QRD build question

Bubbagump · 2nd April 2010

I can't seem to find this answered anywhere, but should there be any concern to the surface between periods in 1D designs? For instance, say I have 3 periods, does bare wall between periods matter? If I have a frame around an entire period (typical 1x4 perhaps) does the 3/4" width of the 1x4 on the edge effect things such that you would want to consider that part of the first 0 depth well? I can't find any consistency in designs as some seem to have fin width sides where as some of the designs in the diffuser sticky

http://www.gearslutz.com/board/2157031-post33.html
and
http://www.gearslutz.com/board/2844942-post36.html

have big fat edges.

Though, it looks like those may be offset by 1/2 a well such that when placed together you get a complete 0 depth well?

SAC · 2nd April 2010

In regards to the 1D diffusor, the 'edge' oriented along the diffusing plane is often designed and built to be a continuation of the diffusor. QRDude provides specifically for this option (thanks again to Bill!).

In theory, the boundary along the perpendicular plane should be a thin as possible from the acoustics perspective. The wider they are, the more reflective they are, and while the effect 'may' not be dramatic, depending on just how substantial they are, they nevertheless vary from the ideal and thus a small additional reflection that superposes with the soundfield exists.

That being said, "How much?" does it impact performance? One would need to measure. Thus the 'best practice' answer would be to incorporate the boundaries into the unit design itself (usually by shifting the sequence such that a zero depth well corresponds to a boundary and to minimize the thickness of the additional boundaries to the greatest degree possible. And as the 1D and 2D QRDs can be built with substantial rigidity and support included in the internal structure, a thick boundary is not really necessary.

2nd April 2010	#1
Bubbagump Gear addict Joined: Mar 2007 Location: Columbus, Ohio Posts: 445 Thread Starter	QRD build question I can't seem to find this answered anywhere, but should there be any concern to the surface between periods in 1D designs? For instance, say I have 3 periods, does bare wall between periods matter? If I have a frame around an entire period (typical 1x4 perhaps) does the 3/4" width of the 1x4 on the edge effect things such that you would want to consider that part of the first 0 depth well? I can't find any consistency in designs as some seem to have fin width sides where as some of the designs in the diffuser sticky http://www.gearslutz.com/board/2157031-post33.html and http://www.gearslutz.com/board/2844942-post36.html have big fat edges. Though, it looks like those may be offset by 1/2 a well such that when placed together you get a complete 0 depth well?

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2nd April 2010	#2
SAC Registered User Joined: Dec 2009 Posts: 2,622	In regards to the 1D diffusor, the 'edge' oriented along the diffusing plane is often designed and built to be a continuation of the diffusor. QRDude provides specifically for this option (thanks again to Bill!). In theory, the boundary along the perpendicular plane should be a thin as possible from the acoustics perspective. The wider they are, the more reflective they are, and while the effect 'may' not be dramatic, depending on just how substantial they are, they nevertheless vary from the ideal and thus a small additional reflection that superposes with the soundfield exists. That being said, "How much?" does it impact performance? One would need to measure. Thus the 'best practice' answer would be to incorporate the boundaries into the unit design itself (usually by shifting the sequence such that a zero depth well corresponds to a boundary and to minimize the thickness of the additional boundaries to the greatest degree possible. And as the 1D and 2D QRDs can be built with substantial rigidity and support included in the internal structure, a thick boundary is not really necessary.