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R/E/P => R/E/P Archives => Acoustics in Motion => Topic started by: Constantin on July 26, 2009, 02:52:22 PM

Title: Skyline Diffusor : avoid repeating pattern
Post by: Constantin on July 26, 2009, 02:52:22 PM

Hi

Just a quick question.
When i build a skyline diffusor, and i want avoid a repeating pattern:
Does turning the sequenze 90 degrees cancel this problem?

cheers
Constantin

Title: Re: Skyline Diffusor : avoid repeating pattern
Post by: AndreasN on July 27, 2009, 06:47:41 AM

Having them side by side gives the benefit of a continous pattern. Flipping it 90' will give the effect of two different diffusers, which gives poor response for the waves that overlap both diffusers as they hit the array. If you want to avoid repetition issues, try using a barker code with the 1's being represented by normal diffusers and the -1's being represented by inverted diffusers. The pattern for the inverted one can be found by taking the prime number minus each number in the sequence.

Title: Re: Skyline Diffusor : avoid repeating pattern
Post by: Thomas Jouanjean on July 27, 2009, 04:08:15 PM

This all comes down to how your original pattern is designed / behaving. Do what the numbers tell you to do.

Title: Re: Skyline Diffusor : avoid repeating pattern
Post by: Constantin on July 31, 2009, 06:41:45 AM

Thanks for your replys  
The reason for this question was just that i was wondering if this is simple way to array some diffusors.
OK.... It`s not hat simple  

Do anybody tested to array different seqences.
1 QRD next to it a PRD and so on????

I read alot about diffusion the last weeks , but until know i still can`t visualize in my brain what realy happens, so i have learn more.


Can somebody give me a tip for a good book about diffusion??

German books are welcome    i still have some problems with technical english  

cheers
Constantin

Title: Re: Skyline Diffusor : avoid repeating pattern
Post by: AndreasN on July 31, 2009, 10:32:59 AM

Constantin wrote on Fri, 31 July 2009 12:41

Do anybody tested to array different seqences. 1 QRD next to it a PRD and so on????

The usual way with QRD's is to use something like the barker code and use a normal diffuser for one of the states and an inverted or different sequence for the other state.

PRD's can be built to arbitary sizes. Have you considered making a single large unit instead of repeating a smaller pattern?

Title: Re: Skyline Diffusor : avoid repeating pattern
Post by: Constantin on July 31, 2009, 04:11:28 PM

Hi andereas, and thanks again  

Quote:

Have you considered making a single large unit instead of repeating a smaller pattern?

It´s not the reason that i want to build something, it`s just the reason that i want to understand it.
I don`t ask for a practical use, just for physical fakts.

It`s just a hobby for me to understand as much about acoustics as possible.
and for the next weeks i want to learn about diffusion.

I would never build a array like i asked for, it`s just interessting to know what happens

cheers
constantin

Title: Re: Skyline Diffusor : avoid repeating pattern
Post by: AndreasN on August 03, 2009, 10:45:12 AM

Hi!

The Book on the subject is: http://www.rpginc.com/book/index.htm - should be enough for most any question on the topic.

Some math and physics helps too. Hot topics: huygens constructs, fraunhofer diffraction, maximum length sequence, quadratic residue, primitive root, RSA enctryption.

That should get you started!


Regards,

Andreas Nordenstam

Title: Re: Skyline Diffusor : avoid repeating pattern
Post by: maarvold on September 14, 2009, 02:14:16 PM

Since I own a bunch of Skyline panels, I emailed RPG about this a couple of weeks ago.  FWIW, I rotated the pattern when I put mine up (several years ago), as that was the best info I had at the time.  But RPG's current advice is:
Do not rotate the pattern.