bedroom / drum room

hi folks am converting a spare bedroom into a drum practice & recording room - looking to get a reasonable degree of isolation and treatment 3m x 3m x 2.7m high carpeted floor one wall is rough curve-faced bricks, painted (double brick to external) a second brick wall has a window - same double bricks third wall is pine clad both sides (bathroom on the other side), no insulation within wall fourth wall is partly pine clad and partly single brick, with a robe recess & shelves - this is where desk, computer, monitors etc will go the ceiling is pine boards and exposed rafters was thinking of using lots of limp mass loaded vinyl - hung like a curtain across window and across the pine clad wall - attached to ceiling in waves ie. a multi-curved contour following the ceiling boards and rafters - and then doing some acoustic panel treatment on the remaining brick wall to minimise reflections any thoughts on this as a minimalist, least effort approach?

Hi. Please read the forum rules for posting (click here). You seem to be missing a couple of things! :)

looking to get a reasonable degree of isolation and treatment

Unless you define what you mean by "reasonable degree", then we can't help you! For some people, it might be "reasonable" if their drums cam through the other side at 95 dBC, while for others, it might only be "reasonable" if the level was 40 dBC. Those are two very, very different scenarios. Unless you define your destination, you will never be able to get there.

3m x 3m x 2.7m high

That's about as bad as it gets! You have a square room, and the height is within 10% of the other two dimensions. You will have severe modal issues in that room: 57 Hz (Can you say "bass guitar" and "floor toms"?), 85 Hz (can you say "large kick drum"?), 127 Hz is a triple mess (rack toms). 213, 222, 228, 235 and 237 are all big issues (snare).... In summary, that would be a pretty bad room for drums. You need to modify the ratio to make it more usable.

was thinking of using lots of limp mass loaded vinyl

I hope you have lots of money! MLV is not cheap. It also will not do what you are hoping it will do. It is mass, plain and simple. It is also very expensive mass, but that's beside the point here: Mass is mass. It will act as mass acts, meaning that it will behave in the way Mass Law predicts. The density of MLV is around 1500 kg/m3, and Mass Law says this: TL= 20log(W) + 20log(f) -47.2 MLV is typically 3mm thick (about 1/8"), so therefore in the range of a typical drum kit, you'd be getting between about 1 to 25 dB of isolation, which puts you in the range of "almost nothing".

- hung like a curtain across window and across the pine clad wall

I'm not sure if you have ever worked with MLV, but trying to "hang it like a curtain" is not something that I'd be inclined to try...

- attached to ceiling in waves ie. a multi-curved contour following the ceiling boards and rafters

Why? What would that achieve?

any thoughts on this as a minimalist, least effort approach?

In acoustics, the "minimalist" approach will get you "minimalist" results. Putting little effort into design will get you little effectiveness in results. Drums are the hardest of all instruments to isolate. Hears a thread that shows what it takes to properly isolate a drum room: viewtopic.php?f=2&t=17363 His initial approach was far from minimalist, and for from low-effort, but was poorly designed and got poor results... until we showed him how to do it correctly, and that got great results. I'd suggest you need to re-think your approach. To get what I would consider to be a "reasonable level" of isolation for a drum kit in your room, 'd be thinking of air-tight seals on the existing room boundaries, beefing up the mass where necessary, then build a proper "room in a room" to create the necessary MSM system that will give you high isolation at reasonable cost. That would not be the minimalist approach, but it would be the least expensive approach that works. - Stuart -

thanks for the detailed response Soundman2020 - I'll read & digest that my thoughts / reasoning for the MLV as a "curtain" was to have mass / air / wall - trying to follow the principals and not lose too much space in the room by my calculations the MLV weighs about 7kg for 1 square metre - about 21kg for a metre wide drop of ~3m - the weight seems doable, if there's any point :/ the mode calculator is interesting - haven't seen that before - my room sucks!!! but it is all I have a slightly more accurate floor plan is attached

my thoughts / reasoning for the MLV as a "curtain" was to have mass / air / wall - trying to follow the principals and not lose too much space in the room

MLV is flexible, and is somewhat delicate: it tears fairy easily. You would find it hard to "hang it like a curtain" successfully, as the weight of the material itself would tend to tear through whatever mounting you used at the top to hang it. A "curtain" 3m wide and 3m high is going to weigh close to 70 kg. You'll need something rather more substantial then a dozen staples, or a few nails. It needs be held in place in several places over the surface. In order to do that, it needs to have a frame to which it can be attached. It also needs to be sealed air-tight, in order to function as an isolation barrier. Even a tiny gap around the edge will completely destroy the isolation. It's not that easy to glue vinyl to anything! Most glues don't work on vinyl. You would need to find one that does (some contact cements do, and there are a few adhesives designed specially for vinyl), and spread it very carefully around the border of each sheet of MLV, for maybe an inch or so, then glue that to whatever surface is behind it. But trying to get a good seal between MLV and brick seems like a tall order...

by my calculations the MLV weighs about 7kg for 1 square metre - about 21kg for a metre wide drop of ~3m - the weight seems doable, if there's any point :/

Take a close look at the equation for mass law: it's not about the total weight, but rather about the surface density. I'm not sure where you got the 7kg/m2 figure from, but MLV is usually specified as "1 psf" (pounds per square foot), and it is 1/8" thick, which is about 3mm. 1 psf works out to 4.8 kg/m2. So either the product you are looking at is not MLV, or it does not actually have a surface density of 7 kg/m2. Assuming you have normal 3mm MLV, and the surface density is 4.8 kg/m2, that works out to considerably less than half the surface density of a sheet of drywall (plasterboard). The surface density of 5/8" (15mm) drywall is around 12 kg/m2. A sheet of drywall costs around US$ 10. The same area of 1 psf MLV costs around US$ 70, but you'd need two layers to get the close to same mass as a single sheet of drywall, so the cost would be about US$ 140. (I realize that you are in Australia, so adjust those figures to AU$ if you prefer). Therefore, as long as you don't mind paying fourteen times as much as you need to for your isolation, and you can figure out a way to hang it without ripping it, and you can figure out a way to seal it air-tight, then it might work... :) And also, that you don't mind your room looking like it is lined with garbage bags... Personally, I'd suggest it would be much, much cheaper, and also far more effective, to just build a conventional stud-framed wall with drywall on one side. The cost would be about one tenth, and the isolation would be a "reasonable degree", without any doubt.

the mode calculator is interesting - haven't seen that before

You should take a close look at what it is telling you. I'm not sure which one you used, but here are the two I recommend: http://www.bobgolds.com/Mode/RoomModes.htm http://amroc.andymel.eu/?l=300&w=300&h= ... ing%20room Beware of calculators that don't include tangential and oblique modes: they don't give you the whole picture. It it only shows axials, then it is only showing part of the issue.

my room sucks!!! but it is all I have

When you build the isolation walls and ceiling around it, you have the opportunity to change that. You can adjust the locations of the new walls to get a more favorable ratio. I missed a couple of things in your initial post, that I just spotted while re-reading it:

carpeted floor

That will have to go. That's the very first thing you should do: rip that out, and get down to a good acoustic floor. Hopefully you have a concrete slab under there, but even if it is just some type of wooden sub-floor, that still beats carpet, big time, hands-down, no questions asked. Carpet is a pretty good way of trashing your room acoustics, since it does the exact opposite of what small rooms need.

fourth wall is partly pine clad and partly single brick, with a robe recess & shelves - this is where desk, computer, monitors etc will go

:shock: Ummm.... I can't see how that is going to work! For your mixing area, one of the most basic, fundamental, elemental, principle concepts is: "symmetry". Your head has to be on the room center-line, and the room absolutely must be perfectly symmetrical about that, to your left and right. If not, then you are not hearing an accurate stereo image and you do not have a true representation of the sound-stage: Your left ear is not hearing the same thing as your right ear. So all your mixes will be sonically "skewed" in one way or another. I can't see how you can get a symmetric setup at that end of the room. The only layout that makes sense in that room is to have your desk facing the window.

a slightly more accurate floor plan is attached

How come you are only isolating two of the walls? That would be like trying to build a fish tank with glass on only two sides of the frame... If you want to isolate a room, you have to do exactly that: isolate the ENTIRE room, not just part of it. Sound is like water: if you only put glass on two sides of the fish tank, water will run out through the other four. If you only isolate two sides of your room, sound will "run out" through the other four. Isolation is an "all or nothing" proposition. Either you do all of the room, or you get nothing. - Stuart -

thanks again for taking the time to respond yes, it's a concrete pad below the carpet, and the back part of the house (where the room is) is recessed into a hill and the house is about 80m from neighbours given the small size of the room, i figured minimising sound reflections inside would be the best for a tolerable recorded sound, so i thought leaving the carpet would help or is there something I'm missing here - not sure why removing the carpet would be better (more reflections?) - will need a mat for the kit anyway the outside walls (blue, opposite the door) are double solid bricks with a 50mm cavity, and the bricks are rough and curved, so nothing really need for isolation (except the window of course), and hopefully minimal internal treatment so a rethink about the MLV then... the pine clad wall to the right of door backs onto a bathroom - the wall has 2 leaves of pine and to the left of door it backs onto another room, but in the robe recess there's a single layer of brick I could remove the drumroom side pine paneling and beef up the remaining bathroom side with a double layer of MDF (zero experience or desire to work with plaster board) & rockwool then leave 100-200mm gap then build a new drumroom inner wall with another double layer of MDF and perhaps also rock wool for the ceiling - attic space above and then corrugated roof sheets, so just trying to stop/minimise transmission of sound to the rest of the house - rockwool between rafters, and double MDF panelling? i used the amroc mode tool originally the bobgold one seems to show a better picture if i shrink the room to 2.7m long, 2.8m wide, 2.5m high at least, that's how i interpret the results - is that right? and the robe recess for the recording equipment is also problematic - not sure if I can get a good mixing environment here - so, not trying for that - this is more about drum practice and recording I will have to get a sound measurement device to work out what levels I play at - but I'm guessing I'm no louder that other loud drummers - I play rock, not metal, not jazz but the target level would have to be less than conversation level - not sure what DB's that is

given the small size of the room, i figured minimising sound reflections inside would be the best for a tolerable recorded sound, so i thought leaving the carpet would help or is there something I'm missing here - not sure why removing the carpet would be better (more reflections?) - will need a mat for the kit anyway

The acoustic response of a room is only partly related to reflections. That's just one of many factors. And even in the case of direct reflections, carpet does very little to help. It's a myth that "carpet is good for acoustics". People see carpet on the walls and floor of a movie house, theater, or other space, notice that it sounds good in there, and wrongly assume that the carpet is doing that. What they don't know is that the carpet is just the facade: it is hiding the REAL treatment that goes behind it. The carpet is just there for decoration, and is used precisely because it does not affect the sound very much! It allows the sound to pass through to the other side, into the actual treatment device. Carpet does the exact opposite of what you need in a small room. Small rooms need a lot of bass trapping (the smaller it is, the more it needs), some controlled absorption in the mid range on a descending curve (more at low mids, less at high mids), and little to no absorption in the high end. Carpet does the exact opposite: It sucks out all of the high end wonderfully, absorbs some of the mid range randomly on an ascending curve, and does nothing at all to the low end. So not only is it useless, it actually makes things worse. Carpet will make your room sound dull, boomy, muddy, and dry. It will suck out your crash and ride, wreak havoc on the hi-hat and some of the snare, trash the toms, and make the kick sound like a wet cardboard box inside a concrete pipe.... Control rooms need to have neutral acoustics. Take a look at ITU BS.1116-2 to get an idea of how tight a control room needs to be kept, acoustically. It is flat impossible to achieve that with carpet. A drum room needs to be bright and lively, but balanced. It is flat impossible to achieve that with carpet. A rehearsal space or live room needs to be "warm" acoustically: It is flat impossible to achieve that with carpet. What your room will need is large bass traps in several of the corners, thick absorption on much of the ceiling, perhaps in the form of one or more clouds, and controlled absorption/reflection on the side walls in strategic places. You will need something like 60 to 80 sabins of absorption in that room, with a coefficient of around 0.15 to 0.2. That's the theoretical ideal for your room, but that isn't really valid, because the math only works for rooms that have a volume of between 30 m2 and 300 m2, but yours only has around 22 m3. The room just isn't big enough to get the decay times that you need for a good musical environment, so your only real option is to make it pretty dead. To do that, you'd need about 200 to 250 sabins of absorption, with a coefficient of around 0.35 to 0.4. That would make it usable for either a control room or a tracking room. It would be rather dead-ish for tracking and playing drums, but it would be well balanced. The other option would be to have variable acoustics: panels that can be rotated, flipped, slid, opened/closed or otherwise adjusted to change the acoustics from a bit more live for tracking, to a bit more dead for mixing.

and the bricks are rough and curved, so nothing really need for isolation (except the window of course), and hopefully minimal internal treatment

I think you are not really grasping the concept of isolation. It is impossible to achieve high levels of isolation at reasonable cost with only a single-leaf wall. If you need high isolation, and want to keep your costs down, then you have no choice but to build a full "room-in-a-room". The reason is simply something called "mass law". That's the equation that describes how a single-leaf wall isolates, and the results are not very heartening. You need huge amounts of mass (surface density) to make that work. Mass costs money. Lots of mass costs lots of money. The only alternative is to do a fully-decoupled two-leaf isolation system, which will get you a lot more isolation for a lot less money, because it does not rely on mass law: it relies on resonance, which is a powerful ally when used intelligently. So, the issue is not that one wall of your room needs less isolation than another wall: that simply is not valid, acoustically. The entire room, as a unit, needs a certain level of isolation, and that can only be achieved by isolating the entire room. As I mentioned before in the fish-tank analogy, you need glass in all sides of your tank to hold water. You need isolation on all sides of your room to "hold" sound. That might not sound intuitive to you, but that's the way sound works. You can't isolate a room by only isolating two of the walls, since there is no way of decoupling the other two walls. You need to have a complete "inner" leaf and a complete "outer" leaf around the room, with an air gap between them.

the pine clad wall to the right of door backs onto a bathroom - the wall has 2 leaves of pine

But they are fully coupled by the studs that join them. Therefore that is a coupled two-leaf wall, which acts much more like a single leaf than it does like a two-leaf.

I could remove the drumroom side pine paneling and beef up the remaining bathroom side with a double layer of MDF (zero experience or desire to work with plaster board) & rockwool

That would would work, but only if you decouple the new drywall from the studs using either resilient channel, or hat channel mounted on RSIC clips.

for the ceiling - attic space above and then corrugated roof sheets, so just trying to stop/minimise transmission of sound to the rest of the house - rockwool between rafters, and double MDF panelling?

Possibly, but ditto: it will only work reasonably well if you decouple the inner-leaf mass on some for of resilient mount. RC, or hat channel plus clips.

I will have to get a sound measurement device to work out what levels I play at - but I'm guessing I'm no louder that other loud drummers -

A good sound level meter is not expensive: around US$ 100 or so (AUS equivalent). Make sure that the one you get has both "A" and "C" weighting, and both "Fast" and "Slow" integration settings. Some of the cheap junk toy ones from China don't. They are useless. Also, a typical rock band will come in at around 110 to 120 dBC. "less than conversation level" translates to less than 60 dBC. So you need about 50 to 60 dB of isolation. That's not so easy to do! It is achievable, yes, but not with MLV curtains. At best, that would get you maybe 30 dB. You need about one thousand times more isolation that that. Yes, 60 dB really is one thousand times more than 30 dB. Decibels is a logarithmic scale, so big numbers are massively bigger than small numbers. People think that 60 dB of isolation must be about twice 30 dB, but in reality it is about one thousand times higher in intensity. Acoustics ain't intuitive! - Stuart -