Greg Reierson wrote on Tue, 27 January 2009 13:11 |
The corners have built-in floor to ceiling traps that are 4' wide, using 2" 702, 2" gap, 2" 703, 2" gap - four layers deep to the corner. |
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The rear wall has a 8'x 9" 'diffractal' type diffusors. |
Ethan Winer wrote on Sun, 15 February 2009 12:35 |
traps are definitely large enough, but having layered gaps is not a good idea. Any chance you can redo the traps to be solid rigid fiberglass? |
Thomas Jouanjean wrote on Sun, 15 February 2009 19:48 | ||||||||||||||||||||||||||||||
I would not recommend "solid rigid fiberglass" but semi-rigid Rockwool of about 60/70kg/m Post by: Bruno Gouveia on February 15, 2009, 07:30:41 PM Post by: andrebrito on February 15, 2009, 08:35:42 PM Post by: Thomas Jouanjean on February 16, 2009, 02:29:39 AM
Which one do you mean? Arkobel seems to be compressed industrial foam in shreds, which is kept and compacted together by glue. I Don't like it very much... Post by: Bruno Gouveia on February 16, 2009, 03:39:29 AM
Yes, Arkobel is something like that. I don't know the exact density he uses but it should depends on the dimensions of the conglomerate panels. Why don't you like it very much? Arkobel is also used in-between walls to decouple them and improve a lot sound isolation, and it also works very well! Post by: Thomas Jouanjean on February 16, 2009, 06:25:41 AM
I never used the "Arkobel" brand, maybe it is different? I tried "similar" stuff, and was never happy with it. To decouple I go straight to Sylomer or Merformer & Co these days - maybe spring systems now and then when only those can be used. Before I found Homatherm, when looking for viable alternatives to Rockwool, I tried the industrial agglomerated foam thing which I got from CARDA near Brussels, seriously heavy stuff in general (like Andre said, it can come in very dense bats, couldn't lift it on my own!) which I did try in various densities, and after playing with it and getting some more info about it - I just dropped it and didn't look back so far. No use for it in decoupling schemes, nor in room acoustics correction. BTW, so which did you mean in Newel's technique, the air gap? Post by: Thomas Jouanjean on February 16, 2009, 06:36:04 AM
I had a look at your website - can you describe what is between you diffusor's back and the studio shell? Any LF treatment in there? Do you have somekind of plans of your room? It's really hard to figure out precisely what you need just from web pages and what you describe. Sounds to me like you should find a designer to design an upgrade to clean up the LF problem properly. Post by: Bruno Gouveia on February 16, 2009, 10:22:01 AM
He uses Arkobel or something similar attached with screws to conglomerate or MDF panels that are mounted in an array normally in the back wall of the control room. I've been at two studios designed by him here in Porto, but I think he has more. I think you can spot the array at the map at this site: http://boomstudios.pt But of course everything you said makes perfect sense and Newel is also a man of science so he obviously uses the techniques you described! Post by: Bruno Gouveia on February 16, 2009, 10:27:02 AM Post by: Steve Hudson on February 16, 2009, 10:39:03 AM
My control room is 23.5' x 16' x 8.75'. We installed two large (6'x4') traps with 6" of 703 and a five inch air gap between the 703 and the rear wall. Would we get better l.f. trapping by eliminating the air gap and installing 4 more inches of 703? Or could we install some sort of membrane trap behind the 703 for the really low freqs? Post by: Ethan Winer on February 16, 2009, 01:40:58 PM
A single gap as you describe is good, and the difference after filling the gap would be minimal. Yes, it will help a little! But only a little. Much better would be to apply the extra four inches of 703 on the outside of the panel. Then the absorption is 10 inches thick, and the air gap helps even more. --Ethan Post by: Steve Hudson on February 16, 2009, 02:24:32 PM Post by: Thomas Jouanjean on February 16, 2009, 03:41:12 PM
Good example of application using Sylomer: http://recforums.prosoundweb.com/index.php/mv/msg/24611/0/0/ 19234/ Bench design system applied to decoupling the whole studio shell, from under 10Hz. Post by: Thomas Jouanjean on February 16, 2009, 03:47:45 PM
Thanks for the details! Interesting technique... Nice studio! Variable acoustics in the LR Though visible ceiling in CR seems quite low for a room that size, do you happen to know which height... 2.60m, 2.70? Post by: Greg Reierson on February 16, 2009, 05:45:49 PM
The empty wells on the back side of the diffusor are filled with fiberglass. The diffusor itself is directly in front of the rear wall which is two layers of 5/8" gyp board on metal studs about 24 IOC, 6" space with fiberglass, then another two layers of 5/8" gyp board.Looking back I wish I had build something into that wall. It's still an option. Just need to know what direction to take.
That will be my next step. I just want to understand the problem a bit better beforehand. Thanks, GR Post by: Bruno Gouveia on February 17, 2009, 04:00:37 AM
Yes, maximum 2,80m to the cloth. There's office spaces above. Also there is a big hollow space for Newel's loudspeakers that aren't installed, and that space re-emits... Also the room is so dry that only at the sweet spot you can hear something really happening. But the live room is great, 110m Post by: andrebrito on February 17, 2009, 08:27:05 AM Post by: Greg Reierson on February 19, 2009, 04:35:11 PM
I'm a bit confused by that. When are resonators appropriate? GR Post by: Thomas Jouanjean on February 19, 2009, 05:21:08 PM
When there are no other options. They're usually buried deep in the room structure, behind the rest of the treatment. Post by: Greg Reierson on March 23, 2009, 08:05:33 PM After taking everyone's comments into consideration I decided to tackle my back wall. I have the luxury of not needing to contain the LF in my room. Low end leakage doesn't bother anyone and there is no significant source of LF outside of the room to bother me. I removed the inner gyp board wall and added a huge amount of porous trapping above and to the sides of my rear diffusor. The combination of more LF leakage and trapping (the trap is now about 5' deep at its deepest point above the rear diff) has made a huge difference. The 60Hz bump is gone and the 105Hz bump is much better. No resonators needed! The next step was to work on speaker placement optimization. With all of the LF changes, the apparent LF in the room was decreased. I assume the modal ringing of the room had been creating a false sense LF power, even though I knew it wasn't right. Now that the ring is gone, the LF is more even, but not as well reinforces as before. Small speaker placement moves can make surprisingly large responses changes. After a few hours of moving the big PMCs a couple inches at a time, I found what seems to be the flattest LF response with the fewest peaks and dips. The RPlusD software (the update to ETF5) made the process of comparing many speaker locations a snap. If you need a measurement tool but don't need to make a career out of it, RPlusD seems to have everything you need. I've been listening all day and I have to say I'm extremely happy with the results of a weekend's work. Thanks to everyone who encouraged me to do it the right way! GR Post by: Thomas Jouanjean on March 24, 2009, 09:31:19 AM Post by: franman on March 25, 2009, 10:28:21 PM |