DIY Diffusors to the Max

[G. E.]

Originally Posted by G. E.

... This time I feel free to let the measurements "decide"...

The last diffusor has been "shipped" today for future testing.

[pathdoc]

GE, do you have plans or a cut list?
I'd like to build some of those.
How big is a single one? Hard to tell from photos.

[G. E.]

Originally Posted by pathdoc

GE, do you have plans or a cut list? ...

Feel free to use the Sketchup-Files inkluded in the ZIP below for these types of diffusors:

• A: 19x(12+3) 2D-PRD diffusor
• B: "BBC-style" 2D diffusor
• C: 17x14 2D-PRD diffusor
• D: N=7 inspired 1D QRD diffusor

[pathdoc]

Thanks, what format are those files in?

[G. E.]

Originally Posted by pathdoc

Thanks, what format are those files in?

... it's ".skp", Google Sketchup's file format.

[Salty James]

Lazarus, Come forth!

[ajbianco]

Originally Posted by G. E.

... it's ".skp", Google Sketchup's file format.

what software are you using to create those funky graphs?

[Parkhead]

Awesome thread!

[Kid_Fiction]

Bump!

How did they work out in the end? I'm thinking about building a couple of these...

[G. E.]

Originally Posted by ajbianco

what software are you using to create those funky graphs?

I'm guessing you mean the Burst Decay graphs done with ARTA - Audio Measurement and Analysis Software.

[GS797]

GE, any progress / news / results from your experiments?
- great job so far by the way, thanks for sharing.

[G. E.]

Originally Posted by GS797

... any progress / news / results from your experiments?...

I've used some of the diffusors (mobile BBC style & N7-inspred 1Ds) in project recording situations (living rooms, etc.) recently together with pouros absorbers to shape the acoustics...

Furthermore I tested the influence of loosely mounted diffusors in front of deep bass absorbers (see pic). At first sight there's no significant tradeoff in bass absorption of the deepest room modes which is good news if you want to reduce HF absorption.

[boggy]

Originally Posted by G. E.

I've used some of the diffusors (mobile BBC style & N7-inspred 1Ds) in project recording situations (living rooms, etc.) recently together with pouros absorbers to shape the acoustics...

Furthermore I tested the influence of loosely mounted diffusors in front of deep bass absorbers (see pic). At first sight there's no significant tradeoff in bass absorption of the deepest room modes which is good news if you want to reduce HF absorption.

Nice!
Which material is used for diffusors?

[G. E.]

Originally Posted by boggy

... Which material is used for diffusors?

They're made of poplar plywood (see build details for more information).

[boggy]

Originally Posted by G. E.

They're made of poplar plywood (see build details for more information).

Great, they aren't heavy too much but they are much heavier than polystyrene for sure.
I like wood!

[zgm6763]

I've been following this thread from the beginning and I'm suitably impressed. Any more testing or opinions based on application? Thanks for sharing the results of all your hard work, GE!

[G. E.]

Originally Posted by zgm6763

... Any more testing or opinions based on application? ...

For example: using some of my "N7"-diffusors never failed to reduce the peak of strong reflections coming from the back wall by ~10dB in the ETC.

[zgm6763]

Very wise the way you made your N7s so portable, easy to move around for testing. That was a real revelation for me. You can easily change the environment around while taking measurements. Very cool.

[localhost127]

Originally Posted by G. E.

For example: using some of my "N7"-diffusors never failed to reduce the peak of strong reflections coming from the back wall by ~10dB in the ETC.

appreciate the input as always, GE.

how many periods are you using of the N7s in your array? do you have a personal limit (to limit lobing) that you've found works best? are you using any inverse/modulation in your array? curious to know how that many periods of lower order (N7)s perform.

thank you!

[G. E.]

Originally Posted by localhost127

... how many periods are you using of the N7s in your array? do you have a personal limit (to limit lobing) that you've found works best? are you using any inverse/modulation in your array? curious to know how that many periods of lower order (N7)s perform. ...

Actually I'm curious myself as well about how multiple N7s (folded) turn out regarding the lobing in ARTA's directivity pattern test-setup. If there's a problem I'll try to overcome this by combining the 1D diffusors with a true 3x2 or 3x4 2D-PRD pattern...

[localhost127]

Originally Posted by G. E.

Actually I'm curious myself as well about how multiple N7s (folded) turn out regarding the lobing in ARTA's directivity pattern test-setup. If there's a problem I'll try to overcome this by combining the 1D diffusors with a true 3x2 or 3x4 2D-PRD pattern...

always looking forward to your findings, GE - thanks!

[string_waves]

very cool

[GS797]

@G.E, I read this thread front-to-back twice now.. and you're work is much appreciated!

- I was wondering if you had test data / graphs of the 1D N=7-inspired QRD's you made? (i didn't see them in this thread, and havent found a similar design + testdata elsewhere either).

- Dont the 'bent' slots form some sort of (resonating) chamber?

[G. E.]

Originally Posted by GS797

... I was wondering if you had test data / graphs of the 1D N=7-inspired QRD's you made?...

No (not yet).

Originally Posted by GS797

... Dont the 'bent' slots form some sort of (resonating) chamber?

For my understanding not because they're bent but for the same reason as every design with wells.