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Today I want to discuss the qrd diffuser measurements from our DIY build plans as its a question that crops up quite frequently and one I was asked in last weeks Google Hangout. Different regions of the world have different thicknesses that they offer to customers. It’s different in North America versus Europe although it’s a lot closer in Europe than it is in most other parts of the world. In the DIY drawings you are seeing the very first prototype measurements and how we’ve refined them. We put them in the plans because we wanted you to see the processes that are involved in building a diffuser because it’s an undertaking and it’s a heavy unit and you have to see that.

Now are a lot of those dimensions and methods that they used building the first prototype the same as it is now? No, because we’ve refined it, we’ve made it easier and we’ve learned so we’ve passed all of that unto you. So when you’re working with the products and we give you a thickness to use, that’s a thickness that we think everybody, can get in most parts of the world.

DIY QD 13 Kit measurements

If it’s a minimum thickness for a product, we’ll specify that to you but as a general rule when you’re dealing with diffusion, the vertical well that divides the trough, when sound energy strikes that divider, if it’s wide, there’s more surface area for a reflection to occur so then we have diffused sound and reflected sound. So we have reflections intermixed with diffusion which is kind of the definition of diffusion but you want to be careful about creating too many reflections that could interfere. So you want to keep your thickness of your wells as thin as possible.

DIY QD 11 Kit measurements

An eighth inch is the best. We use a quarter inch in our drawings because as an eighth inch is very difficult to get and very expensive. It requires a special machine that takes a thicker piece and makes it thinner; see it’s a plainer. So it takes one dimension and then you waste all the other wood, it’s gone. So we use quarter inch because that’s a thickness that most regions of the world have and it’s readily available.

DIY QD 7 Kit measurements

Now, if you don’t have that and 3/8’s is all you have, then you have to plain it down to one-half or at one quarter because 3/8 inch well dividers, not acceptable. Quarter inch is pushing it, eighth inch is even better if you’re in a place where you can get that done rather cheaply. In the United States, North America, it’s very expensive. It’s a piece of quarter inch of the same wood and same surface area might be $20, quarter inch, it could be 200 eighth inch, so you see the difference in cost.

It could be 10, 15, 20 to one of the price because of the labor and the machinery they need to get that wood that thin. And then you have to be so careful with it because it’ll just crack. So you spend all this money and you’re installing it in your diffuser and your elbow slips, it’ll break right off. We’ve done it. It’s like balsa wood and there goes $25. Then you have to glue it back together and that’s not good because it’s a eighth inch so you don’t have anything to work with. So you’re really on a slippery slope here.

Stay with quarter inch. It’s got to be a quarter because that’s the max, because eighth inch is the best. So we’re already compromising and we can’t compromise anymore.

In Summary

You can see all our DIY sound diffuser kits and build plans if you click here. If you want to learn more about this subject please sign up for our free room acoustic treatment videos and ebook which provide step by step instructions on all major room acoustic issues. Get instant access by signing up now. If you would like your room acoustic issues analysed for free by me then please fill in the form here and I will be happy to take a look for you.


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.

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