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DIY Diffusors to the Max
Old 9th May 2015 | Show parent
  #481
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Flooring

Quote:
Originally Posted by G. E. View Post
I just recently worked on the acoustics of a new rehearsal room (±213m^2 floor; ±1.362m^3 volume [[±2,293 square feet; ±48,100 cubic feet) using quite some 1D (walls) and 2D (ceiling) diffusorbers. See some work-in-progress pic and preliminary measurements (floor tiles still to come). The acoustic civil engineer basically called for RT60 = 0,6 ± 0,2s (including 45-75 musicians), preliminary measurements (before/after) taken without musicians, so the rise above 1kHz is part of the equation.
Flooring by the client was in the works last week -- final measurements getting closer ...
Attached Thumbnails
DIY Diffusors to the Max-_dsc2809.jpg   DIY Diffusors to the Max-_dsc2810.jpg   DIY Diffusors to the Max-_dsc2819.jpg  
Old 10th May 2015 | Show parent
  #482
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Question

Quote:
Originally Posted by G. E. View Post
Couldn't resist to process the file (into a MP3) to bring out the reverb (with some Waves L2 gain, the fabulous Waves Kramer PIE and Waves L3-LL Multiband for slight eq & limiting).
Sounds great. Again, if you can share any info on how you calculated your 2D pattern I would appreciate it.

Also, I'm wondering what the reason for your decision to use 1D patterns over the wall traps was. Why not just use the 2D pattern there as well? Was it an aesthetic choice? Or was their an acoustic reason?

Thanks.

Last edited by audiovisceral; 10th May 2015 at 05:27 AM..
Old 10th May 2015 | Show parent
  #483
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robertopisa's Avatar
Reference to Schroeder's book and link to the 2D pattern in AutoCad (RPG BAD panel)

https://www.gearslutz.com/board/9413912-post113.html

-R

Quote:
Originally Posted by audiovisceral View Post
Sounds great. Again, if you can share any info on how you calculated your 2D pattern I would appreciate it.

Also, I'm wondering what the reason for your decision to use 1D patterns over the wall traps was. Why not just use the 2D pattern there as well? Was it an aesthetic choice? Or was their an acoustic reason?

Thanks.
Old 11th May 2015 | Show parent
  #484
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1D/2D Decisions

Quote:
Originally Posted by audiovisceral View Post
... I'm wondering what the reason for your decision to use 1D patterns over the wall traps was. Why not just use the 2D pattern there as well? Was it an aesthetic choice? Or was their an acoustic reason? ...
There are various reasons, first of all I prefer 1D at walls whenever there is an additional massive absorber (the audience or in this case the musicians) near the floor. Basically I want to keep the diffuse reflections within ears reach, no further use to "send" the "horizontal" part to the floor or the ceiling. It helps to get a sense for the room as well. Furthermore the 1D diffusorbers needed to be much more stable because they are physically exposed to human beings. After that I designed/calculated patterns to fit well acoustically (the 1Ds have less absorption on the top as well as the very low end) and aesthetically (well, hopefully). As for the patterns themselves they are large MLS, "folded" in regard to the Chinese Remainder Theorem for the 2D-pattern.
Old 13th May 2015 | Show parent
  #485
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Small Odd Room 1D/2D Workout

Quote:
Originally Posted by G. E. View Post
There are various reasons, first of all I prefer 1D at walls whenever there is an additional massive absorber (the audience or in this case the musicians) near the floor. Basically I want to keep the diffuse reflections within ears reach, no further use to "send" the "horizontal" part to the floor or the ceiling. It helps to get a sense for the room as well. Furthermore the 1D diffusorbers needed to be much more stable because they are physically exposed to human beings. After that I designed/calculated patterns to fit well acoustically (the 1Ds have less absorption on the top as well as the very low end) and aesthetically (well, hopefully). As for the patterns themselves they are large MLS, "folded" in regard to the Chinese Remainder Theorem for the 2D-pattern.
BTW the 1D/2D combination worked out fine in the smaller rooms too, see pics of one of them (additional bass traps in the air condition casing still to be done).
Attached Thumbnails
DIY Diffusors to the Max-_dsc2813.jpg   DIY Diffusors to the Max-_dsc2815.jpg   DIY Diffusors to the Max-_dsc2814.jpg  
Old 13th May 2015 | Show parent
  #486
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Quote:
Originally Posted by G. E. View Post
BTW the 1D/2D combination worked out fine in the smaller rooms too, see pics of one of them (additional bass traps in the air condition casing still to be done).
Nice room. But what about bass trapping ?
Old 13th May 2015 | Show parent
  #487
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Bass Trapping Again

Quote:
Originally Posted by Bilou View Post
Nice room. But what about bass trapping ?
There's already quite some "bass trapping" in the empty room because of the way the room is built (see measurement of the naked room). Some additional bass trapping was done after the photos, final measurements awaiting ...
Attached Thumbnails
DIY Diffusors to the Max-20150417-m03-r2-dodo-sub.jpg  
Old 13th May 2015 | Show parent
  #488
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Quote:
Originally Posted by Bilou View Post
Nice room. But what about bass trapping ?
There is no need for "bass trapping" if room doesn't have bass (LF resonance) problems... as you can see on the measurement graph.


Old 14th May 2015 | Show parent
  #489
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Quote:
Originally Posted by boggy View Post
There is no need for "bass trapping" if room doesn't have bass (LF resonance) problems... as you can see on the measurement graph.


Hi Boggie,

I was talking about the little room. The measurements show no big problems, but the actual RT for high frequencies has certainly be lowered to 0.5/0.6 with the panels, right ?
So bass trapping seems essential to keep a similar RT through the entire spectrum.

G.E., did you use plasterboard construction as bass trapping in the construction of the room ?

Very interested in the final results, as the room looks really nice !
Old 14th May 2015 | Show parent
  #490
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Quote:
Originally Posted by Bilou View Post
Hi Boggie,

I was talking about the little room. The measurements show no big problems, but the actual RT for high frequencies has certainly be lowered to 0.5/0.6 with the panels, right ?
So bass trapping seems essential to keep a similar RT through the entire spectrum.

....
Ah, smaller room, sorry... I can't be sure, because I don't know what is the source of the peak of the decay in the (low) midrange ....

EDIT: I don't see real bass problems, there... anyhow

Last edited by boggy; 14th May 2015 at 11:38 AM..
Old 14th May 2015 | Show parent
  #491
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Odd Room Details

Quote:
Originally Posted by Bilou View Post
... G.E., did you use plasterboard construction as bass trapping in the construction of the room? ...
There were finished plans to do some boundaries out of plasterboard when I started acoustic calculations so I had to weigh them in. The civil engineer basically asked for T60 = 0.4s in the finished room. Size is 32m^2 (~345 square feet).
Old 14th May 2015 | Show parent
  #492
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Quote:
Originally Posted by G. E. View Post
There were finished plans to do some boundaries out of plasterboard when I started acoustic calculations so I had to weigh them in. The civil engineer basically asked for T60 = 0.4s in the finished room. Size is 32m^2 (~345 square feet).
Thank you for the details.
Old 25th April 2016
  #493
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Small "MyRoom Acoustic Design"-inspired room

Another example of a small (net space = ~11m^2 [~120 ft^2]) control room with 1D/2D amplitude grating diffusors over up to 45cm [~1'6"] deep absorption on (slanted) walls and sloped ceiling. Design inspired by Boggy's MyRoom Acoustic Design (PDF).
Attached Thumbnails
DIY Diffusors to the Max-dsc_0008.jpg  
Old 25th April 2016 | Show parent
  #494
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Quote:
Originally Posted by G. E. View Post
Another example of a small (net space = ~11m^2 [~120 ft^2]) control room ....
That looks interesting! Thanks for sharing

Best

Ake
Old 26th April 2016 | Show parent
  #495
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Small room details

Quote:
Originally Posted by akebrake View Post
... Thanks for sharing ...
My pleasure! I'm happy to report that the room is very tight (T30 = ~150ms above 500Hz and ~100ms below 500Hz with the longest mode of [email protected]) and well within AES recommendations. FR (using Genelec 1032A in Stereo) is ±2dB from 40Hz-200Hz unsmoothed and without any EQing. BTW: further optimization still needs to be done at desk, monitor and siderack positioning because of unwanted reflections (most common problem in control rooms). Stereo measurement from preliminary listening position (~40% from back wall).
Attached Thumbnails
DIY Diffusors to the Max-20160415-dk-m02-s.jpg  
Old 26th April 2016 | Show parent
  #496
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Quote:
Originally Posted by G. E. View Post
...over up to 45cm [~1'6"] deep absorption...
Whoa! Over a foot of absorption? What materials are used? 703 (or the like) or fluffy stuff? Or the combination thereof?
Old 27th April 2016 | Show parent
  #497
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Absorbent

Quote:
Originally Posted by azzzy View Post
... What materials are used? ...
I've used 10kPa s/m² absorbent in thicknesses from 5cm to 45cm [~2" to 1'6"]. I may have used 5kPa s/m² material additionally if the room geometry were more cuboid like but here I had to deal with a lot of corners, pipes and stuff that prevented exact calculations. Basically I just filled each gap.

The main design feature -- as pointed out in "MyRoomAcoustic Design" -- here is massive absorption (as allowed by space restrictions) on walls/ceiling, covered with controlled air transparent diffusors.

Rendering shows the basic layout from above the ceiling, the odd geometry comes from two doors that had to stay accessible.
Attached Thumbnails
DIY Diffusors to the Max-20160205-dk-studio-v04b.jpg  
Old 28th April 2016 | Show parent
  #498
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Hi i really need help with using a diffuser calculator.
Im building a custom skyline diffuser : Width 65cm & length 105cm

I have no idea how to use the calculator or which calculator on this website mh-audio.nl - Acoustic to use

can anyone help and post me the correct grid for the diffuser dimension mentioned above ill also like the frequency to range from 800hz to 4Khz or 5kHZ

any help will be appreciated

Thank you
Old 13th November 2016 | Show parent
  #499
GE, I'm curious about how you use your 1D designs.

Using round numbers, let's assume a wall is 10' long x 10' high = 100 sqft of wall. Add a 4' x 8' absorber for 32 sqft, 32% coverage on the wall. The effect of this is easy enough to calculate depending on the absorbent material.

My assumption is if we add slats to cover ~50% randomly, for the purposes of the control room calculator, this becomes 16% coverage above the "filter" frequency, and 32% below. That is, depending on the 1D dimension, below a certain frequency the slats will not reflect (wavelength too long) and above that frequency they will.

Is that correct?
Old 14th November 2016 | Show parent
  #500
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Customizing diffusors

Quote:
Originally Posted by bionic101 View Post
Hi i really need help with using a diffuser calculator.
Im building a custom skyline diffuser : Width 65cm & length 105cm

I have no idea how to use the calculator or which calculator on this website mh-audio.nl - Acoustic to use

can anyone help and post me the correct grid for the diffuser dimension mentioned above ill also like the frequency to range from 800hz to 4Khz or 5kHZ

any help will be appreciated

Thank you
From what I see mh-audio offers a simple calculator that helps to slightly customize a well known BBC skyline diffusor design. It will always be a 12x12 grid so you may fit two equally sized diffusors for example like this in your area.
Old 14th November 2016 | Show parent
  #501
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Coverage

Quote:
Originally Posted by dogears View Post
GE, I'm curious about how you use your 1D designs.

Using round numbers, let's assume a wall is 10' long x 10' high = 100 sqft of wall. Add a 4' x 8' absorber for 32 sqft, 32% coverage on the wall. The effect of this is easy enough to calculate depending on the absorbent material.

My assumption is if we add slats to cover ~50% randomly, for the purposes of the control room calculator, this becomes 16% coverage above the "filter" frequency, and 32% below. That is, depending on the 1D dimension, below a certain frequency the slats will not reflect (wavelength too long) and above that frequency they will.

Is that correct?
I'm not sure if I understand you correctly - do you want to cover 50% of the bass trap area with slats? This is basically a quite good idea for a control room if the bass trapping covers the whole wall! Otherwise there's less need to cover an absorber.

Better to start a new thread where you disclose more detailed plans of the whole room!

~50% covering works just fine when you cover all walls and are prepared for a quite short decay (see pic).
Attached Thumbnails
DIY Diffusors to the Max-gernot_ebenlechner_raumakustik_ts_dsc_0020_gearslutz.jpg  

Last edited by G. E.; 14th November 2016 at 04:01 PM..
Old 14th September 2018
  #502
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Project Studio

FYI, preliminary pic and measurement from a quite small project studio room (21,5m^2 [~231 square foot] combined control room & recording space) with mobile broadband "diffusorbers", bass traps, and EPAs. Two-day build. Longest decay: 350ms @ 48,5Hz.
Attached Thumbnails
DIY Diffusors to the Max-gernot_ebenlechner_raumakustik_po-dsc_8024.jpg   DIY Diffusors to the Max-201807xx-po.t30.gif  
Old 14th September 2018
  #503
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What are these panels? Did you design them? Looks very nice
Old 17th September 2018 | Show parent
  #504
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Custom Diffusorbers

Quote:
Originally Posted by JayPee View Post
What are these panels? Did you design them? Looks very nice
Thanks, glad you like it ... I calculated/designed these custom panels (mounted in front of bass trap modules based on simple air velocity based absorbers) as part of the acoustic treatment for the client (actually as an "upgrade" including modules from their old studio). Usually rooms like this come "as they are", far from being the perfect studio spaces to start with. Anyway my job is to get the acoustics done within a budget. Most of the time I have to optimise for floor space as well and end up building custom modules based on my preferred basic module designs (such as deep diffusorbers for example).
Old 18th September 2018 | Show parent
  #505
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Quote:
Originally Posted by JayPee View Post
What are these panels? Did you design them? Looks very nice
RPG Bad Panel -- Detailed Plans
Old 19th September 2018 | Show parent
  #506
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Good Or Bad

Quote:
Originally Posted by dinococcus View Post
Sure, both (and probably some more out there) share common amplitude grating diffusor attributes. You'll find differences in module size, hole spacing, hole diameter, chosen number theory fundament, marketing messages, and much more ... you guess it.
Old 20th September 2018
  #507
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Anyway, I get the idea thanks guys!
Old 4th November 2018 | Show parent
  #508
Quote:
Originally Posted by G. E. View Post
Sure, both (and probably some more out there) share common amplitude grating diffusor attributes. You'll find differences in module size, hole spacing, hole diameter, chosen number theory fundament, marketing messages, and much more ... you guess it.
how are you folding these Gernot? how did you generate the MLS?

i generated the attached patterns for n<=15 using scipy signal.max_len_seq(n) function....weird that for n10 p=31 q=33 i get the rpg pattern but shifted regarding symmetry
Attached Thumbnails
DIY Diffusors to the Max-n1123x89.png   DIY Diffusors to the Max-n1235x117.png   DIY Diffusors to the Max-n12_45x91.png   DIY Diffusors to the Max-n12_63x65.png   DIY Diffusors to the Max-n15_151x217.png  

DIY Diffusors to the Max-n14_127x129.png   DIY Diffusors to the Max-n10_33x31.png   DIY Diffusors to the Max-n8_15x17.png  
Old 7th January 2019 | Show parent
  #509
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Unfolding

Quote:
Originally Posted by housegezeichnet View Post
how are you folding these Gernot? how did you generate the MLS?

i generated the attached patterns for n<=15 using scipy signal.max_len_seq(n) function....weird that for n10 p=31 q=33 i get the rpg pattern but shifted regarding symmetry
Basically I've applied Wikipedia information on Maximum length sequence and Chinese remainder theorem to calculate patterns.

As you already showed varying the seed sequence some symmetrical patterns come up (for example with seed 0001111111) while others look "shifted" regarding symmetry. I guess the RPG pattern you mentioned has either another one of the 1023 possible seeds (no 0000000000!) or they shifted the pattern "manually".
Attached Thumbnails
DIY Diffusors to the Max-20190107-33x31.gif  

Last edited by G. E.; 8th January 2019 at 09:39 AM..
Old 8th January 2019 | Show parent
  #510
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Quote:
Originally Posted by G. E. View Post
My pleasure! I'm happy to report that the room is very tight (T30 = ~150ms above 500Hz and ~100ms below 500Hz with the longest mode of [email protected]) and well within AES recommendations. FR (using Genelec 1032A in Stereo) is ±2dB from 40Hz-200Hz unsmoothed and without any EQing. BTW: further optimization still needs to be done at desk, monitor and siderack positioning because of unwanted reflections (most common problem in control rooms). Stereo measurement from preliminary listening position (~40% from back wall).
Was re-reading this thread, and may I know how the last measurement looks like? It's old, but, how did you get rid off the 90 HZ and 150 hz dips?

I have exactly the same freq. response right now in my unfinished room.
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