Building low budget absorber

Hi guys, I´m new to this forum but so far it has inspired me alot! Since one month I am planning and building absorbers for a little mixing and rehearsal room. Now I would like to thank the community for all the inspiring footage and construction plans! And now that I fully build my first absorber I think that I can give something back. In case of a really low budget I first looked around to find some bars that are cheap. The cheapest wood I found was at IKEA. They sell bars calles GORM. These are meant to be used to extend a IKEA rack called Albert (I come from germany, so I don´t know if they sell it elsewhere). GORM comes in three sizes: 9cm x 174cm x 1cm (costs 2 € per 2 pieces) 9cm x 110cm x 1cm (costs 1 € per 2 pieces) 9cm x 59cm x 1cm (costs 1 € per 2 pieces) I decided to build three kinds of absorbers out of GORM bars: Tricorner absorbers (59cm x 61cm x 9cm) (I build 4) Corner absorbers (61cm x 110cm x 9cm) (I build 12) Wall absorbers (112cm x 174cm x 9cm) (I build 7) The stuffing is 10cm thick glasswool (One pack costs 17€ and consists of 5 mats 125cm x 62cm x 10cm). On the back of the absorbers I used plastic foil (24squaremeter cost 10€) to keep the wool in the absorber and on the front some cheap carpet (1,79€/squaremeter). Thats it. I inform you when I´ve got news on this project. Here some fotos:

Nice work! Thanks for sharing!

I´m still wondering what the best way is to mount the absorbers into the corners (wall/ceiling). Maybe with some sort of earscrew (screw with a hole?) and some wire? Do you have some usefull know how about this? At the moment we have attatched the plasticfoil to all the absorbers. Today we will complete some more absorbers. Fotos:

You could use hooks and wire, L brackets bent and using screws into inserts in the drywall; use a frame standing vertically, span the corner inside the absorber with 1x3 and use cleats, etc. All are valid methods depending on how heavy the absorbers are and the supporting structure.

Today we could not resist to bring some absorbers to the wall. That feels great and it looks really good. I hope that the acoustic improvement sounds as good as the absorbers look. I keep you informed.

If you can make some more of those, it looks like your ceiling could benefit a lot from having some up there too! - Stuart -

Yes, I want to hang some of those under there. You probably can imagine how aweful the room sounds without any treatment... There will be absorbers in all the corners, walls and some on the ceiling.

Slowly but steady the room gets done. The mounting is really easy, I attatch some detail fotos later.

nice work! how is it sounding now?

Well, the sound changed dramatically. But the only reference I have at the moment is the sound of my handclaps. Tomorrow we´ll lay carpet in the whole room and begin placing the equipment. Can´t wait to hear my speakers and some instruments in there. At the moment our money resources are exhausted, but when there is money I build some more absorbers for the ceiling and the corners at the back of the room.

Tomorrow we´ll lay carpet in the whole room and begin placing the equipment.

Carpet???? :shock: Why would you do that? You are just starting to get together a really good acoustic layout in that room, and now you want to wreck it by adding carpet to the floor? Sorry, I don't follow.... - Stuart -

So no carpet is better? In that case I save the money and build some more absorbers for the wall in the back. Thank you for that quick emergencybreak!!!

So no carpet is better?

Yup! The problem with carpet is that it is "selective". It absorbs some frequencies and not others, randomly. And you never know which ones it is going to hit and which ones not, because the manufacturers of ordinary aren't interested in acoustics, don't do any tests, and don't publish any figures. So it's like Forest Gump's famous box of chocolates: you never know what you're gonna get. The only difference between carpets and Forest Gump's chocolates, is that the carpet isn't very sweet... :) Seriously, the general rule for a studio is "hard floor, soft ceiling". There are many reasons for that, but basically it is what your brain expects, acoustically. So plain old concrete is great. If you don't like the aesthetics, then lay some laminate flooring, but whatever you do, keep it hard and put plenty of absorption on the ceiling to deal with reflections, flutter, etc. A cloud is a great idea for that, and a hard-backed cloud is even better if you have vertical modal problems. With a hard floor then you have one final "ace up your sleeve": If it turns out that your room is still too live after you have done all the acoustic treatment (unlikely, the way you guys are going!), then you can always put in a couple of throw rugs in key places, to add that last extra bit of extra absorption. - Stuart -

I get it. And seriously I must admit that I never saw a studio with a carpet. I studied at the SAE in Cologne and went to several studios with my band. No carpet in all the Studios. Your analogy with Forrest Gump and the diffrent sorts of carpet is great. Thanks a lot! ;) I think we paint the floor with a special concrete paint to get it better looking. About the sounding: Without the absorbers installed we had a dramatic flutter effect. That was horrible. Now there is almost no flutter. And I´m glad we did the absorption on the ceiling. That had a additional effect on the flutter. Next we build some more absorbers for the ceiling and the wall that you cant see on the fotos. At the moment there lies too much crap to post any foto of it. ;)

if you like, you can polish, stain, and seal the concrete to a variety of patterns and colors.

that looks really good, and thanks for the tips on IKEA Gorm. I'm definitely going to get me some GORM wood to build my absorbers :)

Do that, its good. And you don´t need to trim it. I will upload some detail fotos when I have more time. Thanks for the response. Kju