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The Sound Diffuser material options I recommend

Dennis Foley August 18, 2014 4 Comments

Last week I was asked what sound diffuser material option I would recommend, what the sound difference between wood and plastic would be and whether you could ever use cardboard or foam. Well first off, the use of foam as a sound diffuser is nothing more than manufacturing hype and misspeak in order to promote a product or technology that says sound absorption is sound diffusion. It is not.

So if you’re not aware of the differences in those technologies and you purchased a so called foam diffuser product and got it installed in your room, you’ll realize that the terms are misused. It makes me sick to see that because companies take advantage of the ignorance of people and market these things and put names on them just because that’s what people search for. So do some research and if you have any doubts pick up the phone and call me. I’ll always tell you what it’s supposed to be and I don’t really care what other manufacturers claim in order to purely hawk product.

Sound takes on the characteristic of the surface it strikes

It’s going to sound a little bit weird but bear with me here but sounds takes on the characteristics of the surfaces that it strikes. As a good example, sit in your car in your driveway and shut the engine off and leave your stereo on. Listen to that sound, that’s glass sound. Most of the surfaces in your car are glass so you’re going to get a really good idea of what glass sound is. If you have a tone control, turn the turbo all the way up, maximize the treble and really listen to the reflections in your car. You won’t be able to stand it for too long nor should you.

So that’s an example of really nasty sound. That’s the sound that you’d never want. It’s the sound I hear immediately in a room even if you have only one window, I will hear it. It just jumps out at you when you understand what it really is like and hear it and understand it. So glass is a very bad example of a surface that we want to use for anything.

Foam is a sound absorption technology and not a sound diffuser material option

Foam is a sound absorption technology so not a sound diffuser and you would never make a diffuser out of foam. I don’t care what the literature says and I don’t care what other companies claim. Secondly, wood is a wonderful choice for diffusers. Why? You look at all the major studios if you look at all the rooms in the world that have a history of good recordings for voice and instruments, they have lots of wood.

Why? Because the natural materials on this planet produce the best sound and isn’t that something. All the materials that the Earth produces or that we produce from the Earth really makes the best sound, synthetics like plastics and stuff like that; glass, no good so use your natural materials. Wood in our opinion in terms of everything, cost, ease of manufacturing, ease of build and selection, there so many great woods to choose from.

That said, not all woods make for good diffusers for a variety of reasons, cost, ease of assembly, ease of manufacturing there’s some woods that you need special saws to even cut they’re so hard.

Soft woods are the best sound diffuser material option

So, your soft woods, as a general rule, work best for diffusion, here we go with that word best again, but I think in this case we can safely say that your softer woods are best because they’re the most economical. They have beautiful grain that’s easily stained and sealed, they’re readily available in all parts of the North America that I’m familiar with so it’s a good choice; alder, pine works well, it’s economical.

DIY Quadratic Diffuser Kits 7 11 and 13
The above shows a selection of the DIY sound diffuser kits we sell here.

We use a lot of cherry in some of our diffuser builds so your softer woods are good selections for diffusion because remember sound takes on the characteristics of the surface that it strikes. So if it strikes wood, you get a nice, smooth, warm, balanced tonal sound back into the room and that’s why I always tell people that a diffuser is a musical instrument because of that quality plus many others that it can do for you.

So if you really look at the instruments that we have at our disposal in terms of acoustical treatment, the diffuser is almost like a speaker because it has a sound quality of its own. It has a frequency response of its own, it has a place in the room it needs to be. So it’s got a lot of similarities to a speaker and I always jokingly but also seriously tell people that a diffuser is a musical instrument if properly placed and designed within a room.

New videos coming soon on diffusion

We’re going to be doing a series of videos with my friend Bruce who added diffusion to his front wall now he’s adding diffusion to the rear wall. Now he wants diffusion on his ceiling. He is so enthralled and impressed because his life has changed acoustically with the power of diffusion which happens with most people when they hear it.

99% of rooms have poor diffusion. Most of us out there, myself included up to 25 years ago, did not know the power of diffusion and I will tell you this, once you experience it, you will never go without it. Your acoustic life will be changed forever and you will never go back to just using just absorption, maybe for the low frequency cause that’s the only way we can do it but for middles and highs? Diffusion is just an incredibly powerful tool and unfortunately poor diffusion is one of the four major acoustical distortions we all have in our rooms.

Until you hear what it does and what it adds to the presentation, you’re really missing something and we’re trying to change that through these videos and through education and stuff like that because I’m almost getting to the point with all the designs we’ve been doing and customers I’ve been speaking with, and I never thought I would say this after 25 years, but I’m going to have to rank diffusion as almost equal in importance to low frequency pressure management in terms of its impact on the sound quality within your room.

Bruce has listened to music in some of the best rooms in the World

Now Bruce is no spring chicken when it comes to listening in incredible sounding rooms given his son is the head ballerina at the Bolshoi Russian Ballet Company Moscow. So he gets to travel around the world listening to some of the greatest rooms effectively and his feeling is that diffusion at home has been what’s he’s been missing his all life.

And that’s true for a lot of people as it’s everyone’s feeling and that’s what’s so disheartening in a way about it because all these years people have been missing it. People understand absorption, everybody understands that you can’t have glass, you have to cover windows and doors,etc, most people get that. Most people understand that the listening position and the speakers have to have certain space requirements between them. Most people understand that the room size matters to the sound quality so I think we’ve done a fair job of educating people on these minimum requirements that you have to have to achieve some type of sound quality.

But now it’s time to start really dialing in what your electronics and gear are capable of because the missing link in the whole chain is your room and I always tell people, and our studio is a prime example, our gear in the studio was bought at a garage sale that cost less than $500, it sounds almost like 500,000 on certain days and there’s that big of a gap.

Electronics and amplifies have come a long way

Our electronics and amplifiers have come so far that they’ve driven past the room acoustic treatment and we’re a little bit behind on all of that. The tools are good but we need to realize that it’s the room that’s really the element in this equation and when you treat a room for people that have not heard a correctly treated room, there’s just no substitute for the expression on their face, the words that come out of their mouth, the awakening if you will that they’ve had and I guarantee you, everyone that we’ve had in our studio that’s experienced a room properly set up with diffusion, every person that we’ve had in that room has contacted me regarding adding diffusion to the room, to their rooms so that will tell you right away how powerful it is.

It’s just an incredibly powerful technology. Just like managing the low frequency energy in your room and getting the bass to sound defined separated, that’s a great thing you’d know that immediately when you walk into a room and you hit the play button, you know how the room handles the low end immediately, you can tell. Well that same thing is necessary with diffusion and can be achieved with diffusion. And then you get the two together, you’re going to get as close to hearing your music and being in a room but not hearing a room.

In Summary

I hope this discussion on the sound diffusion material options that we recommend has helped. If you would like to learn more about room acoustics please sign up for my free videos and ebook by joining the mailing list here. I send room tuning tips and things for you to test in your room every Wednesday. They are easy to follow and will really help you enjoy more of your music.

Alternatively feel free to contact me directly at: 520 – 392 – 9486 MST or info@acousticfields.com. You can see more of my research and development story and why I started Acoustic Fields at: http://www.acousticfields.com/who-we-are/.

Thanks and speak soon

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Dennis Foley

I am an acoustic engineer with over 30 years’ experience in the business. My technology has been used in Electric Lady Land Studios, Sony Music of New York, Cello Music and Films founded by Mark Levinson, and Saltmines Studios in Mesa, Arizona, along with hundreds of others.Connect with me on Google+

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4 thoughts on “The Sound Diffuser material options I recommend

  1. this is incredible!!! would you have certain preferences that call for a skyline diffuser instead of this one, or is this the optimal diy design?

    • M, The word “Skyline” is a product name for a two dimensional diffuser. It was created By Peter D Antonio of RPG. Two dimensional diffusion and one dimensional diffusion each have their own distance requirements based upon room size/volume/usage. What application are you considering?

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