Absorption of triangular bass traps

[juliangst]

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.

I do all my caculation with the 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.

 

[ozzy9832001]

Well, I can let you now my experience with Triangle traps...

Awhile back I contacted GIK about some traps for my home office. My office has Axial modes at 105hz, 120hz and 140hz. Between the fundamentals and the harmonics it was creating a gigantic mess in the mid bass, as you can imagine. I purchased 6 tri traps per their recommendation. I can't put traps in one of the corners because the doorway is in the way. They are 2ft across and 12" deep at their maximum.

Put those puppies in the corners and waiting to hear and see the magic...and boy was I disappointed. My expectations were way to high and my understanding of how they operate was not nearly good enough. At the end of the day, I constructed a mounting system for those 6 traps and was able to install them above the speakers and on the sidewalls. They operate much better up near the ceiling.

I replaced the corner traps with real corner traps, 16" deep -- they are square. The results were more of what I expected. Combined with the new ones in the ceiling/wall corners, I was getting significantly better results. Yes, they take up more space, but it's space I wasn't going to use either way.

Morale of my story is: tri traps sound like a great idea, but they offer very little over a 4" panel angled across the corner and they are significantly cheaper.

When we're talking about significant room mode pressure and peaks...some of mine were over 12 dB, corner traps just don't add the absorption that is required to really make a dent in the frequencies below 80hz.

 

[EJ3]

Well, I can let you now my experience with Triangle traps...

Awhile back I contacted GIK about some traps for my home office. My office has Axial modes at 105hz, 120hz and 140hz. Between the fundamentals and the harmonics it was creating a gigantic mess in the mid bass, as you can imagine. I purchased 6 tri traps per their recommendation. I can't put traps in one of the corners because the doorway is in the way. They are 2ft across and 12" deep at their maximum.

Put those puppies in the corners and waiting to hear and see the magic...and boy was I disappointed. My expectations were way to high and my understanding of how they operate was not nearly good enough. At the end of the day, I constructed a mounting system for those 6 traps and was able to install them above the speakers and on the sidewalls. They operate much better up near the ceiling.

I replaced the corner traps with real corner traps, 16" deep -- they are square. The results were more of what I expected. Combined with the new ones in the ceiling/wall corners, I was getting significantly better results. Yes, they take up more space, but it's space I wasn't going to use either way.

Morale of my story is: tri traps sound like a great idea, but they offer very little over a 4" panel angled across the corner and they are significantly cheaper.

When we're talking about significant room mode pressure and peaks...some of mine were over 12 dB, corner traps just don't add the absorption that is required to really make a dent in the frequencies below 80hz.

Thanks, I had been thinking along those lines but now I know better.

 

[juliangst]

Well, I can let you now my experience with Triangle traps...

Awhile back I contacted GIK about some traps for my home office. My office has Axial modes at 105hz, 120hz and 140hz. Between the fundamentals and the harmonics it was creating a gigantic mess in the mid bass, as you can imagine. I purchased 6 tri traps per their recommendation. I can't put traps in one of the corners because the doorway is in the way. They are 2ft across and 12" deep at their maximum.

Put those puppies in the corners and waiting to hear and see the magic...and boy was I disappointed. My expectations were way to high and my understanding of how they operate was not nearly good enough. At the end of the day, I constructed a mounting system for those 6 traps and was able to install them above the speakers and on the sidewalls. They operate much better up near the ceiling.

I replaced the corner traps with real corner traps, 16" deep -- they are square. The results were more of what I expected. Combined with the new ones in the ceiling/wall corners, I was getting significantly better results. Yes, they take up more space, but it's space I wasn't going to use either way.

Morale of my story is: tri traps sound like a great idea, but they offer very little over a 4" panel angled across the corner and they are significantly cheaper.

When we're talking about significant room mode pressure and peaks...some of mine were over 12 dB, corner traps just don't add the absorption that is required to really make a dent in the frequencies below 80hz.

More and thicker absorption is always better.
If those GIK Tri traps do barely anything I might reconsider my plans.

Instead of cutting a panel of insulation into 8 triangles I could cut it into 4 (GIK's tri traps are 41cm while insulation cut into 4 pieces would be 62.5cm).
Most bass will be absorbed by the rear wall absorber anyway; I just want something that better than nothing in the front corners.

BTW: I'll receive a package of 2x1m melamine foam tri traps with a side length of 20.5cm tomorrow (just about 45€ for 2 of them).
They'll go into the rear ceiling corner of my office setup.
I hope they'll help at least a little bit.

 

[Matias]

See the attachment.

 

[juliangst]

See the attachment.

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.

 

[sarumbear]

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.

According to their specs even the thickest version is not very effective below 200Hz. Not suitable for a bass trap, don't you think?

 

[subframe]

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

Had you looked one page up, you’d see a description of that very product (with data shown for some product which the author does not specify). Vicoustic also publishes data on that specific product which is readily available. It is not the same as those foam blocks.

Blind skepticism is really no different than blind superstition.

 

[juliangst]

Had you looked one page up, you’d see a description of that very product (with data shown for some product which the author does not specify). Vicoustic also publishes data on that specific product which is readily available. It is not the same as those foam blocks.

Blind skepticism is really no different than blind superstition.

155mm of foam with a bit of an air gap won't do anything below 100hz though. A bass trap should deal with bass and not just upper bass imho. No matter what material they use they can't beat physics.
Their graphs look fine but I wouldn't call that a 'bass trap'

 

[juliangst]

According to their specs even the thickest version is not very effective below 200Hz. Not suitable for a bass trap, don't you think?
View attachment 271494

This is the advertisement for their normal absorbers which are mainly used for first reflections. The basotect triangle traps are available as 25cm, 42cm or 48cm depending on the distributor. So basically the same dimensions as GIK's tritraps or Tri Trap offerings from other brands

 

[sarumbear]

Blind skepticism is really no different than blind superstition.

It is not scepticism, just knowledge of physics. Will you call me a sceptic if I tell you pouring boiling water onto your skin will hurt you?

 

[sarumbear]

This is the advertisement for their normal absorbers which are mainly used for first reflections. The basotect triangle traps are available as 25cm, 42cm or 48cm depending on the distributor. So basically the same dimensions as GIK's tritraps or Tri Trap offerings from other brands

I simply posted the specs from the link you posted.

 

[juliangst]

I simply posted the specs from the link you posted.

I think they don't have graphs for anything deeper than 100mm. That's why all of their products are advertised with this graph

 

[sarumbear]

I think they don't have graphs for anything deeper than 100mm. That's why all of their products are advertised with this graph

Have you wondered why they don't have it?

 

[sarumbear]

Had you looked one page up, you’d see a description of that very product (with data shown for some product which the author does not specify). Vicoustic also publishes data on that specific product which is readily available. It is not the same as those foam blocks.

The product is called a bass trap, yes? Then how come something that is 155mm deep can trap a waveform that is more than 4-5m?

 

[MRC01]

I built my own tube traps and they were effective both objectively in measurements and subjectively in sound quality. Details here. However, they are big and round, and run floor to ceiling, which has low wife-approval-factor (e.g. a look that only an engineer could love), and they affect a wide range of about 2 octaves (40 - 160 Hz). This improved the room as a whole, but if you need to target specific frequencies, you'll want a different kind of treatment.

I ended up adding resonators and bass traps later, but the tube traps came first and made the biggest difference. So IME, they are a great place to start so long as you have the space to make big ones.

 

[ozzy9832001]

More and thicker absorption is always better.
If those GIK Tri traps do barely anything I might reconsider my plans.

Instead of cutting a panel of insulation into 8 triangles I could cut it into 4 (GIK's tri traps are 41cm while insulation cut into 4 pieces would be 62.5cm).
Most bass will be absorbed by the rear wall absorber anyway; I just want something that better than nothing in the front corners.

BTW: I'll receive a package of 2x1m melamine foam tri traps with a side length of 20.5cm tomorrow (just about 45€ for 2 of them).
They'll go into the rear ceiling corner of my office setup.
I hope they'll help at least a little bit.

I think where they work best depends on your position relative to the traps. I'm very close to the Front wall, so for me the front was more important. 200-250hz was nasty reflections off the ceiling.

The 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.

Speaking of which, have you run any measurements to know what exactly you need to tame?

 

[juliangst]

Have you wondered why they don't have it?

I think they mainly sell their foam to commercial places like offices where they're mounted to the ceiling (I also have two 10cm panels on my ceiling).
The air resitivity is also marketed as '8-20 kPa*s/m2' but after a bit of research it seems to be more like 11 kPa*s/m2.

From their website, translated with google translate:

Basotect® is a flexible, open-cell foam made from melamine resin, a duroplastic material. A typical feature is the filigree spatial network structure, which is formed from slim and therefore easily deformable bars. Basotect® impresses with excellent sound absorption values, low weight, high temperature resistance and low flammability. With Basotect® you can, for example, significantly improve the acoustics of restaurants, entrance areas, meeting rooms or aircraft cabins. However, Basotect® is not only the ideal solution for optimizing room acoustics, but also for thermal insulation and air-conditioning technology, Basotect® is impressive thanks to its very good thermal insulation properties and simple, fibre-free processing.

So their main application is not acoustic treatment for hifi or studios in the first place

 

[juliangst]

I think where they work best depends on your position relative to the traps. I'm very close to the Front wall, so for me the front was more important. 200-250hz was nasty reflections off the ceiling.

The 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.

Speaking of which, have you run any measurements to know what exactly you need to tame?

I'll eventually want to move my current desk setup (LS50 with a sub) to the other room (5x6 meters) so I don't have measurements yet.
I do have a pair of old Canton speakers in that room though and once measured them.
Most problems are above 70hz but the Cantons don't produce any significant bass to create problems in the first place.

 

[juliangst]

In my office I now have four DIY 30x30cm bass traps, two 10cm basotect panels on the ceiling, two DIY 10cm panels behind my speakers and one DIY 60x60 panel on the back wall; everything corrected with Dirac live.