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Any advantage to putting clouds on an angle?
Old 10th January 2014
  #1
Here for the gear
Any advantage to putting clouds on an angle?

Hi All,
I'm in the process of (hopefully) finishing up my mix room. One of the last steps is to hang the clouds. I'm going to make four 6'x4'x4" panels with Owens Corning 703 and hang them 10" from the ceiling (to clear a pipe) + the 4" depth of the clouds.
Anyway, most pictures and studios I've seen either angle their ceiling absorption going up from the front wall or do that 'U' shape (like the top of an octagon)with the sides angling down; but I haven't found any information online to support these shapes.
Anyone have any advice on whether I should angle these clouds?

ROOM/BACKGROUND:
The mix position faces a 14.5' wall and the perpendicular wall goes back 9'10". The ceilings are about 12'. I've paneled up to 6'4" and now hear lots of reverb from above, which I'm hoping the clouds + the 4 new corner super chunks will help.
Old 10th January 2014
  #2
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Yes, the angle helps block more sound away from the listening position, sound wavelengths which travel like optical rays, 2khz and above mostly.
Old 10th January 2014
  #3
Here for the gear
Thanks for the reply Opus,
Shouldn't the fiberglass be absorbing those high frequencies too?
Or are you saying that the cloud doubles as wall treatment + ceiling treatment when it's angled?
Old 10th January 2014
  #4
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Yes it sort-of doubles as a wall treatment because stuff that reflects from a wall and also intersects the cloud will be absorbed.
Old 10th January 2014
  #5
Here for the gear
Treatment for secondary + reflections?

Because isn't your point that higher frequencies are more directional? If so, wouldn't the front wall not cause first reflections (because the tweeters are facing the other way)?

Thanks again
Old 10th January 2014
  #6
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That depends on the speakers actually. But the cloud itself is like a solid wall as far as 2khz and above soundwaves go. And the echo inside the room will be cut down by it (because it absorbs secondary reflections and more).
Old 10th January 2014
  #7
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Jens Eklund's Avatar
The only advantage (apart from possibly esthetic) of mounting an absorber (assuming broadband and not partially reflective) at an angel in the ceiling, is to gain depth behind the panel (and thus better low frequency performance) at one end, while keeping some ceiling height at the other end. If possible: Mount the panel with as much air gap behind as possible (or even better; fill the entire depth, or at least half of it, with wool of appropriate flow resistivity for the given depth), even if it does not result in an angel relative to opposite surface; again; assuming broadband absorption panel.

If reflective (at least for mid and high frequencies); we often need to angle panels, primarily to redirect early energy away from the sweet spot, but also on other areas simply to avoid annoying flutter echo that otherwise often becomes very audible in treated rooms.
Old 10th January 2014
  #8
Here for the gear
Well according to (this wonderful) man's site, http://www.bobgolds.com/AbsorptionCoefficients.htm, absoption coefficients for 4" of 703 (I'm doing 2 layers of 2") are:

500Hz=1.24
1000Hz=1.08
2000Hz=1.00
4000Hz=.97

SO there, at least theoretically, shouldn't be any reflectivity in the highs and mids. No?
Old 10th January 2014
  #9
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No, not without a hard surface covering. Jens is saying some clouds are built to reflect on the bottom side.
Old 11th January 2014
  #10
Gear Maniac
 

I was wondering the same thing. I mounted mine on a slight angle as I figured it couldn't hurt.
Old 11th January 2014
  #11
Here for the gear
Ok, so there is no absorptive advantage to angling if the cloud is open backed/unfaced, except the fact that you can cover some of the front wall (which I will do separately). Do we all agree on this? Anyone else?

I guess the wood frames will be reflective, but I'm assuming they do not have enough surface area to worry about.
Old 11th January 2014
  #12
Gear Guru
Nuance

The fabric covering and even the surface of fibre batts themselves have increasing reflectivity as the angle is diminished. Some GS have achieved useful reductions in the levels reflections within their listening zone by angling cloud and side reflection control panels. LEDE room with Haas trigger
DD
Old 12th January 2014
  #13
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Quote:
Originally Posted by onyx000000 View Post
Ok, so there is no absorptive advantage to angling if the cloud is open backed/unfaced, except the fact that you can cover some of the front wall (which I will do separately). Do we all agree on this? Anyone else?

I guess the wood frames will be reflective, but I'm assuming they do not have enough surface area to worry about.
Maybe you should detail your plans with a drawing
Old 12th January 2014
  #14
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Jens Eklund's Avatar
Quote:
Originally Posted by DanDan View Post
The fabric covering and even the surface of fibre batts themselves have increasing reflectivity as the angle is diminished. Some GS have achieved useful reductions in the levels reflections within their listening zone by angling cloud and side reflection control panels. LEDE room with Haas trigger
DD
It's when the incident angel increases that the reflectivity increases:
ISD gap for my room help pls!
But this effect is small for any but drastic incident angels thus not likely to make any notable difference for first order reflections when dealing with panels in the ceiling.
Old 12th January 2014
  #15
nms
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nms's Avatar
Quote:
Originally Posted by onyx000000 View Post
Ok, so there is no absorptive advantage to angling if the cloud is open backed/unfaced, except the fact that you can cover some of the front wall
As Jens said:
Quote:
Originally Posted by Jens Eklund View Post
to gain depth behind the panel (and thus better low frequency performance) at one end, while keeping some ceiling height at the other end.
Old 12th January 2014
  #16
Gear Guru
Relative

Fabrics reflect more and more as the frequency increases and as the angle gets closer to parallel. https://www.gearslutz.com/board/studi...ml#post7648969
As I remember it some GS, probably jim1961 or Nordenstam, posted showing early reflection levels dropping some 10dB from the -20's to the -30's, due to angling the traps.

DD
Old 12th January 2014
  #17
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Jens Eklund's Avatar
Quote:
Originally Posted by DanDan View Post
Sometimes I call angles that tend towards parallel, as opposed to perpendicular, low. Pedantically, and only if one deliberately includes the term incidence, high would be more correct.
www.gearslutz.com/board/7165515-post44.html
Old 12th January 2014
  #18
Gear Guru
An Expert

Russ Berger:-
Quote:
Myth No.4: Acoustically "transparent" materials

The sound-absorbing properties of standard building materials are often given as a noise-reduction coefficient (NRC) rating. Unfortunately, this standard measurement takes into account only speech frequencies and ignores the extremes of the audio spectrum. More important, it measures the absorption of a material or assembly in a test chamber with random incidence of sound on a relatively small sample.

In practice, absorptive materials are often place on walls where the sound is almost always at "grazing" incidence or nearly parallel to the surface. When you drop a rock into the water it sinks, but when you throw it parallel to the water, it will sometimes skip along the surface. Sound behaves in much the same way: many materials that appear "transparent" based on NRC ratings or porosity are actually highly reflective to sound at grazing incidence.
DD
Old 12th January 2014
  #19
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Jens Eklund's Avatar
And how is that quote arguing against what I've stated so far? It's exactly in line with what I've shown.

I was only making sure that we mean the same thing when discussing angles of incidence (since there's been some confusion in earlier threads and it's seems to continue unfortunately).
Old 13th January 2014
  #20
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Glenn Kuras's Avatar
I personally would not angle a cloud if broadband. You want as much of an air gap as you can afford or as Jens said cover the whole area. Not sure what all the other bickering is about.
Old 13th January 2014
  #21
Gear Guru
Devilish Details

Quote:
I personally would not angle a cloud if broadband. You want as much of an air gap as you can afford or as Jens said cover the whole area.
The angle can be seen to increase the air gap rather than diminish it, depends on whether you go up or down! I often wonder though. When there are say 2- 4 panels perhaps with gaps between them, at what point does increasing the air gap lose any benefit? The huge influence of the air gap as seen in suspended ceilings, depends on the whole boundary being covered and sealed. LF will simply pass by little islands of trapping.
Perhaps some cold January day in the cosy GIK test lab?

I don't often angle them either Glenn. But, I would and do consider it an option , especially if the side panels can be angled as well. An overall 'look', with an increase in air gap and that extra 10dB reduction in reflections. In direct answer to the OP, there are advantages.

DD
Old 13th January 2014
  #22
Gear Guru
 
Glenn Kuras's Avatar
Quote:
The angle can be seen to increase the air gap rather than diminish it, depends on whether you go up or down!
I guess if the ceiling is low (standing room) then I would agree.

Quote:
Perhaps some cold January day in the cosy GIK test lab?
Could try it with 2 panels and see. Might not be until Spring though. Way to much on my plate as of right now.
Old 13th January 2014
  #23
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GIK Acoustics's Avatar
 

Quote:
Originally Posted by DanDan View Post
When there are say 2- 4 panels perhaps with gaps between them, at what point does increasing the air gap lose any benefit? The huge influence of the air gap as seen in suspended ceilings, depends on the whole boundary being covered and sealed. LF will simply pass by little islands of trapping.
You would expect losses the same way you expect diffraction losses in any other situation. Adding multiple panels without spacing between them increases the size of the panel, thus dropping the frequency of possible diffraction. Keeping this in mind...you would then expect that increasing the air gap behind the panels will increase efficiency at lower frequencies until the diffraction cut off. If absorption is needed lower than that and can be achieved with spacing, the panel needs to be larger.
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