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DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)
Old 21st September 2013
  #301
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Quote:
Originally Posted by 12ax7 View Post
.
Anybody here ever thought of gluing together stacks of FoamCore material to build these things?
.
I believe I've seen someone do that, but most people opt for wood or mdf. It's nice to have that added durability.
Old 23rd September 2013
  #302
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Quote:
Originally Posted by Arqen View Post
Hey Michael thanks for your kind words! To me, simply seeing people build these is more than enough gratitude.

I think you're good leaving the setup as-is, but another possibility that might look interesting (or weird) is to stagger them:

QRD-Leanfuser-QRD-Leanfuser-QRD-Leanfuser-QRD

Considering how both the QRDs and the Leanfusers were designed, neither of these diffusers are designed to be mounted like this. But I hypothesize that the overall result would yield decent diffusion... possibly more uniform than if you mounted the three Leanfusers in the middle (bear in mind that this is just an intuitive guess).

Either way, the choice is up to you!

Oh no ...I've done too much damn work to settle for just decent diffusion. If it can't at least be very good then I don't really even see the point in all my effort. I'm thinking I may want to take the QRD's and use them somewhere else in the room and make the whole front wall stepped diffusers based on the Leanfuser design model. I have room for seven modules, so would you suggest I try the seven module profiled modulation model? Or is there a simpler seven module model that can give me very good diffusion using the depths I've already incorporated into my builds....which I guess follow the 0 4 5 3 5 4 0 sequence (mine come out to 0 2", 2.5", 1.5", 2.5", 2", 0 and 0, 4", 5", 3", 5", 4", 0).

- Michael
tinnitusintx is online now
Old 23rd September 2013
  #303
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Quote:
Originally Posted by tinnitusintx View Post
Oh no ...I've done too much damn work to settle for just decent diffusion. If it can't at least be very good then I don't really even see the point in all my effort. I'm thinking I may want to take the QRD's and use them somewhere else in the room and make the whole front wall stepped diffusers based on the Leanfuser design model. I have room for seven modules, so would you suggest I try the seven module profiled modulation model? Or is there a simpler seven module model that can give me very good diffusion using the depths I've already incorporated into my builds....which I guess follow the 0 4 5 3 5 4 0 sequence (mine come out to 0 2", 2.5", 1.5", 2.5", 2", 0 and 0, 4", 5", 3", 5", 4", 0).

- Michael
tinnitusintx is online now
Michael, "decent" was a conservative word choice simply because I can't guarantee an idea that has not been verified. There is a good chance it will produce very good diffusion, but it's hard to know without actually testing it. You could test out the idea in AFMG reflex quite easily (my demo of the software has expired, but let me know if you decide to do this and I'll tell you what measurements to use).

To be frank, you'll get very good diffusion if you simply place those four QRDs directly behind you, with nothing in between. It won't span your whole wall, but I think it will cover the early reflection region on the back wall, which is most critical.

That's the simplest 7 module configuration I've found that has high performance. Yes, I suggest you try out the 7 module configuration if you have a good place to put those QRDs, but I don't suggest letting those QRDs go to waste as they are great diffusers. If you're tired of building diffusers, consider using Reflex to test out the 2 combinations of QRDs and stepped diffusers we discussed.

Don't worry, even if you just use the 4 QRDs, you're not going to have to settle for just decent diffusion.
Old 24th September 2013
  #304
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Quote:
Originally Posted by Arqen View Post
Michael, "decent" was a conservative word choice simply because I can't guarantee an idea that has not been verified. There is a good chance it will produce very good diffusion, but it's hard to know without actually testing it. You could test out the idea in AFMG reflex quite easily (my demo of the software has expired, but let me know if you decide to do this and I'll tell you what measurements to use).
Fair enough...can't blame you for that and thanks for the offer.

Quote:
Originally Posted by Arqen View Post
To be frank, you'll get very good diffusion if you simply place those four QRDs directly behind you, with nothing in between. It won't span your whole wall, but I think it will cover the early reflection region on the back wall, which is most critical.
I do plan on putting diffusion on the back wall, but those QRD's are 7" deep and my listening position is 3-4' from the rear wall.....too close for those units (I think QRDude said around six feet). I'm planning on building a few 5-well QRD's that are only 3.5" deep as those allow a sitting distance as close as 3'. However, I'd be most interested in stepped diffuser that would allow a listening position as close as three feet (hint, hint).

Quote:
Originally Posted by Arqen View Post
That's the simplest 7 module configuration I've found that has high performance. Yes, I suggest you try out the 7 module configuration if you have a good place to put those QRDs, but I don't suggest letting those QRDs go to waste as they are great diffusers. If you're tired of building diffusers, consider using Reflex to test out the 2 combinations of QRDs and stepped diffusers we discussed.

Don't worry, even if you just use the 4 QRDs, you're not going to have to settle for just decent diffusion.
I think for now I'll use the dual outboard QRD arrays and the three Leanfuser module arrangement in the center and bring the base of the Leanfusers out three inches further from the wall than the base of the QRD's. I'll build more Leanfusers for the side walls...probably two or three module arrays....and seriously consider the seven module arrangement for the front wall at some point down the line. Thanks again for the input.

- Michael
Attached Thumbnails
DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-photo.jpg  
Old 25th September 2013
  #305
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Quote:
Originally Posted by tinnitusintx View Post
I do plan on putting diffusion on the back wall, but those QRD's are 7" deep and my listening position is 3-4' from the rear wall.....too close for those units (I think QRDude said around six feet). I'm planning on building a few 5-well QRD's that are only 3.5" deep as those allow a sitting distance as close as 3'. However, I'd be most interested in stepped diffuser that would allow a listening position as close as three feet (hint, hint).
I usually use the QRD minimum distance formula as a guideline (minimum distance is about three times the longest wavelength diffused), so I usually consider the minimum listening distance for these units to be 5-6'. However, that guideline is specific to QRDs, and I did optimize these stepped diffusers for close range use so I think you're fine using them at 4'. 3'... I think is pushing it.

Quote:
Originally Posted by tinnitusintx View Post
I think for now I'll use the dual outboard QRD arrays and the three Leanfuser module arrangement in the center and bring the base of the Leanfusers out three inches further from the wall than the base of the QRD's. I'll build more Leanfusers for the side walls...probably two or three module arrays....and seriously consider the seven module arrangement for the front wall at some point down the line. Thanks again for the input.

- Michael
I think that will work well and I look forward to seeing how it looks when everything is mounted!
Old 30th September 2013
  #306
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Got some Danish oil on the Leanfusers and everything mounted up.
Attached Thumbnails
DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-frontwalldiffusers.jpg  
Old 30th September 2013
  #307
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Leanfusers + QRD Diffusers

Quote:
Originally Posted by tinnitusintx View Post
Got some Danish oil on the Leanfusers and everything mounted up.
Michael, great job with the build. It looks beautiful after being oiled!

Eventually I'd like to put up a gallery of people's DIY builds on Arqen.com, and I'm wondering, would you be aright if I showed a photo of yours?

You would get full credit, of course, since you're the one who built them and took the photo.

It's entirely up to you (no pressure). There are plenty of other photos I can put up, but it's nice to show some variety and you're build is different than most of them (and I like your way you've finished them with the Danish oil).

Nice work!

-Tim
Old 1st October 2013
  #308
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Sure thing, Tim. Help yourself! After all, at the end of the day they're your babies! Here are a few more shots.....use whatever you wish. Sorry about the cinder block speaker stands....just say the word and I'll get you something a little more photogenic. If you want something really nice give me a few weeks and I'll have the IRS Betas set up.....

http://www.bobbyshred.com/images/IRS_Beta.jpg

- Michael
Attached Thumbnails
DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-frontwalldiffusers2.jpg   DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-leanfuser.jpg  
Old 1st October 2013
  #309
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Fantastic, Michael. Don't worry about the cinder block speaker stands... I've definitely made my fair share of cinder block speaker stands / other temporary furniture. Of course, it would be great to see some shots whenever you get the IRS Betas set up.

Huge thanks for documenting your work and giving me permission to share the photos!

-Tim
Old 3rd October 2013
  #310
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I love the look and simple build of those finless diffusers. These will be what I will use for front and back walls and possibly ceiling.
Old 4th October 2013
  #311
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Quote:
Originally Posted by hornguy View Post
I love the look and simple build of those finless diffusers. These will be what I will use for front and back walls and possibly ceiling.
Right on! I too like finless designs because I believe the simplest solution to a problem is usually the best... its all about form following function, in a way that's easy to build. Glad you like them and I'd love to see how they look in your room when you're done.
Old 6th October 2013
  #312
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Thank you very much for sharing (for free!) these projects.

If I may ask: is there a way to reproduce the correct diffusion with a 3-module design instead of 5?

In a small room 2,1m large diffusor may be too much, I am looking for a middle size solution.

Again, thank you.
Old 6th October 2013
  #313
Old 7th October 2013
  #314
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Quote:
Originally Posted by OttoPus View Post
Thank you very much for sharing (for free!) these projects.

If I may ask: is there a way to reproduce the correct diffusion with a 3-module design instead of 5?

In a small room 2,1m large diffusor may be too much, I am looking for a middle size solution.

Again, thank you.

I would recommend making 3 A1-LF modules (or 3 A1-frac modules), and mounting the middle out so that it sticks out a bit from the other two. Several people have already done this. While the results have not been tested, I would try mounting the middle module so that it protrudes an additional 5 cm (or 6 cm) from the wall when compared to the side modules.

If you download the demo of AFMG reflex, you can test this to figure out the optimal depth for the middle module.

Hope this helps,

Tim
Old 7th October 2013
  #315
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I'll try, thank you!

If the results of the simulation are acceptable I'll share the graphs.
Old 7th October 2013
  #316
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Fantastic! It would be great to see the graphs.
Old 8th October 2013
  #317
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I will build the A1-LF modules for the rear wall in my listening room. I have 5000mm between the corner super chunk bass traps, what pattern or combination would be most effective along this wall?
Thanks in advance..
Old 8th October 2013
  #318
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I will build the A1-LF modules for the rear wall in my listening room. I have 5000mm between the corner super chunk bass traps, what pattern or combination would be most effective along this wall?
Thanks in advance..
Attached Thumbnails
DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-screen-shot-2013-10-08-4.26.17-pm.png  
Old 8th October 2013
  #319
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Quote:
Originally Posted by Arqen View Post
Fantastic! It would be great to see the graphs.
Here they are (its the first time I'm using this software, feel free to tell me if there's something wrong!):

Old 9th October 2013
  #320
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10-11 diffuser modules

Quote:
Originally Posted by hornguy View Post
I will build the A1-LF modules for the rear wall in my listening room. I have 5000mm between the corner super chunk bass traps, what pattern or combination would be most effective along this wall?
Thanks in advance..
Hmm, I was going to suggest 5 modules using Profiled Modulation 1 + 7 modules using Profiled Modulation 2, but they won't quite fit.

Here are some alternatives:
  • 2 arrays of 5 modules using Profiled Modulation 1
  • 1 array of 7 modules using Profiled Modulation 2, plus 2 additional modules mounted on either side (the depth to mount these side modules at can be determined using AFMG Reflex, otherwise you can try trusting your intuition).
  • 10 or 11 modules mounted using a new configuration that you determine through trial and error simulation in AFMG Reflex.

I expect the 3rd would have the best performance, but it would take some time to figure out the configuration. If you don't want to go through that effort, I'd probably choose the 2nd option.

Hope this helps,
Tim
Old 9th October 2013
  #321
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Quote:
Originally Posted by OttoPus View Post
Here they are (its the first time I'm using this software, feel free to tell me if there's something wrong!):

Glad to see you're testing this out!

Try running the simulation two more times. Once with the angle for the coefficient plot set to "diffuse field", and once with it set to 0 degrees. The diffuse field plot is most important.

Also, for comparison to other measurements, try doing the measurements with the resolution set to 1/3 octave.

If you want to quickly evaluate which configuration is best, you could vary the depth of the center module, and for each configuration run the simulation on the "diffuse field" setting, with a resolution of 1/3 octave.

E.g., you could do 7 trials of measurement with the center module sticking out 2cm, 3cm, 4cm, 5cm, 6cm, 7cm, 8cm


We would gain a lot of insight from that! Alternatively, you could just try for 5 different configurations (3cm, 4cm, 5cm, 6cm, 7cm).

Thanks for exploring the 3 module design configuration. I think you're the first person to actually measure the 3 module performance.
Old 16th October 2013
  #322
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Here they are!

First, a single module:
DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-singlemodule.jpg

2 through 8cm offset for the central module:

DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-2cm.jpg

DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-3cm.jpg

DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-4cm.jpg

DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-5cm.jpg

DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-6cm.jpg

DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-7cm.jpg

DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-8cm.jpg

(sry for the images quality, the forum resize them automatically)

Arqen, what are your thoughts about these simulations? What config is best?
Old 16th October 2013
  #323
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Hardly surprising; the configuration with the deepest total depth results in the highest “diffusion coefficient”, at least for lower frequencies. Worth pointing out once more, is that the diffusion coefficient values for such a small total period width is not representative for the actual performance of the diffuser since the criteria’s for diffusion coefficients is not met: the total period width needs to be at least 16 times larger than the total depth or at least 3 meters. A 3,6 meter total panel width is common to use when measuring or simulating diffuser performance. Smaller panel widths will show beefed diffusion coefficient values due to the small width.

Example: https://www.gearslutz.com/board/attac...efficients.gif
Old 16th October 2013
  #324
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Quote:
Originally Posted by OttoPus View Post
Here they are!

First, a single module:
Attachment 367717

2 through 8cm offset for the central module:

Attachment 367718

Attachment 367719

Attachment 367720

Attachment 367721

Attachment 367722

Attachment 367723

Attachment 367724

(sry for the images quality, the forum resize them automatically)

Arqen, what are your thoughts about these simulations? What config is best?
Hey OttoPus,

Thanks for taking the time to do these simulations! The best configuration would be either of the last 2.

The advantages of the 7cm version is it's lower profile, has (very slightly) better performance at 1 kHz, and slightly more even performance with respect to frequency.

As Jens mentioned, the 8cm version has better low frequency performance. It also has (very slightly) better performance at 1.6 kHz (and very slightly worse performance at 1kHz). Technically I would consider this version to be slightly better from a performance standpoint, but the difference is not very significant.

If you want to do one last experiment to find the best configuration, you could keep the center module at 8cm and run the test with the side modules raised 1cm, 2cm, 3 cm and 4 cm (and if you feel like it, you could also try 5 cm and 6 cm).

That should reveal the best 3 module configuration (that has a total depth < 14cm). Otherwise, if you'd rather get right to building the existing 7cm or 8cm version, that's fine too.

Thanks again for doing the measurements and posting these results. I appreciate it!
Tim
Old 18th October 2013
  #325
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Ready for finishes and assembly
Attached Thumbnails
DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-uploadfromtaptalk1382110416601.jpg   DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-uploadfromtaptalk1382110437734.jpg   DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)-uploadfromtaptalk1382110455144.jpg  
Old 20th October 2013
  #326
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Awesome! They look great!

Crisp, clean looking build. Nice work!
Old 20th October 2013
  #327
nms
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Subbed! You guys have some cool ideas going here
Old 2nd November 2013
  #328
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Argen, what do you think if the outside edges are rounded off with a router? Could possibly provide some better HF scattering? But I think the dimensions might need to be adjusted a bit.
Old 2nd November 2013
  #329
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I'm curious to know how everyone is making these, especially if CNC isn't available?

Is this something that could be made with a table saw?
Old 3rd November 2013
  #330
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Quote:
Originally Posted by OpusOfTrolls View Post
Argen, what do you think if the outside edges are rounded off with a router? Could possibly provide some better HF scattering? But I think the dimensions might need to be adjusted a bit.
That's an interesting idea. To make a significant different I expect you would have to apply this bevelling to as much of the surface as possible. In the extreme case, the surface of the diffuser could be a bunch of semi-cylinders instead of blocks.

In this case, I would keep the average depth of each step the same. This means you would have to increase the overall depth appropriately.

I think adding a high frequency fractal would be a more effective strategy (as it would diffuser HF energy in both space and time rather than just scattering it in space). But I do like your idea. Let us know if you decide to try it out!
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