Decoupling a mixing room or treatment.

[JeromyReno]

The control/mixing room I plan on putting together is only a 10'6" X 12' X 8'6". Would I be gaining a lot by decoupling everything by building an inner leaf of a room inside of the pre existing room. I don't have any sound issues either escaping or coming in. It's already 10" of brick, 1" roxul board, then a 2x4 wall full of roxul, fully sealed triple pane windows. But when it comes to the over all sound of the room and response of the room would I get a benefit from decoupling it from the walls and celing and build a softer wall with a lower resonance, Or should I focus more on saving space to fit more treatment and air volume, stack up drywall and green glue, maybe even leave the back wall soft so the super lows can excape ¯\_(ツ)_/¯

The more I research the more I think I need to do, but I'm not sure if all the stuff that could help is all worth doing in my situation.

[Soundman2020]

The control/mixing room I plan on putting together is only a 10'6" X 12' X 8'6".

That's already very small, in terms of floor area, at barely 126 ft2: specs call for a minimum of 220 ft2 for a critical listening room. I'm not saying it isn't usable, but it won't be world class, even as it is. Taking away further space from that would make it even worse. Also, you need to take into account that small rooms need a lot more treatment, proportionally, than large rooms do, and the smaller it is, the more treatment it needs. Yours is going to need a stack of treatment to get it usable.

Would I be gaining a lot by decoupling everything by building an inner leaf of a room inside of the pre existing room. I don't have any sound issues either escaping or coming in.

Then no, you would definitely not gain anything from building a decoupled room inside the existing room. In fact, since you already have a two-leaf isolation system around you, adding a third leaf to that will probably make the isolation worse, not better. And it would certainly make the internal acoustics worse, simply because the room would be even smaller.

It's already 10" of brick, 1" roxul board, then a 2x4 wall full of roxul,

What is on those 2x4's? Drywall? Plywood? OSB? Nothing? If it is one of the first three, then how thick? How many layers?

But when it comes to the over all sound of the room and response of the room would I get a benefit from decoupling it from the walls and celing and build a softer wall with a lower resonance,

No. You have a two-leaf wall. Adding a third leaf to that could potentially drive the resonant frequency UP, not necessarily down. You'd have to design it very carefully, using the equations for 2-leaf walls and 3-leaf walls, to ensure that the resulting resonant system has a lower resonance than what it has at present.

And no, building a "softer" wall would not do you any good, .... assuming that you mean the same by that as I think you mean...

Or should I focus more on saving space to fit more treatment and air volume

Exactly. You need to maximize floor area and room volume. With such a small room, every inch you save will help.

stack up drywall and green glue,

Now you lost me... why would you want to stack up drywall inside the room?

maybe even leave the back wall soft so the super lows can excape

That's a myth, and a fallacy. You have a 10" thick brick wall back there, so the lows are not going any place, except staying inside the room. Making the back wall "soft" would not change that, neither would making it "hard". If you managed to build a hard back wall and tune it to a useful frequency in the low end of the spectrum, such that the lows would get through, that would be a pretty lousy thing to do for whoever is on the other side of that wall! You'll be sending them highly amplified bass, deafening.... and you'd be distorting the response of your own room. Plus there's the issue of how you would even manage that, when the outer-leaf is 10" of solid brick...

OK, let's take a step back here, and see what you actually have, since I suspect that things are not as they seem...

You say your room is surrounded on all four sides by a 10" thick brick wall. So far so good. So what are the dimensions of the room, just considering those brick walls, and nothing else? Is that the dimensions you gave at the start? In other words, if you measure across from the face of one brick wail to the face of the other brick wall, do you get 10'6"? And when you measure the length from the face of one brick wail to the face of the other brick wall do you get 12'?

So, next you say you have a 1" gap then a 2x4 frame, and that both the gap and the frame are filled with insulation. Right? Then what? Is that frame just open to the room, so you can see the insulation and the framing as you stand inside the room and look around? Or do you have some type of sheathing on that, such as maybe drywall, OSB, MDF, plywood, fiber-cement board, etc.?

Lets clarify that before moving on to what you should do next to get your room usable.

Also, please post photos of the room interior, as it stands right now.

- Stuart -

[JeromyReno]

Sorry I could have done a better job discribing it. I have been trying to draw it in autocad but it's taking longer than expected. I'll draw it out on paper for a faster reference.

The inside walls are just open insulation, my house is over a hundred years old and in a historical area so the outside of it has to look like all the other little brick houses, so I couldn't insulate it from the outside and stuco it to get the best results. So it's insulated from the inside using roxul's recommended system. So it's ancient red brick, 1" roxul board 60, then a 2x4 wall with roxul comfortbat.
My original plan was to go over that with 2x5/8 gypsom and green glue inbetween. This picture is of the rock board 60 and the 2x4 frame before I filled it with comfortbat. I had to run wiring first.

By soft wall I thought no gypsom, on either side of it, leave the cavities full of safe n sound and cover both sides with fire proof canvas or wood with large slots and holes cut out of it. so it's more like a gobo and I'd gain another 11' for low end to travel before coming back. I can't take the wall down like I would like cause it is probably holding the roof up as it runs threw the center of the house and it's where the rafters tie at the middle.

The room is in a corner of the house so only two walls have brick behind them and the others are common 2x4x16centers with safe n sound in them.

I had kind of pictured it as a room almost full to the top with treatment, as long as I can sit in it with monitors and a computer to get a good mix I'll be happy. Even if it's a closet inside.

The whole house is only 475ft2, I know it won't be world class but it like to push the Boundries as far as I can.

I think the walls are 4" brick - air gap - 4" brick - plaster. At least they are where I pulled the windows out.

I'll get more pictures when I get home with the full insulation and all the wall.

I can't thank you enough for taking the time to share your knowledge

[Soundman2020]

Sorry I could have done a better job discribing it. I have been trying to draw it in autocad but it's taking longer than expected

Try doing it in SketchUp. It's sort of the standard design package that we use around here. And it's free! It takes a bit of time to get used to it, but once you do, you'll find it's really powerful.

The inside walls are just open insulation, my house is over a hundred years old and in a historical area so the outside of it has to look like all the other little brick houses, so I couldn't insulate it from the outside and stuco it to get the best results. So it's insulated from the inside using roxul's recommended system.

OK, so the framing visible there is 1" away from the exterior brick surface, but NOT touching it? There are no mechanical connections between the framing and the brick? No nails, screws, brackets, bolts, or anything like that? If so, you have an interesting option. But if there are mechanical connections, then you will nee a different plan.

And that framing was already there when you moved in? Or did you add it later yourself?

Also, your diagram shows many other rooms: How much of that already exists? How much has actually been built?

I had to run wiring first.

Depending on how this plays out once all the facts are in place, that wiring might be in the wrong place. Your wiring should go inside the final, finished room, with no penetrations of the inner-leaf walls for things like outlets, switches, or lights.

By soft wall I thought no gypsom, on either side of it, leave the cavities full of safe n sound and cover both sides with fire proof canvas

Then why build a wall at all? Why build something that serves no actual purpose?

I can't take the wall down like I would like cause it is probably holding the roof up as it runs threw the center of the house and it's where the rafters tie at the middle.

The replace it with a structural beam! Call in a structural engineer to check that out, and tell you what your options are there. The span doesn't seem to be that great, so it should be possible to put a beam of some type across there, supported on posts at either end, which would allow you to have a larger control room. And since that's just a wood frame right now, with no sheathing on it, I'm inclined to wonder if it really is structural (load-bearing). Please post some photos of that wall, especially the top part and whatever is above it.

Also, on your diagram I see several other things that are rather curious, such as a bathroom and a closet that open directly into your control room... that's a bad idea for many reasons: You should never have a bathroom, kitchen, laundry, or any other area associated with water and noise, directly connected to your acoustic rooms in a studio. And the closets will act as some type of acoustic device that will modify the room acoustics in some, but it's impossible to predict what the outcome would be from the info we have so far. It would be far better to have the bathroom and the closet facing the other way (bathroom towards stair well, closet towards living room), with just a blank isolation wall on that side of the room.

Next up: dimensions: You say the CR will be 10'6" X 12' X 8'6, but on the diagram it looks pretty square. It's not possible to figure our which of those walls is 12', and which is 10'6

Did you check those dimensions with a room mode calculator, to check that you have a good ratio? Use one of these calculators to figure out the best dimensions for your room:

http://www.bobgolds.com/Mode/RoomModes.htm

http://amroc.andymel.eu/

Both of those are very good, and will help you to decide how best to build your room. They give you tons of information that is really useful to help figure out the best dimensions.

Another issue: You show the door to the room in the rear corner, but you'll need to move that, since corners are where you will need huge amounts of bass trapping. The door can go in the middle of the rear wall.

I had kind of pictured it as a room almost full to the top with treatment,

It's a small room so it will need a lot of treatment, but don't kill it! If you slap thick insulation all over the walls and ceiling, then the room will be way too dead, acoustically. It will be uncomfortable to mix in, with ear-fatigue becoming a problem, and your mixes likely wont' translate well: they will be too bright, and you will probably over-do reverb effects and dynamics.

Control rooms should have neutral acoustics, not dead acoustics. It should sound natural in there, but also very smooth and even with all frequencies decaying at the same rate, which you will calculate based on the volume of the room.

Take a look at the ITU BS.1116-3 document. It lays out the specs that a control room should meet. That's what your goal should be. So you'll need to treat it correctly to achieve that, rather than just throwing a ton of insulation into it.

as long as I can sit in it with monitors and a computer to get a good mix I'll be happy. Even if it's a closet inside.

Those two statements directly contradict each other! If it is like a closet in side, then you won't be able to do good mixes! And if you can do good mixes in there, then it won't be a closet. Google that document I mentioned, download it, and go over the section that defines the specs for "critical listening rooms".

I know it won't be world class but it like to push the Boundries as far as I can.

It actually can be world-class if you want it to. It's a little small right now, but by making it a bit longer, isolating it a bit and dong the right shape, layout, geometry, treatment and tuning, it can be pretty good. One major thing in your favor is the headroom: you have 8'6" to play with, which is great. With a room 5 or 6 feet longer, and a decent budget, you really could make that pretty darn good.

I think the walls are 4" brick - air gap - 4" brick - plaster. At least they are where I pulled the windows out.

Did you notice any insulation in the gap between the bricks? How big is that gap?

It seems to me that the room should already be pretty well insulated thermally, so I'm really wondering about that strange frame with the extra mineral wool in it. I don't understand why the builders would have done that. It doesn't make a lot of sense.

- Stuart -

[JeromyReno]

I think I can port these Viacad files over to sketchup, I'll see after I install sketchup

Yeah all the insulation framing I installed myself. The pre existing wall that runs threw the house at the back of the room is attached to the wall because it's structural and the one deviding the bathroom from this room(the right wall). The left wall and front wall only attach to the floor and rafters. The R value of these houses are R1.6~R1.8 and that insulation is to get it up to R-23, R-20 is required in this climazone, haha the roof needs to be R-38 and it's at R-1 right now so who knows how I'm going to make that happen Haha. It's only about 10 degrees cooler inside in the summer(90~95deg inside), and 20~25deg warmer in the winter(it's below freezing every night in the winter) with the heater running. Super old houses in the high desert might as well just be a tent.

All the rooms are the preexisting rooms from when it was built. It's hard to get a structural engineer to do stuff to the house cause then they have to get everything up to code and nothing is to code because codes didn't exist when it was build. It didn't even have an indoor toilet when it was built. Just a claw foot tub and a kitchen sink that drained into a troff outside.

It's the house I live in and I'm sleeping in the basement but will eventually live in the attic after I turn it into a small bedroom. I have lived here for just about 15 years and will have it paid off before long.

I was thinking about leaving the gypsom off of these walls like the inside out walls you referenced before to gain some more air space. Even with the celing which would give me 6" more height, I can even leave it off for the front half of the room and it would go all the way up to the roof. The rear half will eventually have flooring on top of the rafters.

Everything that was in this room I shoved in the attic for now so it looks pretty cluttered in the picture

I'll talk to a contractor friend of mine about removing that rear wall and putting in an lvl beam and what that would take/cost and if that's a posibility. If that's the case I could move the closet door too, maybe even make the closet lead into the bathroom. Although that sounds expensive but we will see, I like the idea of it.

I was looking up that brick gap and I think it's just around the windows and doors giving a place for condensation to condense and evaporate out of. So the rest of the walls are most likely solid. It's hard to find info on how they where built. A lot of things are weird sizes and spacing so it's a pain.

I'm really sold on the idea of soffit mounting my monitors after that other thread on it, and making it as rfz as possible now. I found that I can fit them in the walls with a 60deg angle and sit at %38 of the room distance while keeping a perfect triangle.

I put in the numbers of the room with inside out walls on the room calculator and it looks like 63hz would be pretty rough(like kick drums don't have enough problems already). Will the soffit walls effect the room ratio a lot though, seems like it would keep The energy flowing around in more of a circular motion, but I guess the low end isn't really directional.

I measured out where the soffit walls would be in the photo and marked them with blue tape.

Also what are your thoughts on running a monitor that rolls off higher up like the Adam a3x and using a small sub for the low end so I could move it around when tuning the room and set it's output separately from the monitors.

The big diffusers in the back of the room in the drawings where just for an idea, I assume I would measure the room once it's built then start making them based on the room tests

[JeromyReno]

- Stuart -

I guess I should have quoted some of your question so that made better sense but it's tricky from my phone.

I found some tests of the Adam a5x and they start coming down right before that room mode so that could help, I know soffit mounding will increase the low end too. That's why I was thinking even the Adam a3x, to excite less lowend energy

[JeromyReno]

I had a friend that's a contractor come check it out. Doing the beam to open up that wall is way beyond what I can afford, we would have to knock out the kitchen, build two support walls to hold up the roof durning the duration of the work, the cost of a structural engineer and permits with inspections is more than I can do. But he said we can move the door to the center of the room and turn the closet into a corridor to the bathroom. So that should give the room more symmetry leave the corners for bass traps. I won't be able to extend that rear wall out farther though.

I'll redraw the room with those changes too

[JeromyReno]

Alright so this is the latest plan. I can shift the door to the center of the room and move the other two doors so the closet becomes a corridor to the bathroom. This is something I can do myself or with the help of my contractor buddy.

The grey triangles are corner trap and wing ideas.

[Soundman2020]

Alright so this is the latest plan.

It's looking much better like that! Big improvement.

I would suggest moving your speakers further outwards on the soffit baffles, so they are further apart. The reason is that right now they are at about 25% of the room width, which is the 1/4 wave cancellation point... And you will also need more depth behind them, for the soffit framing, ventilation air path, damping, etc. This might mean that you need to angle the soffits a bit different, but that's fine. The angle does not have to be exactly 30° toe-in.

The other thing I'd suggest is to make the rear bass traps a bit wider, ending closer to the door, and perhaps not quite so far into the room (along the side walls).

Apart from that, it's looking decent. Now you can start work on the design for the soffit framing, as that is always complex...


- Stuart -

[JeromyReno]

Alright so this is the latest plan.

It's looking much better like that! Big improvement.

I would suggest moving your speakers further outwards on the soffit baffles, so they are further apart. The reason is that right now they are at about 25% of the room width, which is the 1/4 wave cancellation point... And you will also need more depth behind them, for the soffit framing, ventilation air path, damping, etc. This might mean that you need to angle the soffits a bit different, but that's fine. The angle does not have to be exactly 30° toe-in.

The other thing I'd suggest is to make the rear bass traps a bit wider, ending closer to the door, and perhaps not quite so far into the room (along the side walls).

Apart from that, it's looking decent. Now you can start work on the design for the soffit framing, as that is always complex...


- Stuart -

I'm so thank full for your advice! I'll start redesigning the soffit walls, would 1/5 of the with be a bit better.

[Soundman2020]

I'm so thank full for your advice! I'll start redesigning the soffit walls, would 1/5 of the with be a bit better.

That should be reasonable, but do make sure that you don't line them up with the corners! Putting speakers in the corners is also not desirable...


- Stuart -

[JeromyReno]

Alright, I finally made some visual progress. I got rid of the closet, used the space to expand the bathroom, and that gave me a way to move the bathroom door to face into the living room. Then I moved the door for the room into the center of the rear wall of the room. I got caught up removing all the unsheilded wiring that ran threw the walls and ran MC threw the whole place. But I had to clean out my attic and remove all the old insulation to do all that and got set back almost two months.

But over the weekend into today I managed to frame up the soffits to mount my Adam a5x monitors. The beams are 4x8 solid beams on 2x10 stacked top and bottom plates, screwed in and fastened with Simpson beam brackets and lag bolts. my original drawing had 2x4’s but I figured I might as well go
Overkill on it.

Will be laminating up some 2” thick mdf panels with ¼ pine vanere tomorrow to cover it. I ordered what seems like a billion yards of black burlap to make some basetraps too.

[JeromyReno]

Alright I got the fronts of the soffits all laminated together, cut up and in place. I originally cut the corners of the monitor holes to fit the Adam speakers how soundman2020 did all those a7x monitors but the a5x corners only come back just under a ¼ inch or so and it had flappy paper thin corners and it felt to fragile so I just squared them

[Soundman2020]

Whoaaa!!! Your soffit faces run from floor to ceiling! Where are you going to put your bass trapping??? Also, I don't see any ventilation provision or your speakers: Without that, they'll overheat and burn out rather fast....

It seems you moved a bit too fast with the soffit build... there's more to it than just a front panel.

- Stuart -

[JeromyReno]

Whoaaa!!! Your soffit faces run from floor to ceiling! Where are you going to put your bass trapping???

the idea of a infinite speaker extension seemed like the bigger the better.
my plan was to do big super chunk like corners/wings that would go in front of them on the ground and ceiling, angled like the wings that will go next to them, the ceiling ones might be a part of a cloud asimbly like i have built on the back wall. with the rfz design idea i wanted to keep the floor and ceiling reflections from hitting me on the first bounce.

the back of the desk im drawing up will be a bass trap too.

then i can add back reflections into the room as needed by putting slats over the absorptive panels.

Also, I don't see any ventilation provision or your speakers: Without that, they'll overheat and burn out rather fast....

since i planned on doing a big cloud up top and down low i figured the traps would stop the vent holes on the top and bottom from getting air flow threw them, so i punched holes in the ceiling behind the soffit so i can feed air into cavity behind the soffit from the attic(where my heating ducts run) with a small booster fan mounted in the attic that turns on when it gets hot. if it doesn't have good enough free flowing exchange threw convection of the hot air rising out and the feed tube running in pulling in air to replace it. there is probably hardly a foot behind it with the beams i made it out of. i was going to put rock wool between those beams too.

It seems you moved a bit too fast with the soffit build... there's more to it than just a front panel.
- Stuart -

yeah i had to use my week vacation before the end of the year so i had a week to work on it, and im itching to get it done( actual itching from insulation too haha) if i have to make drastic changes or remake anything im not super bummed on it, it's all a learning process.