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Acoustics: Sept. 2010 issue of S&V

Discussion in 'Acoustics' started by TitaniumTroy, Sep 2, 2010.

  1. TitaniumTroy

    TitaniumTroy Well-Known Member

    Surprisingly this issue has an article on acoustics, most of it ref. a book by Dr. Floyd Toole: Sound Reproduction published two yrs ago. The things that stood out to me were, 8" depth for QRD/math based diffusors. 12" depth for geometrical shaped diffusors, reason being to be able to diffuse down to the 100-1,000 hz level. Wow that seems to me to be some deep diffusors, also he likes them on side walls and placed near the surround speakers.

    Their is even a DIY diffusor and absorption panel, the diffusor is a 4' long triangle shape, but it mentions you could use a sonotube cut in half.
    FYI Dr. Toole is was a member of the Canada's National Research Council for 25yrs and director of R&D at Harmon Int. (home of Revel, JBL, Lexicon, Infinity, etc...). A big chunk of his research went into a set of guidelines/handbood for Consumer Electronics Assc. and the Custom Electronics Design and Installation Assc. (CEDIA).

    I hope some of other members check this article out, and post their feedback. Hard to imagine that S&V even had this article in their as they seem to ignore the subject 99% of the time. :text-nocomment:
     
  2. Flint

    Flint "Do you know who I am?" Superstar

    If you recall, my diffusors are at least that deep and also placed in the rear of the room near my surround speakers:

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  3. Flint

    Flint "Do you know who I am?" Superstar

    But, my diffusors went a step further as I made them with open backs and filled the internal cavity with OC703 absorption material. I then mounted them with a gap between the wall and the diffusor so sound could wrap around the panels and be absorbed in the fiberglass. The result was mid-bass traps around the room which significantly tightened up the bass/midbass.

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  4. Flint

    Flint "Do you know who I am?" Superstar

  5. Flint

    Flint "Do you know who I am?" Superstar

    So, diffusors around the rear of the room are almost always a good thing, but they have to be rather large to be truly effective.
     
  6. Botch

    Botch I.Y.A.A.Y.A.S! Superstar

    Flint, am I understanding correctly? The curved front is actually hard-surface plywood, painted and not covered with a fabric or anything.

    Oh, "diffusers", I think I just answered my own question... :oops:
     
  7. TitaniumTroy

    TitaniumTroy Well-Known Member

    Flint, can the Auralex T-Fusor's be made into spaced diffusor's? Thanks for the pics, I forgot your diffusors had that much depth.
     
  8. Flint

    Flint "Do you know who I am?" Superstar

    By "spaced diffusors" I assume you mean somewhat absorptive in the bass?

    You can, but they are kinda small for that and it could take more work than it is worth.

    That said, I used T-Fusors on the ceiling of the drum/recording room and I filled each one with loose bat-style fiberglass. This lowers the effective diffusion frequency and adds a small amount of bass trapping. I also used silicon caulk around the edge of the T-Fusor to help it stay up and to reduce rattles.

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  9. Flint

    Flint "Do you know who I am?" Superstar

    Diffusors reflect darn near 100% of the sound, they just diffuse the reflections rather than just reflecting like a mirror.
     
  10. TitaniumTroy

    TitaniumTroy Well-Known Member

    Flint, what are the two triangle shaped, wood objects on your ceiling?
     
  11. Flint

    Flint "Do you know who I am?" Superstar

    Angled reflectors... I placed them above the location where I would place stereo overhead mics on the drumset to reflect all sound over 600Hz to the side. I also filled those with fiberglass to dampen them.

    Angled reflectors can be a great way to solve reflection issues in a HT, but they need to be symmetrically placed, aimed perfectly, and require the listening position to never change. I once designed and installed a mastering suite based on hundreds of perfectly placed angled reflectors, but it was costly, complex, and required only one chance to get it right.
     

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