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DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)
Old 10th December 2016 | Show parent
  #721
Gear Addict
 
Arqen's Avatar
 
🎧 5 years
Quote:
Originally Posted by Aram9012 ➡️
Hi there;

I plan to build (3) 4' tall leanfuser diffusors. I live in the states. In order to make the pieces as smooth as possible Ideally I would get the lumber as close to the necessary dimensions as possibly to minimize cutting.

1) the width of each plateau is supposed to be 60mm or 2 3/8 inches. However I found at my local Lowes they have a large selection of wood pre-cut to a width of exactly .5" by 2.5". I know Tim states that the .5" height works well but what about the 2.5" width? Will this work or is it worth the time to rip these down to 2 3/8" exactly.
Yes, that will work. The resulting geometry will have proportions between two performance-tested designs: the original 10 mm step increment version, and the 12-12.7 mm (1/2") increment imperial version. Just make sure your mounting strategy takes into considering stud placement.

A good approach if the individual modules don't line up with studs is to use a french cleat system on rails (PDF download). The rails are fixed to the wall studs and diffuser modules hang off the rails with a French cleat.

Quote:
Originally Posted by Aram9012 ➡️
2) Also between pine, mahogany, poplar, oak, maple, does any wood type have better diffusion performance than the other?
Wood choice has negligible effect on diffusion performance. Although you could make a theoretical argument for denser woods, I've yet to see someone succeed at finding a measurable difference. E.g., last year, a grad student emailed me asking what was wrong with his experimental setup, because he was finding no statistically significant changes by changing the wood.

I'd say the experiment was doomed from the start. Any difference wood type makes to diffusion coefficients are so insignificant that they're overpowered by environmental factors and experimental error.

Choose wood for other reasons (aesthetics, weight, cost, sustainability), and ideally varnish it to minimize absorption.

Hope this helps!
Old 10th December 2016 | Show parent
  #722
Lives for gear
 
Jens Eklund's Avatar
 
🎧 10 years
Quote:
Originally Posted by Arqen ➡️

Wood choice has negligible effect on diffusion performance. Although you could make a theoretical argument for denser woods, I've yet to see someone succeed at finding a measurable difference. E.g., last year, a grad student emailed me asking what was wrong with his experimental setup, because he was finding no statistically significant changes by changing the wood.

I'd say the experiment was doomed from the start. Any difference wood type makes to diffusion coefficients are so insignificant that they're overpowered by environmental factors and experimental error.

Choose wood for other reasons (aesthetics, weight, cost, sustainability), and ideally varnish it to minimize absorption.
+1

Flooring question

Diffusors: opinions about EPS polystyrene?
Old 11th December 2016 | Show parent
  #723
Gear Head
 
🎧 10 years
Quote:
Originally Posted by Arqen ➡️
Yes, that will work. The resulting geometry will have proportions between two performance-tested designs: the original 10 mm step increment version, and the 12-12.7 mm (1/2") increment imperial version. Just make sure your mounting strategy takes into considering stud placement.

Choose wood for other reasons (aesthetics, weight, cost, sustainability), and ideally varnish it to minimize absorption.

Hope this helps!
Great! Thank you so much Tim for the response. I really appreciate it, and I'm really excited to dig into this! I think these leanfusors are fantastic and look better than anything commercially available in my opinion. Also thanks for the mounting advice.

Best;
Aram
Old 12th December 2016 | Show parent
  #724
Gear Addict
 
Arqen's Avatar
 
🎧 5 years
Quote:
Originally Posted by Aram9012 ➡️
Great! Thank you so much Tim for the response. I really appreciate it, and I'm really excited to dig into this! I think these leanfusors are fantastic and look better than anything commercially available in my opinion. Also thanks for the mounting advice.

Best;
Aram
My pleasure. Glad you like the aesthetic. I too prefer stepped diffusers over finned QRD designs. Finless, optimized stepped diffusers are a more direct approach to form following function.
Old 29th January 2017 | Show parent
  #725
Gear Maniac
 
robertopisa's Avatar
 
🎧 10 years
Hello Tim,

can your LeanFractals be employed for the front wall at 2 meters distance from my listening position?
I can line up just three of them, as the speakers are 1.5 meters apart each other.

Thanks
-Roberto

Last edited by robertopisa; 29th January 2017 at 09:01 PM..
Old 29th January 2017 | Show parent
  #726
Gear Addict
 
Arqen's Avatar
 
🎧 5 years
Leanfractal diffuser on front wall

Quote:
Originally Posted by robertopisa ➡️
Hello Tim,

can your LeanFractal be employed for the front wall at 2 meters distance?

Thanks
-Roberto
Hi Roberto,

Yes. We used it that way in the surround sound control room shown below, not because fractal diffusers were essential there, but because the client really wanted them on both front and rear wall, and they also planned to do some tracking and jamming in this room. It was for a private school, and the studio is an interactive classroom where they wanted the acoustic treatments to visually stand out, so the fractal diffuser made sense there.

For stereo listening with monopole speakers, front wall fractal diffusers would be overkill. Most mid-high frequency energy is directed toward the listener, not the wall behind the speakers. They won't hurt, but they're much better utilized on the rear wall.

I usually view the front wall in context with the rest of the room. It doesn't necessarily need treatment, but the rear walls and sidewalls always need treatment.

Old 29th January 2017 | Show parent
  #727
Gear Maniac
 
robertopisa's Avatar
 
🎧 10 years
Nice, thanks a lot Tim for the quick reply!
-R
Old 1st February 2017 | Show parent
  #728
Gear Addict
 
Arqen's Avatar
 
🎧 5 years
Quote:
Originally Posted by robertopisa ➡️
Nice, thanks a lot Tim for the quick reply!
-R
Glad to be of help, Roberto.
Old 3rd February 2017 | Show parent
  #729
Here for the gear
 
Hi Arquen & hi to all, first post here!
l'm Lorenzo from Italy!

I've discovered your designs digging the web for information

Firstly, I would like to thank you for sharing so many to us all, my knowledge about diffusers is now well beyond considering them just cute surfaces for the exhibitionist studio owner

I'm planning to move to a new home, and build my first, true home studio.
I'm considering to build several diffuser for the large (7x5x3,7 m. lwh) dining/control room that I'm looking at!

As a carpenter, I have access to cnc machinery and to (cheap) wood. Also building tools and assembly shouldnt be a great matter.

I kinda fall in love with your Stepfractal design , and i want to ask you... what about appling the same modulation of the A1-Fract at his best to the B2?

And to dare even more, what about mounting seven modules with the same criteria to obtain a 3rd order fractal ?

This should be considered a long term project
Old 8th February 2017
  #730
Gear Nut
 
unqlenol's Avatar
 
🎧 10 years
Hi Tim,

It's been a while since I have participated here. I'm the guy who made this...
It has contributed greatly to my studio. An engineer friend of mine whom I completely trust immediately noticed just from talking in my studio the difference that the diffusor had made.

I was hoping you wouldn't mind sharing your opinion on an idea that I am scheming. It is not a very scientific idea,
but it makes use of mixing up some principles. Cutting to the point, I am daydreaming about a sort of stepped diffusor/ Absorber combo for my front wall. Currently I have my rear wall rocking the diffusor (linked above) that I built based on your generous and sage instruction.

What I am thinking about my front wall is that I want a fairly absorptive central wall area, but not completely absorptive. I want some reflection feeding back and I thought it would be good to scatter or diffuse those reflections in some way – even if the way chosen is not one that would please the purists.

The idea is to take my existing 1200x1200x100(thickness) rockwool absorber (currently centralised on the front wall - so it is not really taking care of the first reflection points there) and build it into a deeper frame. It would be inset into this frame. Then, in front of the rockwool panel, but still within this new frame, I want to put vertical slats of wood configured using your approach as the basis. The big difference is that I want it to be 'stepped slats' which are open on the sides and behind. Not closed, the way it is meant to be.

The idea is that I will get some diffusion, albeit a compromised version - but I will also get some absorption, particularly on the lower end of the spectrum.

The slats would be at least 22mm thick and would be braced to stiffen for preventing unwanted resonant feedback.
They would be 1200mm tall and the width could be decided based on calculations and, also, on what pattern of periods would fit neatly into the available 1200mm horizontal width of the frame.

Thanks in advance for any thoughts on the matter.

Does this make sense. I could draw a picture if need be...

So I want to know if you think that this would be a foolish exercise. I am not after complete perfection. I am happy with 'good enough' - although I know that that kind of talk can be dangerous on GS. I want an affordable and easy to implement solution that will give a balanced an reasonable functional improvement to the central front wall of my 4mx6m room.

I thank you in advance for any advice and I hope this question is useful to others.

Nolan
Old 20th February 2017 | Show parent
  #731
Gear Addict
 
Arqen's Avatar
 
🎧 5 years
Quote:
Originally Posted by Gaz89 ➡️
Hi Arquen & hi to all, first post here!
l'm Lorenzo from Italy!

I've discovered your designs digging the web for information

Firstly, I would like to thank you for sharing so many to us all, my knowledge about diffusers is now well beyond considering them just cute surfaces for the exhibitionist studio owner

I'm planning to move to a new home, and build my first, true home studio.
I'm considering to build several diffuser for the large (7x5x3,7 m. lwh) dining/control room that I'm looking at!

As a carpenter, I have access to cnc machinery and to (cheap) wood. Also building tools and assembly shouldnt be a great matter.

I kinda fall in love with your Stepfractal design , and i want to ask you... what about appling the same modulation of the A1-Fract at his best to the B2?

And to dare even more, what about mounting seven modules with the same criteria to obtain a 3rd order fractal ?

This should be considered a long term project
Hi Lorenzo,

Welcome to the forum! Yes, this is a good approach. However, I would build the A1-Frac design with the 3rd order fractal modulation, because it's easier to build, requires less material, and has had development and testing beyond B2-Frac.

When we do the 3rd order fractal modulation, the asymmetrical shape of B2-Frac becomes an uncertainty rather than an asset. We will no doubt get good diffusion, but we're starting to add elements of voodoo and relying on randomness rather than design intent.

I say this because the purpose of asymmetry in B2-frac was to reduce periodicity for an array that is not depth-modulated. But a 3rd order fractal is depth-modulated, so we may as well use an optimized symmetrical shape like A1-Frac, to ensure uniform scattering is built into the "DNA" of the fractal array.

When doing the optimization, I remember there was something special about the A1 shape, in that the performance was head and shoulders above other 7-step shapes of the same overall width/depth. You can kind of visualize this in this simulation of the basic A1 shape scattering sound. Considering its shallow depth, it's efficient at spreading energy.



My code searched for many hours for competitors with similar overall proportions, but found none. In contrast, the B2 shape had other non-symmetrical competitors of similar performance. It was less of a diamond in the rough.

Of course, aesthetics also play a role. Some people may prefer B2-frac for that alone, but I think A1-Frac looks pretty awesome when mounted with depth modulations. I also get quiet satisfaction that the entire design is built around fractal self symmetry, based around a form that was optimized for symmetrical scattering. But, I'm a nerd who romanticizes form following function.

Below shows what the Leanfractal (A1-Frac) looks like when build as a 3rd order fractal. If you're interested in building this, email me (my first name @ my domain.com), as I have additional drawings and details. Whatever version you decide to build, please share photos. :-)



Last edited by Arqen; 20th February 2017 at 07:37 AM..
Old 20th February 2017 | Show parent
  #732
Gear Addict
 
Arqen's Avatar
 
🎧 5 years
Quote:
Originally Posted by unqlenol ➡️
Hi Tim,

It's been a while since I have participated here. I'm the guy who made this...
It has contributed greatly to my studio. An engineer friend of mine whom I completely trust immediately noticed just from talking in my studio the difference that the diffusor had made.

I was hoping you wouldn't mind sharing your opinion on an idea that I am scheming. It is not a very scientific idea,
but it makes use of mixing up some principles. Cutting to the point, I am daydreaming about a sort of stepped diffusor/ Absorber combo for my front wall. Currently I have my rear wall rocking the diffusor (linked above) that I built based on your generous and sage instruction.

What I am thinking about my front wall is that I want a fairly absorptive central wall area, but not completely absorptive. I want some reflection feeding back and I thought it would be good to scatter or diffuse those reflections in some way – even if the way chosen is not one that would please the purists.

The idea is to take my existing 1200x1200x100(thickness) rockwool absorber (currently centralised on the front wall - so it is not really taking care of the first reflection points there) and build it into a deeper frame. It would be inset into this frame. Then, in front of the rockwool panel, but still within this new frame, I want to put vertical slats of wood configured using your approach as the basis. The big difference is that I want it to be 'stepped slats' which are open on the sides and behind. Not closed, the way it is meant to be.

The idea is that I will get some diffusion, albeit a compromised version - but I will also get some absorption, particularly on the lower end of the spectrum.

The slats would be at least 22mm thick and would be braced to stiffen for preventing unwanted resonant feedback.
They would be 1200mm tall and the width could be decided based on calculations and, also, on what pattern of periods would fit neatly into the available 1200mm horizontal width of the frame.

Thanks in advance for any thoughts on the matter.

Does this make sense. I could draw a picture if need be...

So I want to know if you think that this would be a foolish exercise. I am not after complete perfection. I am happy with 'good enough' - although I know that that kind of talk can be dangerous on GS. I want an affordable and easy to implement solution that will give a balanced an reasonable functional improvement to the central front wall of my 4mx6m room.

I thank you in advance for any advice and I hope this question is useful to others.

Nolan
Hi Nolan,

You're right that "good enough" can be dangerous on GS :-), but I think what you mentioned is actually a good approach. It sounds a bit like the MyRoom Design approach by Bogic Petrovic (boggy on GS).

Also, for stereo listening, the front wall is out of the direct line of fire for mid-high frequency energy from your speakers, so the difference between "optimal" and "good enough" may be inaudible. We also need to consider the full acoustics of the room, especially when choosing treatment for a surface that's out of the direct line of fire. While the side and rear wall reflection points may have hard requirements to meet the RFZ criteria, I view the front wall as a more flexible surface we can use to help balance a room.

In general, we want as much bass absorption as possible, and a blend of both absorption and diffusion at mid-high frequencies. So if you could only have one type of surface in a room, it would be a hybrid surface like you mentioned (or is shown in boggy's paper), with bass absorption underneath.

I like to see experimentation, and what you're proposing honestly sounds like a good approach. There is purpose behind it. At the very least, it's like a slat wall / slotted absorber with improved scattering.

Cheers,
Tim

Last edited by Arqen; 20th February 2017 at 03:00 AM..
Old 21st February 2017 | Show parent
  #733
Gear Nut
 
unqlenol's Avatar
 
🎧 10 years
Tim, thanks so much for affirming my idea! It's good to know that I am thinking the right way. The link to Boggy's white paper is great. Thanks. Interesting read.
Looks like I have to get busy on my grid paper and Reflex!
Old 23rd February 2017 | Show parent
  #734
Gear Addict
 
Arqen's Avatar
 
🎧 5 years
Quote:
Originally Posted by unqlenol ➡️
Tim, thanks so much for affirming my idea! It's good to know that I am thinking the right way. The link to Boggy's white paper is great. Thanks. Interesting read.
Looks like I have to get busy on my grid paper and Reflex!
Thanks for sharing your experiments! I think your last diffuser turned out great. Hope this one goes well too.
Old 24th February 2017
  #735
Here for the gear
 
Galaxy Wizard's Avatar
 
🎧 5 years
Hi Tim,
Thanks a lot for your great job! Thesis is very informative! It (along with book and papers of Cox & D'Antonio) inspired me to try some optimizations of my own for my control room build. Sadly code from appendices was removed. But it is fully understandable in our World...
I also used K-Wave in Matlab and kind of recreated your work. I attach some random screenshot. With faster CPU, utilizing GPU and parallel computing toolbox it works little faster today. Anyway I am going to try BEM (OpenBEM) as well.

I have some thoughts and questions:
In case of diffuser optimization for specific room it seems intuitively that it is better to optimize diffuser response at listener position with the source at monitor position (in addition or may be even instead of overall diffusion optimization). It is not obvious though what should be considered a good response at listener position. I suspect it should be checked for artifacts (especially in case of breaking 3λ rule, which is really interesting). And may be it is a good idea to optimize for less scattering to listener position with source in monitor position to loose early reflections. What do you think?

Thanks again, and best regards
-Niki
Attached Thumbnails
DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-dif-simtest.jpg  
Old 27th February 2017
  #736
Gear Head
 
🎧 5 years
Any thoughts on using this material?
Ultra Board: Foam Board, Ideal for Screen Printing | United Industries

I want to build some diffusers for the ceiling and would rather have something lighter weight than plywood. However I am concerned that they will be more of an absorber than diffuser. I have a sample of the material. It is very rigid and the face is a PVC like material. The center is a foam core though.
Old 27th February 2017 | Show parent
  #737
Gear Addict
 
Arqen's Avatar
 
🎧 5 years
Quote:
Originally Posted by Galaxy Wizard ➡️
Hi Tim,
Thanks a lot for your great job! Thesis is very informative! It (along with book and papers of Cox & D'Antonio) inspired me to try some optimizations of my own for my control room build. Sadly code from appendices was removed. But it is fully understandable in our World...
I also used K-Wave in Matlab and kind of recreated your work. I attach some random screenshot. With faster CPU, utilizing GPU and parallel computing toolbox it works little faster today. Anyway I am going to try BEM (OpenBEM) as well.

I have some thoughts and questions:
In case of diffuser optimization for specific room it seems intuitively that it is better to optimize diffuser response at listener position with the source at monitor position (in addition or may be even instead of overall diffusion optimization). It is not obvious though what should be considered a good response at listener position. I suspect it should be checked for artifacts (especially in case of breaking 3λ rule, which is really interesting). And may be it is a good idea to optimize for less scattering to listener position with source in monitor position to loose early reflections. What do you think?

Thanks again, and best regards
-Niki
Hey Niki,

Nice work! Yes, I bet it's much faster today. My buddy from Ufa just built a mini "supercomputer" (insane GPU array in his apartment) for running deep learning neural networks, and here I am still using the same computer I used for the diffuser optimization. I'm behind the times.

Tangent: You might find it unexpected that my ears have had a long time romance with Russian power metal. It started in high school, when these two Russian immigrants, who everyone was scared of, learned I had a drum-set and invited themselves over. We became best friends (to this day), started a crappy power metal band, and drank ****loads of tea in my parents basement.

Thoughts on your questions:
I like a well-defined initial signal delay gap (ISD gap) followed by diffuse return. If that's the goal, the optimal diffuser behavior would depend on how far it is from the listener. Some of my thoughts on initial signal signal delay are are given in this article on first reflection control.

If we're viewin around 20 ms as an ideal, rear-wall diffusers would be ~3.4 meters behind the listener to achieve this. In that arrangement, diffusers optimized for uniform scattering makes sense to me.

If the diffuser is much closer than 3 meters -- let's say 1.5 meters, giving an initial signal delay gap of only 9 ms -- I would favour (in theory) a diffuser that directs energy to the sides, minimizing the direct return to the listener to ensure the RFZ criteria is met. 2D PRD diffusers with a null in their polar response are good at redirecting energy away from the listener. Another approach is to let that surface be absorptive (including at bass frequencies). Or, to treat the reflection at close range but preserve brightness, use a hybrid absorptive-diffusive device like a 2D binary amplitude surface that diffuses higher frequencies while absorbing mids-lows.

In the opposite case -- this is just speculation, but let's say if the distance to the diffuser is well beyond 5 meters -- a more directional "diffuser" might have some uses and could be cool to experiment with. However, in a critical listening environment, I'm less interested in emphasizing the ISD gap if it's outside the sweet spot rage of 16-25 ms.

In short: I think uniform scattering is a desirable behavior for any rear-wall diffuser that's 3 meters or more behind you. If we place the listening position much closer to the rear wall, I favour reducing the direct energy return, whether by absorption, hybrid surfaces, or redirection.

Great question.
Old 27th February 2017 | Show parent
  #738
Gear Addict
 
Arqen's Avatar
 
🎧 5 years
Quote:
Originally Posted by Pultzar ➡️
Any thoughts on using this material?
Ultra Board: Foam Board, Ideal for Screen Printing | United Industries

I want to build some diffusers for the ceiling and would rather have something lighter weight than plywood. However I am concerned that they will be more of an absorber than diffuser. I have a sample of the material. It is very rigid and the face is a PVC like material. The center is a foam core though.
Acoustically I think it would be fine, but my concern is fire safety. Covering large surfaces of your room with plastic devices creates a fire and smoke toxicity hazard.
Old 27th February 2017 | Show parent
  #739
Lives for snowflakes
 
12ax7's Avatar
 
🎧 10 years
Quote:
Originally Posted by Arqen ➡️
Acoustically I think it would be fine, but my concern is fire safety. Covering large surfaces of your room with plastic devices creates a fire and smoke toxicity hazard.
...Then maybe something like this?:
Tri-Dee - Fire Rətardant Foam Core
.

Last edited by 12ax7; 28th February 2017 at 12:06 AM..
Old 27th February 2017 | Show parent
  #740
Lives for gear
 
🎧 15 years
Hi Tim,

Here's a couple pictures of my room. As you can see it's quite large. My main concern right now is the ceiling. I don't want to deaden this room too much and it got me into thinking about diffusors. It's a work in progress right now.

There is so much space that there is no way I'm going to be able to make that many fractal diffusors, but I wonder if just the A1 stepped diffusors mounted onto 8X4 plywood board would get me a good response.

Just asking your advice as to how you would approach a ceiling like this. It has a height of 9.5 feet.
Attached Thumbnails
DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-dscn2017.jpg   DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-dscn2019.jpg  
Old 28th February 2017 | Show parent
  #741
Here for the gear
 
Galaxy Wizard's Avatar
 
🎧 5 years
Quote:
Originally Posted by Arqen ➡️
Tangent: You might find it unexpected that my ears have had a long time romance with Russian power metal. It started in high school, when these two Russian immigrants, who everyone was scared of, learned I had a drum-set and invited themselves over. We became best friends (to this day), started a crappy power metal band, and drank ****loads of tea in my parents basement.
Unexpected indeed!
I'll PM you some of my crappy stuff, heh
Quote:
Originally Posted by Arqen ➡️
Thoughts on your questions:
I like a well-defined initial signal delay gap (ISD gap) followed by diffuse return. If that's the goal, the optimal diffuser behavior would depend on how far it is from the listener. Some of my thoughts on initial signal signal delay are are given in this article on first reflection control.

If we're viewin around 20 ms as an ideal, rear-wall diffusers would be ~3.4 meters behind the listener to achieve this. In that arrangement, diffusers optimized for uniform scattering makes sense to me.

If the diffuser is much closer than 3 meters -- let's say 1.5 meters, giving an initial signal delay gap of only 9 ms -- I would favour (in theory) a diffuser that directs energy to the sides, minimizing the direct return to the listener to ensure the RFZ criteria is met. 2D PRD diffusers with a null in their polar response are good at redirecting energy away from the listener. Another approach is to let that surface be absorptive (including at bass frequencies). Or, to treat the reflection at close range but preserve brightness, use a hybrid absorptive-diffusive device like a 2D binary amplitude surface that diffuses higher frequencies while absorbing mids-lows.

In the opposite case -- this is just speculation, but let's say if the distance to the diffuser is well beyond 5 meters -- a more directional "diffuser" might have some uses and could be cool to experiment with. However, in a critical listening environment, I'm less interested in emphasizing the ISD gap if it's outside the sweet spot rage of 16-25 ms.

In short: I think uniform scattering is a desirable behavior for any rear-wall diffuser that's 3 meters or more behind you. If we place the listening position much closer to the rear wall, I favour reducing the direct energy return, whether by absorption, hybrid surfaces, or redirection.

Great question.
Thank you for the detailed answer! I've actually studied your articles several times and I must say they give lots of important and useful information in simple and short form, excellent! Importance of ISD gap is revealed very clearly. I am building control room and would like to make less compromise about sound quality. While I like RFZ concept (with diffuse rear wall) my room is barely enough to make it here (and I desperately need massive bass absorption on the rear wall). Also RFZ (with redirection on side walls) ties monitor placement to specific position and there is quite a chance it is not good enough position considering bass response in a small room (which is hard to predict from my little but constantly failing experience before you finish massive building). So I was bravely moving towards NE design (Russian guys tend to build some hardcore things in their apartments, heh). Then I realized that I didn't have enough motivation to work in anechoic environment...

Then I discovered BAD panels and then finally MyRoom mkII concept by Boggy: MyRoom Acoustic Design Mark II
I was thinking to optimize these absorptive PRD diffusers on side walls and ceiling for less first reflections from monitor position (but considering ETC graphs from MyRoom papers that may be overkill since first reflections are already -20 - -25 dB). Also it would be nice to keep them somewhat diffusive let's say down to 500 Hz while sitting in 1.1-1.3 m (little more than 1.5 wave length) to the closest surface. That's why I am digging such custom optimization.
And while it is basically clear with back wall absorber/diffuser, things get much more interesting with side walls and ceiling
But may be I just waste efforts on insignificant things (hard to say before you try)..
Old 12th March 2017 | Show parent
  #742
Gear Addict
 
Arqen's Avatar
 
🎧 5 years
Quote:
Originally Posted by 12ax7 ➡️
...Then maybe something like this?:
Tri-Dee - Fire Rətardant Foam Core
.
Most flame ******ant foam materials actually have worse smoke toxicity. Instead of flame they give off black, chemical filled smoke.

You're free to use whatever material you like, of course, but MDF is one of the best low cost solutions.

Haha, it doesn't let us write rətardant because it contains the word rətard.
Old 12th March 2017 | Show parent
  #743
Gear Addict
 
Arqen's Avatar
 
🎧 5 years
Quote:
Originally Posted by Jonk ➡️
Hi Tim,

Here's a couple pictures of my room. As you can see it's quite large. My main concern right now is the ceiling. I don't want to deaden this room too much and it got me into thinking about diffusors. It's a work in progress right now.

There is so much space that there is no way I'm going to be able to make that many fractal diffusors, but I wonder if just the A1 stepped diffusors mounted onto 8X4 plywood board would get me a good response.

Just asking your advice as to how you would approach a ceiling like this. It has a height of 9.5 feet.
They would be decent, but on the ceiling I'd instead go for a 2D diffuser. The best DIY solution I know for ceiling diffusion is 2D PRD diffusers: PRD Calculator
Old 12th March 2017 | Show parent
  #744
Gear Addict
 
Arqen's Avatar
 
🎧 5 years
Quote:
Originally Posted by Galaxy Wizard ➡️
Unexpected indeed!
I'll PM you some of my crappy stuff, heh

Thank you for the detailed answer! I've actually studied your articles several times and I must say they give lots of important and useful information in simple and short form, excellent! Importance of ISD gap is revealed very clearly. I am building control room and would like to make less compromise about sound quality. While I like RFZ concept (with diffuse rear wall) my room is barely enough to make it here (and I desperately need massive bass absorption on the rear wall). Also RFZ (with redirection on side walls) ties monitor placement to specific position and there is quite a chance it is not good enough position considering bass response in a small room (which is hard to predict from my little but constantly failing experience before you finish massive building). So I was bravely moving towards NE design (Russian guys tend to build some hardcore things in their apartments, heh). Then I realized that I didn't have enough motivation to work in anechoic environment...

Then I discovered BAD panels and then finally MyRoom mkII concept by Boggy: MyRoom Acoustic Design Mark II
I was thinking to optimize these absorptive PRD diffusers on side walls and ceiling for less first reflections from monitor position (but considering ETC graphs from MyRoom papers that may be overkill since first reflections are already -20 - -25 dB). Also it would be nice to keep them somewhat diffusive let's say down to 500 Hz while sitting in 1.1-1.3 m (little more than 1.5 wave length) to the closest surface. That's why I am digging such custom optimization.
And while it is basically clear with back wall absorber/diffuser, things get much more interesting with side walls and ceiling
But may be I just waste efforts on insignificant things (hard to say before you try)..
Yes, I'm a big advocate of both BAD panels, and the MyRoom approach for people who have the space for that much bass absorption. As a general room design philosophy, it's one of my favorite: Combining the massive bass absorption of NE rooms, while preserving some high frequency energy though diffusion. It's striking a balance between anechoic (fully absorptive) and ambichoic (fully diffusive), and the result gives a flexible neutral-but-not-dead room.

I think it's great for multi channel applications, and you could also do some tracking inside a room like that.

Also, thanks for sending me you're stuff. I'll definitely check it out!
Old 31st March 2017
  #745
Gear Nut
 
🎧 5 years
Quote:
Originally Posted by Arqen ➡️
[Click here to get the DIY Diffuser Blueprints]

[SIZE="3"]Hey guys,

You might recall that I was going to give away free blueprints for DIY sound diffusers. Well, here they are:]
Hi Tim,

I have a small room 350L x 290W x 300H in centimeters and due to room restrictions I’m facing the long wall (350cm). The room is heavily trapped with big and bulky traps in the corners. The RT60 in the room is about 0.2ms and I feel like it’s quite dead. I was thinking to place some diffusers on the rear wall to bring some liveness in the room. What kind of diffuser do you recommend?
I should mention that the distance between my listening position and my back wall is 180cm.

Because I’m not good in DIY, I was also thinking to purchase the skyline or the quadratic diffuser from thomann, would they be adequate for my job?

https://www.thomann.de/be/the_takust...yline_wood.htm

https://www.thomann.de/be/the_takustik_sc_diffusor.htm
Old 31st March 2017 | Show parent
  #746
Lives for gear
 
Jens Eklund's Avatar
 
🎧 10 years
Quote:
Originally Posted by petergel ➡️
The RT60 in the room is about 0.2ms and I feel like it’s quite dead. I was thinking to place some diffusers on the rear wall to bring some liveness in the room. What kind of diffuser do you recommend?
Help: Studio is too loud

Also: RT60 is not relevant in small room acoustics. The shape of the ETC is. More here:

https://gearspace.com/board/8295482-post3.html
Old 31st March 2017 | Show parent
  #747
Gear Addict
 
Arqen's Avatar
 
🎧 5 years
Quote:
Originally Posted by petergel ➡️
Hi Tim,

I have a small room 350L x 290W x 300H in centimeters and due to room restrictions I’m facing the long wall (350cm). The room is heavily trapped with big and bulky traps in the corners. The RT60 in the room is about 0.2ms and I feel like it’s quite dead. I was thinking to place some diffusers on the rear wall to bring some liveness in the room. What kind of diffuser do you recommend?
I should mention that the distance between my listening position and my back wall is 180cm.

Because I’m not good in DIY, I was also thinking to purchase the skyline or the quadratic diffuser from thomann, would they be adequate for my job?

https://www.thomann.de/be/the_takust...yline_wood.htm

https://www.thomann.de/be/the_takustik_sc_diffusor.htm
Hi Peter,

Normally I recommend 1D diffusers on the rear wall. But, since you don't have much space behind you, you're better off with 2D PRD (skyline-style) diffusers that reduce the energy returned to the listening position. Of those two choices I would choose their Manhattan diffuser for your specific case.

Bear in mind their SC diffuser does not have wells, so it's not functioning as a QRD diffuser is designed to function. This means I don't know its true performance without seeing performance data.
Old 31st March 2017 | Show parent
  #748
Gear Nut
 
🎧 5 years
Quote:
Originally Posted by Arqen ➡️
Normally I recommend 1D diffusers on the rear wall. But, since you don't have much space behind you, you're better off with 2D PRD (skyline-style) diffusers that reduce the energy returned to the listening position. Of those two choices I would choose their Manhattan diffuser for your specific case.
Hi Tim,

Thank you for replying back so quickly. The dimensions of Manhattan diffuser are 60x60x17cm. How many should I place on the rear wall? Two of them (120x60 cm) would be adequate? Four of them (120x120cm) would be better or overkill?

You said that the 2D Manhattan diffuser will reduce energy to listening position. My room sounds already dead to my ears, so I was looking for a diffuser to scatter uniformly and perhaps enhance the energy back to me.
Is there a possibility the Manhattan diffuser to make my room more dead than already is?
Old 31st March 2017 | Show parent
  #749
Gear Addict
 
Arqen's Avatar
 
🎧 5 years
Quote:
Originally Posted by petergel ➡️
Hi Tim,

Thank you for replying back so quickly. The dimensions of Manhattan diffuser are 60x60x17cm. How many should I place on the rear wall? Two of them (120x60 cm) would be adequate? Four of them (120x120cm) would be better or overkill?

You said that the 2D Manhattan diffuser will reduce energy to listening position. My room sounds already dead to my ears, so I was looking for a diffuser to scatter uniformly and perhaps enhance the energy back to me.
Is there a possibility the Manhattan diffuser to make my room more dead than already is?
It will add a very small amount of absorption but should not make the room feel more dead. Likewise, it will not liven up the room unless you place it over absorption. If you're looking for a more lively sounding room you need to reduce the absorption coverage by replacing absorptive surfaces with diffusive, scattering, or reflective surfaces.

I can't give an honest judgement on how 2 vs 4 will sound as there are too many unknown variables. If your rear wall is already bare, lots of diffusion is better than a reflective wall. So more is better.

If your room sounds too dead already, look at the changing the floor material (if it's carpet, change to reflective), and removing absorption if you have it in non-critical areas (e.g., the front wall). Absorption coverage can be reduced provided it's not at a first reflection point, or providing bass absorption. Absorption at first reflection points can potentially be blended or replaced by diffusion, but that's a big topic in itself with many variables to be considered.
Old 3rd April 2017 | Show parent
  #750
Gear Nut
 
🎧 5 years
Quote:
Originally Posted by Arqen ➡️
Likewise, it will not liven up the room unless you place it over absorption.
Sorry, I don't understand. What do you mean by place the diffuser over absorption? This diffuser weight 30Kg, I think it would be impossible to hang it in front of an absorptive panel.

Quote:
Originally Posted by Arqen ➡️
If your room sounds too dead already, look at the changing the floor material (if it's carpet, change to reflective), and removing absorption if you have it in non-critical areas (e.g., the front wall).
My floor is reflective (tiles) so there’s nothing to remove. I thought that front wall give strong reflections and it’s very critical to cover it entirely. You believe it’s not critical?
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