Diffuser Choice VS Room Size...?

  • Thread starter Thread starter miroslav
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miroslav

miroslav

Cosmic Cowboy
Getting ready to order materials for my DIY acoustic panels, but I also want to add some diffusers at least on my back wall.
While I do know the differences between the basic types of diffusers (QRD, Skyline, Fractal, etc), and how they work and how to determine which frequency range the will affect...I can't find any real info if there is a preference for one type or the other when used in a larger space....?

The most info I find about the size of the room relative to diffuser use, is that diffusers are not recommended for small rooms, where listening positions are going to end up too close to the diffusers, often resulting in skewed acoustics because the different frequencies don't have enough room to diffuse, so you can get comb filtering effects, etc.

OK...but there is never any mention that for a large room or given listening distance...that one type of diffuser is better over another.
So in my case, my front and back walls are about 25' apart...and my listening position will probably be around 6'-8' from the front wall (I still haven't placed my console or monitors in the room for exact distance).

I'm most likely going to go with the QRD diffusers...but I was curious if anyone know of specific info about diffuser selection relative to the room size?
Most of the info I found is about the frequencies affected depending on diffuser depth/design...on diffuser placement...and also on the type of dispersion (horizontal, vertical, 1D 2D..etc.)

I really do love "the look" of the fractal diffusers...but they appear to be much more involved to build. The QRD seem to be the easiest to build if you want a good sized diffuser that has very known/specific math and usage...with the skyline probably the simplest AFA materials and building process, but probably more time consuming if you want to build larger ones.
 
I've found some plans that combine fractal with QRD design...a kind of nested fractal within a QRD...which appear like they will work in most situations and room sizes...and they don't appear to be very complicated to build.

It's a simple formula for the initial panel, and then it's just a matter of repeating the panel, but altering the height/depth of each subsequent panel, which modulates the total combination of panels to avoid repetition of the overall pattern.

I guess they are no easier/harder to build than the typical QRD or Skyline-type...but I really do like the look of these fractal designs.

Sound Diffusers 101: Free Designs for DIY Diffuser Panels
 
I know someone that built some of those skyline panels. They end up being pretty darn heavy. I'm not sure it matters what you use, but I saw those fractal plans before and they looked like one of the easier ones to built, plus a lot of air inside them so not quite the amount of mass.

My own room is too small to worry about, so never made one, though.
 
spantini said:
Here's a room size calculator to determine coverage area with suggested panel sizes and quantities.
Only applies to rooms with ceiling heights of 13-ft or less.

Acoustical Room Coverage Calculator
Click to expand...

That's for absorption panels...it's doesn't involve diffusors.

Also...all those calculators grossly overestimate how much you need...because the calculation assumes an empty room, which it never is.
My large room when empty, had quite a lot of reverberation...so I was doing the same thing, calculating panels...then over the last week I started bringing my amps, drums, some rugs, etc...and the room now sounds almost like it doesn't need anything, though up on the high ceiling I can still hear some flutter.

You don't want to treat an empty room...you want to treat it when it has all the gear and furniture.
Anyway...according to that (and other similar) calculators...I would need over around 44 panels if I used 2" panels....because they figure on the percentage of footage you should cover...and that's the thing, once you bring in all your stuff, that number goes down.

With small rooms you have little choice but making them really dead...but the big problem with that is that very often the HF are attenuated too excessively compared to the low-mids and lows. People think it sounds good, because it's super dead...but the LF is still there, it's mostly the upper mids and highs that are gone, and people assume they have treated their room properly.
They should use more LF treatment, and less broadband....because the LF will also suck up the HF too, but it leans more toward treating the LF...allowing you to have a balance, because even with a dead room, you need to balance the treatment.

Anyway...I'm pretty set on what I plan to do...and will most likely put in less treatment than any calculator tells me to. :)
I can always add more. ;)
 
sasquatch said:
Wes Lachot Design Group || Recording Studio Design and Acoustic Consulting

g
Click to expand...

It's a nice plan, but like so many home/project studios, it's focusing on a smaller space...and the trap/diffuser setup is pretty much the default for that situation.
These plans are great for folks that don't want to put much thought into it...just follow the dots, paint by the numbers...etc.
I've got a bit of a different situation with the size of the room...my layout...the fact that it needs to be a great tracking and mixing space...etc...etc.

Like I said...I've got a working plan, I was just curious about diffusers, and which if any would work best in my situation...and I'm pretty settled on building some of the nested fractal/QRD type I mentioned earlier. They would be best for broadband diffusion, it appears...with less frequency-specific focus. IOW, I can build them on the shallow side, and they will still do a good job across a wide range.
Still not 100% sure if I want to add some diffusers on my front wall though...and if I might do something different there....?

Of course...I've got a lot of building to do! So that becomes the big variable...just how much I want to do. :D
 
For some reason or another I thought someone else started the thread...the link doesn't even make sense to me now.
You'll be looking into the room at console position if I recall.

g
 
sasquatch said:
For some reason or another I thought someone else started the thread...the link doesn't even make sense to me now.
You'll be looking into the room at console position if I recall.

g
Click to expand...

Don't feel bad...I've lost track of all the things that don't make sense to me now. :p

Not sure what you mean "looking into the room at console position"...?

Basically, the door into the studio faces the right side of my console position...which is orientated front/back on the short side of the room.
So when you are at the door...you are looking down the long right-to-left side of the room.

I don't think I ever posted the actual console/mix position layout in all my documentation in the other thread...though I've talked about it.
 
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