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DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)
Old 17th June 2017
  #781
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Quote:
Originally Posted by johnnyc View Post
Nice work. What kind of wood did you use for these?
Thanks! I used poplar. The big plywood bridge piece is birch plywood. In the final version the color and the wood grain pattern you see is completely done by brushing the 2 stain colors. The stain totally covers up all of the original wood.

The only reason I picked the wood that I did was that the hardware store here had poplar already cut and smooth in the dimensions I needed to minimize cutting. The birch plywood was chosen just to match the color of the poplar.
Old 18th August 2017
  #782
Here for the gear
Thank you so much for this!
Old 6th October 2017
  #783
Gear Nut
 

Quote:
Originally Posted by Arqen View Post
Normally I recommend 1D diffusers on the rear wall. But, since you don't have much space behind you, you're better off with 2D PRD (skyline-style) diffusers that reduce the energy returned to the listening position. Of those two choices I would choose their Manhattan diffuser for your specific case.
Hi Tim,

I need your opinion on these two diffusers as their quoted data are looking very strange to me.

1. http://bit.ly/2yMjWMJ - Manhattan
2. http://bit.ly/2geE3w6 - Vicoustic

The Manhattan diffuser which has 17cm depth claims diffusion from 900 to 3650Hz.
The vicoustic diffuser although it has much shallower profile 7.5cm claims diffusion from 470 to 10kHz.

How’s that possible? The only difference with vicoustic is that it has angled surface. Could these angles make such a big difference in the frequency range?
Old 6th October 2017
  #784
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Jens Eklund's Avatar
Quote:
Originally Posted by petergel View Post
Hi Tim,

I need your opinion on these two diffusers as their quoted data are looking very strange to me.

1. http://bit.ly/2yMjWMJ - Manhattan
2. http://bit.ly/2geE3w6 - Vicoustic

The Manhattan diffuser which has 17cm depth claims diffusion from 900 to 3650Hz.
The vicoustic diffuser although it has much shallower profile 7.5cm claims diffusion from 470 to 10kHz.

How’s that possible? The only difference with vicoustic is that it has angled surface. Could these angles make such a big difference in the frequency range?
https://www.gearslutz.com/board/12849704-post2.html
Old 6th October 2017
  #785
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Quote:
Originally Posted by Jens Eklund View Post
So the quoted numbers of vicoustic are nonsense?
Old 7th October 2017
  #786
nms
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nms's Avatar
Quote:
Originally Posted by petergel View Post
So the quoted numbers of vicoustic are nonsense?
100%

It looks like the goal there was just to make something that looks neat and convincing to people who have no idea.

This functioning down to 470hz even though the unit has a max depth of 75mm?

https://www.thomann.de/gr/vicoustic_...fuser_389947_6

Must be quantum acoustics!
Old 9th October 2017
  #787
Gear Nut
 

Quote:
Originally Posted by nms View Post
100%

It looks like the goal there was just to make something that looks neat and convincing to people who have no idea.

This functioning down to 470hz even though the unit has a max depth of 75mm?

https://www.thomann.de/gr/vicoustic_...fuser_389947_6

Must be quantum acoustics!
I have to say that still it sounds very strange to me a big company publishing inaccurate numbers for their products.
If it is so easy, then anyone can claim wonder numbers for their diffusers, basstraps, and in general anything.
Old 9th October 2017
  #788
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Jens Eklund's Avatar
Quote:
Originally Posted by petergel View Post
I have to say that still it sounds very strange to me a big company publishing inaccurate numbers for their products.
If it is so easy, then anyone can claim wonder numbers for their diffusers, basstraps, and in general anything.
This is unfortunately more common that you might imagine:

"Many published low frequency absorption coefficients are nonsense, because the accuracy of the absorption efficiency decreases at low frequencies in standard ISO 354 and ASTM 423 tests, due to inadequate diffusion."
RPG Modex Plate - Acoustic Products

More here:
https://www.gearslutz.com/board/12603036-post44.html


Even more common when it comes to diffusers, partly because it´s costly to measure diffuser performance correctly, and partly because most people have no idea how to interpret the data. Just as an example; some manufactures publish only one graph and then often (or possibly always) the “scattering coefficient” and this is not the same as “diffusion coefficient”. The scattering coefficient is often much higher, especially in the lows, so this curve often looks “nicer” but in order to evaluate performance you need the diffusion coefficient or preferably both (but the diffusion coefficient is the most relevant one). Another common mistake is to measure/simulate only one panel and not many panels together as the intended use.

More here:
https://www.gearslutz.com/board/9509522-post323.html
THE T.AKUSTIK SD-2 RAS-DIFFUSOR - Anyone using this? reckon its any good?
Old 9th October 2017
  #789
Gear Nut
 

Quote:
Originally Posted by Jens Eklund View Post
This is unfortunately more common that you might imagine:

"Many published low frequency absorption coefficients are nonsense, because the accuracy of the absorption efficiency decreases at low frequencies in standard ISO 354 and ASTM 423 tests, due to inadequate diffusion."
RPG Modex Plate - Acoustic Products
I’m aware that RPG is the most reliable company when it comes to coefficient numbers. Since you mentioned modex plate, I believe it must be the best VPR trap in the market for low absorption at such a shallow profile. Unfortunately is very expensive about 500€

I was thinking to buy the hofa basstraps trap - http://bit.ly/2ybfNEz - which surprisingly it has even better low absorption numbers from modex broadband plate, but in general a very similar graph. What’s your opinion on this trap? Nonsense or could it be great trap at a great price?
Old 10th October 2017
  #790
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Arqen's Avatar
 

Quote:
Originally Posted by petergel View Post
Hi Tim,

I need your opinion on these two diffusers as their quoted data are looking very strange to me.

1. http://bit.ly/2yMjWMJ - Manhattan
2. http://bit.ly/2geE3w6 - Vicoustic

The Manhattan diffuser which has 17cm depth claims diffusion from 900 to 3650Hz.
The vicoustic diffuser although it has much shallower profile 7.5cm claims diffusion from 470 to 10kHz.

How’s that possible? The only difference with vicoustic is that it has angled surface. Could these angles make such a big difference in the frequency range?
Hi Petergel,

You're right that this doesn't make sense. The angled surfaces will provide some scattering at higher frequencies, but I don't see any measurements confirming whether or not that is meaningful diffusion.

It looks to me like the Manhattan is quite conservative with their claims, focussing on the range of high effectiveness, while Vicoustic has been very liberal, stating the full range over which some level of measurable diffusion could be claimed/argued. In fact, given its depth, I expect the Manhattan would have a reasonable diffusion coefficient at 500 Hz.

Attached are the published measurements for the Multifuser Wood 36 and 64. The low frequency performance does not make sense, but it's typical to get misleading low frequency measurements when measuring the diffusion coefficient. Rather than normalize their measurements to let you know there is no meaningful diffusion at 125 Hz, companies are unfortunately incentivized to publish the best looking diffusion coefficient plot (not the normalized plot), and the best interpretation of the measurements.

If those are indeed the only measurements they have, I think Vicoustic would be better posting something like 700-4000 Hz (and that still may be liberal, but I have not seen the normalized coefficients). Also, Vicoustic has a sophisticated test lab in Portugal, so I would not be surprised if they do have data above 4000 Hz, but I've not seen it.

Companies probably ask themselves, what can we get away with calling diffusion? Does a diffusion coefficient of 0.1 at 300 Hz mean a surface starts diffusing at 300 Hz? For practical purposes I'd say no, but unless we define a threshold that must be crossed, this leaves a lot open for interpretation.

Finally, the size of the surface has an effect on the data. Companies have an incentive to post the performance of a single device vs an array of multiple. This makes it difficult to meaningfully compare devices of different sizes, because a single smaller diffuser will tend to get a performance boost when compared to an array of diffusers.

E.g., let's assume we're comparing a 2-foot wide diffuser vs an 8-foot wide diffuser. The single 2-foot wide diffuser may have significantly better measured diffusion coefficients than the 8-foot wide diffuser, while the 8-foot wide diffuser has better performance than an array of four 2-foot-wide diffusers. Naturally, the manufacturer of the 2-foot wide diffuser is going to prefer to show the coefficients for a single unit, and they might defend that by saying "well, you can arrange them in infinite different possible array configurations, and rotate / modulate them in different ways, so we just put the performance for a single panel". Unfortunately, a more candid manufacturer who posts the array performance (which does not look nearly as impressive), risks making their device look like an inferior product.

Unfortunately, the bar has been set so low (with many companies posting NO data whatsoever), that there's a lot of room for companies to play with when posting their diffuser performance. And unfortunately, most companies are more likely to exaggerate rather than be modest, because it's a competative environment where bold claims sell.

I've even seen a couple companies make "quantum acoustic diffusion" snake oil claims.
Attached Thumbnails
DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-vicoustic-multifuser-wood-diffusion-coefficients.jpg  
Old 15th October 2017
  #791
Gear Nut
 

Quote:
Originally Posted by Arqen View Post
Hi Peter,

Normally I recommend 1D diffusers on the rear wall. But, since you don't have much space behind you, you're better off with 2D PRD (skyline-style) diffusers that reduce the energy returned to the listening position. Of those two choices I would choose their Manhattan diffuser for your specific case.
Hi Tim, thanks for your answers,

I would like to know your opinion on this diffuser if possible http://bit.ly/2wYE7Gv. As I said before, the distance between my listening position and my back wall is 180cm. Will this 2D QRD diffuser work in my case?
I know that you suggested the Manhattan diffuser http://bit.ly/2gl4OCz but the hofa is almost 1/3 cheaper and way lighter to hang on wall. Do you believe I’ll have similar diffusion results to Manhattan with this one?

Actually these diffusers have very good customer reviews on Thomann site, but as I'm sure you already know reviews may be very inaccurate or even misleading, especially from ignorant users.

Edit: In this video @ 2:14 I found that the diffuse from 700Hz to 2.2kHz
Old 6th November 2017
  #792
Gear Addict
 
Arqen's Avatar
 

Quote:
Originally Posted by petergel View Post
Hi Tim, thanks for your answers,

I would like to know your opinion on this diffuser if possible http://bit.ly/2wYE7Gv. As I said before, the distance between my listening position and my back wall is 180cm. Will this 2D QRD diffuser work in my case?
I know that you suggested the Manhattan diffuser http://bit.ly/2gl4OCz but the hofa is almost 1/3 cheaper and way lighter to hang on wall. Do you believe I’ll have similar diffusion results to Manhattan with this one?

Actually these diffusers have very good customer reviews on Thomann site, but as I'm sure you already know reviews may be very inaccurate or even misleading, especially from ignorant users.

Edit: In this video @ 2:14 I found that the diffuse from 700Hz to 2.2kHz
Hi Peter,

I usually prefer 1D diffusers on the rear wall. But, since you're quite close to it, 2D diffusers make sense as they will return less energy directly to you.

I can't predict how those two will audibly compare to one another, but given that it's a standard 2D QRD diffuser it looks like a safe bet. It uses an established design, while many diffusers out there are based on voodoo.
Old 19th November 2017
  #793
Here for the gear
 

Hi all,

I have a somewhat novel situation that I would love some input from those a bit more experienced than I am in terms of acoustic theory. I have a pair of Quad 2812 electrostatic speakers, and my room is a bit too small to be ideal for them. Specifically, they end up needing to be way too close to the side walls, and a bit too close to the rear walls. Electrostats create a unique problem in that they are dipoles, so I'd like to break up the energy emanating from the back of the panels. From the center of the speaker to the rear wall is 38 inches the available wall space for a diffuser behind each of the speakers is 25 inches on the short side (i.e., right near the screen) and about 40 on the long side of the wall.

So, what I've thought of is as follows:

1. I assume that putting something like a LeanFuser on the walls is going to create considerable problems. Or would it, assuming I put a triangular 10x10x10 bass trap in the very corner?

2. I could put a 46inch wide LeanFuser that spans the corner from about the 22inch mark to the 40inch mark. This would obviously be filled with a good deal of RockWool.

3. The last thought I have involves a convex arc of plywood covered with LeanFuser panels from about the 20inch mark to the 38inch mark. If this last option is best (I'm assuming it will be,) how do I want to figure out the arc and size the individual wells?



What are people's thoughts about the benefits and downsides of these options, and what other options am I not considering.

Thanks much,
Colin
Attached Thumbnails
DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-above-right-speaker-looking-down.jpg   DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-front-center-facing-right-speaker.jpg   DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-listening-position.jpg  
Old 20th November 2017
  #794
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Subscribed great stuff!
Old 20th November 2017
  #795
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I'm not sure I get what you mean.

Quote:
Originally Posted by TheLastByte View Post
Subscribed great stuff!
Old 1st December 2017
  #796
Here for the gear
 

Bump

Does anyone have a minute to share their thoughts?
Thanks,
Colin
Old 14th December 2017
  #797
Gear Nut
 

Quote:
Originally Posted by Arqen View Post
The sky is the limit for wood types. The wood type has negligible effect on acoustics. Weight, cost, appearance, workability and durability are all things to be considered, and different people prioritize different things.
HI Tim,

Since the softness/hardness of material is not an important factor, if I choose the EPS Manhattan diffuser would it give similar results? The only difference between EPS and beech wood diffuser is that EPS is shallower by 2cm and of course softer.

EPS Manhattan Diffuser
Wood Manhattan Diffuser
Old 27th December 2017
  #798
Gear Maniac
 
Qtwister's Avatar
 

This is a new york style diffuser...

pretty decent if it fits into your room :D
Attached Thumbnails
DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-lifebuzz-79030f87adef5da43cf335210f522dad-limit_2000.jpg  
Old 4th January 2018
  #799
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Qtwister's Avatar
 

I see nobody likes my quantum acoustics :D
Old 6th January 2018
  #800
Here for the gear
 

Tim, others, I've read thru this entire thread and it's been most helpful. I plan to build a lean diffusor (probably 3 panels) for my back wall of my studio/practice room however .... The back wall I have is going to be storage with sliding doors. My thought is to make the center sliding door the diffusor. Yes, I know it will be heavy but I'm in a basement and can put it on heavy roller tracks, etc. I'm a contractor so construction is no issue. My question is, are there any acoustic issues I may be creating since the diffusor would not be mounted against a wall? The slider doors to either side of the diffusor would be either flat, heavy panels or possibly broadband absorber panels. The storage behind the diffusor would be about 2 to 2.5 feet deep and filled with cases, gear, etc. Thoughts, issues?
Old 8th January 2018
  #801
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ARIEL's Avatar
I have a smaller drum room in my house studio. 10 by 20 all the walls were covered with primacoustic 3" panels plus the entire ceiling was covered with their stratus panels which sounded perfect for 70's dry rock and disco tone. I felt that the cymbals were just slightly chocked off and needed more air so I built a leanfusor at 8' wide and 6' tall. Wow what a difference it makes, the room still sounds tight but it added back a little bit of that air I wanted to hear but such a smooth way.
Old 8th January 2018
  #802
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ARIEL's Avatar
Quote:
Originally Posted by GregBshark View Post
Tim, others, I've read thru this entire thread and it's been most helpful. I plan to build a lean diffusor (probably 3 panels) for my back wall of my studio/practice room however .... The back wall I have is going to be storage with sliding doors. My thought is to make the center sliding door the diffusor. Yes, I know it will be heavy but I'm in a basement and can put it on heavy roller tracks, etc. I'm a contractor so construction is no issue. My question is, are there any acoustic issues I may be creating since the diffusor would not be mounted against a wall? The slider doors to either side of the diffusor would be either flat, heavy panels or possibly broadband absorber panels. The storage behind the diffusor would be about 2 to 2.5 feet deep and filled with cases, gear, etc. Thoughts, issues?
I just built mine so they are movable, they are about 8" from the wall/window and I hear no issue at all. They make the room sound great and well worthwhile to do/install.
Old 8th January 2018
  #803
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Quote:
Originally Posted by ARIEL View Post
I just built mine so they are movable, they are about 8" from the wall/window and I hear no issue at all. They make the room sound great and well worthwhile to do/install.
Do you have any pics or some details on the construction?
Old 8th January 2018
  #804
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Quote:
Originally Posted by johnnyc View Post
Do you have any pics or some details on the construction?
Sorry no details on the build but I can take a picture of the final thing I built.
Old 15th January 2018
  #805
Gear Maniac
 

Hi,
Would mounting 4 of the Leanfusers(1200mm) on a rear wall that has a 6" point at center be ok? In other words; the wall have been designed with a soft "V" coming out from the wall and spreads out about 8ft in each direction to the corners. Where it connects back with the wall. Similar to picture example attached. And instinctually I would think that hanging them without the stand-offs would be fine since they’re hung on and angle. True?
Thanks
Attached Thumbnails
DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-8df69a25-c527-4dd8-9b70-f8053254f44a.jpeg  
Old 15th January 2018
  #806
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Quote:
Originally Posted by ARIEL View Post
Sorry no details on the build but I can take a picture of the final thing I built.
That would be good. Always enjoy seeing finished builds
Old 15th January 2018
  #807
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Quote:
Originally Posted by ARIEL View Post
I just built mine so they are movable, they are about 8" from the wall/window and I hear no issue at all. They make the room sound great and well worthwhile to do/install.
Thanks for the input Ariel on "movable" diffusors. Would love to see your build. I'm pretty sure I'll go ahead with my idea of a sliding diffusor panel unless someone has a good reason that it will have 'issues'. I've got a lot to do before I get to the diffusor though. Gotta strengthen the main beam of the house along with utility moves/updates and I'm digging the basement floor down a foot or so. Kind of major surgery! LoL. Hope to be in finishing stages and building the diffusor sometime this summer. Question Ariel: what does that 6X8 panel weigh (rough guess fine!) and what material did you build it out of?
Old 18th January 2018
  #808
Gear Nut
 

Quote:
Originally Posted by Arqen View Post
The sky is the limit for wood types. The wood type has negligible effect on acoustics. Weight, cost, appearance, workability and durability are all things to be considered, and different people prioritize different things.
Can anyone help me with this ?

Since the softness/hardness of material is not an important factor, if I choose the EPS Manhattan diffuser would it give similar results? The only difference between EPS and beech wood Manhattan diffuser is that EPS is shallower by 2cm and of course softer.

EPS Manhattan Diffuser
Wood Manhattan Diffuser
Old 18th January 2018
  #809
Gear Head
 

Quote:
Originally Posted by petergel View Post
Can anyone help me with this ?

Since the softness/hardness of material is not an important factor, if I choose the EPS Manhattan diffuser would it give similar results?
Hardness/softness is not an important factor (suppossedly) for wood. EPS is a different animal which will absorb high frequencies instead of diffusing/reflecting them.
Old 18th January 2018
  #810
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Jens Eklund's Avatar
Quote:
Originally Posted by Jerbery View Post
Hardness/softness is not an important factor (suppossedly) for wood. EPS is a different animal which will absorb high frequencies instead of diffusing/reflecting them.
Not true, assuming painted to seal the porous surface of EPS: Diffusors: opinions about EPS polystyrene?
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