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Author Topic: Real diffusion possible on low ceiling?  (Read 7363 times)

mmazurek

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Real diffusion possible on low ceiling?
« on: February 29, 2008, 08:14:05 pm »

Is actual diffusion (other than just 'random bouncing of sound') possible on a lower ceiling height (around 7'2" finished)?


I'm obviously looking at getting rid of flutter, but am looking for the best possible solution to this impediment.  Making the ceiling 'dead' or 'pretty dead' seems like it will also make the room more boring.

For isolation purposes (to and from above), the finished ceiling will be 2 layers of 5/8" sheetrock/green glue between, most likely suspended from Isomax clips.


Are these Hemifusor/Space Array types of diffusors a recommendation for this type of duty?  Them being 3 or 4" deep seem very appealing for this.

Other ideas?  Or maybe ideas for two different treatments in two different rooms with this same issue?
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Steve Hudson

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Re: Real diffusion possible on low ceiling?
« Reply #1 on: March 01, 2008, 02:06:58 pm »

In my experience, diffusion works best when the diffusor is at least ten feet from the listening position. For a low ceiling, absorption is probably best as it acts as if it extends the height of the ceiling.
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Greg Reierson

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Re: Real diffusion possible on low ceiling?
« Reply #2 on: March 01, 2008, 02:45:40 pm »

You can also use reflectors on the ceiling to bounce sound towards the back of the room. That will maintain a live surface but keep early reflections from hitting the listening position.


GR
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mmazurek

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Re: Real diffusion possible on low ceiling?
« Reply #3 on: March 01, 2008, 06:23:10 pm »

I'm sorry I wasn't more specific.

This will be in the rooms, not the control room.


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Ethan Winer

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Re: Real diffusion possible on low ceiling?
« Reply #4 on: March 02, 2008, 12:19:39 pm »

mmazurek wrote on Fri, 29 February 2008 20:14

Making the ceiling 'dead' or 'pretty dead' seems like it will also make the room more boring.

Better boring than hollow, boxy, and phasey. Very Happy

--Ethan

maarvold

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Re: Real diffusion possible on low ceiling?
« Reply #5 on: March 11, 2008, 05:56:27 pm »

My mentor, who has been recording orchestras since the late 60's, feels that it is generally best to not remove energy from the room, so he would prefer diffusion to absorption.  He also does not like cylindrical diffusors--he says, "they scatter too much".  And I saw a studio reworking where they made the room somewhat more controlled and also put half-round cylindrical diffusers on the [high] ceiling and I felt the room unquestionably lost some magic.  
Having said all that, he's used to working in big spaces.  To me (who works more in medium-sized and smaller rooms), I don't like rooms that are too 'dead' because they seem compressed and lifeless.  But I also don't like rooms where--if you record multiple passes, or multiple instruments in the same space (but at different times)--you hear the sonic signature of that space becoming more and more obvious as it becomes part of the recording 2, 3 and even more times.  

In my mix room I have an 'acoustic cloud' of 4 RPG Skyline diffusers around 28" above my head and that works great: I don't feel like I hear the ceiling, even though it's only around 7 1/2 feet high.  But some people say if you get too close to diffusers, things start to sound 'phasey'.  So part of the answer is probably in what you want to record in the room.  I like Skylines a lot.  Yes, I know they're expensive, but there is no easy way to build them yourself, I have 12 in total and I'd be really bummed if they were removed from the room.  
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Michael Aarvold
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mmazurek

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Re: Real diffusion possible on low ceiling?
« Reply #6 on: March 11, 2008, 06:11:46 pm »

I understand the 'room buildup' with layering tracks.

I'll be working with three different sized/shaped rooms, so hopefully I can mix it up a bit.

The two main rooms will have about 7'2" finished heights.
The third will have varying heights due to enclosed pipes/HVAC.

Maybe one with 2" 703 hung 2" down (6'10" to the 703), and maybe I'll experiment with the other a bit.

I've got 4 RPG Skylines in the rear of my control room to experiment with.  Maybe I'll also get 3-6 quadratic diffusors to play with and use them on walls if a ceiling doesn't give the desired effect.

Thanks for all the insight.
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gullfo

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Re: Real diffusion possible on low ceiling?
« Reply #7 on: March 12, 2008, 12:49:56 pm »

i think you'll find a difference between skyline and QRD type products in terms of how close you can get before you are affected by diffusion/specular effects (which are different than simply a flat wall would produce). in addition, the incident angle plays a role in skyline vs QRD lobing so it would be useful to look at the specs on each product to determine where it could be effective or problematic. for a skyline, there are no wells so it's effectively omnidirectional and has slightly lower efficiency over a broader range (which would appear smoother in a smaller space). the QRD tends to be more effective on certain frequencies which can produce  a lobing which would be less desirable on a low ceiling as opposed to placing it further away (like on the back wall).
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Glenn Stanton

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mmazurek

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Re: Real diffusion possible on low ceiling?
« Reply #8 on: March 13, 2008, 05:50:35 pm »

So should I only look at Skylines?

Or are you just mentioning the differences between them and the QRD style diffusors?

I only considered the QRD style for ceiling use because of the lower profile (4" depth).  RPG's are more like 6" deep, which wouldn't work on my ceilings.

I'm trying to get one room a nice diffused sound, one more lively, and one more dead(ly).
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gullfo

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Re: Real diffusion possible on low ceiling?
« Reply #9 on: March 14, 2008, 03:47:32 pm »

i think the QRD may not give the evenness that you would like, in a close proximity... maybe something like a space array or omnifuser is more suited to you needs.

http://www.auralex.com/partscience/spacearray.asp
http://www.rpginc.com/products/omniffusor/index.htm
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Glenn Stanton

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mmazurek

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Re: Real diffusion possible on low ceiling?
« Reply #10 on: March 14, 2008, 09:14:32 pm »

Yeah, that might be the ticket.

It looks like I can put em up easily, and 're-install' elsewhere if need be.

Maybe have a 4'x4' 703 cloud area and a 4'x4' Space Aray area in a different spot in the room.  Like I said before, I can always take em down and put em on a wall if it doesn't work well.

Thanks Gullfo for all the help and follow-up.
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