Wooden Ceiling Diffuser

[flez007]

mep - I had some ceiling diffusors custom made, two rectangular frames of nearly 1.2 by 0.45 mts < wooden frames and absorbing material covered by a thin cloth similar to a speaker grill (actually look like flat speakers) - at almost 2 inches deep - they make the trick!

 

[microstrip]

to the right is the speaker position.

Something like this sketch?

 

[Mike Lavigne]

Something like this sketch?

you have the general idea. but those angled panels have a shallower angle all the same. and they are above and forward of the listener, not so far forward as you have pictured. although where they are located likely depends on your ceiling height to some degree and listening distance from the listener to the speakers. and there is absorbtion above the panels.

they don't need to really capture and deflect upward all the direct sound from the speaker, but their angle deflects much of that direct sound from the first reflection along the ceiling backward (to retain that energy) as well as up. the main idea of this design is to reflect random (2nd, 3rd, 4th reflection) musical energy back downward to retain that energy in the room. as far as first reflections; it more blocks the rebound than the initial wave.

most ceiling diffusers tend to absorb energy and 'life' from the music since they are so close to the listener. this approach adds space and depth to the soundstage as well as adds focus.

retaining musical energy in the room thru diffusion is the main theme of a Rives room.

 

[rbbert]

And yet, most rooms are far too "live", so we're always looking for that ideal balance. Avoid reflections that smear imaging or alter frequency balance (since lower frequencies often tend to be less reflective than higher), but avoid too much absorption. All diffusion (no absorption) might tighten focus and imaging but won't allow correct frequency balance.

 

[Bill Hart]

Two questions: first, would it make sense for the ceiliing diffusors to be adjustable to accomodate changes in speakers, using something that works almost like a venetian blind, where you can adjust the tilt of the 'slats'?
Second, given what's been said, how effective are those lattice work 'cells' that you see- the ones sold in sections that can be bolted together to form 'clouds' that suspend from the ceiling?
Throw in question - I like high ceilings, which not only feel less claustrophic, but probably have a less pronounced effect on the sound. Am I right?

 

[Mike Lavigne]

And yet, most rooms are far too "live", so we're always looking for that ideal balance. Avoid reflections that smear imaging or alter frequency balance (since lower frequencies often tend to be less reflective than higher), but avoid too much absorption. All diffusion (no absorption) might tighten focus and imaging but won't allow correct frequency balance.

my experience is that rooms that seem to be too live simply need minimal treatment to break up slap echo. that is a cheap problem and easy to fix unless there are WAF issues or maybe an impossibly tall ceiling or maybe joining rooms or hallways or huge windows.......or maybe the room is smallish for the speakers and you have too much energy. in a typical home rectangle room i would prefer to start with a very live room and treat it with diffusion. until you've dealt with first refections and slap echo it's hard to judge the frequency balance.

as far as correct frequency balance there are inexpensive diffusion products which can be tuned by how they are loaded. as an example you can fill an Auralex T-Fusor ($59 each 2' x 2' panel) with some sort of material and it will become absorbtive, or leave it empty and it will not 'hardly' change the frequency.

 

[Mike Lavigne]

Two questions: first, would it make sense for the ceiliing diffusors to be adjustable to accomodate changes in speakers, using something that works almost like a venetian blind, where you can adjust the tilt of the 'slats'?

the panels are hung by chain, and are not very heavy. the adjustment to different speakers or position would be by moving the anchor points. the angle should not change much between different speakers and listening positions.....it would only change much with a change in ceiling height.

Second, given what's been said, how effective are those lattice work 'cells' that you see- the ones sold in sections that can be bolted together to form 'clouds' that suspend from the ceiling?
Throw in question - I like high ceilings, which not only feel less claustrophic, but probably have a less pronounced effect on the sound. Am I right?

high ceilings are the 'lottery' of acoustic challenges. you would first have to listen and measure to determine the solution....or even if you need a solution. and high ceilings can be an unpredicable issue for bass response. i'd prefer a reasonably high flat ceiling that i can treat; say 9' to 11' feet tall. then i can control what is happening.....and first reflection times would not be too short to begin with so solutions don't need to be extreme.

 

[mep]

My room is an "L" shaped room with the "L" portion going to the left at the sitting position. My room is 15' W at the speaker end and 23' D with 9' ceilings. The "L" shape adds approximately another 4' to the room width making it 19' W. I certainly hope that the ceiling diffuser will be money well spent and add more articulation to the sound I'm already getting in my room. I would really appreciate some ideas for lights to mount to the diffuser as I'm struggling with that.

 

[KeithR]

My room is an "L" shaped room with the "L" portion going to the left at the sitting position. My room is 15' W at the speaker end and 23' D with 9' ceilings. The "L" shape adds approximately another 4' to the room width making it 19' W. I certainly hope that the ceiling diffuser will be money well spent and add more articulation to the sound I'm already getting in my room. I would really appreciate some ideas for lights to mount to the diffuser as I'm struggling with that.

You can also buy the diffuser part of a BAD panel from RPG and create custom frames. Then drop the frames 2" from the ceiling. May not work as well as a complete setup like MikeL, but much better for lower ceilings.

 

[mep]

If I do this it at all, it will be custom built. Since my ceiling is 9' high, having a 12" diffuser will still give me an 8' ceiling height over the area where the diffuser will be mounted which I hope and think is just dandy. Right now I'm just waiting for my carpenter to get back to me with the price. He came to my house last night to eyeball my room and figure out where the diffuser will be mounted. I spent a bunch of money to have an addition built onto my house so I could have this room in the first place, but I didn't know then everything I have learned now about what makes up a great room. The good news is my room is underground which reduces noise coming into the room. My exterior walls are all poured concrete with insulation on both the outside of the concrete and inside of the concrete. The interior walls of course are studded and have drywall installed. The foundation between my stereo room and the original house has a 3' separation that runs the width of the house and which is filled with dirt. From the street, you can't see any separation between the addition to the house and the original house. That separation between the foundations created a sound barrier that for the most part stops sound from transferring to the original part of the house. If I have the music playing very loudly in my room, once you walk upstairs and open the door into the kitchen, you can barely hear a sound. That means my wife can't bitch that my stereo is too loud which is so priceless.

I'm just trying to makes things better with regards to my room.

 

[NorthStar]

Two questions: first, would it make sense for the ceiliing diffusors to be adjustable to accomodate changes in speakers, using something that works almost like a venetian blind, where you can adjust the tilt of the 'slats'?
...

---- Very interesting you asked that; I was thinking the exact same thing.
...Remote controllable adjustments (measurements, and preference), like you just said; with various different pairs of loudspeakers (different off-axis sound propagation).

 

[Bruce B]

---- Very interesting you asked that; I was thinking the exact same thing.
...Remote controllable adjustments (measurements, and preference), like you just said; with various different pairs of loudspeakers (different off-axis sound propagation).

I have plantation shutters in one end of my room with 4" of 703 behind them. I love the variability with those and the overhead panels.

 

[JackD201]

Here's an old pic sans the area rug and the rest of the furniture which were removed by the magazine artistic director who shot the room for an article.

I use two types of ceiling work. Three actually but the rear third are bass traps.

The wave in front is Almute with a special adhesive with ply backing on metal frames. Almute is a sintered aluminum that can be shaped and can be cut with saws used for wood. By itself, 3mm Almute has an Absorption Coefficient similar to 4" of fiberglass. This increases in lower frequencies when given airspace. As such there are open cells in the ply so as to trim the absorption. Diffraction is provided by the curvature. The particular design of this cloud was taken from Almute as it was used by Sony in one of their control centers.

Almute being very light can be hung easily and angled the way Mike's are. It is a dead material and doesn't ring.

In the middle is a more traditional absorber/diffusor with helmholtz type behavior. This is above the listening position and does not deal with direct early reflections.

*note that my speakers have rear firing tweeters and that's why the the wave cloud extends behind the speaker plane

 

[NorthStar]

-- What a room Jack!

 

[flez007]

Here's an old pic sans the area rug and the rest of the furniture which were removed by the magazine artistic director who shot the room for an article.

I use two types of ceiling work. Three actually but the rear third are bass traps.

The wave in front is Almute with a special adhesive with ply backing on metal frames. Almute is a sintered aluminum that can be shaped and can be cut with saws used for wood. By itself, 3mm Almute has an Absorption Coefficient similar to 4" of fiberglass. This increases in lower frequencies when given airspace. As such there are open cells in the ply so as to trim the absorption. Diffraction is provided by the curvature. The particular design of this cloud was taken from Almute as it was used by Sony in one of their control centers.

Almute being very light can be hung easily and angled the way Mike's are. It is a dead material and doesn't ring.

In the middle is a more traditional absorber/diffusor with helmholtz type behavior. This is above the listening position and does not deal with direct early reflections.

*note that my speakers have rear firing tweeters and that's why the the wave cloud extends behind the speaker plane

I hate you again Jack!!!! (envy talking)

 

[HedgeHog]

I hate looking at pix like these...they are so good looking I tend to forget what topic is being discussed. Nice space, Jack!

So, is it recommended that absorption be used in the ceiling's FRZ and diffusion over the listening area?

 

[NorthStar]

-- Why is that that everyone's hating Jack?

 

[JackD201]

I hate looking at pix like these...they are so good looking I tend to forget what topic is being discussed. Nice space, Jack!

So, is it recommended that absorption be used in the ceiling's FRZ and diffusion over the listening area?

This is a bit of a trick question because all diffusors also absorb. One has to determine the frequencies absorbed and how much they are absorbed then apply these in terms of percentile coverage vis a vis everything else. I'm not a fan of dead rooms. While they allow (providing that they are uniformly "dead" across the spectrum) you to hear more of what's on the recording and only whats on the recording, this is a set up I would require more for work and not for pleasure. For pleasure, I want balanced and even coverage and incidentally that is what diffusion is really for. It's meant to spread out energy evenly. For pleasure that means you have a better chance of getting sound even if you move around a lot, something you don't do when working on a track.

In my experience the ceiling is the most neglected. If using point or quasi-point source loudspeakers, there is really nothing one can do about floor reflections. A rug helps in the high frequencies but that's it. In my opinion, if you aren't at about 12 feet or higher you're going to need a bit of ceiling work. At 8 or 9 ft, unless you are using a linesource it should be mandatory.

It isn't just the first reflection which should be easy enough. The second reflections will hit the floor and all other walls except the front. I like redirecting reflections to an absorptive second area or one that is also diffusive. Since you can rule the floor out as mentioned, there's little choice but to absorb some of the energy up there to minimize the energy at the second reflection point. Luckily, the ratio of diffusion to absorption can be tuned for ceiling treatments as they can for any other treatments. The math can be tedious but it can be done. In my case, I hadn't practiced for almost a decade so I hired a professional to do the math for me based on predefined targets.

There's a bit of nip and tuckin' that went on in my room because the almute cloud and almute front bass traps were custom jobs. It required sending the 3D CAD drawings to Japan for them to simulate the numbers. The rest of the treatments built here were designed to hit target around the almute fittings. The beauty of it was that the Japanese found the project so trippy (Almute is used for industrial uses like inside automotive exhausts, train stations, sports arenas, cafeterias, lobbies, etc) that they didn't even charge me for the simulation. I was so intrigued by the aesthetic possibilities of the material since it is so easily bent and cut. There's also the WTF?!? factor of using something you can not identify as anything else but metal.

Our dining room seats 14 people. I have a noisy extended family. We are a pretty jovial and boisterous bunch. The dining room has glass on two sides so I knew if I didn't do anything about it we'd all go deaf. I had Almute installed over perforated gypsum in the ceilings and it did he trick. I figured if it could work for Pepsi's commissary there's no reason it couldn't work for us too.

Pepsi Co. here http://www.almute.com/images/almute_gallery/pepsico3.gif

You'll see Sony's wave cloud in the homepage.

I should add that it isn't that expensive a material. A 6x8 cloud would require about $400 worth including the adhesive. Only basic woodworking skills are required for the frames and cutting the material itself.

 

[Bill Hart]

Jack- does Almute make any 'off the shelf' panels, or is it all custom work?

 

[JackD201]

-- Why is that that everyone's hating Jack?

I Love You All