building diffusion on my back wall

[Glenn Kuras]

Sure you can make them small but why? I would think if you are going through all the hassle to build one it would be easier building it as one vs 4.

[tumdrum]

I can't find plans online for size only freq which is 2x2 online

[Rod Gervais]

Originally Posted by Glenn Kuras

Sure you can make them small but why? I would think if you are going through all the hassle to build one it would be easier building it as one vs 4.

Agreed it would probably be easier to build - but would be a PITA to build in place - and probably quite heavy/cumbersome to install once built....... (I am assuming he is referring to the BBC skyline diffusor)

Rod

[tumdrum]

Yes I am

[tumdrum]

Anyone know of any plans that would help me build it in one piece rather than 4?

[adrumdrum]

A wood prd diffusor("skyline") around 600X600mm weighs around 20 kg.
the most common lengths for D.I.Y is 0 (0 no piece of wood), 50mm(1), 100mm(2), 150mm(3), 200mm(4).
and 45X45mm wood(or 2"x2") and plywood grund plate.
I think diffusion range is 800-4 kHz (correct me if I'm wrong)

A Windows program to calculate PRD(or only use the drawing with the lengths I wrote):
http://www.mh-audio.nl/user/acoustic%20calculator.asp

or:
mh-audio.nl - Skyline
but I found an error, Frequency high is not Hz it should be kHz(for example 35 hz is 35 khz)

[tumdrum]

Gotta get my calculator out, I'm merican. Lol thanks

[localhost127]

Originally Posted by tumdrum

Yes I am

why build the BBC PRD when proper calculators exist of which you can tailor the design specs to your personal requirements??

the BBC PRD isn't even a true PRD - it's an array of many smaller PRDs (hence the 12x12 wells, of which do not adhere to the PRD rules).

Calculate a Two-Dimensional Primitive Root Diffuser
www.hxaudiolab.com
QRDude: Quadratic Residue Diffuser calculator

[localhost127]

Originally Posted by tumdrum

So my room is 20.5 ft long, 14ft wide, and 7.9 ft tall. I am building adequate bass traps for my room but I'm wanting to put diffusers in. I have seen many people have them on the back wall where the couch is. I'm considering the BBC diffuser for the back wall. Is it bad to make 4 2x2 panels and put them together to make one large panel? Any suggestions?

what is the purpose of the room?

do you explicitly need to disperse energy in vertical and horizontal planes?

[tumdrum]

It's a control room for mixing. This sounds like a stupid reason but, I figured dispersion on both planes would give me a better result than on 1 plane. No reason really, I just figured it would be more beneficial.

[localhost127]

Originally Posted by tumdrum

It's a control room for mixing. This sounds like a stupid reason but, I figured dispersion on both planes would give me a better result than on 1 plane. No reason really, I just figured it would be more beneficial.

are you emulating any particular response?
are you planning to attenuate high-gain early arriving indirect signals (reflections) and then presenting a later-arriving semi-diffused sound-field via the rear wall diffusers? if so, it is more appropriate to use 1dimenional diffusers with the wells oriented vertically such that the spatial dispersions take place in the horizontal plane (to induce lateral arriving returns). 2D diffusers are inherently more lossy and will disperse energy to the floor/ceiling of which is not entirely useful in such an application.

what is the distance from listening position to rear wall? it is best advised to allow 3x wavelength of the design frequency as minimum seating distance to the diffuser. eg, a QRD/PRD with a design frequency of 400hz (2.825ft) would require minimum seating distance of (3 * 2.825ft) = ~8.5ft ... which puts you in the "far-field" of the returns.

[tumdrum]

Approximately 12 ft in front of the diffuser.

[tumdrum]

But I will also have a couch about 6 in in front for clients to sit.

[tumdrum]

Is there a program you can enter frequency AND dimensions you want and it gives you plans on how to make it?