Quadratic Residue Diffuser Design Frequency , help

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Quadratic Residue Diffuser Design Frequency , help

Postby tecnogadget » Thu Nov 22, 2012 12:27 am

Hi! Im building a QR Difusser , im using the QRDude calculator , wich is a good software.
My concerns are about choosing the Design Frecuency. Im going to use it in my home cinema , and place it behind the seatings.

What should i care more about? Low vs High frequencies . For example:
A low frequency design like 400Hz with a HF cut off 1500Hz.
Or a higher frequency design like 1000Hz with a HF cut off 6500Hz
The problem is that to achieve a very high cut off , the Well Width should be narrow , and that makes it more difficult to build.

I currently have absorber acoustics panels with fiber glass and bass traps.
So.... Should i care about a low frequency Difusser design? Or a high frecuency one?
Or even a broadband design covering a wide range of Frequencies.
Thanks
tecnogadget
 
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Re: Quadratic Residue Diffuser Design Frequency , help

Postby bert stoltenborg » Sun Nov 25, 2012 5:44 pm

Is there a problem you have and want to cure with this contraption?
If you view life with the knowledge that there are no problems, only opportunities, you are a marketing manager.......this is my personal philosophy
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Re: Quadratic Residue Diffuser Design Frequency , help

Postby tecnogadget » Mon Nov 26, 2012 1:33 am

No there is no probem at all. I just want to improve the acoustics and responce of my music room with the adition of a Diffuser. It's all part of an auralization process. Audiophiles try to improve their listening experience all the time , pushing it as far as posible , thats our nature :)
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Re: Quadratic Residue Diffuser Design Frequency , help

Postby bert stoltenborg » Mon Nov 26, 2012 10:03 am

If you want to IMPROVE things I wonder if you want a schroedertype diffusor.
See what it does:
viewtopic.php?f=8&t=3831

In addition you could read what f.e. Floyd Toole says about using these things in smallish rooms.
If you view life with the knowledge that there are no problems, only opportunities, you are a marketing manager.......this is my personal philosophy
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Re: Quadratic Residue Diffuser Design Frequency , help

Postby tecnogadget » Mon Nov 26, 2012 5:03 pm

I think we are talking about the same thing , the QRD diffuser is built usign Schroeders' invention of number-theoretic its a Maximum Length Sequence Diffusor.
I just want to know how critical is the design frequency bandwith. Its a convenience thing. High , low , or broadband
I'll read your pdf , looks interesting
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Re: Quadratic Residue Diffuser Design Frequency , help

Postby bert stoltenborg » Mon Nov 26, 2012 5:14 pm

A MLS diffuser is something else.
http://en.wikipedia.org/wiki/Diffusion_%28acoustics%29

If you are serious about this, I have to answer there is maybe a pseudo-theoretical design frequency, but hardly a practical one.
As it is a kind of 1/4 wavelength device, 4 x the depth of all the wells,2 x the width of the wells and 2 x the heights of the wells will do some resonating.

And I'm not trying to be cynical.
If you view life with the knowledge that there are no problems, only opportunities, you are a marketing manager.......this is my personal philosophy
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