Bass Trapping non 90° corners

[Paranoidandroid]

I am doing a pretty major acoustic treatment to a pretty large room. This room is weirdly L shaped, and used for listening to music, movies, but mostly music rehearsal for a 60 piece string orchestra.

My question is in regards to Bass Traps. Is there a protocol for dealing with treating corners that are not 90° to clean up bass in a room? I have 2 acute angles, 1 obtuse angle, 1 right angle, and one right angle on top of a door that I can not treat. (see attached image) I would likely bass trap the four corners with a 2'x4' 4" thick corner absorber in each corner mounted a foot below the ceiling. Where each blue circle is.

Ceiling is standard height, 2x4' ceiling tile, walls are cinderblock (ew!) floor is carpet over cement.
I am treating the walls and ceiling with absorption and diffusion.. so this is only about the corners.


Does that sound right, or do the non 90° angles treat Bass enough differently that I should look at some other option.

Thanks!

 

[highfigh]

I am doing a pretty major acoustic treatment to a pretty large room. This room is weirdly L shaped, and used for listening to music, movies, but mostly music rehearsal for a 60 piece string orchestra.

My question is in regards to Bass Traps. Is there a protocol for dealing with treating corners that are not 90° to clean up bass in a room? I have 2 acute angles, 1 obtuse angle, 1 right angle, and one right angle on top of a door that I can not treat. (see attached image) I would likely bass trap the four corners with a 2'x4' 4" thick corner absorber in each corner mounted a foot below the ceiling. Where each blue circle is.

Ceiling is standard height, 2x4' ceiling tile, walls are cinderblock (ew!) floor is carpet over cement.
I am treating the walls and ceiling with absorption and diffusion.. so this is only about the corners.
Does that sound right, or do the non 90° angles treat Bass enough differently that I should look at some other option.

Thanks!
View attachment 21786

The fact that you only have a short section of parallel walls tells me you won't have much problem with standing waves- it's not the corners that cause these, it's the surfaces that are parallel or very close to that. Your main issues will be with first and second reflections, overall reverberation and dispersion.

 

[Paranoidandroid]

That Makes sense.

We are putting up 20 2'x4'x 2" high range absorber panels on the walls, and 16 2'x2' diffusors mostly on the ceiling.

Would you say leave the corners as they are then?, or would treating the 90 degree corner next to the short section of parallel? There are 6 panels and a diffusor planned treating the 2 walls that would create the standing waves on the parallel walls.....

Thanks!

 

[highfigh]

That Makes sense.

We are putting up 20 2'x4'x 2" high range absorber panels on the walls, and 16 2'x2' diffusors mostly on the ceiling.

Would you say leave the corners as they are then?, or would treating the 90 degree corner next to the short section of parallel? There are 6 panels and a diffusor planned treating the 2 walls that would create the standing waves on the parallel walls.....

Thanks!

I would start by downloading Room EQ Wizard and getting some kind of mic so you can see what's happening in your room. It's a huge help in seeing what you have and you can see the effect of placing a single panel, then moving it to get the best results. I did that and it completely eliminated the suck out in the bass range that was making me hate listening to my system. Because my room is basically rectangular, I did need to treat the corners but your room is very different. It would be easier for us if you could show where the speakers and your seating will be placed, too.

 

[mtrycrafts]

Where will your screen and speakers go?

 

[Paranoidandroid]

That is not an easy answer There are 2 screen locations, and multiple speaker locations based on different setups. Every spot in the room needs to be as neutral as possible. I realize that a music rehearsal is not the same as dedicated home theater, but the theory on Bass Trapping is the same, and we have 25 cello and bass players in here at once.

That said, very few sound consultants for rehearsal rooms recommend trapping bass in corners, even when there are massive bass issues. One of the other rooms I had looked at had a RT of 9 seconds at 250 hz..

I just ordered a calibration mic for Room EQ Wizard. I think the statment "it is complicated, look at the data" best applies.

 

[highfigh]

That is not an easy answer There are 2 screen locations, and multiple speaker locations based on different setups. Every spot in the room needs to be as neutral as possible. I realize that a music rehearsal is not the same as dedicated home theater, but the theory on Bass Trapping is the same, and we have 25 cello and bass players in here at once.

That said, very few sound consultants for rehearsal rooms recommend trapping bass in corners, even when there are massive bass issues. One of the other rooms I had looked at had a RT of 9 seconds at 250 hz..

I just ordered a calibration mic for Room EQ Wizard. I think the statment "it is complicated, look at the data" best applies.

The location of the energy source makes a big difference WRT treating the room. Look at any concert hall- it's designed to have the musicians on the stage and the panels are angled in a way that only works when this arrangement is used.

The fact that you'll have multiple instruments in a wide variety of places works in the same way as using multiple subwoofers- it will blend the room modes in a way that they won't be purely constructive or destructive interference.

Look into those two terms (constructive interference and destructive interference)- it's harder to conceive of how this works if you only consider sound, but it works the same way for two dimensional energy in water Changing the width to height allows a better view.

http://www.falstad.com/ripple/

 

[Paranoidandroid]

An update. A few of the 2" absorbers are hung. None of the diffusors. However, today was my first time getting to listen to the room with my calibration mic. I am really looking forward to getting rid of these comb filtering artifacts and hot spots for sure. 30 dB differences on the SPL is not exactly a greatly smoothed out room

This is room #1 of 3 that I am doing this month.

RT, Waterfall, and SPL are attached. once I get more treatment done, it will be nice to see these improve!