Absorption of triangular bass traps

[MengW]

In the past three years, I used PSI AVAA to decay low-frequency energy, and I am very satisfied (except for the price).
In Comsol simulation, the value of the AVAA working surface impedance can be estimated at 120 Pa*s/m between 15 and 150Hz.（be modelized by a ¼ of cylinder of approximately 50cm tall and 20cm diameter.）
The research paper, Low frequency absorption by velocity control through acoustic resistance

https://www.mbakustik.de/wp-content/uploads/article_aes.pdf

FYI.

 

[bungle]

IThe tri traps did something, they helped with decay and some minor pressure issues, but I just felt for the money, they could have been way better. I just needed something way better to tame the issues.

Some people have put them in corners so that they look like square Soffits, and got better results. Of course they are then like poorman’s soffits, but a bit more versatile as you can experiment with ”looks” vs ”efficiency”.

 

[MengW]

I'm planning to build some bass traps.
The rear wall will be treated with about 40cm of glass wool but I want something more attractive for the front wall.
I really like the looks of triangular bass traps; they're not as visually intrusive as square bass traps to me.

Porous Absorber Calculator. This only works with absorbers of uniform thickness and triangular bass traps obviously have varying thickness.
I'm only taking axial modes into account.

How would you calculate a triangular trap and compare different flow resistivities?
Do you just pick the different depths of the triangle and look for an average?

I'm not sure if I should build them out of glass wool or get something with higher Flow resistivity like melamine foam (which is more expensive but saves me a lot of work).

Insulation like glass wool (~5 kPa*s/m2) would have better absorption with thicker depths but as the triangle tapers down melamine foam (~11 kPa*s/m2) would have better absorption.

Considering the size, I would cut a panel of glass wool (125x62,5cm) into 8 triangles, stack them, and hide the whole thing with a farbic covered wood frame.
For melamine foam I would pick this type of triangular bass trap. It's pretty much the same size as the glass wool triangles.
It's not as cheap as DIY but still a lot less expensive than finished Tri-traps from GIK for example.

And the COMSOL simulation software may be useful for comparing the acoustic performance.

You can create any shape, set the flow resistivity of the filling material, or the surface acoustic impedance.
Set the speaker position and sound pressure level, and get the frequency response result of the listening position.
A few years ago, I used comsol to analyze the living room and compared the different layouts of the current room.
There are video tutorials on the Internet, which are not too complicated, and you could operate it after watching it once.
Btw, the animation of ray acoustics is very interesting. If you use ray acoustics to calculate the reverberation time, you may need a good computer.
For analyzing low frequencies, pressure acoustics could be referred to.

 

[sarumbear]

I used PSI AVAA to decay low-frequency energy, and I am very satisfied...

Ditto. I use two on each corner of the room behind the Salon2 pair.

 

[g_t_r]

The 'Don't be fooled' section reminds me of those 'Super Bass Traps' by Vicoustic. This brand can't be anything but a ripoff.
Most super highend setup ironically have a lot of Vicoustic stuff.

View attachment 271488

I have those vicoustic bass-traps in my room and in fact I didn't take any measurements, but to my ears are very, very efficient. The problems with bass overload from big 15inch bass speakers almost fully disappeared. And before placing those bass traps it was 1 big "booooom" on the bass covering whole music spectrum. So it works brilliant. What is even more interesting, I had Rockwool pt80/100 absorbers in the corners before and almost no difference, it was even subjectively worser as high freq were damped.