absorbent ceiling in live room

Hi, I just think about two options. I have a live room of 33m² and a ceiling height of 3m. (V = 100m³) There are no parallel walls. But the 3m ceiling is parallel to the floor. We decided to build a new decoubled ceiling. I calculated that I need at least 20-30m² or more area of absorbtion. (Sabins) So I have some options: 1. make the ceiling parallel and make it "completely" dead by applying 100mm Rockwool Sonorock. This should prevent flutter echos. 2. angle the ceiling zick-zack, add only some clouds where they are needed and apply the rest of absorbers on the walls. 3. a combination of both What do you think? Thanks Thomas

What type of room are you talking about? Control room? Vocal booth? Live room? - Stuart -

Soundman2020 wrote:

What type of room are you talking about? Control room? Vocal booth? Live room? - Stuart -

As I said in my third line a "live room" 8)

Thomas - I'd add clouds that have a solid backing on the topside and absorption on the underside. I'd then hang them with chains and angle them to break up the parallel.

John Sayers wrote:

Thomas - I'd add clouds that have a solid backing on the topside and absorption on the underside. I'd then hang them with chains and angle them to break up the parallel.

Thanks for input. But a question: But, why a solid back? And not use the (parallel) ceiling as a back? I think due to absorbtion the angle is not neccessary, isn't it? As far as I remember, please correct me, 100mm absorbers absorb at least down to 250 Hz with more than 0.5 absorbtion coefficent, and near 1.0 from 500Hz up. Why tstill angle them? And where to place them? Only above some spots (e.g. the drumset)? Or in the whole room?

It's the low end that is affected by the angling. The 3m parallel will have a fundamental of 55hz and Ist harmonic at 110hz. They are the frequencies that will give you a problem.

John Sayers wrote:

It's the low end that is affected by the angling. The 3m parallel will have a fundamental of 55hz and Ist harmonic at 110hz. They are the frequencies that will give you a problem.

That is clear, but I cannot see, how an angled cloud could help that much when even a whole a angeled wall only changes (to good or bad, though) the modes to unpredictable and uncalculateable frequencies and nulls and peak positions.

well angled walls actually work in stopping modes caused by standing waves. Same with the ceiling. By that I mean that when you walk around the room there are no points where the low end changes. In a room with bad modal problems the low end changes as you step in and out of positive and negative nodes which not what you want as an outcome in a sound studio.

John Sayers wrote:

well angled walls actually work in stopping modes caused by standing waves. Same with the ceiling. By that I mean that when you walk around the room there are no points where the low end changes. In a room with bad modal problems the low end changes as you step in and out of positive and negative nodes which not what you want as an outcome in a sound studio.

Philip Newell "Recording Studio Design" Second Edition, Page 136 "So, whilst angling of reflective surfaces is a viable technique for reflexion control at middle and higher frequencies, at low frequencies geometric solutions are usually not able to produce the desired results, and hence absorbtion must be resorted to ... " Still confused, Thomas

well believe Philip or me - My rooms don't have room modes and the low end stays uniform throughout the room. I'm not at all confused about it! Jamie's studio http://www.johnlsayers.com/Pages/cerniglia.htm had floor to ceiling modes in the low end directly related to the mode between floor/ceiling. After the installation of angled clouds they went away.

"So, whilst angling of reflective surfaces is a viable technique for reflexion control at middle and higher frequencies, at low frequencies geometric solutions are usually not able to produce the desired results, and hence absorbtion must be resorted to ... " Still confused, Thomas

Thomas, you are not really listening to what John is saying, and confusing it with what Newell is saying. John is talking about absorbent clouds, angled from the ceiling to give them both broader bandwidth and more effective surface area, plus breaking up room modes with non-parallel surfaces, whereas what you are quoting from Newell is talking about "angling of reflective surfaces " for specular diffusion, if I'm not wrong. Newell is saying exactly what John is saying: Angling REFLECTIVE surfaces works for treating highs, not lows. For lows you need to do what both John and Newell are saying: "absorbtion must be resorted to ... ". A ceiling cloud is absorption. That's what both of them are saying. Absorption works better than diffusion at low frequencies But John goes one better, and makes the absorption reflective on the top for different reasons than what Newell is talking about. John doesn't angle it as a diffuser. Like John said, his angling of that hard surface is to break up the parallel surfaces, which therefore destroys the standing waves. It deals with flutter echo and room modes, not diffusion. The angled cloud is a dual-purpose device that does two things at once, and John explained what they are, but you are looking at what Newell said about a different phenomena and trying to apply it to John's design. To me, they are two different things, but both of them are saying the same thing, when you read it right. But like John said: More important than book theory is that his designs have been proven to work in numerous rooms around the world. - Stuart -

Hi John and Stuart, it begins to get clearer now ... a little bit ... :idea: Thanks. I never doubted that it works. I just wondered why. This forum offers great receipes how to do something, but often lacks in the explanation why. This is important if you want to modify some of the receipes.

well Thomas , may I suggest you look elseware for answers your questions - we've done the best we can do and to be honest- I'm not intersted in taking this any further.

John Sayers wrote:

well Thomas , may I suggest you look elseware for answers your questions - we've done the best we can do and to be honest- I'm not intersted in taking this any further.

The answer was answered. Thanks John.