HF, Broadband and Bass traps

All material is ordered and is expected this weekend. I have a few questions only!, before starting to build treatment! Little background: I have two options of my design, see pics Kaj 5 & 6. In Kaj 5 pic do I hope to get the best low frequency absorbtion, I have a thread in construction for building a LR/rehearsal room, we play rock and blues pretty loud at times. I have ordered mineral wool 70% is (100 kg/m3, 50mm thick and Glasswool 30%, 35 kg/m3. I plan to build Helmholtz broadband absorbers angeled 11 deg and have 2x50mm mineralwool at the deeper end of adsorber (700-800mm deep). And use 100mm of glasswool in the shallow part, about 1/3rd of absorber. Absorber to be built on 2"x4" studs OC 400mm, fabrics and 22mm thick pine wood planks in 50, 70, 95, 120 mm width. I will use the Helmholtz calculator from this site (the corrected one) Thanks for a good tool!! and I going to use the average depth in the calculations. Bass traps in the corners made of 50+50mm mineralwool cross the corners. the dimentions are for dual layers outer insulation batts 100x1200x2390mm and the inner batt 50x600x2390mm. The single layer is 100x600x2390mm batt in the corner. I will use the standing wave calculation of the room modes for the room to have as target frequencies for calculation of slot gaps. Room dimentions: 8267mmx7283mmx2390mm. i'll treat the other walls only if required later, need to test the room how it will sound (measure with white noise) before I know what is required in addition. The walls and ceiling is covered with wood board, floor covered with plastic carpet, same as for bathrooms. We will put laminate floor on top later. So what is my problem? Anyone out there that can see any advantage with design as per pics Kaj 5 and/or 6? Have I done a misstake in the way I intend to use the calculator and picking the target frequencies? Any good ideas out there for where to put the instruments: PA speakers, Drums, electric guitarsx3 electric bass guitar and keybourd (he use the PA-system)? greatful for any help! Cheers Kaj

version 6 is the way to go IMO. There is more variance in angles making it more diffuse. cheers john

Thanks John, We have started to make the frame work 2x4" OC 400mm or less. See attached pics. Question. I have ordered 70% of the insulation mineral-wool 100kg/m3 (705) and 30kg/m3 Glass-wool (703) all 100mm thick. My idea is to use little bit more of the Glasswool at the shallow part of the absorbers and only Mineral wool at the deepest sections see pic. Is this ok? And yes I'll cover with fabrics and place the slats on top of this. Having the slats dimensioned to 20X50/70/90/120/140mm, but have not yet received them. You can see in the Studio construction thread for more details. http://www.johnlsayers.com/phpBB2/viewtopic.php?t=7182 Thanks in advance. Cheers Kaj

Subject title sounds like an oldie but goldie; The insulation arrived and we pushing to get the slats delivered as well. You can find project progress in thread; http://www.johnlsayers.com/phpBB2/viewt ... 3395#53395 What I still struggle with is if I should blend (mix) different insulation density into the same absorber wall? Or keep the same kinda stuff in each wall? I have my brain on overclocking mode and feel exhausted about not knowing if I doing right, the confidence dont come easy today, any experience out there to confirm or redirect me? My thinking is to have the less density insulation closest to the bass traps for higher frequencie trapping (thought that its good to keep the corner trap balanced out with HF V/S LF, as well as the most shallow place (knee) of the wall where Helmholtz absorber working on a higher frequencies, it might be wrong but I cant know this before its tried. So if you know give me a hint, we move on tomorrow and will put up the slats on Sunday, no way back from there. This is what I'm going for: 8) :oops: :roll: My latest overclock idea is to place the 100kg/m3 (green)and the 35 kg/m3 (yellow) as per attached pic. pls stop me now if I doing wrong, tied to find on the forum but cant find anything that really make me confident to proceed. Cheers Kaj

Dear readers, another Bass trap is born. The design of the room we building acoustic treatment are not problematic in the low end but, I think its not any harm to put in some kind of bass absorbtion. The first is made of a 45 degree 50 mm mineral wool slab 600 mm width 100kg/m3. covered with cotton fabrics. Tomorrow its time for the bigger bass trap, I'll try toget some pics as the job goes, and hopefully will I have some progress on put some insulation slabs in the frame work of my slat resonators. Calculation to come later............. Cheers Kaj

I have updated my thread in construction forum, where you can see the latest progress with our Basstrap and Helholtz absorber, http://www.johnlsayers.com/phpBB2/viewt ... 3460#53460 :D Kaj

Go to this thread and follow the work in progress with the helmholtz absorbers; http://www.johnlsayers.com/phpBB2/viewt ... 3539#53539 It has been fun so far and tomorrow we hope to start to intall the slats, I pray for that as I going back to work abroad again very soon and cant update this thread before in January, unless my mates sends me the pics of the progress, if any during X-mas festivities. Hope I have enough time to take some more pics tomorrow and update again. Cheers Kaj :D :D :D :D :D :arrow:

See thread for more pics and details in the building of a wall/Helmholtz absorber. http://www.johnlsayers.com/phpBB2/viewt ... 3543#53543 Cheers Kaj

:D :D :D I have some new pictures see thread. http://www.johnlsayers.com/phpBB2/viewt ... 3565#53565 Cheers

Been too swamped with life to get here as often as I'd like - one thing to keep in mind: the formula used in the slat resonator calculator is essentially the same as the one in Everest's Master Handbook of acoustics - when that was written, about the only type of material available was OC 703 fiberglass. If you change to a different material, you will change the airflow resistance of the absorber, and this will affect the center frequency. Don't ask me how, I'm not into heavy math and haven't had time to get that deep into absorber theory (even tho I bought several book$ on the subject :oops: ) Since you're using variable depth absorbers, I don't think that fact is as critical as if you were targeting a specific frequency - see Len Morgan's thread for his experience on this very subject... Steve

Steve, Swamped or Bogged? I can understand you! I'm just now in a bit of air flow resistance (AFR) turbulence in the flight to Japan from Copenhagen have to hold my glass if I want to keep any liquid inside the glass, but there is Swedish air-hostess willingly topping up, lucky me. Thank god for internet on long distance flights. Now I have time to polish/rework all inputs into my own ideas. I will try to find on internet the air flow resistance on my insulation used and compare with OC 703/705, but I'm of the opinion that I, had it lowered by using higher AFR, Having 8 hrs in Narita before connecting flight, so I will have time, unless the drink topper lead me astray!! DONT THINK SO!! Question; anyone out there having OC 703/705 AFR in metric or Imperial figures? or even better built a absorber with OC705 or any othe rigid insulation slabs, any feedback I can find maybe one chart of AFR for my insulation but its not the American standards that most books are written refering to!! But I'll take my time to find out a bit on the way, and if you Steve feel :oops: dont you dare, I have to infra-red if I should be compared with you. So now a second question, Could I, as I expect, have a lowering in absorbtion frequency, if higher AFR constant for our combination of insulation of the absorber is used compared with OC703/705?? Cheers

Steve, I have sent an email to PAROC, for verification if the pdf file I found is applictable for m purchased insulation, see links for the products and the pdf file for air resistance faktors, for me this saying nothing as I has nothing to compare the figures with. I would need to get OC 703/5 details but I still searching for that,, http://www.paroc.com/spps/BI_attachment ... _table.pdf http://www.paroc.com/Channels/com/marin ... e+Slab+100 http://www.paroc.com/Channels/com/Build ... ROC+UNS+37 Note that UNS 37z that I have do not NOT look like the picture in the link, its much more fluffy. :evil: Why cant they supply the same information for all products, arghh :evil: Cheers

Been in contact with Len Morgan, and nothing to worry about my design/construction. I have updated the the construction thread with a few pics again. :) http://www.johnlsayers.com/phpBB2/viewt ... 4200#54200

We are a bit further on the way to reach a nice music rehearsal studio. See pics at link: http://www.johnlsayers.com/phpBB2/viewt ... 4326#54326 Cheers Kaj :D :D :D :D :D :!:

I have tested only by ear and find it necessary to trap more mid range frequencies. Here is a link to what I have done!! http://www.johnlsayers.com/phpBB2/viewt ... 4553#54553 Cheers kaj :D

See link, http://www.johnlsayers.com/phpBB2/viewt ... 4751#54751 We have now completed the absorbers and only wall mounted Mid and High frequency panels on the walls and the slated ceiling panels. I might run that project in this thread in paralell with my construction thread. And some pics that show the progress soo far :lol: :lol: :D Cheers

Hi, Finally at the stage where I can take some actions towards the High Frequencies. We have made three 1,2x1,2m HF absorbers, its a simple construction and can be adjusted later if required (change insulation thickness and or density). Just now are they filled with 95mm OC 703 similar stuff. and only < a few mm of air cavity assume 100% filled. I had my son to help with the stapler to fix the fabrics inside the frame work, they are mounted on guiding wood strings fixed to the wall. The sound and the reverb in the room after this installations are very balanced in my opinion, I feel the sound to have equal reverbation time in high and low, by ear. Will check more thorough later with analyzers and test signals. I also have a construction thread as some of you might seen already, see link; http://www.johnlsayers.com/phpBB2/viewt ... 5066#55066 Cheers