Acoustic Panels and Bass Traps

Are Bass Traps Necessary and How Many Do I Need?


When you hear your first recording captured in a regular room you quickly want to fix acoustic problems. When I first started recording I also asked myself are bass traps necessary for clean audio.

Bass traps (bass absorbers) are necessary to absorb low-frequency sound waves (below 300 Hz) that would otherwise create a bass boom. Bass traps eliminate bass waves by absorbing the sound and changing it into heat energy. Wall panels eliminate mid to high frequencies (300 Hz to 2000 Hz).

Amateur podcasters and other artists who record at home often wonder about the appropriate home recording set-up. They want to understand how they can improve their work without overspending on equipment- what equipment pieces are a must-have, and what they can do without.

Here are few article that go more in-depth of room acoustics:

Are Bass Traps Necessary?

Bass traps have an important role to play in a recording space, and you cannot replace them with anything else. Let’s understand the reasons:

  • It’s not possible for a small room in a house to not have bass issues. If you think your home recording space has no such problem, you need a reality check. Bass frequencies do not get absorbed by the other objects in the room. They bounce off the walls and pool in the room corners, creating a bass boom. Sometimes, the bass frequencies drown the rest of the sound.
  • Bass traps are a cost-effective and simple way to fix bass issues. You might feel that your podcast anyway has to undergo a post-production process, and you can fix things then. But that is pretty time-consuming. The excess time will eat up the value of any dollars that you might have saved by not buying the bass traps.
  • Acoustic panels and other soundproofing materials do not remove bass frequencies. They absorb and eliminate high and mid-range frequencies, but leave out low-end bass frequencies. If you think that your acoustic panels are going to solve all the issues and you don’t need bass traps- well, you need to do some rethinking.
  • Bass issues are the reason why sound becomes uneven in your room. All small to mid-size rooms face acoustic issues. The smaller the room, the more bass traps you need. If you record at home, it is an absolute must.
Bass traps for corners
(wall-ceiling-wall)
Bass traps for wall joints
(wall-wall)
Wall acoustic foam
good foracoustic treatmentacoustic treatmentacoustic treatment

Bass traps for cornersBass traps for wall jointsWall acoustic foam
Best forlow-frequencyfrequencies
(below 300 Hz)
low-frequencyfrequencies
(below 300 Hz)
mid to high frequencies
(300 Hz to 2000 Hz)
shapecubes to be put in room cornerswall-wall or wall-ceiling jointssquare walls/ceiling panels
thickness4-8 inches4-8 inches1-2 inches
check current pricecheck current pricecheck current price

How Many Bass Traps Do I Need?

In general, you will need somewhere around 12 to 20 bass traps for a regular-sized recording room.

If you have a home studio, I understand that you would not want to buy as many bass traps.

So in this section, we will discuss how to get effective acoustic treatment with the minimum number of bass traps. Another question is where exactly you have to install the bass traps.

As we discussed earlier, bass frequencies tend to accumulate in the room corners. So that is where your bass traps should be placed. You must learn these fine details, as the placement has an immediate impact on the performance of bass traps.

Podcasting studio reverberations

Bass Traps on Trihedral Corners

When it comes to bass traps, you should first focus on the trihedral corners of your room. Trihedral corners are those where two walls and ceiling, or two walls and floor coincide. Ideally, you should cover all the trihedral corners. In a standard cubical room, you would need 8 bass traps for that. After you have covered these corners, you can place additional traps in room corners.

Now, what if you don’t have or you can’t buy 8 bass traps at the moment? If you have a very tight budget or you need a temporary fix for the situation, you should give priority to the upper trihedral corners. Use four bass traps to cover them.

Bass Traps on Room Corners

The dihedral room corners are the second priority. You can consider them for bass trap placement if the trihedral corners have been covered. In this scenario, you would need more than eight bass traps. I leave it up to you to decide the additional number.

If you find it tough to install the bass traps on the trihedral corners, the next alternative is to place the bass traps only on the dihedral corners. You should opt for this approach only when you find covering the trihedral corners tough (say you don’t have any support for installing them on the upper trihedral corner).

Bass Traps on Walls or Ceilings

Corners are definitely more important when it comes to placing bass traps. If you are done with the corners (in either of the two scenarios), you can place the additional bass traps on the walls and the ceiling.

Broadband Bass Traps vs Tune Bass Traps

Broadband Bass Traps

Broadband bass traps, or porous absorbers, are commonly used to treat acoustic issues in home studios. They are usually constructed of rockwool, fiberglass, or acoustic foam. They are pretty versatile- they do a great job of removing standing waves, speaker boundary interference, room modes, etc. And that’s the reason behind the moniker ‘broadband’.

Broadband or porous absorbers rule the bass trap markets due to their affordability. But there is a catch- they aren’t very great with low-end frequencies. If you want your broadband absorber to eliminate the extreme low-end frequencies, you would have to place them quite far from the wall. That’s because for porous absorption to work best, the bass trap should be placed at 1/4th wavelength of sound waves.

But that would be pretty impractical, especially for small studios. To overcome this challenge, most companies create very thick porous bass traps.

If the very low-end bass frequencies are a major source of concern, then you have another option that we are about to discuss.

Tuned Traps

Tuned traps or resonant absorbers perform the opposite function. They eliminate specific low-end frequencies, instead of offering a wide range of coverage. And their placement is quite easy. You have to keep them close to the walls, and there is no hassle involved in their installation

There are two kinds of tuned or narrow-band absorbers-

Helmholtz Resonator– It consists of a small hole in an air-tight cavity, which absorbs bass frequencies.

Diaphragmatic Absorbers– It uses a vibrating panel to remove bass waves. It has a simple design and it occupies less space than a Helmholtz resonator, contributing to its popularity.

Room acoustics for podcast recording

Which One Should I Go For?

Broadband or porous absorbers are cost-effective and absorb a wide range of frequencies. Therefore you must invest in them. Then what about resonant absorbers? Can’t you just place a couple of them for more perfection?

It is true that a combination of broadband and resonant absorbers work best in absorbing the bass frequencies, but the use of resonant traps called for more preciseness. You need to rope in a professional who can evaluate the studio and customize it for you. If you plan to put in some money and create a professional studio, this is what you should do- opt for a combination.

But if you record at home and there are no changes on the cards, you may not find resonant traps very useful. They are efficient only when they are specifically designed for that particular space. You can simply go for broadband bass traps.

Choosing the Broadband Traps

Choosing the Broadband Traps

Broadband bass traps are of two types.

Corner Bass Traps– These are triangular, and their additional mass helps further in absorbing low-end waves.

Panel Bass Traps– They leave an air gap between their surface and the wall. You can cover more surface area with them.

Both kinds give similar results, so you don’t have much of decision-making to do here.

If you are not sure yet about adding bass traps or panels to your room, check this post:

In Conclusion

If you are a dedicated podcaster, you would like to pay attention to the sound quality of your podcast. Your recording skills, equipment quality, and post-production process plays an important role in that. But new podcasters often miss the one area that needs their attention- the room acoustics!

Bass issues are pretty common. The details of sound get lost when bass frequencies become dominant. That is very undesirable in a podcast as it hampers the clarity.

With proper acoustic treatment which includes the right placement of bass traps, the sound will be evenly distributed across the room. It would remove the dominant bass wave and ensure that your podcast is audible.

About the Author

Chris Land

I'm the owner and creator of ImprovePodcast.com, the site dedicated to providing actionable solutions for podcast creators. My goal is helping people to develop their podcasts into effective marketing and sales tools.


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