Space coupler simulation
PaulP
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#1
29th November 2009
Old 29th November 2009
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Space coupler simulation

------------------------------------------------------------------
EDIT : After having posted this I discovered that I was not using
the simulator properly (see
post #21), so the following images are
in error. There are some interesting comments in the thread though
so I won't delete it. When I get around to it I'll perform new tests
and post those.
-------------------------------------------------------------------

Like a few others around here I've been attracted to space couplers.
What's said about them seems to make some sort of sense and they look
good. So I put a mockup of one in the Ripple Tank Simulator to see
what would happen.

The biggest surprise is that the coupler acts like a solid wall at very low
frequencies. There seems to be a minumum frequency that will make its
way through the coupler. The depth of the cells has some effect, a very
shallow coupler offers less resistance to low frequencies than a deeper
one. I also think that the thickness of the divider walls is important to
some extent.

There has been mention of an AES paper on space couplers. If anyone
knows the wherabouts of an online copy or could send me one I'd be very
interested in reading about the math involved.

I offer the following as food for thought. I have no idea if any of it makes
sense or not...

-->
I figured I might as well delete the pictures that were here to save some
space and not lead anyone astray. I'll try to post some new images soon.
-->

Paul P
#2
29th November 2009
Old 29th November 2009
  #2
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DanDan's Avatar
Space Coupler

Hi Paul, you have probably seen this already. bigsoundsmallroom.pdf
I too am very curious about these devices. Unfortunately they are awaiting testing and the designer is no longer with the company, or vice versa.....
I am not familiar with that ripple tank. However, horse sense says that low frequencies will pass right through. Or Neigh?
Audio Engineering Society (AES) for White papers. I must take a look.
DD
PaulP
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#3
30th November 2009
Old 30th November 2009
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Quote:
Originally Posted by DanDan View Post
However, horse sense says that low frequencies will pass right through.
Tell that to the math running the simulator

If I make the cells really shallow, just a single dot in the simulator, low
frequencies do go through fairly easily.

Paul P
#4
30th November 2009
Old 30th November 2009
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Hi Paul!

Have a look at the 2D wave java applet: 2-D Wave Simulation - select multiple slits and adjust the parameters as suited. Think you'll find it to be more accurate than the one you've built in the ripple tank!
PaulP
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#5
30th November 2009
Old 30th November 2009
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Quote:
Originally Posted by Lupo View Post
Have a look at the 2D wave java applet: 2-D Wave Simulation - select multiple slits and adjust the parameters as suited
Another interesting simulation. But I think it's dealing with slits in thin
material and not fairly deep wells. It's with light so that maybe the largest
wavelength is still very small. Also the amount of stuff getting through
goes down as the frequency goes up, the opposite of the ripple tank.

If I draw very shallow cells in the ripple tank, 1 dot deep, bass goes
through easily, as do higher frequencies.

If the ripple tank is not in error then maybe there's some sort of
cushioning effect caused by the air (water ?) being pushed through tubes.
Speaking of water, perhaps the density of the medium has an effect,
something not addressed in the ripple tank.

Paul P
#6
30th November 2009
Old 30th November 2009
  #6
I've been looking at the idea since Aurelex came out with them as a way to keep a small space from sounding quite so small. I'm also looking for a cheaper solution. I just can't see paying that much for such a simple device. I understand from one article that it has a fire rating, which likely contributes to the price, but I still can't afford them, I would need about 100 of them, at least 50.

I can't see it having any effect, but I wonder if he shape of the holes is a factor also. I am thinking one could be easily made with 3" PVC pipe glued together in a square frame. One could also vary the depths of the holes and/or vary the hole size pretty easily too. The space between the pipes (since they're round and would have gaps where the "corners" would be) could be filled (or not) with fiberglass for a small amount of absorption.

I know there are quadratic calculators out there, I am wondering if there is simulation software or calculators for space couplers as well.

Scott

edit:
I seem to remember that some decades ago, some company made a microwave oven that had no glass, but only a metal screen. The claim was that the holes were of a size that the waves could not pass through. I don't know if that's just an old myth or if my memory is bad, but there may be some truth to it after all. I've always kind of wondered.
PaulP
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#7
30th November 2009
Old 30th November 2009
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Quote:
Originally Posted by plus6vu View Post
I can't see it having any effect, but I wonder if he shape of the holes is a factor also. I am thinking one could be easily made with 3" PVC pipe glued together in a square frame. One could also vary the depths of the holes and/or vary the hole size pretty easily too.
If something is possible, terry j has probably built a prototype :

Perhaps terry could tell us if this experiment has progressed.

Paul P
#8
30th November 2009
Old 30th November 2009
  #8
That's what I'm talking about. Terry, let us know how it works when you find out, eh?

Scott
#9
1st December 2009
Old 1st December 2009
  #9
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Quote:
Originally Posted by PaulP View Post
Another interesting simulation. But I think it's dealing with slits in thin
material and not fairly deep wells. It's with light so that maybe the largest
wavelength is still very small.
Correct! Not that much useful for us.

Light provides some striking examples of phase gratings, btw, with the coloured hue of CD's being perhaps the most known example.

Quote:
Originally Posted by PaulP View Post
Also the amount of stuff getting through
goes down as the frequency goes up, the opposite of the ripple tank.
That's why I thought it was more suitable, since that's the expected response.

There's a lot of things that doesn't work out quite as expected in these sims. If you know what to look for and get the desired results, fine! But I've grown weary of using the simulations to draw any conclusion regarding unexpected results..

Quote:
Originally Posted by PaulP View Post
If the ripple tank is not in error then maybe there's some sort of
cushioning effect caused by the air (water ?) being pushed through tubes.
Speaking of water, perhaps the density of the medium has an effect,
something not addressed in the ripple tank.
It's probably something about the density, yes!

Practically speaking, I would ignore the source side of the phase grating, concentrating solely on the output side of the grating.


Had a play and found pretty much the same as you. Not to overdo you or anything, but this picture may help illustrate why phase gratings are such cool objects:
Space coupler simulation-phasegrate.jpg
Source is at the bottom for a change. It can be clearly seen how the waves reflects along the walls of the grating, focusing most of the energy back where it came from - the middle. The openings on the sides shows how the angle of incidence affects the output angle, with most of the angled input have the same angle on the output. It's also easy to see the waves bouncing back and forth on the phase grate walls before they exit on the other side.
#10
1st December 2009
Old 1st December 2009
  #10
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Quote:
Originally Posted by plus6vu View Post
That's what I'm talking about. Terry, let us know how it works when you find out, eh?

Scott
Hi Paul and scott

that was just mucking about showing 'easy alternatives to making a 'proper' space coupler. I mentioned in my first post a few of those variations, and yeah for sure, I just had to do it, even if only to satisfy my own curiosity!

I reckon it looks pretty good, but way too modern for my room.

I also just for kicks based it on a prd actually, and placed the correct length in the correct spot. Have NO idea if that is good or bad in terms of space coupler effectiveness, just part of the mucking about.

I will be using rectangular rather than square for mine.

Feel free to go for it guys !!

Quote:
Originally Posted by Lupo View Post
Attachment 146469
Source is at the bottom for a change. It can be clearly seen how the waves reflects along the walls of the grating, focusing most of the energy back where it came from - the middle. The openings on the sides shows how the angle of incidence affects the output angle, with most of the angled input have the same angle on the output. It's also easy to see the waves bouncing back and forth on the phase grate walls before they exit on the other side.
Try moving the source way off to one side.

AFAIR that is the whole basis for the supposed increased effectiveness when placed over absorption, the waves that would have glanced off at anything other than normal incidence are now directed into the trap, thereby increasing it's effectiveness.

That may (or may not) show up in your sims if you put it off to one side. Hope you kept the code!!
#11
1st December 2009
Old 1st December 2009
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Quote:
Originally Posted by terry j View Post
Try moving the source way off to one side.

AFAIR that is the whole basis for the supposed increased effectiveness when placed over absorption, the waves that would have glanced off at anything other than normal incidence are now directed into the trap, thereby increasing it's effectiveness.

That may (or may not) show up in your sims if you put it off to one side.
Like this?

Space coupler simulation-phasegrate_angled_incidence.png
PaulP
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#12
1st December 2009
Old 1st December 2009
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Thread Starter
Space couplers certainly look good for higher frequencies, especially if you
happen to be sitting in the adjacent room . The main reason for my post
however was their performance at bass frequencies which, according to the
simulation, is very poor. This goes against what is advertised.

I guess I'll have to build one, play a low tone and stand on the other side to
see what comes through.

Paul P
#13
1st December 2009
Old 1st December 2009
  #13
Gear addict
 

I can tell you that this thread is fantastic...specifically the drive to uncover what is going on with the "Coupler". I'll give some background that may be helpful.

The AES white paper is by Russ Berger (mid 90's) on the concept of "loosely coupled space" for recording studio design application. It details a moderate size tracking room and how the lower portion has a "tighter" decay rate than the upper portion. It then proposes the desirable benefits of this application. And, if you look at any of Russ's full scale projects in past 10 years, you'll see this concept (even if the eye can't easily detect the two spaces).

So the Coupler is 2'x2'x3". The grids are 3/8" thick and the wells are 3"x3". It is in fact the Space Array with no dividers. So...at Auralex when this product has being evaluated, the first and only application brought forth was a non-architectural way to acheive a "loosely coupled space". The mainstream application being a drop tile grid with roughly 3' above, 30% couplers and possible diffusion panels in upper chamber. The results would be similar to the above referred AES white paper. Soon though then Auralex Chief Acoustical Engineer Jeff D Szymanski realized off the off-axis benefits of the product...developed with great conversations with Russ...we started experimenting with the product. In the Auralex testing room we would create multiple subsets of environments proving that the coupled space could orient horizontally as well as vertically and that really lush acoustical results could be created (providing you have enough units). Note, all these applications are systems, where the couplers benefits are in total relation to absorbers and the original space...not a stand-alone item. So in real world application as I recall, Jeff D Szymanski, took many couplers as part of update of now Sweetwater editorial content provider (and long time writer/editor) Mitch Gallagher's basement project studio...nothing special: 7.5' ish ceiling with drop grid (pink fluffy between joists). Maybe (6) or so Couplers were place in ceiling between speakers and mix position. As the revised treatments were completed, subjective listening revealed that content below 40Hz was now audible, the ceiling portion being the piece that gave this benefit.

BTW- I never saw testing results...I know Jeff D. testing just about everything but in that time he moved on to other employment. To my knowledge Russ Berger Design Group has not tested the Couplers. I know Auralex subsequently was in process of testing the Couplers in some fashion by independent lab. One of the issues of testing the Couplers is that the main benefit is with off-axis reflections and off course standard testing practices are normal incident.

I have used this product in many many application and always am pleased. Somtimes, it's a critical function, sometimes a supportive role, sometimes just more architectural interest.

You'll see many in Russ's smaller rooms and he's fully supportive of the benefits above mix, especially in lower ceiling rooms (less than 10'). You'll also see many in rooms of Carl Tatz.

So after all this, I think the ripple tank simulation is very compelling...don't know why you're getting the LF impass PaulP...but I agree with Lupo (if I'm not putting words in his mouth) that I wouldn't put trust in the LF response of the simulation. I've heard LF pass through Couplers.

BTW- one additional application of Coupler, place 4" in front of glass...control specular reflections, retains energy in space and you retain visual communition.
#14
1st December 2009
Old 1st December 2009
  #14
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Jeffs

Welcome Jeff, thanks for the insight. I have been in touch with Auralex, who told me they intended doing some tests. I and also tried to get some testing done by a home builder. I hope Auralex do the tests. It should be fairly easy to measure say a small room with significant corner traps, then fully front the four corners with Space Couplers. The 40% improvement mentioned should be obvious.
Speaking of which, surely this 40% came from somewhere. Can we ask Jeff Syzmanksi? Anyone know how to contact him?
A thought. I imagine an approaching LF wavefront as a big smooth surface, a bubble.
I cannot envisage a light grid such as the Space Coupler diminishing this in any way, even 90% off.
Conversely I imagine an approaching HF wavefront as very uneven. I can just about visualise a lot of bouncing due to the smaller wavelengths and the myriad angles on the wavefront surface. I may be raving though......;-)
DD
PaulP
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#15
1st December 2009
Old 1st December 2009
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Jeff, do you know if the SpaceCoupler was patented ? I just spent a few
minutes searching the patent office and came up with little, though I did
come across yours for a monitor isolator.

Paul P
#16
1st December 2009
Old 1st December 2009
  #16
Gear addict
 

PaulP- I doubt it is. In fact, if you look at a company named Conwed (a division of Owens-Corning), they sell same piece for aesthetic ceiling options...btw- I've checked and they are more than Auralex :-). I do think it would be low ball for another acoustics manufacturer to bring same thing at retail level...in simple reverance to Russ Berger's contribution to our industry. But, I would have no ethical twinges about DIY.

DanDan, I'll contact both Jeff Szymanski and other former Auralex Lead Acoustical Engineer Gavin Haverstick...I think I asked Gavin a couple months ago this same question when TerryJ first brought up his DIY effort.

DanDan, I suggest you ask Jeff Szymanski at StudioTips...he'll very likely respond.

My next application, I'll do my best to test in progress to document in room application...projects get so pushed for completion it's somtimes hard to do this.

In the Auralex facility is a fairly decent upper level project control room. We (I say we 'cause I was part of design) had pretty solid angled cloud system for ceiling control...when we placed a grid of Couplers below that...I was amazed at how it both solidified the LF response and improved imaging. Point is...maybe Auralex could readily test with & without test in room. I'll ask them.
PaulP
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#17
1st December 2009
Old 1st December 2009
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Quote:
Originally Posted by Jeffrey Hedback View Post
PaulP- I doubt it is. In fact, if you look at a company named Conwed (a division of Owens-Corning), they sell same piece for aesthetic ceiling options...btw- I've checked and they are more than Auralex :-). I do think it would be low ball for another acoustics manufacturer to bring same thing at retail level...in simple reverance to Russ Berger's contribution to our industry. But, I would have no ethical twinges about DIY.
I was only interested in a patent for the information it would contain. I have
no plans whatsoever to go into the acoustic treatment business.

I'm kind of surprised that it wasn't patented, if that is the case. Just about
everything else is.

Paul P
#18
1st December 2009
Old 1st December 2009
  #18
Gear addict
 

Sorry PaulP...didn't mean to imply anything at all personally. I actuallly agree.

In the day, I was urging my bosses to more seriously document the Coupler and boldly state how innovative it was. I also urged them to submit for TEC Award (marketing fluff in reality, but shows commitment...which is important at some level). I think it's cool how things have a life of their own and in this respect, the Coupler is becoming more valid as these discussions continue.
#19
2nd December 2009
Old 2nd December 2009
  #19
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Ta

Thanks Jeff. I have been in email contact with Gavin. He was hoping to do some tests, but I reckon it never happened. Let's find the other Jeff and get him into a dark room with just one lightbulb......
DD
#20
2nd December 2009
Old 2nd December 2009
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Jeff, thanks for your contributions on this little known part of acoustics!


Quote:
Originally Posted by PaulP View Post
Space couplers certainly look good for higher frequencies, especially if you
happen to be sitting in the adjacent room . The main reason for my post
however was their performance at bass frequencies which, according to the
simulation, is very poor. This goes against what is advertised.
Measurements, simulations and predictions based on theories is an art. It's generally a good idea to question the test method if the results are unexpected.

A quick way of getting a ballpark idea of the acoustic performance of various materials and constructions is to imagine what it would sound standing outside a loud party inside a house built with said constructions. I see no reason to believe a house made of space couplers would block low frequencies while letting high frequencies pass through!


I'm a bit rusty on the optics part of physics and don't have time to read up on this now. Though I do remember that various phase gratings have been used with light waves for a wide range of applications. A lowpass can be built using two perpendicular layers, but I'm not able to imagine a setup for highpass at the moment. If there is one? Knowing how build it for that purpose would make it easy to avoid any incidental building error to that effect. A bit of googling may bring up the relevant construction methods. Anyone up for some digging?


Cheers,

Andreas Nordenstam
PaulP
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#21
2nd December 2009
Old 2nd December 2009
  #21
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I just talked to Paul Falstad, the author of the simulator. I feel a bit like
an idiot now that I realize the answer was in his help file (which I did
read a while ago but too quickly for some parts to sink in).

For simulations of sound in air the "Fixed Edges" box must be unchecked.
When it is unchecked low frequency waves go right through the coupler,
as if it weren't even there.

I'll run some more simulations when I have a bit of spare time.

Paul P
#22
2nd December 2009
Old 2nd December 2009
  #22
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Replicator

Horse Sense rules. I remember Mr. Ed!
On the ancient TV theme, relax, use the Replicator and make yourself a nice cup of Cerrulean Tea! :-)
DD
#23
2nd December 2009
Old 2nd December 2009
  #23
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Quote:
Originally Posted by PaulP View Post
For simulations of sound in air the "Fixed Edges" box must be unchecked.
When it is unchecked low frequency waves go right through the coupler,
as if it weren't even there.
Heh. Puts some perspective on the previous tests with the program.. Must redo some of them now! Thanks for the finding!
#24
22nd March 2010
Old 22nd March 2010
  #24
Gear nut
 

Quote:
Originally Posted by Jeffrey Hedback View Post
7.5' ish ceiling with drop grid (pink fluffy between joists). Maybe (6) or so Couplers were place in ceiling between speakers and mix position. As the revised treatments were completed, subjective listening revealed that content below 40Hz was now audible, the ceiling portion being the piece that gave this benefit.
Jeff, I know this is an older thread, but I'm hoping you're still around to comment. In my home theater, I have a 7.5 foot ceiling as well, but i have sheetrock and not a drop ceiling. Is it still possible to achieve the "coupled space" concept by mounting couplers directly to ceiling-mounted absorption panels (such as OC703 panels)?
#25
23rd March 2010
Old 23rd March 2010
  #25
Gear addict
 

Hello Gremmy,

At 7.5' ceiling height with drywall ceiling it's a bit iffy. Do you have a floorplan and pics (if you have a thread already here or eslwhere...send a link)? Some of the factors may boil down to distances betweeen speakers and surfaces, other acoustical treatments and the like...glad to look closer if I could get a better idea of your space.
#26
23rd March 2010
Old 23rd March 2010
  #26
Gear nut
 

Quote:
Originally Posted by Jeffrey Hedback View Post
Hello Gremmy,

At 7.5' ceiling height with drywall ceiling it's a bit iffy. Do you have a floorplan and pics (if you have a thread already here or eslwhere...send a link)? Some of the factors may boil down to distances betweeen speakers and surfaces, other acoustical treatments and the like...glad to look closer if I could get a better idea of your space.
I don't have any "up to date" pics of the room, but it's pretty easy to describe it.

1) Room is rectangular (when the door is closed, it is a sealed rectangle) measuring 19ft. (length) x 11.25ft. (width) x 7.5ft (high)

2) My speakers are firing down the length direction of the room

3) Speakers are behind a "false wall", very close to the front room boundaries (I have a lot of insulation on the front wall and on the side of each left/right speaker to reduce SBIR and kill front wall reflections).

4) Seating position close to 41% off the back wall (I started at 38% and scooted forward based on measurement data)

5) Most first reflections are being handled by mineral wool absorption panels (there are 8 4x8 panels inbetween the speakers and the listening position, all on the side walls).

6) Back wall is highly diffusive. I have 3 QRD diffusers back there (N11, N11, N31) + two 4x2 1D Binary Phase Gratings positioned in the corner. I will be adding more diffusion on the rear side walls as well.

7) Back and front corners have bass traps from floor to ceiling.


8) Floor is carpeted.
#27
23rd March 2010
Old 23rd March 2010
  #27
Gear interested
 

the idea of an open grid acoustic ceiling is not new, its been used widly in the UK for many years with the soffitf the ceiling being clad in insulation of some sort. I will have to see if i can find any old brochures on it, but 15 years ago a company in the UK made latice acoustic tiles that were the same thing but in plaster...
#28
24th March 2010
Old 24th March 2010
  #28
Gear addict
 

First, great to see you here mattyRPG. I work closely with RPG USA (Jeff Madison and Janette).

gremmy,

As I understand your space verses the one I referenced, I would NOT expect the same benefit in lowest octave. It's not to say that a "SpaceCoupler" application above your listening area would have merrit. If the 3" deep couplers (commercial or DIY version) were put in tandem with 3" 703, you would get a significant absorption boost from approx 80Hz>400Hz. Along with this, it's very likely that the overall surround experience will increase/enhance (more exact/detailed panning, frequency definition, etc...) I'm NOT saying the SpaceCoupler is a "cure all" but the phase grating of off-axis energy is a real tool. In your case, some of the biggest variables are in relation to your surrounds/diffusors and the first reflection point on ceiling between LCR and viewing location. I can't comment fully on the surround/diffusor aspect with available information...the match between diffusors and front radiating/di-poles/bi-poles are very different applications. As for the first reflection point on ceiling (which didn't seem to be mentioned), I suggest a similar 3" 703 type solution (with no Coupler).

Just an overview comment...if you did employ the "SpaceCoupler" ceiling treatment, you could VERY likely add some strategic reflective areas in front half of the sidewalls for a more natural feeling and sounding space.

Look forward to your comments gremmy and sorry PaulP for taking over this "long-ago" thread.
PaulP
Thread Starter
#29
24th March 2010
Old 24th March 2010
  #29
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Thread Starter
Quote:
Originally Posted by Jeffrey Hedback View Post
Look forward to your comments gremmy and sorry PaulP for taking over this "long-ago" thread.
No problem at all. Any info on space couplers is good info. I had planned on
updating my pictures but further simulations were not terribly successful. It
continues to look to me like the diffusion is more pronounced in the coupled
space than the main space, ie I don't see much of the diffused sound getting
back into the main space. This may or may not be the fault of the simulator.

The simulator has undergone some changes. It now has better features but
for some reason has slowed down a lot and it's now a bit painful to use.

Paul P
#30
24th March 2010
Old 24th March 2010
  #30
Gear addict
 

+1 SAC...PERFECTLY stated! 100% on target.
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