Absorption/Diffusion in my small room?

[Jens Eklund]

experimental skyline diffusor with pics - comments appreciated

1D diffusor - vertical or horizontal?

ISD gap for my room help pls!

4m x 5m x 2.5m room - modal resonance problem


Your room is small, so diffusers are not the first thing you should consider.

[Akayds]

Originally Posted by Jens Eklund

experimental skyline diffusor with pics - comments appreciated

1D diffusor - vertical or horizontal?

ISD gap for my room help pls!

4m x 5m x 2.5m room - modal resonance problem


Your room is small, so diffusers are not the first thing you should consider.

thanks for the very helpful information. Based on that, i think i am going to put absorption on the ceiling, first reflection points and some more on the side walls, 1D QRD diffusors on the rear wall and i cant reall work on the front wall theres a window. So, correct me if im still doing something wrong here please i appreciate the guidance

EDIT: oh and about my bass trap problem, i can only use 2 corners out of the 4 + all the ceiling corners and that's considering im using pressure based traps which takes less space. will that be a problem?

[Jens Eklund]

Originally Posted by Akayds

thanks for the very helpful information. Based on that, i think i am going to put absorption on the ceiling, first reflection points and some more on the side walls, 1D QRD diffusors on the rear wall and i cant reall work on the front wall theres a window. So, correct me if im still doing something wrong here please i appreciate the guidance

EDIT: oh and about my bass trap problem, i can only use 2 corners out of the 4 + all the ceiling corners and that's considering im using pressure based traps which takes less space. will that be a problem?

Do you realize that your ISD-gap will be very short if you decide to use diffusers on your rear wall? If you are ok with that (a short ISD-gap), you do not want to add broadband absorption on your rear sidewalls since this will defeat the purpose of the diffusers. Use pressure based absorption on any surface not related to early reflections if you intend to achieve a good termination of your ISD-gap and a (semi) diffuse field following it.

[Akayds]

Originally Posted by Jens Eklund

Do you realize that your ISD-gap will be very short if you decide to use diffusers on your rear wall? If you are ok with that (a short ISD-gap), you do not want to add broadband absorption on your rear sidewalls since this will defeat the purpose of the diffusers. Use pressure based absorption on any surface not related to early reflections if you intend to achieve a good termination of your ISD-gap and a (semi) diffuse field following it.

right, im far from being a master at this h. so what do you think my acoustic treatment set up should be in my room then? if i want an ideal ISD-gap for home studio. Just absorption pannels?

[Jens Eklund]

Originally Posted by Akayds

right, im far from being a master at this h. so what do you think my acoustic treatment set up should be in my room then? if i want an ideal ISD-gap for home studio. Just absorption pannels?

It is not possible to achieve an “ideal” ISD-gap (assuming a termination of it) in such a small room. This is why diffusers shouldn’t be your main priority. Not saying you can’t use diffusers in that room, but if you decide to do so; you really need to understand what diffusers do (and what they don´t) and how to use them properly, but before all that; you need to measure your room in order to know what needs to be done depending on what kind of speaker response you want (and what is possible considering your room size). Focus on your early reflections and modal/SBIR issues first.

[Radial185]

Originally Posted by Jens Eklund

Do you realize that your ISD-gap will be very short if you decide to use diffusers on your rear wall? If you are ok with that (a short ISD-gap), you do not want to add broadband absorption on your rear sidewalls since this will defeat the purpose of the diffusers. Use pressure based absorption on any surface not related to early reflections if you intend to achieve a good termination of your ISD-gap and a (semi) diffuse field following it.

Could he not make broadband traps on the sidewalls reflective with a plastic covering underneath to still make the diffusion effective? Mids and highs not effected?

[Akayds]

Originally Posted by Jens Eklund

It is not possible to achieve an “ideal” ISD-gap (assuming a termination of it) in such a small room. This is why diffusers shouldn’t be your main priority. Not saying you can’t use diffusers in that room, but if you decide to do so; you really need to understand what diffusers do (and what they don´t) and how to use them properly, but before all that; you need to measure your room in order to know what needs to be done depending on what kind of speaker response you want (and what is possible considering your room size). Focus on your early reflections and modal/SBIR issues first.

ill keep that in mind, i have checked these modes calculators and stuff but im not sure what to do with the information it gives me which leads me to not being able to do anything about it cuz i dont understand the numbers

im reading about it now

EDIT: k so now i understand what axial tengential and oblique modes are and how it can be problematic, so if i understand correctly i should treat the room to minimize modes? p.s. i calculated modes for my room with http://www.bobgolds.com/Mode/RoomModes.htm maybe you could help me understand what the results mean, all i understand so far is that the lows are problematic

[Jens Eklund]

Originally Posted by Akayds

ill keep that in mind, i have checked these modes calculators and stuff but im not sure what to do with the information it gives me which leads me to not being able to do anything about it cuz i dont understand the numbers

im reading about it now

EDIT: k so now i understand what axial tengential and oblique modes are and how it can be problematic, so if i understand correctly i should treat the room to minimize modes? p.s. i calculated modes for my room with http://www.bobgolds.com/Mode/RoomModes.htm maybe you could help me understand what the results mean, all i understand so far is that the lows are problematic

Again: First you do measurements. Once done, you can see what your actual problems are (instead of trying to predict them, this might be useful if you´re building a room from scratch and want to avoid modal cluttering). Identify your modal issues by looking at the decay plots (waterfalls etc.) and then find out what surfaces are related to your problematic modes (and now you can use modal calculators to get a hint of your modal frequencies but remember that modal calculators are a simplification of the real world so unless your room is a perfect rectangular space with solid boundaries and no openings, the reality will differ from the predictions).

[Glenn Kuras]

1) some ppl say diffusers wont do much in a small room although they also say it helps make a small room sound larger than it is, so should i make diffusers? if so, what type of diffuser am i looking for and where should i place them?

(i love the look of skyline diffusers and thought i could cover the ceiling with it but should i?)

The problem is not the upper frequencies in your room but the low end. You really should focus on bass trapping.

2) if i do not need diffusers i was planning on making 12 pannels of 24"x48"x2" in mineral wool/fiberglass 703 does that sound correct? im afraid to kill the sound instead of treating it(p.s. 12 is if i dont need diffusors)

If you put 2" panels all over the place you will end up absorbing the upper frequencies but the low end will be bouncing all over the place. Once again you need bass trapping. Make the panels 4" or thicker and straddle as many corners as possible with them. Don't forget that a room has 12 corners you can put bass trapping - Ceiling to wall corners, wall to wall corners and floor to wall corners. See the following video that talks about corners and testing
Video: Testing Bass Trap Placement
Your room is small so most of the room "tone" you might have is not really all that useful. Most of it is just a comb filtering mess.

Edit: You can also mix in some tuned trapping in your room but you really want to start with broad band in corners. See the following test with broad band and adding tuned after.
GIK or Realtraps?

[Akayds]

Originally Posted by Glenn Kuras

The problem is not the upper frequencies in your room but the low end. You really should focus on bass trapping.



If you put 2" panels all over the place you will end up absorbing the upper frequencies but the low end will be bouncing all over the place. Once again you need bass trapping. Make the panels 4" or thicker and straddle as many corners as possible with them. Don't forget that a room has 12 corners you can put bass trapping - Ceiling to wall corners, wall to wall corners and floor to wall corners. See the following video that talks about corners and testing
Video: Testing Bass Trap Placement
Your room is small so most of the room "tone" you might have is not really all that useful. Most of it is just a comb filtering mess.

Edit: You can also mix in some tuned trapping in your room but you really want to start with broad band in corners. See the following test with broad band and adding tuned after.
GIK or Realtraps?

thanks for the info, ur right, but is there a way to make diy pressure based bass traps? cuz the pannels in corners will take alot of space in my room which is already quite small. also, pressure based bass traps are like a specific material with an odd shape i hardly believe it cant be reproduced at home.

p.s. heres a sketch of my room

[GIK Acoustics]

Originally Posted by Akayds

thanks for the info, ur right, but is there a way to make diy pressure based bass traps? cuz the pannels in corners will take alot of space in my room which is already quite small. also, pressure based bass traps are like a specific material with an odd shape i hardly believe it cant be reproduced at home.

As stated earlier, I would focus on broadband absorption. Around 12 panels would be a good start, though 2" won't do much to help the low end significantly. I would definitely recommend at least 4" thick traps.

Pressure based traps are great, but they are difficult to construct properly, and a lot of people build ones that fail. Not saying you can't do it, but I've just seen lots of unsuccessful DIYs (here on Gearslutz) so I'd make sure you do a lot of research on the subject before building them. Until then, thick broadband trapping can do a lot of wonders for a small room, so I'd start there. This way you will have only a couple problem frequencies so you know exactly what you need to tune your pressure traps to, and how wide of a Q you need, etc..

We have a lot of general info on our Acoustics Primer on our site you can check out to get the general idea of some of the room problems and how to properly treat them here: Acoustic Primer - Room Setup, Testing, Treatments

[Glenn Kuras]

thanks for the info, ur right, but is there a way to make diy pressure based bass traps? cuz the pannels in corners will take alot of space in my room which is already quite small. also, pressure based bass traps are like a specific material with an odd shape i hardly believe it cant be reproduced at home.

To also add to what Alex said, you also need to know where to place them and what frequency to tune the traps. Small rooms have problems through out the low end so you would end up building different ones for different frequencies and placed in different areas. Where with broad band it is what it is, broadly covering more frequencies. Not to mention it takes a lot of them.
As far as taking up room you would be surprised how much room is does not take up and you can always cover ceiling to wall corners around the room. The following video talks about testing corners but also explains different corners in the room.
Video: Testing Bass Trap Placement

[Akayds]

Alright thanks alot as soon as my room is ready ill start measuring. By the way 2 days ago i bought 12 x roxul safe n sound 3 inches thick 2by4 rockwool. I was planning to make 12 pannels should i really have minimum 12x 4 inches thick pannels?

Sent from my Galaxy Nexus using Tapatalk

[Glenn Kuras]

Just make as many as you can.. You can always add more over time.

[Akayds]

By the way is 3 inches thick fine for broadband pannels? Or should i really be lookin for minimum 4 inches?

Sent from my Galaxy Nexus using Tapatalk

[Glenn Kuras]

Originally Posted by Akayds

By the way is 3 inches thick fine for broadband pannels? Or should i really be lookin for minimum 4 inches?

Sent from my Galaxy Nexus using Tapatalk

For straddling corners no less the 4 inches and honesty if you have the funds go with 6 or more inches.

[boggy]

Originally Posted by Akayds

Room Dimensions:
Length: 11.5ft
Width: 9.2ft
Height: 8ft

Heavy LF absorption below 200Hz (in every corner and wherever it works, is needed to maintain damping of all relevant room interferences) AND strong diffuse field (to bring back reflections) is needed for your room.
You don't need to care about an ISD gap, especially in a such small room (IMHO)

Originally Posted by Akayds

Hey guys, i read for quite a while on the subject but i still need help. My room is currently not treated at all and i will start making DIY pannels as soon as im done painting it and here are my questions:

1) some ppl say diffusers wont do much in a small room although they also say it helps make a small room sound larger than it is, so should i make diffusers? if so, what type of diffuser am i looking for and where should i place them?

You need both...
Your diffusers need to work from about 1kHz (10-15cm depth)

Originally Posted by Akayds

(i love the look of skyline diffusers and thought i could cover the ceiling with it but should i?)

Yes, try not to stop LF absorption with it. Keep air flow continuous, and uninterupted to your LF absorption behind diffusers.

Originally Posted by Akayds

2) if i do not need diffusers i was planning on making 12 pannels of 24"x48"x2" in mineral wool/fiberglass 703 does that sound correct? im afraid to kill the sound instead of treating it(p.s. 12 is if i dont need diffusors)

You need both... as I said already....

In AES paper:
Davidovic Z., Petrovic B.: Acoustical Design of Control Room for Stereo and Multichannel Production and Reproduction - A Novel Approach, 129th AES Convention 2010, San Francisco, CA, USA, I actually show a new acoustical treatment of two small rooms (one of it is a bit bigger than yours) with measurement results, and following basic principles I already describe above (in short).
Later, this topic is discussed here: MyRoom Acoustic Design
With more information and (free) papers.

Originally Posted by Akayds

EDIT: 3) the rear wall right corner is blocked by a door (cant put basstraps) and also the front door left corner, should i still put basstraps on the 2 remaining corners? and do i absolutely need basstraps on ceiling corners?

use ceiling corners above doors, but try to keep symmetry. You really need to damp down all room interferences below about 200Hz

Originally Posted by Akayds

thanks alot guys you're really helpful!

feel free to ask specific questions about the room i have to work with

You're welcome!
Before all, you need to take care for a best position of your loudspeakers and listener... using acoustical measurements
Try to find useful advices about this topic here:
Speaker placement methods
(thread is short, no long debate there)

Good luck!

[Akayds]

Also, should i fill the corner with roxul or put the pannel and leave the corner empty (slash let air behind)

Sent from my Galaxy Nexus using Tapatalk

Edit : thanks alot boggy ill be lookin into it altho im a bit more confused now haha

[boggy]

Originally Posted by Akayds

....
Edit : thanks alot boggy ill be lookin into it altho im a bit more confused now haha

Try to prepare yourself and learn something before you start.... improvisations arent helpful if you don't know what you doing.

For small rooms LF treatment, I think this thread is useful:

Tim's Limp Mass Bass Absorbers

[Akayds]

Thanks, really good thread although there is alot of debating goin on there. I havent studied in acoustics so i dont completely follow all the posts on gearslutz and the more i read about it the more i feel like its more complicated than it should be for my room :/ is there a link on how to make diy bass traps version of like vicoustics because 12" deep pannels at 45 degrees in corners is really starting to take some space :(

Edit: update, i have bought rockwool and its supposed to be 40kg/m cube as i read online but i didnt find the density on the package itself. there is 12 sheets of 3 inches thick u think that will do it? To have at least a significant upgrade?

Sent from my Galaxy Nexus using Tapatalk

[Akayds]

So i just reread the whole thread and i overlooked glenn's response about the thickness e damn smartphones, anyway i decided i was gna make 6 inch rockwool basstraps and 3 inch pannels at first reflection and im gonna go from there, ill measure the room first this weekend tho just to make sure and ill post the results, thanks to all the replies!

Sent from my Galaxy Nexus using Tapatalk

[boggy]

Originally Posted by Akayds

Thanks, really good thread although there is alot of debating goin on there. I havent studied in acoustics so i dont completely follow all the posts on gearslutz and the more i read about it the more i feel like its more complicated than it should be for my room :/ is there a link on how to make diy bass traps version of like vicoustics because 12" deep pannels at 45 degrees in corners is really starting to take some space :(
........

try this: My Experiment with a Metal Panel Absorber

(it's long thread, but there you can find information about "thin" LF broadband absorbers)

Also, link I already post above, is again about resonant absorbers...
Resonant absorbers is more complicated, I don't recommend it to non skilled people, but they are only way to save some space and get acceptable LF treatment.

[Akayds]

Nice stuff! I think ill still go with the 6" rockwool since im not an expert, but will definitely try this later. It looks promising

Sent from my Galaxy Nexus using Tapatalk

[pitchfork]

damn smartphones

Yeah, and some people are trying to MIX on them

In regards to your threads title...

I posted the same question over 10 years ago on an acoustics forum.
That thread is now part of a Science website database. I think you might find it interesting if nothing else.

http://www.natscience.com/Uwe/Forum....act-or-fiction


btw..this thread might be viewed by some here as..ad-nauseum. Ignor it

[Akayds]

I will be reading this thanks

Sent from my Galaxy Nexus using Tapatalk

[Akayds]

Alright, update, im about to install pannels but ive encountered what could be a potential problem. I have a wardrobe really close to the left front corner and 6'8" tall and i was goin to change the door so i can put basstraps in the corner and above the wardrobe door while having access to the wardrobe. Now i had it all figured out till i found out the kind of door i would need is like accordion doors made of like vinyl plates. Will that be a problem? If so how can i treat the wardrobe issue to make it as if it was a wall? I also forgot to mention it is pretty damn close to the first reflection point which i havent pinpointed yet. Thanks in advance!

Sent from my Galaxy Nexus using Tapatalk

[boggy]

Originally Posted by Akayds

Alright, update, im about to install pannels but ive encountered what could be a potential problem. I have a wardrobe really close to the left front corner and 6'8" tall and i was goin to change the door so i can put basstraps in the corner and above the wardrobe door while having access to the wardrobe. Now i had it all figured out till i found out the kind of door i would need is like accordion doors made of like vinyl plates. Will that be a problem? If so how can i treat the wardrobe issue to make it as if it was a wall? I also forgot to mention it is pretty damn close to the first reflection point which i havent pinpointed yet. Thanks in advance!
......

You can build movable trap/panel over wardrobe door, so when you need wardrobe, move your panel....

[Akayds]

Im already building a movable basstrap for the corner, also above the door if i put a bass trap the door wont open unless it can open sideways or take a little space when opened(accordion) its really the bass trap above it that takes like an inch on the upper door :/

Sent from my Galaxy Nexus using Tapatalk

[boggy]

Originally Posted by Akayds

Im already building a movable basstrap for the corner, also above the door if i put a bass trap the door wont open unless it can open sideways or take a little space when opened(accordion) its really the bass trap above it that takes like an inch on the upper door :/

Sent from my Galaxy Nexus using Tapatalk

It will be better if you draw something about what you plan to build, so we can better understand you.
try Trimble SketchUp, it's free.