need some help with a odd shaped room with 20ft ceiling

[rony316]

i have an odd shaped room that i need some help desiging a layout for and framing. no live room or booth. just main room and bathroom. this will strictly be a listening/mixing room so needs to be as flat as possible.

the room is all cement bricks and solid concrete. 25x12x20

i was thinking about framing splayed walls with soffit speakers and need some suggestions.

attached is a sketch of the exact DIMENSION

any suggestion are appreciated.

thanks

[Soundman2020]

any suggestion are appreciated.

First suggestion is to deal with that curved wall! That's a major problem. That has to end up as a flat wall. I'd suggest playing around trying to fit the largest possible rectangle into that space, then adjusting as necessary to get a good room ratio.

Since it is going to be higher than it is wide for sure, you can swap the "width" and "height" parameters in the room mode calculators, since they assume that the smallest dimension is the height.

So this is basically a control room? I have a feeling it's not going to be a very big room, probably no more than about 8 feet wide.

i was thinking about framing splayed walls with soffit speakers and need some suggestions.

Soffit mount for sure, if you want good response and minimized artifacts from speaker/boundary interaction. And splaying the walls might help you maximize space inside.


- Stuart -

[Soundman2020]

Here ya go:

Optimized-shape-1.png

I played around a bit, and that's about the best you can get it, constrained by the dimensions of that space. The ratio is close to one of C.P. Boner's good ratios, and works fairly well.

Those are the dimensions for the final inner surfaces of the room: you'd still have to put the framing outside that, somehow.

- Stuart -

[rony316]

hey Stuart , thanks for your help with this.

i had something similar in mind but not with the same ratios.

i see that you limited the height to 11' 2" 5/8 from the available 20 feet. what would you do with the extra space? leave it empty?

would you fully close the room with Sheetrock first and THEN treat with absorption on the inside? or would open studs/insulation with fabric finish work? (brick > stud > insulation> fabric) (fake walls)

thanks

[rony316]

i have been using the room calculator and you are right on the money. the dimension you gave are best.

i will be closing with Sheetrock on outside, but leaving HALF the inside for fabric covered insulation for absorption.

[Soundman2020]

i see that you limited the height to 11' 2" 5/8 from the available 20 feet. what would you do with the extra space? leave it empty?

I couldn't find a good ratio with the ceiling any higher than that, and for a control room eleven feet is pretty good anyway. You could maybe go a bit higher, then hang a large, angled hard-backed cloud over the front of the room, to deal with the modal issues to a certain extent.

What would I use the additional space upstairs for? HVAC! You have more than plenty of room to get all your HVAC up there, so it will not take up any space at all inside the room. You'll have about six feet of clear space up there, maybe more, and I doubt you'd need more than about three or so for the HVAC, so you might also be able to fit in some storage up there, accessible up a ladder, or something like that.

would you fully close the room with Sheetrock first and THEN treat with absorption on the inside? or would open studs/insulation with fabric finish work? (brick > stud > insulation> fabric) (fake walls)

Fake walls aren't walls at all, for sound waves! Sound waves don't care what the walls look like: all they care about is mass and rigidity. Insulation and fabric have none of either, so sound waves wont even "see" them at all. But drywall has plenty of both, and sound waves will be impressed by that!

So the boundary of the room at those dimensions, is the surface of the drywall facing the room interior. That's what we are concerned about, for modal calculations. That's the actual acoustic boundary of the room.

Once the room is built to that stage (complete inner-leaf boundary in place and sealed), then you can run a simple acoustic test on it using the REW software, to see how it performs in its worst possible state, and use the results to determine what treatment is needed. Yes, it is possible to predict a lot of that in advance, and you could actually install all of your bass trapping and first reflection point absorption before testing... but then you'd have nothing to compare it against! Also, prediction is one thing, but reality is another.... There's no such things as perfect building materials, you can't build perfectly straight, perfectly homogenous walls, and slight variations can cause large deviations from prediction. So it's best to do a "baseline" test with just the shell in place (inner-leaf walls and ceiling, doors, windows, soffits, desk, etc.), but no treatment at all, then install the basic treatment, and do another test. That way you can see how your empty room really reacts in real life, as opposed to what was predicted, and then you can see the effects of the treatment you installed, and see what you still need to do with the next round of treatment. If you do that at each stage of your treatment, you can see what is working, what isn't, and how much further you have to go to get within spec.

- Stuart -

[Soundman2020]

i will be closing with Sheetrock on outside, but leaving HALF the inside for fabric covered insulation for absorption.

I'm not sure what you are saying there. The shell of the studio must be complete, unbroken, massive, rigid, and continuous. You can't leave out half of it!

In other words, each of your walls must be built as a frame with at least one layer of drywall on it, and the entire ceiling must be built the same way. When that is done, then as you stand inside the room and look around you in all directions, all you see is drywall, everywhere. No fabric, no insulation, no gaps, and none of the original walls that were there before you started.

Once you have that situation, then you have your isolation system in place. Then, and only then, can you start installing the insulation and fabric, which is the treatment.

Isolation does what the word implies: it isolates the room from the rest of the world. Doing that makes it sound bad inside. That's why you need treatment: to make it sound good again. Isolation and treatment are two very different things: opposites in many ways. You cannot use treatment materials to isolate a room, and you cannot use isolation materials to treat a room. Materials that isolate are massive, heavy, hard, solid, rigid, such as drywall, plywood, OSB, MDF, glass, thick metal, etc. Materials that treat are light, soft, fluffy, flexible and porous, such as fiberglass, mineral wool, acoustic foam, fabric, etc. They can be used in combinations to do different things, yes, so sometimes the fluffy ones are used as part of an isolation system, and the heavy ones are sometimes used as part of treatment systems, but in general the hard, heavy rigid ones are use to stop sound getting in/out by defining the boundary of the room, and the soft fluffy ones are used to get the room sounding nice inside.


- Stuart -

[rony316]

i completes understand. what im basically trying to say is would i be able to just install only 1 face Sheetrock on the OUTSIDE of the wall, and keep the inside just empty studs so i can fill with insulation and close it off with fabric in the areas where its needed? (FOR EXAMPLE THE FRONT HALF OF THE ROOM WILL MOST LIKELY BE ABSORPTIVE)


i attached a picture.

thanks

[Soundman2020]

would i be able to just install only 1 face Sheetrock on the OUTSIDE of the wall, and keep the inside just empty studs so i can fill with insulation and close it off with fabric in the areas where its needed?

Ahhh! OK, now I understand. What you are describing is usually called "inside out" construction, where the drywall faces the wall cavity and the studs face the room. That's actually very common here on this forum, as it saves space when things are very tight, under some circumstances.

If you do it that way, you do have to be careful about over-treating the room: having too much absorption. That's nearly as bad as having too little absorption, in some respects.

THE FRONT HALF OF THE ROOM WILL MOST LIKELY BE ABSORPTIVE

If you are going to soffit-mount your speakers, then the front half of the room should be reflective, with the rear half being absorptive. That's the basis of RFZ design: using hard reflective surfaces at the front to re-direct all first reflections past the mix position towards the back of the room, where they can be absorbed and reduced in intensity, or diffused, or both. So if you want to follow the RFZ concept, then you should keep the front part mostly reflective.

- Stuart -