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Author Topic: Broadband traps with "Homatherm FlexCl"  (Read 11490 times)

elmolemon

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Broadband traps with "Homatherm FlexCl"
« on: March 30, 2009, 11:31:00 am »

Hi,

i'm new in this forum and wanted to say hello to everybody! Smile


I plan to build some broadbandtraps for my homestudio and i plan to place them at the early reflection points similar to the following pictures:

http://www.johnlsayers.com/HR/images/room.jpg  

http://www.gearslutz.com/board/attachments/so-much-gear-so-little-time/25210d1160689897-my-insprirations-diy-basstrap-builders-neko-06.jpg



I already have superchunks in the corners of my room, but i want to place some absorption-panels left and right of my listening position and behind my speakers (like in the second picture).

I plan to use Homatherm flexCl as the insulation-material for my absorption panels and i plan to build them as broadband-panels to be effective even at low frequencies and to even out the low frequency response of my room.

How deep should i build the panels? I thought about 15-20cm. I ask because i've read that flexCl is almost too dense to be suitable for broadband-traps.

Otherwise i've seen that the insulation-material used for "Amsterdam Mastering" was flexCl and i like the idea that it is not a health issue like rockwool is/maybe.

Now i'm unsure if flexCl is the right material for my purpose (if yes, how deep should i build?) or if there is another favorable (european/german) material i should look into.

Thank you for your help!  Smile
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Thomas Jouanjean

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Re: Broadbandtraps with "Homatherm FlexCl"
« Reply #1 on: March 30, 2009, 01:41:32 pm »

Hi, and welcome!

For ER points I would try first with 10-12cm thick. Flex CL is really good in LF, and as broadband too (you can find info about the 4cm one on the german Homatherm site, it will show you it's a good broadband material.)

A good thing would be to have it with at least an air gap of 12-15cm from the wall. Maybe you can just build something really rough, install and try with 10 cm Flex CL + measure. If you feel you need more, then add up. When satisfied, build a clean looking system.

Beware that Flex CL has two sides, point the waffled side towards the wall.

We indeed use it on all our projects for some years now...
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Thomas Jouanjean
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elmolemon

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Re: Broadbandtraps with "Homatherm FlexCl"
« Reply #2 on: March 30, 2009, 03:57:05 pm »

Hi Thomas,

thanks a lot for your quick answer! Sounds great! I think i'll go with flexCl!  Very Happy
I'm really quite glad to have found my final material! Smile


But i have some more questions concerning the depth of the traps. You said 10-12cm for the ERs..  
So what depth would you recommend for the panel on the wall behind my speakers and which depth for the wall behind the listening position?

I know it's hard to tell, without knowing my room, but what would you recommend for efficient absorption?
I use K&H O300 which go down to 40 Hz and my room is 5,10x3,40x3,20m and i have it setup like in the first picture, with superchunks in the corners.


So:

1. I'm going to build panels like in the second picture for the ERs (wooden frame, depth:10-15cm) and try to place them 10cm off the wall, ok?

2. In which depth should i build the panels behind the speakers and on the back-wall (again they will look like in the second picture)?

3. I plan to add some more traps over the time behind me on the sidewalls. It should be ok to build them like the ER-panels (depth: 10-15cm), right?


Thanks again for your input!


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franman

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Re: Broadbandtraps with "Homatherm FlexCl"
« Reply #3 on: April 02, 2009, 10:03:56 am »

Thomas,

I looked at this material, and I'm interested in using it on some EU projects were doing. I can't seem to get the website to translate to English. is this a recycled celulose material??? You say you use it all the time (like I use OC 703)... You use this as the surface layer in trapping as well. Does it cut nicely and friction fit well into framing? Thanks.

FM
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Thomas Jouanjean

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Re: Broadbandtraps with "Homatherm FlexCl"
« Reply #4 on: April 02, 2009, 12:52:37 pm »

franman wrote on Thu, 02 April 2009 09:03

Thomas,

I looked at this material, and I'm interested in using it on some EU projects were doing. I can't seem to get the website to translate to English. is this a recycled celulose material??? You say you use it all the time (like I use OC 703)... You use this as the surface layer in trapping as well. Does it cut nicely and friction fit well into framing? Thanks.

FM


Hi Francis,

It is basically recycled paper. As I understood, a few companies collect all the unsold newspapers and magazines in a few EU contries and transform the whole thing into insulation bats. It's paper cellulose, with a flame retardant in it.

I use it for surface and/or inner parts of traps, depends on the project. I still use Rockwool sometimes in wall partitions but less and less. And it's usually a question of budget VS needed performance. I can ship you a couple samples if you want? It's always good to have it in hand and get a feel of it all. An interesting feature is the fact that there is waffled side and a soft side.

Overall, it's ok to use, very easy to glue for ex. It's not as bad for workers as rockwool or fiberglass, but it's hell dusty... And will seriously dry up the room in the begining. It can be hard to cut because of it's texture, your workers will need an electric saw to be efficient. It also "pushes" a lot so studs substructure needs to be well done and the bats cut max 10mm bigger than the frame. So use wise, it's pretty different from rockwool.
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Thomas Jouanjean
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franman

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Re: Broadband traps with "Homatherm FlexCl"
« Reply #5 on: April 02, 2009, 02:42:51 pm »

Thanks Thomas... I'll contact you about getting a sample. I think I know the stuff, as we have similar products here in the US, but I've never used it for acoustic treatments... only in exterior walls as thermal insulation. I've been 'shy' about trying it. Do you have any data on it's Absorption Coeficients, etc../???
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elmolemon

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Re: Broadband traps with "Homatherm FlexCl"
« Reply #6 on: April 02, 2009, 03:33:13 pm »

Great! Thank you Thomas for the additional info!

Maybe you have a sec to look at my other questions..  Embarassed
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Thomas Jouanjean

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Re: Broadband traps with "Homatherm FlexCl"
« Reply #7 on: April 02, 2009, 04:28:56 pm »

franman wrote on Thu, 02 April 2009 13:42

Do you have any data on it's Absorption Coeficients, etc../???


I'll PM you about that... The measurements are not public because privately financed.

Though there is public data availalble from the german site for 4cm one.
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Thomas Jouanjean
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Thomas Jouanjean

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Re: Broadband traps with "Homatherm FlexCl"
« Reply #8 on: April 02, 2009, 05:05:20 pm »

elmolemon wrote on Thu, 02 April 2009 14:33

Maybe you have a sec to look at my other questions...


Hey Smile

What I can recommend is that you play with air gaps and measure everytime you change the configuration. And basically take it step by step.

I propose you try and build really rough "prototypes", try out, measure, play with placement, amount of material (depth) and try to figure out the point where adding more has a marginal effect. This point is actually pretty obvious when measuring.

I know it sounds like a long process, but it'll allow you to learn the room and take the right decisions. From here I can only give you rather general advice. Once you get your LF rather controlled, then move on to diffusion etc.

For your front wall, these aren't so easy to figure out as (most) speakers are (quasi) omni in LF so your problem will be mainly to avoid boundary interferences with front wall in those freq. It's also a question of how much the boundary reflection will influence (smear) the bass response and what you can realistically do about it. 60Hz has a wavelength of ~5.73m, 40Hz of ~8.60m. Dealing with those is not easy! But 100Hz has a wavelength of 3.44m and is easier to treat. So the question is: what freq band is it worth treating your front wall with? 10cm should work fine, 15cm is a safe bet, 20cm is pbly overkill.

(EDIT to add to the general confusion: How much of those 40-60-80Hz will go through the wall? How much will stay in the room?)

I would maintain my attention on the front corner traps, but not necessarily do anything about the front wall itself. (Note to Elmolemon: I don't like absorptive front walls  Rolling Eyes )

Side walls + back walls need attention - be heavy handed with your back walls and corners.

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Thomas Jouanjean
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elmolemon

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Re: Broadband traps with "Homatherm FlexCl"
« Reply #9 on: April 03, 2009, 01:46:04 pm »

Thank you very much Thomas! This was some very important info for me!

I'll build and try what works best over here..  Very Happy
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franman

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Re: Broadband traps with "Homatherm FlexCl"
« Reply #10 on: April 06, 2009, 11:30:00 am »

Got to agree on the 'not liking absorptive front walls'  as well. If we're mounting monitors in-wall, then we like the wall to be extremely rigid and the surface hard.

FM
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Chris Griffith

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Re: Broadband traps with "Homatherm FlexCl"
« Reply #11 on: April 11, 2009, 12:40:50 pm »

franman wrote on Mon, 06 April 2009 09:30

Got to agree on the 'not liking absorptive front walls'  as well. If we're mounting monitors in-wall, then we like the wall to be extremely rigid and the surface hard.

FM


Does you feel the same if you're only using nearfields?
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franman

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Re: Broadband traps with "Homatherm FlexCl"
« Reply #12 on: April 11, 2009, 04:16:41 pm »

No.. not at all. In a room that is using ONLY stand mounted mid or near fields, my approach is completely different than in a room with wall-mounted main monitors. In this case, we almost always use deep trapping at the front corners and a soft front design.
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jimmyjazz

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Re: Broadband traps with "Homatherm FlexCl"
« Reply #13 on: April 11, 2009, 06:33:57 pm »

Is this material available in the states?  Fran, you hinted at a US version . . . any specifics?
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franman

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Re: Broadband traps with "Homatherm FlexCl"
« Reply #14 on: April 27, 2009, 10:55:46 pm »

(....Looooong Delay)....

Jimmy...no specific source, but I've seen this stuff before... Recycled 'stuff' mushed together into a spongy looking blanket.... (reminds me of the recycled sponge we've used in the carribean LOL)... I'd have to do some digging to find the US Equal... anybody else>???
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elmolemon

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Re: Broadband traps with "Homatherm FlexCl"
« Reply #15 on: May 12, 2009, 05:27:05 pm »

I try to enter the the final stage of my planing, but i still got some remaining questions..  Smile


franman wrote on Sat, 11 April 2009 22:16

No.. not at all. In a room that is using ONLY stand mounted mid or near fields, my approach is completely different than in a room with wall-mounted main monitors. In this case, we almost always use deep trapping at the front corners and a soft front design.


Hi Francis,

my room is setup quite similar to the room in the graphic in my first post above! What does your statement mean for my room concerning the front wall behind the stand mounted speakers?

I plan to place absorption panels behind my speakers and the front wall just like in the photo (see first post) above.



Thomas Jouanjean wrote on Thu, 02 April 2009 23:05


I would maintain my attention on the front corner traps, but not necessarily do anything about the front wall itself. (Note to Elmolemon: I don't like absorptive front walls  Rolling Eyes )

Side walls + back walls need attention - be heavy handed with your back walls and corners.




Hi Thomas,

i thought it would make sense to treat not only the front corners (which are already treated), but also the area behind my stand mounted speakers, as they are quite close to the front wall..

You wrote, i should be heavy-handed with the back of my room. How deep can i go with the flexCL without adding air gaps between the layers? I don't have too much space available and it would help me a lot if i had just a rough idea where a single layer of this material reaches its "limit".  I always feel a little discouraged if i read that flexCl is supposed to be most efficient in less deep layers and less efficient in deep layers due to its density..

I've read in the Amsterdam-Mastering construction thread that you use flexCl in layers of 10-12cm and above you also recommended 10-12cm for the early reflection points.  What does this mean for me in relation to the advice to be "heavy-handed" with my backwall? Can i forget about the forum-talk and go deeper without additional air gaps between the layers or would i waste my money on the material? Confused

Thanks a lot in advance!    
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Thomas Jouanjean

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Re: Broadband traps with "Homatherm FlexCl"
« Reply #16 on: May 13, 2009, 09:16:21 am »

Well... You need to calculate / figure out what your room needs and work from there. Did you measure?

My general advice is for sure to use air gaps/ have a distance from the walls! if you have it direct on the walls it will be less efficient (good to have it where there is velocity). If you want bit less deep system you can work with porous + tuned systems.

Attached a very quick and dirty explanation in drawing, it's easier than words. The formula is a good indicator, though in real-life, it does not behave exactly like that. But it's a good start!

Play around, test etc...

index.php/fa/12183/0/index.php/fa/12184/0/
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elmolemon

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Re: Broadband traps with "Homatherm FlexCl"
« Reply #17 on: May 13, 2009, 04:11:45 pm »

Shocked

Thanks a lot Thomas for your effort!!!

I did some measurements with fuzzmeasure and i got some peaks (55Hz & 110 Hz) and dips (72Hz & 144Hz).

From what i see on your graphic, i'm going to leave air gaps between my absorption panels and the walls for sure!  Smile

But to be honest i don't really "get" your graphic.  Rolling Eyes

About the formula: F= targeted frequency? Absorbed frequency? In which scale unit are "T" and "P"?  



Apart from that i don't want to keep on bugging you about the recommendable depth of the flexCL-layers too much, as i know your measurement data is private...  Embarassed

But as flexCL is avaiable in depths up to 18cm, maybe you can give me at least a hint if it makes sense to use it in (single-)layers of 18cm (or even more), without exceeding the absorption abilities of the material or if i should stick to less deep layers for an efficient material/absorption-ratio?
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J.F.Oros

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Re: Broadband traps with "Homatherm FlexCl"
« Reply #18 on: May 13, 2009, 04:31:36 pm »

At least for a theoretical point of view, to see how the absorption curve is affected by various values, you can also try to experiment different absorber thickness and air gaps with the very powerful porous absorber calculator written by Chris Whealy :
http://www.whealy.com/acoustics/Porous.html
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Thomas Jouanjean

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Re: Broadband traps with "Homatherm FlexCl"
« Reply #19 on: May 14, 2009, 05:35:38 am »

elmolemon wrote on Wed, 13 May 2009 15:11

Shocked
I did some measurements with fuzzmeasure and i got some peaks (55Hz & 110 Hz) and dips (72Hz & 144Hz).

[snip]


About the formula: F= targeted frequency? Absorbed frequency? In which scale unit are "T" and "P"?  



So you now have your main pb freqs identified, determine which mode they belong to now Smile and go from there. Room size will tell you that (size vs wave cycle length).

F= estimated lower frequency of efficiency (although, this is based on 1/4 wave theory, which is very debatable in itself. Treatment actually does work much lower than the results you get with this...)

T and P are in meters.
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Thomas Jouanjean
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Constantin

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Re: Broadband traps with "Homatherm FlexCl"
« Reply #20 on: May 14, 2009, 06:45:30 am »

Hi Thomas
What do you think about the results of the porous absorber caclulator?
Is this close to your real world experience in the bassfreq.
Since the Formula from Delany and Bazley (i think this calculator is bsed on this)is not good for low freq. what theory of calculating would you prefer?

cheers
constantin Razz
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