Attic Shaped Studio

#511

yes, concave peaks will concentrate the energy - which is why locations like peaks, wall-ceilng, wall-floor, and wall-wall corners are excellent places to add absorption as modal supporting energies converge. getting rid of oblique and tangential modes will help even the space - sometimes as much as the main axial modes. in your case, the peak with the notches etc are currently scattering some frequencies and resonating others. filing those will attenuate those and the larger room volume will help slightly.

#512

Thank you George. Yes, the amount of time, work (and sealant!) required for the necessary attention to detail is quite something, it never fails to surprise me even after all those years! It's also a working studio so I have to keep it open as much as possible even during these improvements. Regular clients are fortunately very understanding, some have even been in recently when there wasn't a ceiling

Cheers!
Jennifer

norg wrote:Source of the post I just wanted to peek in and say how inspiring your project has been for the duration. Both in terms of your attention to detail as well as a comfortable dose of reality in terms of the length of time projects like this can take. Thanks for taking all this time to share your journey!

-= george =-

#513

Thanks Glenn, that all makes sense. I'm delighted to report that all that scattering has provided acoustic benefit for a band recording session yesterday, even in this unfinished state. I asked the drummer to setup underneath the raised ceiling. We got a really nice lively sound compared to the usual place at the back of the room, which is drier. Even the bass drum had more of a bloom on it. Nice to have the choice! There was also more space for the other musicians in the room as the drummer could sit next to the side wall rather than having to be some distance from the knee wall at the back of the room.

Cheers!
Jennifer

gullfo wrote:Source of the post yes, concave peaks will concentrate the energy - which is why locations like peaks, wall-ceilng, wall-floor, and wall-wall corners are excellent places to add absorption as modal supporting energies converge. getting rid of oblique and tangential modes will help even the space - sometimes as much as the main axial modes. in your case, the peak with the notches etc are currently scattering some frequencies and resonating others. filing those will attenuate those and the larger room volume will help slightly.

#514

coolio! once you do get the insulation up there and covered with cloth - adding slats will provide the scattering effect + some resonator effects.

#515

Makes sense, thanks Glenn. I've been investigating the use of space couplers (like in Lester's room) in the ceiling for their scattering and possible absorption enhancing effects. The wells in these are about 75mm wide and deep. Ideally there should be space coupler, then at least 75mm gap, then absorption. The modules are 300m deep with 200mm absorption which only allows a 25mm gap if the space coupler is set flush with the ceiling. In visual terms I'd really, really like to do this... one reason is that people sometimes hear with their eyes when evaluating a room and the flush space couplers imply *something* acoustic wise going on behind the treatment in the ceiling. Acoustics is of course the priority, but if I can combine the visual and acoustic, it's a win win.

If I can get them flush with the ceiling it'll look something like this.

Cheers!
Jennifer

#516

coolio. most space couplers are typically ~100mm deep or so with some minor edge scattering at high frequencies. but if you have 75mm deep space couplers, then mounting them flush and leanving 25mm (e.g.) of air to the surface of the absorption should work fine.

#517

something like this

#518

Lovely stuff, thanks Glenn!

#519

I've plastered and painted the raised ceiling. That was quite a job, it's all edges and corners! Next step is fitting the insulation for the absorbers.

#520

sadly, you'll be covering it up

on the plus side, you'll be gaining nice acoustics

i'm almost wondering if you can just hang some rectangular absorbers into those slots.

#521

gullfo wrote:Source of the post sadly, you'll be covering it up

Tell me about it LOL! Still, I sleep better knowing it has been done properly :-)

i'm almost wondering if you can just hang some rectangular absorbers into those slots.

Probably could do this and it would be good, but the plan is a little bit different. The height of these recesses is 310mm, except for over the cross beam area. I'm going to put 200mm thick low density insulation in the 310mm areas, and 50mm medium density over the cross beams, then cover the whole lot in wadding. This will leave approximately 100mm in the recess to flush fit the space coupler, with a small gap between it and the insulation above.

Cheers!
Jennifer

#522

Glenn, you were interested to see if the modal behaviour of the room changed with the raised ceiling. I've just taken a measure with no insulation in the ceiling and here's the results.

Left speaker, before (black) and after raising the ceiling (red)

Full range version of the above with VAR smoothing

Looks like quite a good result too me, especially considering there are now fewer absorbers than when the previous measurement was taken.

The substantial volume increase from around 180Hz upwards also explains the increased sound transmission to the other room, especially as the increase I noticed was mostly in the snare thump / vocal range which closely corresponds to this.

The correlation between left and right speakers has also improved. Left is black, red is right. This is a particularly pleasing result.

Cheers!
Jennifer

#523

it's definitely dispersing more evenly. the addition of the absortion should level that a lot. and peaks if they're still significant can be controlled by gentle EQ cuts with parametric EQ (i have a Behringer "Feedback Destroyer" which i use as parametric EQ across a number of frequencies and there are other products that work with REW as well to tweak the response).

#524

All makes sense Glenn thank you.

I've added some 50mm thick medium density insulation below the cross beam parts of the ceiling. Mainly to absorb any specular reflections or flutter echoes bouncing off them.

Roughly covered with fabric to prevent the dark material showing through the wadding that will be placed below them

As expected they haven't altered the frequency response much, but they have had a significant effect on RT60. Left speaker, black before these cross beam absorbers, red after:

The right speaker shows similar improvement:

Seems like quite a big effect from adding just under 1 square metre of thin absorption.

Cheers!
Jennifer

#525

I've added 200mm thick glasswool to the centre recesses, and an approximate wedge shape of the same to the ends. The fabric is a rough covering to hold the insulation in place; it will all be hidden by a sheet of wadding above the space coupler. The centre glasswool has also been covered in fabric since I took the photo.

Frequency response plot for left speaker. Black is with only the cross beam absorbers I attached yesterday. Red with the newly added 200mm thick recessed absorbers. Some incremental improvements.

RT60 for left speaker. Black is with only the cross beam absorbers I attached yesterday, red with the 200mm absorbers added today. Nice.

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