# Australia/Sydney Room Treatment Materials?



## liquidlino (Dec 29, 2022)

Looking to build my own panels. I can find lots of how-tos and seems straightforward (did joinery as a hobby for a while, so making some simple boxes is easypeasy). However, I don't want to use fiber-glass as the acoustic packing (as I understand it still sheds fibers, and my daughter and wife have asthma, and apparently it exacerbates it) - I saw some recommendations for material made from recycled jeans, but can't find it in Australia. Likewise, anything I find online that isn't glass wool etc, doesn't seem to want to ship to Sydney for some reason. Anyone have any recomendations for non-fiber-glass material that I can buy in Sydney or have delivered?


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## DCPImages (Dec 29, 2022)

liquidlino said:


> Looking to build my own panels. I can find lots of how-tos and seems straightforward (did joinery as a hobby for a while, so making some simple boxes is easypeasy). However, I don't want to use fiber-glass as the acoustic packing (as I understand it still sheds fibers, and my daughter and wife have asthma, and apparently it exacerbates it) - I saw some recommendations for material made from recycled jeans, but can't find it in Australia. Likewise, anything I find online that isn't glass wool etc, doesn't seem to want to ship to Sydney for some reason. Anyone have any recomendations for non-fiber-glass material that I can buy in Sydney or have delivered?


I did see acoustic foam / insulation in pyramid or egg-carton form at Clark Rubber if that is of any use.
D


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## liquidlino (Dec 29, 2022)

DCPImages said:


> I did see acoustic foam / insulation in pyramid or egg-carton form at Clark Rubber if that is of any use.
> D


Hmm, i understand foam to be too lightweight, only really helps with high end reflections. I'm looking to build panels about 20cm deep that should control down to low bass, 100hz or so.


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## milford59 (Dec 30, 2022)

Could you use fibreglass, but pack it into sealed plastic “pillows” of suitable dimensions offsite, before bringing it onsite and putting it into the panels? This should ensure that no fibres can leak and cause issues.


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## liquidlino (Dec 30, 2022)

milford59 said:


> Could you use fibreglass, but pack it into sealed plastic “pillows” of suitable dimensions offsite, before bringing it onsite and putting it into the panels? This should ensure that no fibres can leak and cause issues.


Interesting idea. You mean wrap it in gladwrap sort of thing? Would it still work though, I thought only breathable material could be used, non breathable like plastic blocks sound getting into the material and getting absorbed?


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## elucid (Dec 30, 2022)

I bought Earthwool from Bunnings and made frames for it then stretched calico over. They work so well as absorption panels.

I have a the whole back wall covered with the panels and one at the front above the monitor.

Edit: it’s not fiberglass and is non-itchy.









Earthwool R2.7 SHD 90mm x 580mm x 1160mm 6.7m² Insulation SoundShield Wall Batt - Pack of 10


Find Earthwool R2.7 SHD 90mm x 580mm x 1160mm 6.7m² Insulation SoundShield Wall Batt - Pack of 10 at Bunnings. Visit your local store for the widest range of products.




www.bunnings.com.au


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## elucid (Dec 30, 2022)

@liquidlino you are welcome to come and check them out if you want. I’m in Bondi if that’s local enough for you.


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## liquidlino (Dec 30, 2022)

elucid said:


> I bought Earthwool from Bunnings and made frames for it then stretched calico over. They work so well as absorption panels.
> 
> I have a the whole back wall covered with the panels and one at the front above the monitor.
> 
> ...


Oh wow, I didn't realise earthwool wasn't fiber glass! That's dead easy then. How deep are your panels, and do you by chance have a before and after measurement chart for your room? Particularly a waterfall?

I'm at St Ives, I might well take you up on your kind offer of a visit! We have family staying at the moment, but maybe in the next few weeks. 

Btw, great headphones collection. I also have hd650 and at-50. Don't recognise the others though?


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## Jdiggity1 (Dec 30, 2022)

I essentially did the same as @elucid. 2.7 Earthwool from Bunnings, built the frames with MDF (I should have gone with Pine) but I chose a fabric from Spotlight to wrap them in. Used weed netting on the backs. Not really sure why, in hindsight. Could have just gone with the same fabric all the way around.






Shitty pic, can't fit it all in on phone. Standard panels on side walls, one turned horizontal on the back wall behind big screen, then two attempts at bass traps I made with the same materials. Foam is doubled up in thickness in those, with air gap.

I'd offer for you to see mine too, but that's about a 5-hour trip...


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## liquidlino (Dec 30, 2022)

Jdiggity1 said:


> I essentially did the same as @elucid. 2.7 Earthwool from Bunnings, built the frames with MDF (I should have gone with Pine) but I chose a fabric from Spotlight to wrap them in. Used weed netting on the backs. Not really sure why, in hindsight. Could have just gone with the same fabric all the way around.
> 
> 
> 
> ...


Looks like you used the same Bunnings acacia benchtop as me too for your desk!?

Right, I'm sold. Was planning on plywood for my build, as it's super stable, no expansion / contraction, and get Bunnings to cut it to sizes I need with their big wall saw. 

Same question, do you have any waterfall plots? How deep are your panels? Are you happy with bass control?


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## elucid (Dec 30, 2022)

liquidlino said:


> Oh wow, I didn't realise earthwool wasn't fiber glass! That's dead easy then. How deep are your panels, and do you by chance have a before and after measurement chart for your room? Particularly a waterfall?
> 
> I'm at St Ives, I might well take you up on your kind offer of a visit! We have family staying at the moment, but maybe in the next few weeks.
> 
> Btw, great headphones collection. I also have hd650 and at-50. Don't recognise the others though?


I've worked with rockwool before and it's horrible stuff. No matter what you cover yourself with it ends up all over you and itches like mad for ages. I hate to think what we were breathing in the studio with that stuff in the roof and walls.

Earthwool is nothing like it. You can handle it without any protective gear at all and it's just soft and itch-free. It cuts easily with a box cutter-style knife, too.

I confess I didn't take any measurements before I put it up because the room so obviously needed treatment. It's a tiny room and suffered from too much sound coming back at me from behind. I use Sonarworks and this gives me a fairly large adjustment - mainly removing bass which I may build traps for but I have so little room in there that I'm not sure about yet).

My panels are 90mm deep and the difference from what is was is astonishing. It's now a room I can mix in where it wasn't before.

I used pine for the frames and added a bevel on the front outside edge (with a router) to make it look nicer - especially where the panels are stacked together on the rear wall this makes them look much more 'professional' fwiw. I joined the frames with pocket holes (https://www.carbatec.com.au/kreg-jig-hd).

The other headphones are AKG K701s, DT770s, and some 'consumer' ones I rarely use buit are theoretically there for sanity checking. I forget the brand (I'm not at home to check). The 650s are actually Massdrop 6xx phones (apparently 'identical' to the 650s).

Feel free to drop in if you want. After the next couple of weeks I'll be available enough most days.


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## milford59 (Dec 31, 2022)

liquidlino said:


> Interesting idea. You mean wrap it in gladwrap sort of thing? Would it still work though, I thought only breathable material could be used, non breathable like plastic blocks sound getting into the material and getting absorbed?


That’s a good point - I am not sure about that - but reading the rest of the posts it looks as though you may have an alternative solution - which is great - and I wish you all the best with your plans.


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## colony nofi (Jan 1, 2023)

It might be worth doing a tiny bit more research before settling on the material you buy.

To clear up a misconception / misinformation, earthwool most definitely IS fibreglass.
It is just spun differently / manufactured differently and that mitigates many of the issues with it compared to other fibreglass products. It also behaves differently to other fibreglass in regards to low end absorption, and buys you a better deal in most circumstances. 

When choosing what to buy, look at exactly what you are trying to do with your material.

About 5 years ago I spent a good 3 days calling up different manufactures around australia and managed to get tonnes of data on both absorption material and general building materials for walls (best bang for buck mass etc). I still have the spreadsheet somewhere - there's about 100 different materials on the market in australia which are suitable in some way - all with their own plusses and minuses. 

If I was going to put $ into treatment, Id measure the room (REW is free) and look at the plot quite closely before settling on the material and what you end up doing / how much of walls / corners you wish to cover.

This is not terribly hard, but could improve things for you significantly.

Then you're going to need to do a bit of research. Different insulation materials have very different densities, as well as flow resistivity (which tends to be used mostly when modelling behaviour of porous panels)

Now, if you are not treating much below 250hz, almost any material can be used. But treating below that, there are a few different options. Our large mix room we opted for 450mm with 100mm air gap of very low density material. For the entire 5.5 x 3.1m back wall. It did amazing things. But then so did 200mm of polyester material with an air gap for ceilings in two recording spaces. 

And yes - polyester really is super. In australia it started with just Tontine Acoustisorb - which in smaller amounts - 50mm and 100mm with air gaps, really is a wondrous material. There are two other alternatives now which have slightly different performance. Martini Polymax is amazing stuff - just slightly different rating which makes a difference down low under 200hz, and there's a third which I can't remember off the top of my head. These are ALL polyester. They range from 36-48kg/m3 - which is much denser than the ceiling bats mentioned earlier. This makes them very useful for BROAD range mid low to high absorbers when used 100mm thick. 100mm air gap behind them makes a huge difference. Like - at these amounts, it grants you an extra octave of absorption which is a big deal when you realise how hard it is to absorb lots of low freq. Not cheap, but SO much nicer to work with than any spun fibreglass product.


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## colony nofi (Jan 1, 2023)

Tontine 100mm with 200mm air gap (!!) vs 450mm of earthwool







Also interesting - earthwool vs polyester 100mm no airgap






Note : this is just ONE of the earthwool ceiling batt products. Their flow resistivity ratings actually vary WILDLY. And its not at all related to the "R" value either. I have yet to work out why they vary so much, but the data is the data.


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## liquidlino (Jan 1, 2023)

colony nofi said:


> Tontine 100mm with 200mm air gap (!!) vs 450mm of earthwool
> 
> 
> 
> ...


I'd found acoustisorb and polymax in my research, but I can't seem to find a stockist in Sydney. But maybe I should drop the distributor a line and find out more.

Ideally I'm trying to control down to 100hz. I've measured my new room with rew this morning, and it has a node at 124hz, and at 48hz. I've no hope in controlling the 48hz, but I'd like to try to tame the 124, and smooth out the lumpy response curve above that, and in particular I have 300ms decay for most of the range above 400hz, but then it gets progressively worse. It's a wooden floored solid double brick wall room all four walls, with large french glass doors along one wall. So its highly reflective. So much so that I can barely hear the monitors directly its all room sound, and very very blurry. 

I'm 50/50 on even trying. I'm renting so can't fix stuff to the walls. There's plenty of space to put 200mm air gap behind 200mm panels at the front and back, but then it's high ceiling, and panels need to be free standing, so I don't think I can go higher than 1200mm. I don't have anywhere to put panels along sides nor a cloud.


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## elucid (Jan 1, 2023)

liquidlino said:


> I'd found acoustisorb and polymax in my research, but I can't seem to find a stockist in Sydney. But maybe I should drop the distributor a line and find out more.
> 
> Ideally I'm trying to control down to 100hz. I've measured my new room with rew this morning, and it has a node at 124hz, and at 48hz. I've no hope in controlling the 48hz, but I'd like to try to tame the 124, and smooth out the lumpy response curve above that, and in particular I have 300ms decay for most of the range above 400hz, but then it gets progressively worse. It's a wooden floored solid double brick wall room all four walls, with large french glass doors along one wall. So its highly reflective. So much so that I can barely hear the monitors directly its all room sound, and very very blurry.
> 
> I'm 50/50 on even trying. I'm renting so can't fix stuff to the walls. There's plenty of space to put 200mm air gap behind 200mm panels at the front and back, but then it's high ceiling, and panels need to be free standing, so I don't think I can go higher than 1200mm. I don't have anywhere to put panels along sides nor a cloud.


It‘s easy to go down the rabbit hole, chasing perfection, but I chose not to do that. For me it would be a case of diminishing returns - my room is too small to ever be excellent. I’ve been involved in building and treating a few recording studios and so, with my very small space, I struck a balance and now, as I said above, I have a room I can mix in where I didn’t have that before. I’m happy with what I have.

But I’m in the fortunate position of not renting so I can drill in the walls and so on.

The panel above my monitor is actually velcroed to the wall to stop it falling forward on its legs. If you can use Velcro then you could consider that. If you want an airgap then you could build a frame onto the back of the panels and Velcro that to the wall. If there is any chance of someone pulling it forward then that’s not going to be safe, obviously.

Your mock-ups sound great. Were they done in the room you have or on headphones?


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## liquidlino (Jan 1, 2023)

elucid said:


> It‘s easy to go down the rabbit hole, chasing perfection, but I chose not to do that. For me it would be a case of diminishing returns - my room is too small to ever be excellent. I’ve been involved in building and treating a few recording studios and so, with my very small space, I struck a balance and now, as I said above, I have a room I can mix in where I didn’t have that before. I’m happy with what I have.
> 
> But I’m in the fortunate position of not renting so I can drill in the walls and so on.
> 
> ...


I think I will build five 200mm deep panels, see how it works and go from there, three across back wall, two at the front. 

Mockups... Those are essentially unmixed. Just some light mastering and some eq on the reverb channels, just before the reverb tails, to tame some metallic sounding resonances. The only mockup I've spent time mixing has been the universal logo, this one here. Used saturation and eq and compression on brass in particular to get it to sound right. All the mockups are vsl synchronized special editions, with synchron strings pro and elite strings. Still debating the synchron brass, they just extended the sale, so looks like I have another two weeks of indecision ahead of me!
View attachment 2022-10-20 Universal Logo.2022-11-13 06_39_35.mp3


But all my mixing so far has been headphones really. Haven't had treated room yet. I compose on monitors and mix on headphones.


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## SammyBrown (Jan 1, 2023)

colony nofi said:


> And yes - polyester really is super


Wow thank you so much!

I went down this rabbit hole about a year ago but just ended up confused because all the advice was American based and I struggled to find similar non-fiberglass options over here. All the panels are going up in my room so I definitely want to avoid Rockpool/glasswool products.

I found polyester but didn't get any good data on absorption and acoustic performance, so this is amazing, thanks for the info. I guess acoustic panels are back on the to do list.


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## colony nofi (Jan 2, 2023)

liquidlino said:


> I think I will build five 200mm deep panels, see how it works and go from there, three across back wall, two at the front.
> 
> Mockups... Those are essentially unmixed. Just some light mastering and some eq on the reverb channels, just before the reverb tails, to tame some metallic sounding resonances. The only mockup I've spent time mixing has been the universal logo, this one here. Used saturation and eq and compression on brass in particular to get it to sound right. All the mockups are vsl synchronized special editions, with synchron strings pro and elite strings. Still debating the synchron brass, they just extended the sale, so looks like I have another two weeks of indecision ahead of me!
> View attachment 2022-10-20 Universal Logo.2022-11-13 06_39_35.mp3
> ...


So a little tip.
If you can't affix to walls, there's a very simple effective style panel that can be made by :
Grab 18mm mdf. Hate mdf, but hey. 25mm is easier in the end - but also much much more expensive in Aus.
Cut it into 4 strips 300mm wide (so you get 4 pieces 2400x300 ish)
Then cut two of the pieces in half.
Now make a box 2400x1200 out of the pieces. Use the two extra 1200x300 pieces as extra bracing. With 18mm mdf you MIGHT need one more vertical brace - you can use a couple lengths of 70x35mm pine framing for instance.
Cover the back with fabric - staple it in place.
Now fill the chambers with the earthwool mentioned earlier. 
Cover the front and sides with material and staple around the back. 
Grab some screw in feet for the bottom (rubber type) that you can also use to level the box. 
Boom. These are extremely useful and effective boxes. You can even then cover the outside in Plywood (6mm or 9mm) if you want it to look really super schmick. If you do that, make the mdf box slightly smaller so the pieces of ply are big enough to cover the whole 2400 side. You'll get what I mean when the first one you make is too big 

These boxes are VERY stable vertically. You can straddle a corner with them and they are an amazing bass trap. (IF that is your intension, look into 32kg/m2 polyester, which is awesome in this instance and will likely even help your 48Hz issues)

Stick them 100 or 200mm off walls at front or sides for superb reflection control as well as decent bass control. They can be moved with 2 people nice and easily, and fit thru doors when you need to leave.

When you make them well, they can even look like they are meant to be permanent.
The difference 300mm gets you is quite substantial. And, if there are still problem high freq reflections, just make simple 100mm ish thick panels to hang on walls - they can be hung with even just 2 really good screws (renting can be a pain). But above 100mm and things get a bit heavy / cumbersome to do that way. Simple cleats work well - and you can build air gaps in by attaching 90mm thick pine framing timber to the back if that's your want.

I would personally go for a combo of 300mm and 100mm panels rather than a bunch of 200mm panels. You WILL be able to get a really good sounding room using this style of thing. I've had a 5.1 mixing room for post done with this (covering about 80% of the wall area) and with a 100mm ceiling cloud - in a room only 2.4 x 3.4 (x 2.8 height) - NO good from a size perspective, but ended up being better than many bigger mix rooms. It might end up a little dry, but you'll at least know what's going on with your mix!
(If I could, I'd work in "NE" type rooms any day - and the work Northwood has done for super dry rooms that are a pleasure to work in is amazing. Now, that takes time and lots of cash to get a room like that, and none of this DIY treatment will get close. 

But. You can make something workable for sure.


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## Jdiggity1 (Jan 2, 2023)

liquidlino said:


> Looks like you used the same Bunnings acacia benchtop as me too for your desk!?
> 
> Right, I'm sold. Was planning on plywood for my build, as it's super stable, no expansion / contraction, and get Bunnings to cut it to sizes I need with their big wall saw.
> 
> Same question, do you have any waterfall plots? How deep are your panels? Are you happy with bass control?


Sorry for the delayed response. The desktop is actually Merbau, 2100 x 1050 mm. Not sure if they still sell it. (here's the desk "plans" if it's interesting to anyone: )
Was built specifically to hold a Roland A88-mk2 at the front (as shown in the previous image). Over a year and a half old and it's still going strong.

I don't have waterfall graphs, no. It was just extremely obvious that I needed something, even if it were only a single panel either side of the listening position, it makes a big difference.
I built them for my previous rental, then carried them across to my current rental (only been here a couple months), haven't performed any measurements here. I tend not to get too analytical, as I rely on headphones most of the time anyway. I do measurements with REW when testing speaker and sub positions, though. I find those make a bigger difference to the frequency response than panel position.
Reflections and imaging are another story, but I honestly just follow my ears with those aspects. It's never going to be amazing where I am.
My panels are 1200H x 630W x 80D (mm). 8 cm isn't all that deep, but I couldn't afford to lose much more width in my room.
And to correct my last post, I did not actually purchase EarthWool. I purchased "SoundScreen R2.0" 1160x580x70mm. I believe that decision was made so that I could keep the panels relatively thin.
You should ultimately take advice from the other members in this thread over mine, fwiw.


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## liquidlino (Jan 2, 2023)

Jdiggity1 said:


> Sorry for the delayed response. The desktop is actually Merbau, 2100 x 1050 mm. Not sure if they still sell it. (here's the desk "plans" if it's interesting to anyone: )
> Was built specifically to hold a Roland A88-mk2 at the front (as shown in the previous image). Over a year and a half old and it's still going strong.
> 
> I don't have waterfall graphs, no. It was just extremely obvious that I needed something, even if it were only a single panel either side of the listening position, it makes a big difference.
> ...



Ah, yes merbau, that's what mine is, you're right! I just bought the 2400x600 for $100, bought some metal legs from eBay for $100, and some under desk cable trays from IKEA, been a great solution. Been working from home all through COVID on it.


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## liquidlino (Jan 2, 2023)

colony nofi said:


> So a little tip.
> If you can't affix to walls, there's a very simple effective style panel that can be made by :
> Grab 18mm mdf. Hate mdf, but hey. 25mm is easier in the end - but also much much more expensive in Aus.
> Cut it into 4 strips 300mm wide (so you get 4 pieces 2400x300 ish)
> ...


Ah, I think this is a GREAT idea. 1200 wide and then decent height, and 300 deep. I probably can fit two at front, one at back. Then see where I'm at with measurements. Thanks!


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## Pier (Jan 3, 2023)

liquidlino said:


> I don't want to use fiber-glass as the acoustic packing (as I understand it still sheds fibers, and my daughter and wife have asthma, and apparently it exacerbates it)


I built some absorbers a couple of years ago with rockwool. Initially for my studio but since I moved to headphones most of those are in the home theater room now. My wife has asthma and she doesn't have any issues when binging Netflix for hours.

I used high density rockwool which is much easier to handle than the fluffy stuff.

For the fabric on the front I used some stretchy stuff that lets air through. I spent like 30 mins at the fabrics store like an idiot blowing through fabrics to find the one that worked best.


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## HCMarkus (Jan 3, 2023)

The key to building quality panels is the fa bric you use to cover them. You need just the right amount of stretch. Guilford of Maine FR701 has been the standard for years. I can confirm: it works really well.

I used fiberglass in my studio and have had no issues (me or my clients) whatsoever over the years. I built the panels outside (I live in San Diego, CA, so the weather cooperated nicely) using a frameless technique. Drywall Corner Bead (Edge Metal) cut with tin snips and folded around the edge of a rigid panel (front only for 1" material, front and back for thicker panels), tacked in place with spray glue, then wrapped with FR701 results in rigid, lightweight panels.

For clouds, a frame composed of suspended ceiling cross-members worked nicely; very light, yet rigid. Attached thru rigid glass (6 lb/cf) with self-tapping screws and large fender washers.


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## liquidlino (Jan 3, 2023)

So I'm warming up very much to oversized 300mm 2.4x1.2 panels, would fit beautifully in the room. However even using MDF, costs stack up rapidly, and I imagine would be quite heavy. 

So... Any reason why I shouldn't make a skeleton stick frame, by having a 2400x1200 sheet cut up into 2400x20 sticks, and then creating depth by using little pieces like a ladder frame, and then several cross supports across the width? It's $110 for a sheet of plywood, and that'd make all the sticks needed, including spacers etc. It'd be like how houses are made in Australia, in miniature. I could add cross supports both front and back for extra rigidity and holding the material in place as well, not relying on the fabric to hold material in place. 









Ecoply 2400 x 1200mm 19mm Plywood Pine Structural CD Grade


Find Ecoply 2400 x 1200mm 19mm Plywood Pine Structural CD Grade at Bunnings. Visit your local store for the widest range of products.




www.bunnings.com.au


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## Pier (Jan 3, 2023)

liquidlino said:


> So I'm warming up very much to oversized 300mm 2.4x1.2 panels


Mine are aprox 60x120cms (+ the frame) and about 25cm deep. You need to leave an air gap between the absorber and the wall so that the panels can absorb lower frequencies.

I definitely would not recommend doing those huge panels. Building and moving the panels is going to be a lot more difficult. Making smaller panels is a bit more work and more expensive in wood etc but OTOH you'll gain a lot of flexibility in moving/placing the panels and you won't need such a huge space for building.

I don't have a wood shop so used our Costco car tent as a temporary working space:


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## liquidlino (Jan 3, 2023)

Pier said:


> Mine are aprox 60x120cms (+ the frame) and about 25cm deep. You need to leave an air gap between the absorber and the wall so that the panels can absorb lower frequencies.
> 
> I definitely would not recommend doing those huge panels. Building and moving the panels is going to be a lot more difficult. Making smaller panels is a bit more work and more expensive in wood etc but OTOH you'll gain a lot of flexibility in moving/placing the panels and you won't need such a huge space for building.
> 
> I don't have a wood shop so used our Costco car tent as a temporary working space:


Size isn't the issue. Just went to spotlight to look at fabrics and the bolt width is the issue. Biggest bolts are 150cm wide in most breathable fabrics. Did the whole mouth breathing looking like a twat thing. Quite surprised in the difference in breathability between similar looking fabrics. 

So I will have to make smaller panels out of necessity. I think the stick frame idea is good though, so might just go for making lots of 1200x600x300 panels to start with, and can always put them on top of each other with some metal hardware to join them together for safety. That works well, as each panel will hold three insulation batts (1200x600x90 each). Pack of ten batts is 90 dollars.


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## Pier (Jan 3, 2023)

liquidlino said:


> That works well, as each panel will hold three insulation batts (1200x600x90 each).


You don't need to fill the whole thing with insulation. You're not going to do a lot more absorbing of two layers vs three. That's not how it works (unfortunately). Check the specs of the manufacturer to compare the absorption charts at the lowest frequency of 2'' vs 4'' vs 6''.

For absorbing lower frequencies more efficiently you want to move the insulation as far away from the wall as possible. Of course in most cases it's not practical to have a gap larger than 30cm.

Absorption is more efficient when the wave is in its highest velocity and that happens at 1/4 of the wavelength away from the wall.











The Science of Acoustic Foam - How Acoustic Foam Effects Sound Waves


There’s more to acoustic foam than meets the eye (or ear). Acoustic foam is an easy and inexpensive way to combat sound interference. Learn more at SoundFix




www.soundfix.co.uk





For 100hz that's 1 meter which is impractical. You won't be able to do much below say 80Hz. Doesn't matter how much absorption you add.

See these measurements with about 10 panels I showed earlier.

Before:






After:


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## liquidlino (Jan 3, 2023)

Pier said:


> You don't need to fill the whole thing with insulation. You're not going to do a lot more absorbing of two layers vs three. That's not how it works (unfortunately). Check the specs of the manufacturer to compare the absorption charts at the lowest frequency of 2'' vs 4'' vs 6''.
> 
> For absorbing lower frequencies more efficiently you want to move the insulation as far away from the wall as possible. Of course in most cases it's not practical to have a gap larger than 30cm.
> 
> ...


Lol, so much conflicting advice. But it's the internet, what's new!

But brownie points for posting measurements pier. I'm not familiar with flame charts, what is the y axis, is that ms decay to RT60? Or something else? That's a dramatic improvement of whatever it is... 

I can have total depth of about 500mm on front wall. Back wall is up to me but I think no more than 500mm or it'll look stupid. So maybe 180mm deep with 300mm of gap might be best setup?


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## colony nofi (Jan 3, 2023)

Pier said:


> You don't need to fill the whole thing with insulation. You're not going to do a lot more absorbing of two layers vs three. That's not how it works (unfortunately). Check the specs of the manufacturer to compare the absorption charts at the lowest frequency of 2'' vs 4'' vs 6''.
> 
> For absorbing lower frequencies more efficiently you want to move the insulation as far away from the wall as possible. Of course in most cases it's not practical to have a gap larger than 30cm.
> 
> ...


You absolutely can treat 50-100hz well in a room with 300-450mm thick low density earth wool.

You just need a fair bit of it.

For example. In a 5x6x3.2m room, it took 16m2 of 450mm thick and 5m2 of 300mm traps (diagonal over corners) plus a bunch of 100mm traps and various ceiling treatment.

For a 3.2x2.4x2.8m room, 9.6m2 of 300mm thick and 4.8m2 of 100mm thick and another 3.6m2 of 100mm thick hung off the ceiling made for an amazingly good sounding (and flatter than you’d expect) room.

The large traps need to be full to work. With low density (approx 3000sabines works great) fibre.

There is tonnes of (university) research on this - as well as bbc public papers.

This doesn’t mean there are not other approaches. But this is one approach that does work.

They are not that heavy. Two person lift.

But doing it with “strips” of ply rather than mdf might work well - likely a tiny bit better - but not sure of the stability at the size I mentioned. But if you’re handy with wood, I’d imagine you could come up with bracing that works nice and easily.

Another reason for just using 300mm strips is time - these large boxes can be made super quickly. A piece of mdf is under $50 for 18mm at bunnings. And linen fabric from ikea at $15/m is absolutely perfect and looks a million bucks.

1500mm wide fabric is perfect for the large absorbers - they’re only 1200mm wide. You end up with a seem on the wooden frame sides - but that’s cool. Cover in thin ply if you don’t like that 

As for the air gap - the physics is a bit more complex than “you need the air gap to absorb low freq”. For example, in a corner (high density) trap, filling the trap with 14000 Sabine material will give you more bottom end absorption than leaving a gap inside the corner trap. There’s interplay between where the panel is placed (pressure behaviour in the room), the density is the material, the thickness of the material, and air gaps. There are quite a few decent models for figuring out exactly what the trap will get you as far as absorption goes - some take into account random incidence, others not. Some take into account position in room, others don’t. But they are good enough to let you know you are designing the right thing.


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## liquidlino (Jan 4, 2023)

colony nofi said:


> You absolutely can treat 50-100hz well in a room with 300-450mm thick low density earth wool.
> 
> You just need a fair bit of it.
> 
> ...


This is all superb information. But.. I think too much for this humble rental treatment.

I went to Bunnings today. They'd sold out of the 580 wide earthwool. And they said narrowest they can cut sheets is 300mm. So I'm going to go with 300mm deep, 1200x600 boxes to start. I can make more and stack them if the first four don't improve the room enough. Figure I can do a mini stone henge at the front, which would give 1800mm effective height (1200+600). 

Just have to find some material! All polyester is fully sold out everywhere right now.


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## Pier (Jan 4, 2023)

liquidlino said:


> But brownie points for posting measurements pier. I'm not familiar with flame charts, what is the y axis, is that ms decay to RT60? Or something else? That's a dramatic improvement of whatever it is...


The Y axis are milliseconds. Not sure why REW says only "m"!



liquidlino said:


> I can have total depth of about 500mm on front wall. Back wall is up to me but I think no more than 500mm or it'll look stupid. So maybe 180mm deep with 300mm of gap might be best setup?


Honestly before embarking on this I would do some measurements with REW, even with an uncalibrated mic. Although there are very cheap calibrated mics.

It's unlikely but maybe you've hit the geometry jackpot and you don't have big issues below 100Hz.

Here's some good info about gaps etc:









Rock wool, glass wool, hemp - which material is best suited for absorbers? — Jochen Schulz


Are you determined to improve the acoustics in your recording studio or home theater? Then a broadband absorber is the first choice! The only question is which material do you use best? I will use examples for different absorber depths to show you which flow resistance achieves the best absorption a




www.jochenschulz.me





As you can see, there's barely any difference between 30cm insulation vs 20cm + 10cm gap.

In those measurements, 40cm of insulation seems to be the best if you can afford the space and the materials.



colony nofi said:


> You absolutely can treat 50-100hz well in a room with 300-450mm thick low density earth wool.


Jesus who can remove 450mm in a home studio! 😂

(well apparently @liquidlino lol)

But yeah, technically of course you can treat any frequency. Even using Helmhotz resonators and whatnot.


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## liquidlino (Jan 4, 2023)

Ok, Quick update of WIP. I went to bunnings, got 2400x1200x12 sheet non-structural plywood cut into 8 x 1200x300x12 and 16 x 600x300x12. Used corner clamps (super cheap and already had them) and 8g 40mm chipboard screws to screw into simple boxes, with a single 300mm wide brace across the back. Filled with 3 batts each of Earthwool R2.5 Acoustic insulation.

Here's room measurements using a calibrated Dayton XLR mic through Motu M2 into REW using calibration file for the mic, with no room correction enabled on computer:
Frequency Response




RT60




Waterfall





Then here is with three panels across back wall, and one sideways stacked on top
Frequency Response

RT60




Waterfall





You can see that the RT60 has come down significantly from about 650ms average to about 350ms average. Still way higher than I'd like, but wow, what a difference it makes already! Here's some very basic recordings to demonstrate the difference, using the calibration mic, so it's quite bass heavy etc:

No Treatment
View attachment untitled.2023-01-05 08_12_25 01 No Treatment.mp3

4 Panels Back Wall
View attachment untitled.2023-01-05 09_55_54 02 4 Panels Back Wall.mp3


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## liquidlino (Jan 4, 2023)

And 4 Panels back wall Frequency Response compared with no treatment. Not a dramatic change to be honest. But I was much more interested in fixing RT60 than FR, so I'm happy so far. Next job is to put fabric on the panels and then put them into their proper places, and remeasure.


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## liquidlino (Jan 4, 2023)

And finally, some listening notes. Before treatment, I could literally barely hear the speakers, it was all room reverberation, and really mushy sound. Now, with the panels like in the photos, I've applied a room correction EQ from REW, and listening to favourite tracks, I can clearly hear the speakers, rather than the room, and everything is much more in focus. I can hear compression pumping on the EDM tracks, where I couldn't hear it at all. And the bass sounds really well controlled and damped now. It's well on its way to being a decent sounding room (by my amateur standards)


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## Pier (Jan 4, 2023)

The panels are doing great above 200Hz. You can see how the peaks around 6khz, 300Hz, and 500Hz have been tamed. Not much absorption is happening below 100Hz though.

The FR doesn't tell the whole story. This was my studio after adding the panels. Looks decent but the room was still unusable.






If you're using waterfall graphs try lowering the min boundary of the decibel values. Right now your graph only goes as low as 65db and doesn't show the data below. That's why you're seeing those weird cut crests below 200Hz.


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## Pier (Jan 4, 2023)

BTW these were my RT60 before and after the panels.











It helped a lot but it's still bad even with a lot of absorption.

The issue is the room is almost a perfect cube and the ceiling is vaulted... so yeah that's why I ended up moving to headphones lol.


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## liquidlino (Jan 4, 2023)

Pier said:


> BTW these were my RT60 before and after the panels.
> 
> 
> 
> ...


So you're still around 500ms RT60 average - yeah that's quite high. I think my 350ish is still quite high, I'll have a think about what I can do about that - probably just another few same panels, and stack them up - it's a 3m high ceiling. This new room is sort of a cube as well - I think it's about 4x3x3. Much bigger than my old 2.4x2.4x2.4 perfect small cube. My problem with headphones is that it triggers my tinnitus, so I try to limit headphone wearing to just the very final critical mixing. And the more I can do mixing on the monitors the better, just leave headphones for the bass/sub-bass.


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## colony nofi (Jan 4, 2023)

Maybe this is too much info, maybe not... but I'm going to show something quickly just in case someone gets something out of it.
@Pier makes some good points, and some good info. The problem is that general info is general, and acoustics are generally quite specific. So while the spirit of what was said is a great starting point, its a little more complex than written.

For example - porous absorbers work better when velocity is highest. However, they also can be even better at boundaries depending on what you are trying to do. Thus for instance the use of super chunk bass traps. 

And curiously, depending on material, air gaps do NOT always make positive benefit.

For flow resistivity of 12,000 rayls/m, (approx where a lot of poly sits) you end up with a situation where if the material is > 250mm thick, adding an air gap behind can DECREASE the efficiency of the panel, (albeit by small amounts) even when moving that panel towards the 1/4 wavelength position. On the other hand, with lower flow resistivity of fibre glass, you almost cannot have a big enough air gap.

Fun can be had combining materials as well. Really strange things happen regarding materials when placed in layers... the order of layers can dramatically change the outcome - some positive and some negative - in different frequency ranges.


Anyway - here's a little gif.
First its showing the negative / neutral effects at 250mm of air gaps for polyester, and then showing how the LOWER density material thrives with larger and larger air gaps - and makes for better bass absorption while being far less expensive - if you have the space!

(Poly of course has many many uses - this is just demonstrating how different density material behaves differently)







Then - there's the curious case where just filling up the air gap with the same material increases the bass performance. Here we have a 200mm panel and 200mm air gap. Now, I fill that air gap up so its 400mm of material, and the performance is a LITTLE better. 
Now, I personally would fill it up every time - but only as its easier to build, and the 2000 rayls/m material is dirt cheap (and happens to come in nice 430mm widths). If I were using expensive material, I'd go for the air gap any day of the week.







Finally, there's some super results that can be had for choosing the right materials. From the above graph, you see that 2000 rayls/m material at 400mm (200+200 air gap OR filled) make great low frequency absorbers. However, 6000 rayls/m at 300mm with no air gap do even BETTER - by 20% or more. If you don't have the space, that can really add up.



Now - 300mm is about the thinnest I have been able to reliably get results with for any material with this type of panel - but an absorption co-efficient of > 0.5 at 67htz will make a huge difference to the low end of a room.

And then at 2000 rayls/m (SUPER cheap batts) you can get similar results once you have an air gap... and these results get even better when you straddle the trap across a corner (most of the time - there are always exceptions, though for these kinds of things, I really don't see the REAL WORLD exception to this rule)





Now - the final piece of the puzzle is choosing your materials wisely.

Info direct from Knauf - manufacturer of earthwool (spun fibreglass) insulation :

R 3.1 140mm thick batts (usually for walls) 2000 rayls/m
R 2.6 90mm thick wall segment bats 15900 rayls/m

Both wall batts. MASSIVELY different materials for sound (but only small difference for thermo performance, which is what they are made for)
I use ceiling batts for thick traps myself - better bang for $ - and easy to build.
EDIT : the gifs do not work on this forum. I've uploaded them if anyone wants to view ( they will auto download in most cases)

https://www.dropbox.com/s/xtlio6syxpefmdz/air_gap.gif?dl=1https://www.dropbox.com/s/vulfwrsenohp7x0/flow_resistivity.gif?dl=1


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## liquidlino (Jan 4, 2023)

colony nofi said:


> Maybe this is too much info, maybe not... but I'm going to show something quickly just in case someone gets something out of it.
> @Pier makes some good points, and some good info. The problem is that general info is general, and acoustics are generally quite specific. So while the spirit of what was said is a great starting point, its a little more complex than written.
> 
> For example - porous absorbers work better when velocity is highest. However, they also can be even better at boundaries depending on what you are trying to do. Thus for instance the use of super chunk bass traps.
> ...


Fantastic info as always... where do you get the rayls/m ratings from the Knauf website? I've done a google, but can't seem to find this info? Do you know what the R2.5 90mm Earthwool product is rated at?


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## liquidlino (Jan 4, 2023)

Ok, so I've put the panels in their places that I intended. I'm sure I'll experiment further over coming weeks/months with speaker and panel placements, and make some more panels too. But here's an interesting view. As I understand it, one of the critical measurements for a mixing room is the relative volume of early reflections to the listening point, with the target being -20db minimum attenuation by 15-20ms. I've gone for 15ms here to analyse before and after shots below. What we want to see is as much of a gap between the initial sound level (red top line) and the level measured at 15ms (bottom blue line). The before-room-treatment first graph shows all the lines bunched up at the top in the under 1khz range. This is very bad - basically means the listener is hearing the room as much as the speakers. Once treated, even with just these four small panels, it is easy to observe how in the sub-1khz region, even down to 100hz, really good attenuation has been achieved, meeting the -20db objective. Before treatment, it was sitting at -10db. That's a massive improvement, and correlates with my subjective listening that the bass region has hugely tightened up in the room.

As expected, sub-bass (sub 100hz) hasn't changed at all.

Suprisingly the 1khz only changed marginally... I think this is where I need to start thinking about side panels to absorb first reflections.but more broadly it can be seen that the gap from initial sound to 15 ms levels are generally better in the treated room for greater than 1khz.


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## colony nofi (Jan 4, 2023)

liquidlino said:


> Fantastic info as always... where do you get the rayls/m ratings from the Knauf website? I've done a google, but can't seem to find this info? Do you know what the R2.5 90mm Earthwool product is rated at?


I made a lot of phone calls, and have some contacts within suppliers just from speccing for studios over the years... and had access to all the industry data for a while after doing acoustics on a project at the powerhouse museum... but that's a loooong story.

Another Aussie tit-bit.
There's a sleeper product in australia for larger traps- Fletcher Insulation
Mitre 10 sells it. FirmaSoft R 3.5 ceiling bats. 2700 Rayls/m. I have a product sheet here for it somewhere.
Oh - here's the link :


https://insulation.com.au/wp-content/uploads/2020/10/TDS-FirmaSoft-Batts-Ceiling-Rev0.pdf



175mm thick. A bag Does just under 8m2 of 175mm thick traps (or 4m2 of 350mm - and it does compress to 300mm and it seems to actually do slightly better in performance that way - but the differences are very slight. I measured it once and it was SO similar it wasn't funny!)









FirmaSoft R3.5 Ceiling Insulation Batt L1160 x D175mm


Soft to handleStay firmly in placeLow dust formulaMade in AustraliaUp to 80% recycled contentNon-combustible




www.mitre10.com.au





Their R5.0 batts are 220mm thick, which can also be useful - 4500 Rayls/m

Their ceiling batts (like earthwool/pink batts etc) comes in 430 and 580mm widths. The 430mm is perfect for laying on top of each other as one deep trap at the back of a room.

Pick the flow resistivity that works for you. When you manage to cover a whole wall like this (around 1/6th of the entire surface of the studio) and then make 2 other corner traps for the front corners, hang some clouds, then you can get acoustics better than some designed rooms super easily so long as you take care of first reflections. There were some KOOKY acoustic designs back in the day that passed as good listening rooms.


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## colony nofi (Jan 4, 2023)

liquidlino said:


> Fantastic info as always... where do you get the rayls/m ratings from the Knauf website? I've done a google, but can't seem to find this info? Do you know what the R2.5 90mm Earthwool product is rated at?


Can you take a picture of the packet - there's a good chance I have the info. 

Earthwool is one of those products with WILDLY different flow resistivity figures for different products.

R2.0 wall batts are 3887 Rayl/s, where as the R2.5 batts are a special high density unit - and are approx 15900 Rayl/s.






So - here's one trap for you - 100mm thick with 200mm air gap using the R2.5. With a good sized air gap, you get good low freq absorbtion - but negligible for under 150hz if no air gap.




And here's another - using the full 300mm thick material. Note that it is WORSE than the above with only 100mm of material - the air gap in this case is super important.
Now - the 300mm thick version is also one of those traps where an air gap behind makes no difference to bad (small)difference




I would personally look at another material - but it can still work of course.


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## brett (Jan 5, 2023)

Martini absorb is another good polyester product available in Oz depending on the flow resistivity you are after.

Some good advice from @colony nofi above. Remember, the thicker the panels (better absorption down low), the lower flow resistivity you want. 



Multi-layer Absorber Calculator



I bought the material to cover the panels at https://www.innova.com.au/products/application/acoustic-solutions. More expensive than off-cuts, but looks much more professional. Very happy.


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## liquidlino (Jan 5, 2023)

colony nofi said:


> Can you take a picture of the packet - there's a good chance I have the info.
> 
> Earthwool is one of those products with WILDLY different flow resistivity figures for different products.
> 
> ...


Well I already have the R2.5 HD, so this might explain the lack of any effect below 100hz. I haven't wrapped two of the 300mm panels, so I will experiment with taking 2 batts out of them and big air gap. Could be interesting to see if bass absorption improves.


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## Pier (Jan 5, 2023)

colony nofi said:


> @Pier makes some good points, and some good info. The problem is that general info is general, and acoustics are generally quite specific. So while the spirit of what was said is a great starting point, its a little more complex than written.


Thanks for all the great info!


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## colony nofi (Jan 5, 2023)

brett said:


> Remember, the thicker the panels (better absorption down low), the lower flow resistivity you want.


Unfortunately, this is also not entirely true.
The relationship is not linear. I can pull the math out if you are interested.
So - it comes down to what octave you are interested in, and for panels THICKER than 300mm

Often people forget that they CAN treat bottom end with simple absorbers if they use enough of them and you have 300mm of space to spare. Aiming for 18-25% surface coverage for a 75m3 room, or 33% for a 35m3 room (with some of that over corners) will do wonders. Not everyone can afford that much space, but if you're serious about hearing bottom end, its a good way of making the treatment without having to go to membrane / hermholtz / other esoteric absorbers - which CAN be done but is super tricky and needs to be tuned in a space, and needs to tackle VERY specific areas. (Ie, tune EACH trap in place, and make sure each trap is placed in exactly the correct location)
You will end up working in a fairly dead room - but with the right setup (make sure floor is reflective, and that you have some other reflective surface that is NOT in first reflection points - this can even be done in surround rooms - you can "train" your ears and brain to work in this kind of environment.

Thomas' rooms (Northwood) are like the end game when it comes to this kind of idea - and imo he's a genius and has created an amazing system. I can't wait to hear new rooms of his in Sydney (they are coming....)

Anyway - lets have some fun. The Multi-layer absorber calculator @brett linked is awesome for anyone wanting to DIY this stuff. Its the best I've seen. I'm lucky to have some software tools that give a little more control / model what's going on with pressure conditions in the room - but 90% of the time for the rooms folk are talking about here, that is complete overkill and not needed.

So lets start with 450mm. 





Brett's statement holds true here down to 50Htz 

(you can see the statement doesn't hold true below that mark with the crossing point of 3000rayl/s and 6000rayl/s absorbers. In truth, it would be VERY difficult to measure differences down there - position of the treatment will make tonnes more effect on the room than the differences in the absorption co-efficient.)

But lets go to 300mm. Still thick for DIY'ers (but not really for commercial rooms - I understand that!)






We can see that there is significant difference at 50hz - enough for one to want to look at using 6000Rayl/s over 3000rayl/s.
You can also look at the graphs of the 12000 Rayl/s (which is the same thing as Pa.s/m2 for anyone confused) and at 50hz the results are virtually identical, where as the other absorbers all have significant changes between the two thicknesses. This is a little of why Brett's statement exists around the place - as there's definitely diminishing returns for higher density material vs thickness.

To me, its all just incredibly interesting - and its behaviour like this that got me into doing some acoustics subjects while at uni doing music composition / sound design many moons ago. 

And in all honesty, its not THAT complicated. The math is fairly simple (its an approximate model after all) and there's still room out in the wild for someone to write a simple 10 - 20 page primer on info around porous traps that most with high school level maths / physics could understand. I don't have the communication skills to pull it off, but I hope someone does it. There's a few text books I have that have all the info, but its just not terribly approachable (nor are textbook prices!!!)

There's also TONNES of forum posts like this one - but again, it relies on people trawling, and judging how trust worthy info is etc. Thus, some sort of published primer which is reviewed could be useful. Just another little tangent.... sorry


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## colony nofi (Jan 5, 2023)

And for a couple more fun graphs - you can see how the low density stuff really isn't terribly useful below 300mm thick (there ARE exceptions of course - and for $ if you are not interested in the sub-octaves, its amazing) , and how choosing the right material depending on what you are trying to do is critical.
Here's 200mm, and for fun, that same 200mm with 250mm air gap (to match the final thickness in the previous post of 450mm)











Once you get an absorption co-efficient of greater than 0.5, you can REALLY make a difference to a room with decent sized traps.


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## colony nofi (Jan 5, 2023)

I REALLY digress, but here's some good (Aussie) research on absorption co-efficients, flow resistivity, density, and differences of measuring / modelling.


https://www.acoustics.asn.au/conference_proceedings/AAS2012/papers/p55.pdf


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## colony nofi (Jan 5, 2023)

One more set of graphs.
This is for Martini Absorb 100mm thick.
This stuff I still think is gods gift to DIY'ers if you can get hold of it in small amounts (its easy in larger quantities)
Its PERFFECT for suspended ceilings. It is self supporting - doesn't need any frame. Just hang it. Give it 200 or 300mm air gap, and its a perfect ceiling for a tracking room, voice booth, or listening room. You can leave it exposed, or add a fabric framed ceiling if you wish.


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## colony nofi (Jan 5, 2023)

And for anyone else that needs 300mm traps, here are 4 valid alternatives.
All slightly different results, and I'd choose based on exactly what the room needed plus what is easiest to build .
So ceiling, I'd go 100mm polyester. 
Wall (fixed to wall) I'd look at the 6000 rayl/s fluffy. And likely use that inside movable boxes as well (as they'll see further improvements when off the wall)
The multi-material versions are in there just for fun. Like - you COULD increase the bottom end absorption just a little by filling the air gap with low density material for a suspended ceiling - but it is way more bother than its worth given real world experiences and the tiny changes in modelled performance.


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## aeliron (Jan 5, 2023)

liquidlino said:


> Looking to build my own panels. I can find lots of how-tos and seems straightforward (did joinery as a hobby for a while, so making some simple boxes is easypeasy). However, I don't want to use fiber-glass as the acoustic packing (as I understand it still sheds fibers, and my daughter and wife have asthma, and apparently it exacerbates it) - I saw some recommendations for material made from recycled jeans, but can't find it in Australia. Likewise, anything I find online that isn't glass wool etc, doesn't seem to want to ship to Sydney for some reason. Anyone have any recomendations for non-fiber-glass material that I can buy in Sydney or have delivered?


I hear discarded kangaroo pouch fur is the hot new acoustic treatment. Impossible to find in the States. You lucky dingo!


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## brett (Jan 5, 2023)

colony nofi said:


> Unfortunately, this is also not entirely true.
> The relationship is not linear. I can pull the math out if you are interested.
> So - it comes down to what octave you are interested in, and for panels THICKER than 300mm


Yes, I agree entirely. Not linear at all but a very useful guide for DIYers!

Great stuff above. 👏👏


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