Ceiling Treatment - Low Ceiling, Decently Large Room

[noblenote]

Hi everyone. Was hoping to get some feedback.

My room is 27.25 feet long, 22 feet wide, but only 7.25 feet tall (with drywall). Without drywall, in between the ceiling josts gives me about 7.875 feet of space.

I am a big fan of ceiling absorbption, but I a having a hard time choosing thickness. No matter what, I am committed to removing the drywall and filling the space in between.

The problem is that the joists are about 7.5 inches deep. This means if I wanted max ceiling height of 7.25 feet or so, that I would only have 7.5 inches of ceiling absorbtion. For this thickness, something like rockwool would probably make the most sense.

Alternatively, I could build another set of 1x8s accross the existing joists, and be able to fill in 14 or so inches of absorbtion, in which case I would use fluffly fiberglass with a GFR of circa 2,000. This would bring my ceiling down to about 80 inches of height (about 6.66 feet).

Aesthetically, I would greatly prefer the higher ceiling. This is not a mixing room, its just a critical listening space for 50/50 music and movies (I will have a projector and monitors mounted in heavy front wall (i.e. I am using non-environment princples, but given the length of the room I may put some QRD diffusers on back wall in front of absorbtion for some reflections).

Thoughts on what you would do? Floor is going to be either wood or tile (concrete foundation).

 

[kemmler3D]

As a tall guy I would consider the 6'8" ceiling a nonstarter.

I think it's also possible to end up with a weird result if you cover the entire ceiling with 6-8" absorbers. You'll end up with a short decay everywhere except in the bass.

I definitely recommend putting up some diffusers (BAD, PRD, or QRD if you can afford it) as part of this project to keep the overall response more even.

Subjectively the diffusers can sort of help make the space sound bigger, which could help with the low ceiling.

Are you also planning to treat the walls at all?

E: I see you are, cool.

Overall I would say that the 14" treatment is maybe both too much and not enough. It will absorb really effectively except in the low bass. So my broad advice is to think about absorbing/ diffusing evenly, not necessarily maximally.

 

[noblenote]

As a tall guy I would consider the 6'8" ceiling a nonstarter.

I think it's also possible to end up with a weird result if you cover the entire ceiling with 6-8" absorbers. You'll end up with a short decay everywhere except in the bass.

I definitely recommend putting up some diffusers (BAD, PRD, or QRD if you can afford it) as part of this project to keep the overall response more even.

Subjectively the diffusers can sort of help make the space sound bigger, which could help with the low ceiling.

Are you also planning to treat the walls at all?

E: I see you are, cool.

Overall I would say that the 14" treatment is maybe both too much and not enough. It will absorb really effectively except in the low bass. So my broad advice is to think about absorbing/ diffusing evenly, not necessarily maximally.

Thank you, kind sir! Yeah, 6'8" is rough without question, even for me as a short guy.

Indeed; that's what I'd be worried about. The porous abs. calculator shows about 0.8 coefficient at 200hz, but just under 0.6 at 100hz. So not terrible, but yeah 50-150hz would have high decay times compared to the rest of the spectrum.

That's a good suggestion. Absorbtion on the entire ceiling in a way is quick and easy; but I think you are right, its probably best to test with a combo of abs and diffussion. Really appreciate your feedback

 

[kemmler3D]

The porous abs. calculator shows about 0.8 coefficient at 200hz, but just under 0.6 at 100hz. So not terrible, but yeah 50-150hz would have high decay times compared to the rest of the spectrum.

Yep, this is the problem in a nutshell and it typically only gets worse as you go lower in frequency.

Look into BAD (binary amplitude diffuser) panels, I think GIK acoustics and maybe RPG sell them. For reasons which are somewhat obscure to me, adding the diffuser panel on the front of absorptive material somehow evens out and actually extends the absorption lower than just the porous material alone. So you get a pretty effective diffuser (technically just scattering, but supposedly they still sound good) and absorber in one.

There are also Modex (generic name VPR) bass traps which are kind of big and heavy, but are also lower profile and so could go in the ceiling along with other stuff. This can get you several dB of absorption even down into the bottom octave, or just about.

Alternately stick helmholtz absorbers here and there once you've figured out what the room modes are.

None of it is cheap but all can be done DIY if you're so inclined.

I would also say to go step by step in adding treatment... do measurements, add what appears to be needed, measure and listen again, repeat. As noted above it's entirely possible to overshoot and end up with a boxy / boomy / too-dead sound in the room, which is not the goal.

 

[theREALdotnet]

You could take off the drywall in places where you want to apply absorption and fill the 7.5 inches of space between the joists with absorbers, flush with the rest of the ceiling.

 

[noblenote]

Yep, this is the problem in a nutshell and it typically only gets worse as you go lower in frequency.

Look into BAD (binary amplitude diffuser) panels, I think GIK acoustics and maybe RPG sell them. For reasons which are somewhat obscure to me, adding the diffuser panel on the front of absorptive material somehow evens out and actually extends the absorption lower than just the porous material alone. So you get a pretty effective diffuser (technically just scattering, but supposedly they still sound good) and absorber in one.

There are also Modex (generic name VPR) bass traps which are kind of big and heavy, but are also lower profile and so could go in the ceiling along with other stuff. This can get you several dB of absorption even down into the bottom octave, or just about.

Alternately stick helmholtz absorbers here and there once you've figured out what the room modes are.

None of it is cheap but all can be done DIY if you're so inclined.

I would also say to go step by step in adding treatment... do measurements, add what appears to be needed, measure and listen again, repeat. As noted above it's entirely possible to overshoot and end up with a boxy / boomy / too-dead sound in the room, which is not the goal.

I very much like the idea of testing and using tuned traps; although I hear some don't like tuned traps because frequency can change with temperature (expansion/contraction, etc.) Thank you very much for the feedback, it is greatly appreciated

 

[noblenote]

You could take off the drywall in places where you want to apply absorption and fill the 7.5 inches of space between the joists with absorbers, flush with the rest of the ceiling.

You could take off the drywall in places where you want to apply absorption and fill the 7.5 inches of space between the joists with absorbers, flush with the rest of the ceiling.

Very good idea; I see much sheetrock dust in my future

 

[Lion♡]

I would consider the 6'8" ceiling a nonstarter.

A few years ago, when I was enjoying speakers, I treated my room’s ceiling with approximately 13-15 inches of glass wool.
Leaving aside the positive and negative effects it had on my listening position, having such thickness in a room with a 2.3m ceiling made me chuckle every time I walked in.
Unless the ceiling is as high as a cathedral, traps installed on the ceiling are more noticeable than you might expect.
OP should keep in mind that they are more visible than expected when making a choice....

 

[theREALdotnet]

Very good idea; I see much sheetrock dust in my future

Better use polyester material, like Martini Absorb XHD or similar.

 

[noblenote]

Better use polyester material, like Martini Absorb XHD or similar.

In lieu of sheetrock?

 

[theREALdotnet]

In lieu of sheetrock?

Sorry, I think I read "rock wool" instead

 

[ozzy9832001]

My ceiling is 7'10" and I have panels on it. They are 7.25" thick with a 6" airgap. Other than the occasional bump when I stretch, they really don't impact me much. At first, yeah maybe they added a bit of a weird feel to the room, but you get used to it after awhile.

 

[Hipper]

From what you say I assume there are two things you should be trying to achieve - bass control and eliminating ceiling reflections.

For bass control you don't need to use the ceiling except maybe the corners: wall-wall, wall-ceiling, and perhaps wall-floor. That's if you can tolerate the aesthetics of bass traps. You can also use EQ to finish off the job.

For reflections I suggest you first work out if you have a problem at all.

I have an 8' (2.4m) ceiling in a room 13' 9" x 12' 8" (4.2m x 3.68m). I use 'The Thirds' speaker/chair measurements so my ears are about 5' (1.5m) from the speakers. In these circumstances with my speaker drivers said to have a 30 degree spread I do not get any ceiling reflections that I notice. To test this I once temporarily secured two acoustic panels to the ceiling, one for each speaker, at what I considered to be their reflection points. I used a suitable length piece of wood (a 'T' shaped piece would be ideal) and jammed it between the panel and the floor to hold the panel in place. I heard no difference with the panel in place or removed - no ceiling reflections (I probably also used REW to measure any difference but if I did I can't find the measurements!).

My advice is therefore to first test if ceiling reflections will really be an issue with your speakers in your set up. If you do have an issue there may be other solutions then sticking panels on the reflection points of the ceiling (you won't need them anywhere else on the ceiling). For example you could place a suitable panel on top of your speaker so it overhangs the drivers by an amount suitable to stop ceiling reflections. These panels would not need to be especially thick - 3" say.

I once also looked into tuned bass traps. It sounded like a good idea as despite having lots of bass traps I had a persistent issue at 50Hz. However in order to solve this I needed to find out exactly where in the room to place the tuned bass trap. I played 50Hz test tones and stuck an SPL meter in every conceivable spot but could not find where the problem was. In the end I used EQ to sort the issue and am very satisfied.

 

[Vuki]

Knauf acoustic drywall plates