How to Make a Super Simple Diffuser with Bass Trapping

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Homemade acoustic treatment is a rewarding way to save a few dollars and feel accomplished about your carpentry abilities.

Homemade absorbers are a popular DIY project for the home recording engineer. They’re fairly simple to make and really effective in the corner of your studio. Diffusers are more complex, but you can get away with a really simple design.

This weekend I created five 2×4 bass traps to go with my already purchased Auralex foam.

And man my studio sounds good.

How to Make the Panels?

I followed Jon Tidey’s instruction over at AudioGeekZine.com. He has a really good tutorial on how to make homemade absorption.

The only difference in my case was:

  • 4 inch Panels – I bought 3 4″ inch Owens Corning Fiberglass boards as well as 6  2″ Roxul Mineral Wool boards. I combined these to make 6 4 inch panels. The thicker the panel, the better the bass trapping. I wanted to control that low-end as much as possible.
  • Different Cloth – I didn’t use speaker cloth as Jon did, since it was too expensive. Rather, I found some cheap breathable fabric that I put on the first two traps. After I finished that I bought cheap black gauze for the rest. I would spend a little extra money next time to get fabric rather than the gauze. It rips easily so you have to be extra careful.
  • Diffusion – I made one of my panels into a simple diffuser that I placed at the back wall.

How to Make the Diffuser?

Many diffusers are simply panels with convex angles that direct sound in different directions. Other diffusers are more complex and involve complex mathematical ratios to help scatter and diffuse the sound most effectively.

I simply put a thin MDF board on top of one of my bass traps, put some leftover wood in the middle and angled it down on top of one of the bass traps. Here is the MDF panel with the wood stapled to it. The wood panel in the middle will act as the highest point on the diffuser so that when I push the ends down, the panel will end up in a convex shape.

homemade diffuser panel

After I laid the board on top of the bass trap I simply stapled it in place with a helpful serving from my staple gun. Then I finished it up with some black cloth to make it look better.

homemade diffuser for home studio

To attach it to the wall I nailed a picture frame hanger to the back and hung it on a nail on my back wall.

how to make diffusion acoustic treatment

Since this diffuser is actually a bass trap as well, it has the extra bonus of eating up the lower frequencies while diffusing the higher ones.

The MDF panel reflects the higher frequencies and the convex angle of the panel helps scatter them all around the room instead of having them bounce right back into my ears.

The lower frequencies won’t stop at a measly MDF panel but some of them will get absorbed by the fiberglass inside.

Is this one just as effective as a complex quadratic diffuser? Probably not, but it sure beats the bare wall behind it.

Bass Trapping and Acoustic Treatment 101

My room is sounding better than ever because of these traps. My old Roominator kits from Auralex are great, and I still use them, but the extra absorption and bass trapping I’m getting from these panels is making my room more balanced and my music clearer.

If you’re interested in learning more about acoustic treatment, whether it’s DIY or store-bought, check out www.UnderstandingYourRoom.com. I’ve been listening to that webinar while doing my studio remodel and the tips Joe and Gavin hand out have been invaluable to me.

Check it out here.

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  • Dave Chick

    I was JUST about to do something just like this for the backwall of my new space!  Cool!

    • http://audio-issues.com Björgvin Benediktsson

      Simple and easy Dave. If I can do, most probably can since I’m still surprised I didn’t amputate myself with the staple gun ;)

  • Mike

    Hi Bjorgvin,

     I enjoyed your DIY bass/diffusor article. I just wanted to add that the device attached to the face of the absorber is really termed a sound redirection device. It redirects the energy that strikes it in an opposite direction angle that matches its strike angle to the device.

    A true sound diffusor will spread out certain chosen frequency ranges in two dimensional space. You are correct, they are more difficult to build. The particular diffusion sequence one chooses is based on the room use, whether playback or monitoring, specific room boundary surface, and how far away from the diffusor the seated or monitoring chair is. True sound diffusion requires a certain amount of distance between the diffusor and the seat so that the diffused waveform has time to fully form. Diffusion adds depth to your sound stage in a way absorption can never accomplish. If you think your absorbers made your room sound better, you will enjoy diffusion. Diffusion will make your room sound larger.

    For your next absorber project, go to the U.S. Gypsum company and order their Thermafiber product for your cabinet fill. It is a steel slag product and we have had good results with it.

    Cheers.
    Mike
     

    • http://audio-issues.com Björgvin Benediktsson

      Yeah, it’s definitely now a real quadratic diffuser like I said, and there might be some ambiguity as to what is called a diffuser, but I’m going to take the liberty of using that word since it’s familiar to the community.

      Thanks for the tip Mike. I’ll keep that in mind.

  • Interface Audio Ogden

    A good friend & business partner & I will be, working setting up an LLC, moving my project studio from the house to a 1,500 sq ft commercial facility in the next couple months. this project will for sure be on my list of DIY acoustic treatment must haves. 

    • http://audio-issues.com Björgvin Benediktsson

      Good to know. It would probably be a great way to make a live room sound live and controlled.

  • http://twitter.com/Huacoustics Hyped Up Acoustics

    Great little project here, to add I think you would have got a lot more control of your bass frequencies by making the enclosure air tight. The open ends on your device reduces the “springy-ness” of the air behind the board which would have had a very effective dampening effect on low end frequencies. Sealing the edges with acoustic sealant and appropriately shaped wood would suffice. Otherwise the main benfit you get is the deflection of high end frequencies and absorption of medium frequencies absorbed by the rock wool. That said if t his has tamed  your bass then great!  Check out http://www.hypedupacoustics.co.uk for more useful tips