to build wooden frames to set the panels into. I advise using very light wood because they insulation is already kind of heavy. Your next question is whether you want this frame exposed visually when you hang them.
I kept mine exposed and it was a pain in the rear to staple the fabric inside perfectly so it looked tucked in but still wrapped around the insulation.
I'm going to fully wrap mine soon, so I recommend you do that from the start. You want a fire-resistant fabric that's still breathable to air, and wrap your rectangles like a present and wrapping paper. You can staple the fabric to the back of the frame, and cut another rectangle piece for the sole purpose of covering the back. The point is to keep insulation fibers from floating around in the air. To reiterate, your main concern here is simple but threefold. You want to ask yourself what color fabric you want, you want to make sure it's fire-resistant, and finally if you want to expose the frame or not.
I suggest wrapping it completely, having done the opposite before as seen below. Hanging them is a challenge and nobody has "the right way. I invented my own method as seen below that worked out okay:.
For the sake of completion, here's what they all looked like when it was said in done, in an apartment about a decade ago:. I plan on wrapping those in dark grey fabric and building even more soon. Try to think ahead and look at a lot of pictures of recording studios online to see different designs, because it's hard to undo or start over. It's a lot easier to get it right the first time! The panels I showed you above are critical for building front wall and back wall traps and even bass clouds.
Bass traps that include only sound absorbing materials that are only a few inches deep may therefore not be effective in attenuating low frequency standing waves within a room. It is believed that such traps might be effective in reducing the amount of reverberation in the room, which may appear to improve the room acoustics, but may not necessarily eliminate room standing waves.
An alternative approach involves the use of one or more panels within the bass trap that are tuned to the room standing wave frequencies. Such bass traps, called diaphragmatic absorbers, behave in a similar manner to Helmholtz absorbers, and can be more effective than bass traps that rely only on sound absorbing fibers or foam. Going back to our single degree-of-freedom oscillator analogy, a properly tuned panel will vibrate at a complementary frequency and effectively damp out a room acoustic mode by creating a resonant peaks that are each lower than the original resonant peak of the room.
Since panels have several vibration modes over a wide frequency range, it is possible to tune and damp a panel in a manner that will attenuate several room acoustic modes over a wide frequncy band. Because they do not rely on the oscillation of a volume of air like a Helmholtz absorber or on the depth of sound absorbing insulation, diaphragmatic absorbers can be compact and packaged in a relatively small panel.
Bass traps that incorporate diaphragmatic panels must be tuned sufficiently low to enable cancellation of low frequency room acoustic modes. Many diaphragmatic bass traps on the market incorporate a sheet of plywood, which may not have sufficient compliance to attenuate the lowest room acoustic modes. It is a well known fact among audiophiles that bass frequencies tend to pool in corners of a room. Higher frequency noise will tend to interact with several surfaces within a room and decay at a much faster rate than low frequency noise.
Acoustical energy does not necessarily propagate in directions that are orthogonal to a room i. The absorption spectrum is not the same for resonant and porous traps. The first ones have narrower spectrum, while the porous are broader. The issues regarding acoustics have always been topical.
Bass traps have that role - to maintain the desired balance! The foam increases air resistance which results in reduced wave amplitude. You can put it on the wall, on the door, you can even attach it to the ceiling. No matter where, it will serve the purpose, and that would be removing residual sound!
Polyurethane comes either as polyether or as polyester. They absorb the velocity of sound waves, and using friction, they turn the waves into heat.
In the case of sound absorbing, the sound will not be blocked. Pros and Cons of Foam Bass Traps As we mentioned, foam is not a typical soundproofing material, it more of a sound absorbing one. We could say it has a multifunctional purpose. Acoustic foam is available in various colors and textures. You can adjust the room not only to be acoustically pleasant but visually as well.
Due to the material itself, in case of fire, it will release lots of smoke. To be honest, the answer to this question is rather individual. However, this goes for situations where one puts foam traps in smaller places.
As a matter of fact, you do get reduced echoes, less vibrations and more heat. I have few ideas for you, so if you think they sound promising, give them a try! One of the ways is to have carpet nailed to the walls. Another option is to staple cup holders to the wall.
Installing them requires much time and patience and the overall benefits are pretty small. They are actually much smaller than the ones you can hear when using foam as a trap. Soffit style bass trap around the edge of the ceiling with floor-to-ceiling bass traps in the corners. Bass energy buildup can vary from corner to corner due to factors like your speaker and subwoofer placement, as well as the geometry of your room.
You may not be able to treat all your corners, so a great way to prioritize bass trap placement is to determine which corners have the most bass buildup. Corner treatment is the foundation of your bass absorption plan of attack, but there are other places where bass traps are useful. Remember, bass waves are reflecting off all surfaces of your room… they are not just accumulating in the corners.
Peaks and nulls caused by non-modal problems like SBIR are best treated by adding low frequency absorption to the wall and ceiling reflection points that are causing the problems.
As you treat these reflection points you can simultaneously treat other acoustical problems in your room. Focus on corner bass absorbers. In most domestic sized rooms, arranging broadband bass traps in the corners will noticeably reduce the overall liveliness or ambience in the space.
This is because most broadband bass traps are surfaced with a porous material like acoustic foam, rockwool or fiberglass. These devices absorb over a wide bandwidth — not just low frequencies — so we can classify them as broadband or wideband absorbers.
Broadband absorbers reduce the decay times at all frequencies in the audible spectrum: low, medium and high. They let you add enough bass absorption to tightly control your low end without killing all the mid and high frequency energy which would render your room lifeless and sterile. These devices are surfaced with a reflective material such as a wood scatter plate or plastic membrane , instead of a porous, sound absorbing material.
On the other hand, if you want to further reduce decay times in your room, additional broadband absorber panels can be arranged on your walls. Your first reflection points are a good place to start as they typically need treatment anyway broadband absorption, diffusion, or hybrid acoustic panels that provide a combination of the two. In general, mounting broadband absorbers on your walls and ceiling reduces liveliness, flutter echo and ringing in your room. Broadband absorption also helps to flatten the frequency response of your room, giving you a more neutral, controlled listening environment.
You want to reduce the liveliness a bit further while treating early reflections and flutter echo, so you place additional broadband absorbers at your first reflection points on your sidewalls and ceiling, and on the wall behind you you could alternatively use diffusion here.
The images below show example room treatment layouts that incorporate low frequency absorption. To avoid clutter, the following examples show minimal broadband absorption on the walls and ceiling. In practice, additional broadband absorbing panels and perhaps diffusion would be applied as needed to achieve the desired level of liveliness. Critical listening rooms often pair a reflective e. To prevent slap echo and flutter echo we usually want to avoid any large areas of bare wall or ceiling.
If you were to apply heavy broadband absorption to the front of this room it would become a live-end, dead-end LEDE room. This gives the room a flatter bass response than similar sized rooms with less optimal ratios. Acoustically, cubic rooms have the worst ratios You may not be able to choose the size of your room… but if you can, avoid cubic rooms like the plague. Corner bass absorption helps control room modes and other LF problems like standing waves and acoustic interference. Broadband bass traps are used as acoustic panels to absorb early reflections, creating a reflection free zone RFZ around the listener.
Optimized acoustic diffusers scatter back wall reflections, making the room sound more spacious and airy, with a hint of liveliness. Floor-to-ceiling corner bass absorbers are an efficient strategy to control room modes and reduce other low frequency problems like comb filtering caused by speaker placement relative to walls. Rear wall diffuser reduces flutter echo and slapback, while enhancing the sense of spaciousness.
Broadband absorber panels at the ceiling and sidewall first reflection points create a reflection free zone around the listener a hanging ceiling cloud may be used instead of the ceiling bass traps shown.
Example room layout when obstructions prevent rear corner bass trap mounting. Example room setup 3. Primacoustic FullTrap used on back wall and to absorb first reflections around the listening position.
Primacoustic FullTraps arranged on back wall, sidewalls and ceiling a hanging ceiling cloud can be used instead. MaxTrap corner bass traps used elsewhere. Broadband bass traps absorb over a wide range of frequencies, but with limited efficiency.
In contrast, tuned bass traps absorb extremely efficiently over a narrow range of frequencies. They are narrowband absorbers. The tuned absorber absorbs sound energy most efficiently at its resonant frequency. Here it has a very high sound absorption coefficient.
In pro audio terms, it effects an acoustic signal kind of like how a notch filter a bandstop filter with a high Q effects an audio signal. They are also called pressure absorbers because they act on the pressure component of a sound wave. Naturally, they are useful at the boundaries of your room where the resonant room modes have maximum pressure see guy runs into wall video.
The most common type of tuned trap is a tuned membrane trap, or panel absorber. Panel absorbers let you efficiently absorb low frequencies under Hz in a surprisingly compact form factor. They may also be tunable. The Helmholtz resonator is common in older recording studios, but tends to be trickier to design and build to spec.
The Vari Bass by Vicoustic is an example of a tunable Helmholtz resonator. Tuned absorbers are often chosen to target particular room modes, so they are best specified on a room-to-room basis.
They can be mounted directly in the corners of your room or positioned in hot spots to tame offensive peaks and nulls. For example, you could place them flat against the surface of the wall behind the listening position. You can use acoustic measurement software like Room EQ Wizard to find hot spots for particular modal frequencies, but it can be tricky and time consuming.
If you need help optimizing your low end consider a professional room acoustics analysis. Purpose-built recording studio control rooms have extensive low frequency absorption build right into the walls.
These acoustic control walls are basically giant bass traps, designed to minimize low end decay times and equalize the room response, making it as neutral as possible for critical listening.
The absorption systems in Hidley control rooms are often several feet thick! Obviously this is not practical for the typical hi-fi listening room or home recording studio setup. Luckily, good bass absorption can be achieved in less space by using well designed bass traps, mounted in the right places. The images below show an example of how you could take maximum advantage of the corners to achieve significant bass control, with commercially available or DIY bass traps, without taking up much floor space.
Also shown is back wall diffusion and basic RFZ treatment at the first reflection points broadband absorption on the sidewalls and ceiling. The front corner bass absorbers are surfaced with reflective material e. Never forget: Bass absorption is the foundation for a tight, balanced sound in every domestic sized media room… be it a mixing room, mastering room, hi-fi listening room, home cinema or man cave.
Place bass traps in the corners of your room to damp low frequency resonant room modes and reduce nulls caused by bass waves bouncing off the wall behind you. Start by treating the four power corners if you can.
Start with broadband bass traps to gain control of the full bass frequency range. Then, if you want further control consider adding tuned membrane bass traps, or panel absorbers, to target the most problematic room modes. The more bass absorbers you apply, the flatter and tighter your low end response. What should I expect to hear? With proper bass management your room will have a more even sounding response across the audible spectrum.
Overall your soundstage will sound more unified and naturally balanced with tighter definition between tones.
You will hear the frequency balance and transients in your music with greater clarity. You will hear details that were previously masked by your boomy low end. You will be able to make better mixes, trust your ears when mastering or critical listening, hear nuances you never new existed and better connect with your music.
A tight low end will dramatically enhance your listening experience. Do you know someone who might find this guide useful? If so, please share it Tim, man, this is absolutely fantastic….
None of the info here is new to me, but your manner of presentation and explanation is concise, easy to comprehend and practical. Thank you!
Michael, thanks for reading! I hope this helps people out. It was going to be short but I found it hard to address bass treatment without addressing mid-high frequencies since most bass absorbers have broadband effects. Thanks for your awesome feedback! The info, visual aids, suggested treatment scenarios….. Very nicely done! Hi Tim, great presentation and very educational. I have got a question. I tried to google but not much info. Thanks for your post, very accessible for me.
So it seem that adding bass traps to our dining room might get us the most bang for our buck, instead of adding carpet yuck, I have 2 small, messy kids or sound absorbing celing tiles. I was wondering, for my purposes, do you think I would be okay simply to hang drapes in all of the corners of my dining room? My husband is quite handy and is excited to try out the DIY to build traps, but I wanted to check with you first if you thought that our needs may not require such drastic measures.
This info comes just in time for I am currently at the stage of finishing the new Elektrophonik studio in Haren, the Netherlands. Pictures of the development can be found at the website elektrophonik. Since this studio is mainly built using ecological friendly materials like sandpanels which I make myself and natural sheep wool insulation it has become a bit of a time consuming activity.
But within two weeks I hope to be up and running and rehearsing with the Elektrophonik Orkestra. Thanks a million Tim, for me this is very useful information indeed!
I love builds like this. Congrats on nearly finishing your build and I wish you the best with the Elektrophonik Orkestra! Your Elektrophonik Orkestra project sounds very cool!
Hi Tim, Great Guide. I recently moved to an new home. One reason why i selected this house is because i now have the oppurtunity to build an decent home studio. The Room has an angled insulated roof covering to whole lenght of it. I consider this as an advantage. Disadvantage of the room is, i have a door in the corner behind me and an window in a corner in front of me.
As you guide says, the are still an lot of options. I know this is never enough trapping and i am not convident this homemade corner traps are effective enough. I love the design of the Pimacoustics full and corner traps, but these are way to expensive for me, to buy these as an gamble. So here are my Questions : How effective are these Primacoustic traps for real? If yes, do you know where to find drawings to build them meself. Or : if i build porous traps what would be better material, Rockwool or GlasWool.
Sorry for all these questions, but i want to do this right. Thanx for sharing your Knowledge! When corner mounted I. A good approach is to build several with different center frequencies, say, 30 Hz, 50 Hz and 80 Hz, and place them where bass buildup is strongest for each particular frequency. To test bass buildup at specific frequencies you can use a sine wave at that particular frequency, instead of pink noise.
Good article but you should remember to point out that resonant devices like membrane absorbers and Helmholz absorbers inherently have a phase shift and a time delay so you may introduce artifacts that are very hard to identify by listening but are also very annoying. Thanks for bringing this up! Hey Tim, this is a great article, thank you so much for sharing it. I just wonder why the bass traps should be made of low density material. I tend to stay away from materials like fiberglass etc.
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