Lattice as Space Coupler

[Wakena2003]

Should this lattice work as a Space Coupler?

[jhbrandt]

I don't see any attachment or link.. but lattice won't work... space couplers require a certain depth which is somewhat related to the coupling frequency... they create acoustic lenses of a sort.

Cheers,
John

[DanDan]

Not sure if John can see the pics. The second one may be promising, it looks like it may be deep enough, just can't see in far enough to know. The depth in SC's here is equal to the width of the wells.
DD

[jhbrandt]

I see it now...

All I can say is, 'Try it!'... you may obtain some diffusion from the surface as well.. and placing them next to absorbent panels will probably increase the absorption of the panels at glancing angles... plus adding the aforementioned diffusion..

Your guess is as good as mine. I doubt if it would hurt anything.
Cheers,
John

[localhost127]

can anyone answer why are space couples often recommended for clouds?

[DanDan]

Space couplers under clouds is a killer combo.
The couplers increase the LF absorbtion of the fibre cloud alone, by around 45% at 125Hz etc. This helps with the height mode.
The combo prevents destructive reflections from overhead, including flutter. At the same time they promote indirect reflections, leading to a little HF bloom.
DD

[localhost127]

Originally Posted by DanDan

Space couplers under clouds is a killer combo.
The couplers increase the LF absorbtion of the fibre cloud alone, by around 45% at 125Hz etc. This helps with the height mode.
The combo prevents destructive reflections from overhead, including flutter. At the same time they promote indirect reflections, leading to a little HF bloom.
DD

thanks, Dan.

may i ask how the dimensions on the coupler are related to effective frequency? (or largest freq 'seen' by the space coupler)?

[DanDan]

You are welcome. The couplers seem to defy logic. I have seen the actual test results. It is a 45% increase in LF absorption in the 125Hz third octave.

The HF effect is not measured or published afaik. However I can tell you that I like what I hear when speaking singing or playing acoustic near them.
A friend Acoustician, who's opinion I trust, uses them quite a bit, particularly under clouds.

DD

[jhbrandt]

Originally Posted by DanDan

Space couplers under clouds is a killer combo.
The couplers increase the LF absorbtion of the fibre cloud alone, by around 45% at 125Hz etc. This helps with the height mode.
The combo prevents destructive reflections from overhead, including flutter. At the same time they promote indirect reflections, leading to a little HF bloom.
DD

Well stated, Dan. That has been my experience and impression... but, have you done tests that show that much?
I will be beginning an 'on-site' build here locally in Jakarta Indonesia, and will be using Space Couplers in this fashion. We will do with/without testing while we are at it and post results here and on my site. Hopefully this will provide some valid data that folks can rely on.
Cheers,
John

[DanDan]

Nice one John. No I have not done such a test. However Auralex have sent me the test data which I see no reason to doubt.
It would be good to see on site testing, please do have a go, although it may prove difficult to extract an LF absorption figure from a relatively small area of cloud.

DD

[localhost127]

Originally Posted by jhbrandt

Well stated, Dan. That has been my experience and impression... but, have you done tests that show that much?
I will be beginning an 'on-site' build here locally in Jakarta Indonesia, and will be using Space Couplers in this fashion. We will do with/without testing while we are at it and post results here and on my site. Hopefully this will provide some valid data that folks can rely on.
Cheers,
John

John,
can you please elude to the dimensions and their relation to effective frequency?

[jhbrandt]

A depth/width of 4" or 100mm is equal to the length of 3.38kHz. 1/4 of that would be 845Hz. I doubt seriously that frequencies lower than 400 would be affected much by that grid size and spacing.
A space coupler with 4" depth/width grid, the center of the pass-band would be 1.69kHz. A smaller grid would shift the center frequency higher.

Cheers,
John

[Wakena2003]

And what about a square shelf to put at the back of the control room?

I own 2 units of this model:



And I'm planning to hang it together at the back wall of my control room.

Cubes are about 30x30x30 cm (1ft). The two shelves together will be 120 x120 cm (4x4ft).

Here you have one of them:

[jhbrandt]

I have NO idea.

We're getting into experimental here. You want to improve absorption behind you? Use them empty and center them where you need max absorption. I don't know. Usually you want some return energy from the back of the room... I would use/recommend a diffusor.

Cheers,
John

[localhost127]

Originally Posted by Wakena2003

And what about a square shelf to put at the back of the control room?

I own 2 units of this model:



And I'm planning to hang it together at the back wall of my control room.

Cubes are about 30x30x30 cm (1ft). The two shelves together will be 120 x120 cm (4x4ft).

Here you have one of them:

i had an idea a while back to use ikea expedit's like those in your photo as space couplers for greater LF absorption at corner traps. (place them in front of corner traps) unfort, i dont have the luxury of having a large enough (dedicated) listening room to even implement corner traps at the moment (the joys of living in the city) - so that experiment is indefinitely hold - but im still curious to test.

[DanDan]

The well dimensions of the Space Coupler, as John has shown, seem capable of affecting only high frequencies. However the test shows quite a dramatic increase in LF absorption of a panel fronted by couplers. Go figure.
Well, lets figure. If one considers a Space Coupler as a device rather than a collection of smaller devices, then it may make sense. A sort of large wave guide grating if you will.
Presumably in the test they used the normal Lab sample, i.e. 10M^2 or so.
DD

[John White]

Originally Posted by jhbrandt

A depth/width of 4" or 100mm is equal to the length of 3.38kHz. 1/4 of that would be 845Hz. ...
A space coupler with 4" depth/width grid, the center of the pass-band would be 1.69kHz....

John,

Just some clarification-

I have: 1130 (ft/s) / .3' (4") as 3,767Hz. Am I calculating this correctly? I don't know enough to comment on the 1.69kHz pass-band except to say that it doesn't correspond to my primitive math.

Regarding "1/4 of that would be..." - is that suggesting the frequency would be affected up to 1/4 it's size? I would have thought the wave would "bend" around it. Certainly that can't be linear so that 1/2 the size of the coupling depth affects half the wave, 1/4 size....

Thanks

[jhbrandt]

Dan,
Haha.. yeah, I know. It's probably due to the overall size. Can you send me that testing data that you got from Auralex?

One thing I know from experience, is that it does increase effective absorption and adds a slight HF 'bloom' as you said.

I am sure that it can/will affect the LF wave, but how much is unknown without testing.

John,
The calculation for 1/2 wavelength is: 1130/.333(ft.)/2=1695Hz (4"=.333')
1/4 wavelength is similar: 1130/.333(ft.)/4=847.5Hz

-- that's all I was doing. Usually, the calculation used for lowest reflecting wavelength of an object... like the well width in a diffusor, or geometric shapes. It's simple and gets you close.

Cheers,
John

[John White]

Originally Posted by jhbrandt

John,
The calculation for 1/2 wavelength is: 1130/.333(ft.)/2=1695Hz (4"=.333')
1/4 wavelength is similar: 1130/.333(ft.)/4=847.5Hz...

I see now.

So it's effective to 1/4 wavelength? That is a surprising and welcome bit of information.

Is the depth of 1/4 the wave length half as effective as 1/2 wavelength or does the effectiveness of the well depths or spacing drop off exponentially after a 1:1 ratio?

Thanks,

[jhbrandt]

John,

A 1/2 wavelength calc is very close to phase calculations for an electronics filter. A filter pass-band is usually measured from a -3db point - relating to a 45 degree phase shift and -6db per octave roll off.

So 1/4 wavelength calculation is more like a -12db per octave roll off.

This is a gross oversimplification, but it get's you close.

Cheers,
John

[Adhoc]

There are some explanations how a lattice may improve absorbtion in this book. Just down load and happy reading. (I am too lazy search out which chapter again... It is good literature by the way. )

http://www.iperf.org/acoustics.html

[Greg B]

I just put some couplers up in my studio. I mounted them with rigid fiberglass spacing them a couple inches off of the wall. Mounting them wasn't so tough, but I probably should have used a quicker painting method than a tiny little paintbrush. Took about 5 hours each, but they have a cool distressed hand-painted look.

[Chris_Nicks]

Hi guys! do you know what the dimensions of a space coupler is for increasing 125hz absorption by 40% while effectively diffusing the highs?

[Greg B]

Originally Posted by Chris_Nicks

Hi guys! do you know what the dimensions of a space coupler is for increasing 125hz absorption by 40% while effectively diffusing the highs?

That info was specific to the Auralex "Space Couplers" which I believe are no longer made but have virtually the same dimensions as the couplers I posted above in the piano shot. (2.75" wells with about a 2.25" depth). So the total size ends up being 2' x 2' when you consider the width of the wood (about .25").

For that application, simply place them in front of absorption material to increase it's effectiveness, or alone they can still help diffuse, couple, and eliminate flutter echo (many different ways to use them).

[Chris_Nicks]

that looks neat greg! whats with those white squares? so the whole thing is 16" x "16?

[Greg B]

Originally Posted by Chris_Nicks

that looks neat greg! whats with those white squares? so the whole thing is 16" x "16?

Sorry, I was a bit off (was going from memory). I'll correct my original post. Total size should be about 2' x 2' square.

[Chris_Nicks]

oh. no prob man.. aren't you supposed to put those spacers in front of the bass traps?

[Greg B]

Originally Posted by Chris_Nicks

oh. no prob man.. aren't you supposed to put those spacers in front of the bass traps?

The Auralex Space Couplers were originally designed for loosely coupling spaces to make smaller spaces sound larger and reduce/eliminate flutter echo, but it was also discovered that they can help increase absorption when used in front of absorption treatment. The way I've used them in the photo is actually one of the applications suggested by Auralex in the PDF manual for their Space Couplers. I even replicated their basic mounting method.

In this case I didn't use them to increase any absorption, but for diffusion/flutter reduction which was more their original purpose.

[Chris_Nicks]

ohh.. do you think its doing a better job of diffusing in comparison to QRD diffusors?

[Greg B]

Originally Posted by Chris_Nicks

ohh.. do you think its doing a better job of diffusing in comparison to QRD diffusors?

Hard to say actually. They definitely have a pleasant effect on the high end and with the new treatment it definitely killed a bad "poiing" I would get off that wall The room has a combination of multiple types of diffusion and absorption, including the Skyline Diffusors, so I measure the overall result which is definitely "Room is better treated than not treated" and I like the effect the Skylines and couplers have on the walls that are furthest from where I usually place mics (I use absorption on most early reflection points and diffusion further away). I might add 2' x 2' absorption panels in the spaces around those couplers, but I'm actually liking where it's at right now. I want that room to stay lively (but controlled lively).