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Wood acoustic diffusers have become a decorative item - loved the idea!

sarumbear

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Hi

As an acoustician I am tired to tell people not to think room treatment only as absorption. In most small rooms absorption often creates more issues than it solves. Diffusion is a better solution. However, all I hear: they are expensive, ugly and difficult to place in a room. I am hence pleasantly surprised when I stumbled upon these on Etsy!


Not all are done correctly but nevertheless any similarly constructed panel will diffuse the sound in a room. They are a much better choice than foam panels to stop a reflection from a wall -- much, much better. Taste is personal but there are so many to choose from that finding one to your taste shouldn't be a problem. They are not unaffordable either.

Absorbers work on reducing the reverberations. Reverberations increase sound in a room and makes the sound bright. Due to the limitations of the materials absorbers are ineffective at low frequencies. This makes the rooms to sound bass heavy, dull sounding, and not a nice place to listen music to. Diffusers on the other hand stops reflections by scattering the sound so that reflections occur at very high frequencies and hence at less amplitude. This makes the room to disappear (figurately speaking). Here is a good article about diffusers and DIY options. Here is another more technical one.

I hope you will try a diffuser on your room when you need acoustic treatment. If you are already using one I love to hear from you. If I can be of any help do please ask.

All the best
 
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sarumbear

sarumbear

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I couldn't resist to post this example. :cool:

il_1140xN.2338001542_1qi1.jpg
 

Hipper

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They all look very pretty. What do they actually do, exactly. In other words, where are the measurements?

I know that GIK quadratic diffusors cover a range 650-3,000 Hz. Not bass.

I tried a couple of those GIK diffusors and I could hear them. They were too close. I presume distance from the listener will depend on the frequencies it alters.


These days I don't use diffusors, just copious amounts of absorbers, mostly bass traps but also other thinner panels to deal with reflections. I add to that some EQ. I like the sound but at around 200ms decay times over most of the spectrum it may sound a bit dry to some.

My suggestion is to try them but make sure you can return them if not liked. Or just buy them as a work of art if you like that.
 

puppet

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3D art as diffusers. Your second post got me wondering how hard it would be to have the blocks actuated to dial in a specific response. Some day I suppose. Does anybody offer an absorbent panel with adjustable wood slats mounted in front (like vertical blinds) yet?
 
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sarumbear

sarumbear

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They all look very pretty. What do they actually do, exactly. In other words, where are the measurements?
It’s difficult to define/specify a diffuser as it alters reverberation in the room, hence results are room dependant. Similar to the bass traps you use, which are similarly difficult to define them with a generic response.

Having said that diffusers and their effectiveness are properly researched subjects. This is a seminal paper, which has recently been updated by the authors. Here is some background on the subject with test results.
 

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sarumbear

sarumbear

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3D art as diffusers. Your second post got me wondering how hard it would be to have the blocks actuated to dial in a specific response. Some day I suppose. Does anybody offer an absorbent panel with adjustable wood slats mounted in front (like vertical blinds) yet?
The length of the blocks and their scatter is defined by a formula depending on the diffuser type. It is pretty complex subject but its wiki page gives a decent outline if you want to research further.

The great thing is there’s no bad diffuser, just a not very effective one, and diffusion is never a bad thing unlike absorption.
 

DJBonoBobo

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As an acoustician I am tired to tell people not to think room treatment only as absorption. In most small rooms absorption often creates more issues than it solves. Diffusion is a better solution.

The great thing is there’s no bad diffuser, just a not very effective one, and diffusion is never a bad thing unlike absorption.

I have no technical expertise myself and get irritated quickly. On the one hand, I've been dealing with the optimization of my room for a long time (two examples of my "quest" for better room acoustics: 1 and 2), but I'm increasingly frustrated that I can't find any consistent guides.

As far as I know, there are no reliable measurements or tests anywhere on room acoustic measures, and if you buy something yourself, you actually have to decide beforehand and only know at the very end - after you have spent hundreds or thousands and assembled everything, whether the effect has occurred as desired.

Even if you hire a professional, you don't know what you're going to get - at least I've heard various rather dissatisfied testimonials. You certainly can't generalize all that, but it seems to me to be very difficult to really get a good picture yourself of what measures are really useful and which are not.

The discussion of what to do with reflections from the side walls alone is already completely opaque, since there are renowned experts for all variants who argue convincingly in favor of one or the other measure (diffuse, absorb, reflect).

My state of knowledge so far was that especially in small rooms absorbers should be preferred (as broadband as possible) and diffusers do not work or are even harmful. You now write the opposite.

As I said, I know nothing better but certainly much worse than you. But you make it sound as if the use of diffusers in small rooms is relatively clear and unambiguous - is that so?
 
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sarumbear

sarumbear

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As far as I know, there are no reliable measurements or tests anywhere on room acoustic measures
Just read your sentence: it’s your own room. Not other one of the same exists. It is bespoke to you. How do you expect that there will be a measurement of it anywhere?

Even if you hire a professional, you don't know what you're going to get - at least I've heard various rather dissatisfied testimonials. You certainly can't generalize all that, but it seems to me to be very difficult to really get a good picture yourself of what measures are really useful and which are not.
That is true but then again how is it different to hiring a caterer for your party and be dissatisfied? Like with choosing any professional, communication is the key. If you communicate what you want and you are both satisfied that each of you understood what to expect, before starting the job, the results should be better than what you had before.

The discussion of what to do with reflections from the side walls alone is already completely opaque, since there are renowned experts for all variants who argue convincingly in favor of one or the other measure (diffuse, absorb, reflect).
When it comes to acoustics the only experts are the ones who studied the subject. An EE, an audio equipment designer, a Hi-Fi guru are not experts. Acoustics is as different to audio as dentistry to a brain surgeon. Both treat your head but neither is an expert in other’s field. Who are those experts you refer to?

My state of knowledge so far was that especially in small rooms absorbers should be preferred (as broadband as possible) and diffusers do not work or are even harmful. You now write the opposite.
Yes I do because they are.

You admit that you are not acoustician. I started my post that I am. I went to school for two years to receive a masters degree. The school was part of an architecture college. (I also have degrees in EE but they are not relevant.)

As I said, I know nothing better but certainly much worse than you. But you make it sound as if the use of diffusers in small rooms is relatively clear and unambiguous - is that so?
Yes, I make it sound like that because I know.
 
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hex168

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Do these look useful? Bill Waslo generally knows what he's doing, but as far as I know, not an acoustician either.

I think they would look good in Calder colors, but that would depend on one's room.
 
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sarumbear

sarumbear

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Do these look useful? Bill Waslo generally knows what he's doing, but as far as I know, not an acoustician either.

I think they would look good in Calder colors, but that would depend on one's room.
A diffuser’s elements are sized according to a formula. You choose the diffuser type (different type’s response are similar, unlike absorbers) and apply the formula as per the lowest frequency you want the diffuser to be effective. Most diffusers are wood, hence basic carpentry skills and basic understanding of math is enough to build one.

There are umpteen sources on the internet for the formulas. However, as I said, a basic understanding of math is needed. I recall seeing some sources that has tables (like the log tables of the past) where block sizes are pre-calculated.

Or, you can buy one. Almost all acoustic treatment shops sell diffusers.

Edit: I found some sources, which may help: A book on DIY diffusers, a calculator to calculate the blocks, and a post about building them?
 
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DJBonoBobo

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You admit that you are not acoustician. I started my post that I am.
It probably got lost in translation, but I didn't mean to question that you have more knowledge than I do. Actually, my point was to learn more about it, because you wrote you are an acoustician.
Unfortunately, with what I've read, it's hard for me to see what background the relevant people have that I perceived as experts.

Ultimately, I think it's a shame that there is a lot of conflicting information and it's difficult for someone like me to get things "right". But of course that's not directed at you, I was just using your thread as an opportunity to express that. Sorry for that.
 

MAB

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Thanks for this helpful thread. The calculator link is super useful, I was going to go off and randomly build diffusers with my usual variable results. Per your advice, any diffuser is likely better than no diffuser but now I feel informed and motivated. I just need to figure out a dusting protocol...

I'm loving this in soft amber lighting, with the quartz bulbs overhead.
1667930840103.png

I promise you, whatever I end up doing it will not be this awesome!
 
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sarumbear

sarumbear

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It probably got lost in translation, but I didn't mean to question that you have more knowledge than I do. Actually, my point was to learn more about it, because you wrote you are an acoustician.
Unfortunately, with what I've read, it's hard for me to see what background the relevant people have that I perceived as experts.

Ultimately, I think it's a shame that there is a lot of conflicting information and it's difficult for someone like me to get things "right". But of course that's not directed at you, I was just using your thread as an opportunity to express that. Sorry for that.
No need to apologise. I was simply explaining the situation. I was not offended.

The about page of each profile here helps to understand what background the posters has. Not everyone use it but I believe it is important to publish information about your background to substantiate what you say.
 

kemmler3D

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It probably got lost in translation, but I didn't mean to question that you have more knowledge than I do. Actually, my point was to learn more about it, because you wrote you are an acoustician.
Unfortunately, with what I've read, it's hard for me to see what background the relevant people have that I perceived as experts.

Ultimately, I think it's a shame that there is a lot of conflicting information and it's difficult for someone like me to get things "right". But of course that's not directed at you, I was just using your thread as an opportunity to express that. Sorry for that.

One of the sources of conflicting or misinformation on acoustics is the 99 million home studio types who post about acoustics on forums, youtube, instructables, etc. The concepts aren't that intuitive (I am still learning, and I sold acoustic foam for a living for a while) but they FEEL very intuitive at first, so you get a lot of statements of common sense repeated that aren't right, or are only right in specific situations.

Rule of thumb, anyone who tells you you just need thicker foam to control bass doesn't know what they're talking about. ;)
 
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sarumbear

sarumbear

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Ultimately, I think it's a shame that there is a lot of conflicting information and it's difficult for someone like me to get things "right".
Such an apt observation especially being said on this very day…
 

kemmler3D

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@sarumbear a question for the learned while we are here - building diffusors out of wood makes for an attractive product. However, they end up being very heavy, expensive, and probably time-consuming to make. Is the solid mass of the wood necessary to create reflections, or could you use a lighter / thinner material?

I ask because it would be pretty much trivial to 3D print diffusor panels and paint them whatever color you want. Angled faces and other fancy features like that, likewise easy. But the mass would be much lower. A 20cm x 20cm panel might weigh 250g or something.
 
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sarumbear

sarumbear

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@sarumbear a question for the learned while we are here - building diffusors out of wood makes for an attractive product. However, they end up being very heavy, expensive, and probably time-consuming to make. Is the solid mass of the wood necessary to create reflections, or could you use a lighter / thinner material?
The thinness of the material is not important as long as it is rigid.

I ask because it would be pretty much trivial to 3D print diffusor panels and paint them whatever color you want. Angled faces and other fancy features like that, likewise easy. But the mass would be much lower. A 20cm x 20cm panel might weigh 250g or something.
The area of the diffuser vs the room volume is an issue. If you can 3D print panels at sizes over 1m then it’s a good option. I have no idea about the process though, hence can’t comment further.

According to a seller on Etsy who sells a pair of panels, covering an area of 108cm x 61cm and 15cm deep weighs 27kg. Do you think that is very heavy?
 
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sarumbear

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I tried a couple of those GIK diffusors and I could hear them. They were too close. I presume distance from the listener will depend on the frequencies it alters.
Can you explain what you meant by "I could hear them". What was it that you are hearing compared to the bare wall?
 
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