Yeah nothing but the flu, flu and flu lately. So only get some hours on the PC to figure out some symmetry to all these walls, corners, straddeling corners, straddeling ceiling/wall corners absorbers and diffusers planned.
I've was gonna start on the large ceiling sub-bass trap this week, and do some preliminary measurements to verify starting point, but no such luck. If the flu's name is Carlsberg, Heineken or Corona, I don't give a shit but it's not going away as fast as usual....

So only thing I'm sure of is that I'm having a row of diffusers along the ceiling/wall corner, the others is not decided yet, I'll use Jens Eklund's Optiffusor because it's really wideband, light, cheap and goes down low. That's the green stuff in the drawing.

So across the 2 back corners with the door and the window, I'm striving for symmetry, but that's hard with doors and windows. The grey plates across the corners is the absorber (w/h 1.8x2m), barely visible behind the yellow rectangle. Where the door is, there's a entrance "hole" so not complete symmetry. In front of the absorber is a PRN (bass/air transparent) diffuser, marked in yellow, there are 4 of these, for illustration.

The absorber itself is supposed to be moveable, sturdy and flexible, and the diffusor is hinged to the front and can be removed, for only absorption, and replaced by a hinged plywood plate for reflection, to make the acoustics a little adjustable.

Over the absorbers/window/door in both corners (2->2.7m) I'll make a large pink fluffy absorber (marked red), these will be fronted partly with one Optiffusor.

If someone understands any of this, I will be impressed

On the walls under the green boxes goes the VPR's, mentioned earlier... Not a focus now....

I'm back after flue, flue and f.....in flue.

So opened the ceiling today for building a 20"x7"X3" bass trap, up there. If that doesn't work, I'll retire. Ah I'm already retired early so that was a fake threat, I have to renew my language as I'm getting older, which is hard to remember. What was I saying? This is getting out of hand already! Of course I didn't get to do any measurements, so I'm a total idiot. Dementia at 53, it's a hard life, but lots of low bass trapping is never wrong, in the long run. I will have my head up in the ceiling all week and build this shit. As it is I have 4 cubic meters of 3000 k/pas m/2 absorbers to use. Holy Christ, this is gonna be fun.

As always if you can put on Bela Fleck with "Flight of the cosmic hippo" at obscene levels, your good to go. A'int you?

How many control rooms/studios can do that?

Illustration photo, made a mineral wool frame around the perimeter, now gonna install to layers of 4" 3000kPas/M2 with some air in-between.... Maybe the sub-bass and the martini will be equally dry...

Done 2/3 of the double layer ceiling absorber. Pretty good job for a 5 hour shift on a Thursday. Last shift tomorrow I hope.

Jez, I have done some work this week too. Sounds good, sound isolation wise. Not dead quiet but better than expected. Electrician coming in today. Still no VPR plates, and gonna cover the steel beam with some poly's made of cut in half paper tubes... Been thinking to much so gonna experiment with diffusor and absorber placement next week, idea is to try to absorb most of the closest reflection points and diffuse the furthest away reflection points. So that means absorption on the side walls and diffusors in corners and end wall... This has to be done in part by moveable screens...

Theory about need for more absorption the lower you go in frequency still holds....

Anything new?

I had a big job extending the house so kind of lazy days here, the room is in use by bands but the acoustics is not finished. There is the same sub bass traps as originally built, so I just ordered the rest of the VPR's now from Don-Audio that will be about 25 sqm of VPR's to level the bass/mid-bass not the sub-bass, and diffusers from Jen's Eklund and GIK Acoustic's Versifusor. I hope I will get by to mount them and do some proper acoustic work in October. I'm kind of nervous that the tenants will think it sounds like crap with a neutral, diffuse room... I'm really having a hard time figuring out the diffusion. I ordered 3 or 4 I didn't decided yet, of Optifusor for low level diffusion on the back and a little side wall. It's only 8 sqm in a room of 60sqm with a surface area of about 200sqm, another 8sqm of Versifusor from GIK Acoustic's. It's not much. Maybe it will work.

As it is today...

Anyways, I've turned extremist ?
I work on the basis that the need for absorption increases with lowering frequencies.
Any absorption above about 3xScrøder is meaningless
In theory that's where you have a diffuse field.,from the theory of critical distance But I'm a novice. Correct me please...

The room is in use but I have not gotten to do any meaningful acoustic work or analysis of the room. I have 3 mobile free standing absorbers in 3 corners. The plan as of now is to install the VPR's on the back and side walls, and start mounting some of the diffusors in the ceiling mostly, and walls.

I don't work much indoors during the summer half of the year. So the other half is closing in. After reading about VPR's it says one should preferably use hot rolled steel plates, and not cold rolled steel plates as they are more rigid, less flexible. Unobtanium in Norway. So ready on one of the side wall is 12,6 sqm. of Caruso Isobond WLG-035, the other side wall will have 4,5sqm and the back wall 7.5sqm. I can't do this before I have documented the steel plate and done some initial measurements. Which ever way you turn, the ass is behind you.
So for some diversion of my troubles, I bought some close distance GIK Acoustics Versifusor's to use in the ceiling, it's EPS so takes ages too rub with sandpaper to get smooth even used some plaster/putty before painting. Still don't f.... look like a piano finnish...

My son was in Edinburgh Scotland in the art school Edinburgh Academy with his strings youth orchestra, it was a medium large oval room maybe 500 sqm, high vaulted ceiling with a galleri and lots of large intrusions, chandaliers, ornamented figures in the ceiling and lots of other ornaments all around (aka diffusion) and a lifted window canopee in the center of the ceiling, not a bare room at all, but all brick. For strings it was heaven, sitting in the middle of the room was immaculate, astounding airy immersive sound.
If we do rock or blues (amplified music), we don't need that, we need short even decay across frequency, especially drums and bass, and somewhat guitars and certainly vocals, the chorus ladies and all other acoustic instruments live in a short decay world, that they can do nothing about, their remedy is to work in a space with good diffusion for the wibe.
Long and short decay is 2 different worlds that try to meet...

Cold-rolled sheets should be fine for a VPR, but if you were making a plate reverb for example, wouldn't be the best choice.

I could not get REW to display the right scales on that Soundcraft mixer, everything is like divided by 5. 200Hz is 40Hz and so on. I sat there all evening and gave up, I checked physically the dip and peaks around 45 and 130hz to confirm this. The X legend is just screwed up. I used 9sqm of Jen's Eklund's Optifussor on the walls and 12 sqm of GIK's Versifusor in the ceiling. 3 out of the 5 of the 1,5x3m VPR's are in function.... And yes the Time window of the waterfall is 800ms, a good deal long, did so to show decay is pretty even, generally... And I just put the mic randomly next to the mixer where I sat, not a head in given position kind of thing.

I'm content. I knew I did that room after "the book", and that I never got to take the time to measure along the way, that didn't bother me, but it was not ideal. If you know where your going what's the point of checking, it's just confusing. Measuring is always confusing. And takes a lot of time. It's a stupid thing to say, and I know. But I was pre-determined to a goal of how I planned it, if theory works, this works. The goal from the beginning was increasing absorption the lower you go in frequency and keeping most close reflections diffused or absorbed. And from the beginning of this thread you can see those monstrous bass traps in the ceiling and back wall. They work. This project worked, I'm content.

And this room a very acceptable acoustical space with some mediocre PA speakers and no DSP ROOM CORRECTION sounds fresh, but still lagging very far behind a room with good speakers and DSP, all else equal. By far.