Bass Trap Shapes Compared: Which Design Actually Works Best? (with diagrams)

[@anonymousbrowser4448]

Do you have the REW measurements to demonstrate what you claim? I thought we would also see it practically in use

[@urbanman1516]

Wow. I've been thinking of this all month and then he drops this video. I swear Jesco has a way of putting out the perfect videos to answer all my questions. By far, best channel on acoustics. Something so trustworthy about him.

[@LBJedi]

So, to summarize, if space is at a premium, the square may be the best choice. If space is not an issue, but material is, the panel may be the best. Correct? For performance, an L-shaped trap could be the mirror of the corner’s angle might be the best. If, for example, You have 8” of material depth on the two sides of the L, you could have an 8”x8” air gap in the corner.

[@Hamachingo]

Careful when hugging the corners with insulation, you’re asking for mold. Keep it 2-3 inches off the wall, stepped superchunk works great. Air gaps improve bass response but also increases comb filtering so I personally avoid it on first reflection points. If you vary the air gap on all your identical panels it averages out so maximize the gap where the low room modes are.

[@jasperoudejans2012]

Excellent video! I have the right most bass trap design in my studio, 25 cm thick and 60 cm wide. My measurements show that it’s super effective and it wasn’t expensive 😊

[@thomaz8099]

What material did you use for the absorbtion?

[@jasperoudejans2012]

@ Rockwool

[@microteche]

Great explanation for my current build, I actually settled on soffits for this reason, thanks

[@surfmisa180]

Nice videl. There is also the cylindrical type

[@plexibreath]

I built some bass traps from Jesco's course, it was well worth the money. The space is mainly for tracking but I mix in here as well. My drummer loves the way his drums sound in this space.

[@fescolfaro]

The super chunk is obviously the most effective way to deal with this problem, because it represents the last amount of space lost. I have 6 of those in my room, plus two triangular ones.

[@Diogrus]

Hey Jesco. Your videos are quite informative, and already helped me a lot, and this one come in an awesome time. Hope I can join your course in a not far-away term. But for now, I just finished building two upper front (tri)corner bass traps for my home studio and some thick clouds, and already been planning what to do to add two more upper rear (tri)corner bass traps and also a wall/ceiling bass trap in front of me. I've made the bass traps with 04 layers (8") of polyester wool with 35kg/m³ (other materials are quite hard to find here in Brazil) across the corner, leaving a bunch of air gap behind it, and the ceiling clouds with 03 layers (6") of polyester wool with 35kg/m³, leaving another 6" behind it. The sound already is WAY better, but it still has room for more improvement (and, well... cubic room. kkkk). Thanks mate!

[@joelglaser5657]

Excellent! Thank you Jesco.

[@cabomusico]

Hi Jesco, what about round or cilinder shape bass traps?? Thanks.

[@basiltoyomusic]

Ha, that's like the even more elaborated answer to my question, than the one you gave me as feedback on the treatment plan. By the way, I can totally recommend Jesco's online course.

[@gaborozorai3714]

Doesn't the panel have a greater surface area than the square? The back of the panel also counts as that is what meets soundwaves reflected off the corner and back through the air gap.

[@lekko_doneba]

What about putting the same panel in the corner and then putting another corner filled trap? Would that out preform the square? Or is it better with having that air gap?

[@paulmastermann2200]

Would you recommend Vicoustic for pure Hifi listening? Thanks in advance

[@mikehuntington4440]

I've actually turned all my corner bass trap around, and put them backwards. They are finished nicely so...they still look fine. But ya, they are definitely more effective this way.

[@bayard1332]

Basically a 20-24" square cardboard box 4' high filled with rockwool is by far the best and most effective bas management unit, just use as many as you can in the right places.

[@seanb3303]

Bass acoustics are funny and unpredictable. I was able to reduce a mid bass dip by removing a bass trap and allowing that reflection to do its thing 😉

[@damsonskyduo7945]

From my (limited) understanding, it’s low end pressure that builds up in the corners rather than velocity (and therefore reflections). So do these types of panels/materials typically used for velocity and reflections actually work in the corners to control the low end in a room? I’m thinking no. Of course it will treat the low mids to highs depending on thick you go, but you’d still have the same issue with panels on flat walls - having to be so thick before they really start affecting the true low frequencies. Am I in the right track here or talking nonsense?

[@TheNewThink]

What's your reflections on what you present here, and the laboratory tests by John Brandt and Ron Sauro? I don't ever see John Brandt using this in any design, and his approach is based on laboratory testing.

[@flaviomedeiros8161]

I would like to know more about airflow resistance factor... What happens when comparing the same kind of bass trap, one made with rockwool rated with 5000pa.s/m² and the other with 10000pa.s/m². Will the absortion factor increase twice?

[@FOH3663]

Porous absorption calculator is out there.

[@Zhiloreznik]

5000 will have more absorption until the very lowest frequencies. Better in most cases

[@RadekPilich]

Hey, that's close to my unsubmitted unanswered question - what about horizontal vs vertical placement in corners if you have the space? With typical EU 120x60 cm panel, is there a benefit placing those horizontally rather then vertically? With horizontal placement, obviously there will be more material in a single corner. But let's say the overall amount of panels in the room remains the same - is it better for bass absorption in the corners to go horizontal rather then vertical? I have even seen people tilting the horizontal panels in corners, so they are not 45 degree angled but maybe 20-25 degrees.

[@claudioa.dmedina2020]

does this suggest that circular traps are pretty good?

[@FubukiCards]

No

[@claudioa.dmedina2020]

@@FubukiCards in that case, why? in terms of actual area it is better than some of the examples in the video.

[@FubukiCards]

@@claudioa.dmedina2020 The sides of the circle aren’t very thick while the middle part is too thick (since leaving an air gap would make the sides even less useful). If you’d use the same volume but in a rectangular shape, the sides become just as thick as the middle and now it makes sense to use an air gap.

[@tomburden]

What about a square and 2 triangles?

[@JulianFernandez]

thanks!

[@mantaproject]

I saw a video recently where Eric Valentine says that the best bass trap for him is a tube trap. He claims that when he put multiple tube traps in, the whole spectrum came together nicely. ps: I'm just saying, I believe you more than Eric (sorry Eric)

[@weschilton]

I prefer dodecahedrons in my corners.... actually I just like saying dodecahedron. Its a 50-cent word!

[@rjb7569]

Beware! The Dodecahedrons are invading! Take cover!

[@Oneness100]

I have been taught a completely different method of figuring out what low frequency absorption you need, how much and where to place them. Also, what isn't discussed are there are three types of low frequency mode types. Axial, Tangential and Oblique. They are the unwanted sound pressure between 2, 4 or 6 surfaces, respectively. The other issue are coincidental, which is when you have dimensions that produce problems where the dimensions produce a problem around or at the same frequency or within about a 5Hz difference. Example. if your room has a square floor plan, this will create coincidental modes along both front/back and side to side. This can also happen if the height is similar or the same or a multiple of either the front or side walls dimensions. A Cube would be the worst since all 6 dimensions are the same. Now, the first step is figuring out what frequency (s), the amplitude and their location and the best one to attack are the Axial modes. Why? Axial modes are the biggest in terms of amplitude, and they are the most difficult to fix and they also, unfortunately, require the most amount of absorption and they are typically the fundamentals and they typically start around 30Hz to 50Hz in most rooms. if you go after the Axial mode problems, if you use the right product, you can actually fix the Tangental and Oblique problems as a result. Yes, it is expensive and it requires a LOT of surface coverage depending on the size of the speakers you are using, volume levels being played at and how smooth of a response curve you're looking for. Why do these problems exist the first place? It's because our rooms are simply not designed to absorb low frequencies belong 100Hz in the first place. Ultimately, we should use rooms that are designed where the low frequency problems below 100Hz down to 30Hz are built into the actual room structure walls, floor and ceiling, but this is expensive, but I've seen rooms where this was done so you don't need any "bass traps" in the room because it's all handled within the structure of the room itself. But the thickness of the walls, ceiling were 16inch thick using 2x12 studs and they had calculated the internal depth of each wall cavity specifically figuring out what "bass trap' was actually built into the structure. The result is effectively a flat response curve down to +/- 1 or 2 dB no matter where you stood in the room. But these types of rooms are EXPENSIVE, plus they are fixed structures that you can't pack up and take with you when you move to another location. But for those of us that have prebuilt rooms where the walls are typically 2x4's with sheet rock, then we need to effectively build a "room within a room" with large, deep bass traps along each wall, floor and ceiling to really achieve a smooth room response curve. The problem is that it's expensive and it takes a lot of units, and it will reduce the usable floor space as a result. Also, for those that use double wall using 2x4's with sheet rock, those STILL will not absorb the low frequencies in the 30Hz to 50Hz range. Now, as far as corner traps? NOPE. I would NEVER, EVER use them. Why? First off, it's simply not enough surface coverage. I've seen before and after measurements of bass traps on the corners and they didn't really do much in terms of lowing the peak of the low frequency problem. They typically just cut a small amount of the decay, but the peak still existed. they aren't absorbing the Axial mode problems. I would highly suggest going after Axial modes with low frequency absorption instead. the results will be much better, but they require more surface coverage thus using more units. To go after 30Hz to 50Hz problems, you need at least 12inch to 16inch deep cabinets. You simply can't get around this. If you are using absorption that's less than 12inch, then you aren't going after the 30Hz to 50Hz range, you are probably going after more like 60Hz or higher. I've been in rooms where there were large bass traps that were up to 16inches deep and about 5ft tall and they had double front wall with an air gap and they used a VERY dense, and porous material that's MORE dense and porous than building insulation (mineral wool, fiberglass, etc.). The results were the best I've ever heard because they really went after the low frequencies and were capable of absorbing enough of the problem where you could hear individual notes, instrument separation like I've never heard before. Please comment on specifically why you think this is not the best way to approach fixing the problem.

[@FOH3663]

Quite the contrary, ... corner placement is ideal for addressing modal resonances regardless of type. All modal resonances terminate in corners. So, such placement is optimal for effectiveness as it damps axial, tangential, and oblique resonant energy. Regarding higher density material for bass trapping, care must be taken to not utilize excessively dense material in a thicker panel. With porous absorption, when transitioning from typical thicknesses, to thicker more effective trapping ... one must use less dense more porous material. A common rule of thumb is 4" or less in thickness, rigid insulation is ok. At 6" to 8" or more in thickness, it's best to use less dense material. Of course there's superior approaches to bass trapping, ... ie., waveguided hangers, etc. However, for mammoth bang for your buck, extremely effective, inexpensive and easy to DIY, corner mounted porous absorption works every time. Thanks Good stuff (plus, via careful loudspeaker placement and listening postion, one can avoid some of the biggest modal problems)

[@Oneness100]

​@@FOH3663 "Quite the contrary, ... corner placement is ideal for addressing modal resonances regardless of type. All modal resonances terminate in corners. " When you say terminate in the corners, what exactly do you mean? Do you mean that you can't measure any modes in the side walls or within the room? Yeah, right. Measure.. You can take a dB meter and put sine waves at 30, 35, 40, 45, etc. etc to 100Hz and measure from around the room measuring the corner and then go another 2 ft and see what the measurements are. In the +dB ranges, that's where you need to put a low frequency device. The notion that only in the corners do low frequency (under 100Hz) pressure is located is pure, unadulterated GARBAGE. Even room mode calculators like AMROC can show you a 3d representation of just Axial modes and they are NOT in the corner, they are along the entire surface. Axial modes are the most audible, the biggest in terms of amplitude and thus the biggest problems within a small room. If you can fix that, then the others fall in line. the lowest frequency problem ARE Axial modes. Think of those as the fundamental. Here's a link to a room and it shows JUST the Axial modes. amcoustics.com/tools/amroc?l=21&w=17&h=9&st=false&so=false&ft=true&r60=0.6 Click on each frequency and look in the 3D rendering where it's located. Where ever you are sitting, you are either where there is peak a null or somewhere in between at various frequencies so this notion of just treating the corners is absolute nonsense. terminating in the corner has nothing to do with how to treat the problem. I haven't seen a single room where they placed low frequency absorption just in the corners and that flattened out the room response curve to +/-2db down to 30Hz. Please show me one and maybe I will believe you. The corners represents a VERY small surface coverage and it's just not enough for low frequencies, even mid's modal pressure problems.

[@Oneness100]

@@FOH3663 Less dense? Less dense won't absorb as much. You need MASS. I've ran into you before and we've had arguments and you never seem to actually provide indisputable proof, so please stop arguing unless you can show proof. I've been in rooms with corner traps and they has massive low frequency problems. I've been in rooms that had low frequency absorption along the entire walls and they didn't. So, I've been in both scenarios.

[@Oneness100]

@@FOH3663 It also depends on the size of speakers. I mean, if you are using small mini monitors that only go down to maybe 50Hz and you have them in a near field placement and they are several feet from each wall, then that's a different scenario. But if you are using substantially larger speakers and you have some distance between the speakers and the listening position and it's not a Near Field setup, then you WILL have problems.

[@kylecoffey6010]

This is very interesting! I would love to hear more details on the types of dense & porus absorption you've mentioned. When you day you were taught a completely different method, where did you learn. I'm always interested to learn methods in acoustics because they vary greatly!! Plz direct to some sources to further learn! Thx for posting! 🤜💥🤛

[@savoirfaire8979]

This all sounds like too much work.