First post, drum practise room design planning

Hi, This is my first post, so hello and thanks for the great resource here! I have been holding off from posting because I have been studying so that I can contribute as much as I can, first, before asking for input. I think I'd get more help if I know more to begin with (by asking better questions etc). But now, regardless, here I am. I've been reading a couple of good sources like, "Build it like the pros" by Rod Gervais and, "Recording Studio Design" by Philip Newell. I have been talking to other people who are doing a similar build to me locally etc... but trying to politely ignore folks who spout misinformation! They're everywhere. Background: I teach 23 students per week and practise numerous hours per day on the drums. I do so currently with a muted drum kit which has it's downsides. I have been planning to buy my own house and build a sound isolated room for many years, and now it's happening. I have land and a builder and the dimensions of the room I am building (see picture below). I have included the area location in relations to the suburb and main roads and local parks, and a floor layout, ad the room sketch up printscreen. I want to go from using the muted kit in my current home to unmuted drums in my new home from now on. I play everything from light jazz to heavy metal. My main problem will be low frequencies of the bass drum. I have not measured a decibel level for my drumming volume. I would say it varies wildly from next to nothing to extreme; but I don't play the extreme volumes very often, nevertheless... I would be willing to accept a standard 'known' loud drumming dB level as my worst case scenario. I rang the Wanneroo shire and asked their noise threshold requirements. Musical instruments are considered 'equipment' so bound by the following restrictions if complaints are made AND if 'operated' for more than one hour in total between 7am and 7pm: 45deb base level Monday through Saturday (and factors like proximity to major roads etc) 35deb base level Sunday (and the same above factors) from 7pm-10pm 40dB base level All days (+ factors) all the above is using a LA 10% calculation (?). I believe this is a calculation of the percent of time that the noise restrictions are broken during the test time. I hope that means something to some one. Long story short: to achieve 35dB total while playing at extreme volumes would ensure no restrictions on my practise. To be honest, I would like to calculate the effective sound reduction of my room treatment first, and then see what implications that would have for me, and then reassess if my design is suitable before going ahead. Furthermore, my house (which is still without titles) and is currently still vacant bushland does not have any known factors (which may make my restrictions less severe). Location: My goal is to build a sound proof drum room in my new (to be constructed house). Residential setting, against external double brick wall. Building: (see picture) Dimensions are to scale in Sketchup. Letters A B C D E are all external distances A= 4325mm B= 4721mm C= 4896mm D= 3000mm E= 1721mm F G H I J are all internal distances (which I have left out for now incase the internal structure changes as plans develop). Height of the main room (external room) will be 31c (roughly 9 ft or 2743 mm). So the internal room I build will have to be smaller than that. Currently uncalculated. In sketchup I have made all wall go to 2440mm. There must be a window (dimensions unknown at the moment along E (external wall). The external wall along D is double brick 250mm (100mm brick + 50mm gap + 100mm brick) Design: Room within a room, mass air mass. Single room with no need to for separate recording or mixing room. Air conditioning and air ventilation needed, electricity, and lighting needed (of course). Walls and roof will be the same design concepts. Questions about this below. Everything will be built on top of the existing slab. I will lay various materials ont he floor. Still need to research this. Budget: Been working on a rough figure of $10,000 AUD but can go higher... At $20,000 I might put my foot down. Cheaper the better, but quality the priority. Skill level: I have never done construction in any sense before, but I am open to learning, quick to learn, and capable of teaching myself anything. Time constraints: I have been told I'll get titles around April 2014... so in all likeliness I won't actually be in building stages (of the house) until May earliest. Then I can begin my sound proofing after the house is build around 2015 I don't have any specific questions at the moment, will will post back to this thread with them when I do. I'm guessing your feedback will prompt some good questions any way. Time is on my side.

Two questions, Based off the information on this page http://johnlsayers.com/Recmanual/Titles/Acoustics3.htm 1) Given my goals (especially as I see it the bass frequencies being the major factor to attempt to reduce), can I create the smaller option of the two internal walls (that is the 200mm total space versus 300mm total space)? Would it be better to do the larger one as far as sound isolation is concerned? If so, would it be worth it given the space loss? 2) In the diagram on the page linked above, I see two layers of 16mm plasterboard used instead of varying sizes. Won't that allow for some resonance. Would it be better to have 16mm and 15mm? (and again is that too close in size? would 16mm and 14mm be better)? Matt

Hi Matt, and welcome to the forum! :)

but trying to politely ignore folks who spout misinformation! They're everywhere.

Oh yeah! :) There's about a hundred of them for each of the good guys.... (conservative estimate).

I want to go from using the muted kit in my current home to unmuted drums in my new home from now on. I play everything from light jazz to heavy metal.

:shock: That's quite a variety! Both in styles, and also in levels.

My main problem will be low frequencies of the bass drum. I have not measured a decibel level for my drumming volume. I would say it varies wildly from next to nothing to extreme; but I don't play the extreme volumes very often, nevertheless... I would be willing to accept a standard 'known' loud drumming dB level as my worst case scenario.

Around 115 dB is average. It's not just the kick drum that does it, either. The toms and even the snare have a fair amount of low frequency content in them too. And assuming that your drumming will be accompanied by an electric bass, there's a not more lows in that too.

45deb base level Monday through Saturday (and factors like proximity to major roads etc) 35deb base level Sunday (and the same above factors) from 7pm-10pm 40dB base level All days (+ factors)

And, of course, as with most noise restrictions, those are practically impossible to comply with, without some pretty serious isolation. To pot things in perspective: a normal conversation between two people will register at about 65 dB. Whispering sweet nothings in your lover's ear will hit about 35 to 40.... Anyway, there are a few things in your favor: those are "A" weighted levels, meaning that they are far less sensitive to low frequencies than "C" weighting measurements, and those are probably measured either at the property line (good) or at the point where the complainant is located (even better). So the challenge is to get 115 dB inside your room, down to 35 dB at the property line. That's a difference of 80 dB. Hopefully, your room is far from the property line, as distance helps a lot. If you have a choice of where to build this studio, then keep it as far away as you can from your neighbor's houses, in all directions. Each time you double the distance between "you" and "them", you get a decrease of 6 dB, theoretically (less in real life). So if you measure 66 dB at 1m from your wall, then that should be around 60 dB at 2m, 54 dB at 4m, 49 dB at 8m, 43 at 16m, 37 at 32m, 31 at 64m, etc. In real life, the loss won't be that great, since there are likely walls, trees, cars, and other surfaces that reflect sound as well, but it gives you an idea.

Location: My goal is to build a sound proof drum room in my new (to be constructed house). Residential setting, against external double brick wall

There¿s actually no such thing as "soundproofing" in the strict technical sense, and the term means different things to different people anyway, so acousticians prefer to use the term "isolation", or even "transmission loss", which is sort of the same thing. These basically mean reducing the amount of sound that makes it from point "A" to point "B". Perfect isolation is impossible: any sufficiently loud sound will penetrate any conceivable barrier. But you can get pretty darn good isolation. The more money you have, then better it can get! :)

Budget: Been working on a rough figure of $10,000 AUD but can go higher... At $20,000 I might put my foot down. Cheaper the better, but quality the priority.

How much of this structure exists already? Are the brick walls already in place, for example? If there is nothing at all there yet, then I guess that your studio will be going inside the house-that-is-yet-to-be-built, and the 20k budget is in addition to what the actual house will cost you? Or did I misunderstand what you were saying?

Skill level: I have never done construction in any sense before, but I am open to learning, quick to learn, and capable of teaching myself anything.

You might want to consider hiring a contractor, or at least an experienced builder, for the first week or two, until you get some of the skills under your belt. His knowledge of methods, techniques, materials and tools can save you a lot of time and money!

Time constraints: I have been told I'll get titles around April 2014... so in all likeliness I won't actually be in building stages (of the house) until May earliest. Then I can begin my sound proofing after the house is build around 2015

Great! So you have quite a few months to learn about acoustics and construction. In addition to the books you have already read, I'd add "Master Handbook of Acoustics" (affectionately abbreviated "MHoA") by F. Alton Everest. That's sort of the "Bible" of acoustics, and walks you through all the basics with not too much math. Highly recommended.

1) Given my goals (especially as I see it the bass frequencies being the major factor to attempt to reduce), can I create the smaller option of the two internal walls (that is the 200mm total space versus 300mm total space)?

MSM is a tuned system. It isolates by "fight fire with fire". It "fights sound with sound", sort of. It works like this: "MSM" means "Mass-Spring-Mass", which refers to the principle of physics on which this isolation works. This is a bit harder to explain, but it is the key to why you get isolation. If you hang a weight from a spring, and give it a nudge, it will bounce up and down for a looooong time, at a fixed rate that does not change. It doesn't matter how hard or how gently you pull down on that weight before releasing it, the rate of the bounce will ALWAYS be the same, at "X bounces per minute". It is a tuned system that is resonating at its natural resonant frequency. If you wanted to make it bounce faster or slower, then you would have to make the weight heavier or lighter, or you would have to change the spring for another one that has different resilience. There's no other way you can make it bounce differently, because the mass and the spring act together to "tune" the system to a specific frequency. This is the basis of the "Mass-Spring-Mass" principle. Another example: Have you ever pushed a child on a swing? Notice that the swing only ever goes at one rate, no matter how hard or soft you push? For each child, the swing will always complete full cycles in exactly the same time period: "X per minute". To make it go faster or slower, you have to put in a lighter or heavier child, or change the length of the ropes. This too is an "MSM" system. So is a grandfather-clock pendulum, which is why pendulums used to be used for timekeeping: they always swing at the same rate. Now, what would happen if you tried to force that swing with the child to go at a DIFFERENT rate? Let's say that you want it to go 50% faster: how do you do that (not changing the child or the ropes)? Answer: you cannot do it easily, since the mass and the spring (rope/gravity) are resisting all changes to the resonance of that system. You would have to physically force the swing through the entire cycle, using all your strength at each point to make it go at a different speed. You'd have to put a huge amount of effort into doing that, but as soon as you release it, it will immediately go back to swinging at its natural rate, effortlessly. Your MSM wall does the exact same thing. The two leaves are the two masses, and the air in between is the spring. The wall is a tuned MSM system. It will resonate at only one natural frequency, and will resist all other frequencies. There is one frequency where it will vibrate and resonate and sing like crazy, directly and effortlessly passing all the energy from one side to the other. So what good is that to you? Well, if you tune it so low that it can only resonate at a frequency BELOW the threshold of human hearing, then it will naturally resist passing all other frequencies! We have a word for that: isolation. :) So if you tune your walls such that the resonant frequency is below 20 Hz, then it will isolate across the entire spectrum. The way you "tune" the walls is the same way you "tune" the kid in the swing: either you change the mass, or you change the length of the rope. Either you change the mass on each leaf of your wall, or the distance between them. More mass = lower frequency. More gap = lower frequency. So you simply select the amount of mass and the size of the air gap such that the resonant frequency is lower than the lowest frequency you want to isolate. Simple! The mass on either side of the wall, and the air gap between them, all work together to vibrate at a certain frequency. The resonance is governed mostly by the mass on each leaf and the distance between the leaves. The higher the mass, the lower the frequency. The bigger the air gap, the lower the frequency. Like I said, the idea is to get that resonant frequency down as low as possible, because the wall is actually an amplifier at that frequency (helps the sound to get through the wall, and boosts it along the way!), is neutral at about 1.4 times the RF (resonant frequency), isolates OK at 2 x RF, and isolates well at 3 x RF and above. So, if you can get your RF down to 10 Hz, then the wall is already isolating at 20 Hz, which is generally considered to be the lowest frequency audible to man. There are two ways to reduce the RF of an MSM wall: 1) add more mass to each leaf. 2) increase the air gap. A wall with 3 layers of 16mm drywall on each side of a 12" gap gets you pretty close to that ideal situation. So, answering your question: if you reduce the air gap from 300mm to 200mm, you force the resonant frequency up the scale, to a much higher frequency, so you reduce your isolation for low frequencies.

Would it be better to do the larger one as far as sound isolation is concerned? If so, would it be worth it given the space loss?

The larger the better, within reason. Once you get the resonant frequency down below half of the lowest frequency that you need to isolate, there's no real need to carry in increasing the gap, or adding more mass.

2) In the diagram on the page linked above, I see two layers of 16mm plasterboard used instead of varying sizes. Won't that allow for some resonance. Would it be better to have 16mm and 15mm? (and again is that too close in size? would 16mm and 14mm be better)?

Well, yes and no. And maybe too! :) Here's the thing: even though the two individual leaves have their own resonant frequencies, as you rightly point out, that isn't a major concern for the MSM system, which is made up of the entire wall. There are several things going on here: the parts act individually, but they also act together. So each panel resonates at its own frequency, but the system resonates at a different frequency, and that's the one that matters. The individual characteristics are not even considered in the MSM equations: all that comes into play is the total mass on each leaf, and the size of the gap between. So if you substitute 14mm instead of 16mm for one of the leaves, well then you have reduced the mass on that leaf, and therefore also reduced the total isolation of the system.... - Stuart -

Thank you Stuart for your response. I intend to read it fully (when not rushed) and respond to all your points that need response. But for the moment, i.e. today, I need to get an answer on a quick question. I hope any one can answer this. The builder needs to know whether I want 28 courses or 31 courses of bricks in my drum room (height) I originally planned for 31cc but now they are saying it causes the garage to need to go up too etc, creating another $1900Aud in costs (in addition to my original additional price for raising the roof from 28cc), So what I'm asking it two things: 1) is 28 courses of brick too low for comfort or sound isolation? 2) is it worth the money therefore to go to 31cc? Thanks

A general rule of thumb in acoustics is that "the higher, the better". High ceilings generally make a room sound more spacious and airy, and especially if this is a drum booth where you will have overhead mics hanging above the drums. If those are just a few inches below the ceiling, then you can expect artifacts such as reflections, phasing issues, comb filtering, etc, due to that, but if you have several feet between the mics and the ceiling, those all go away. However, there's also the issue of budget, and sometimes you just have to live with what you have, even if it isn't ideal. A non-optimum drum booth is better than no drum booth at all! So if raising the ceiling would break the bank, then it's probably not an option. What would be the final inner-leaf ceiling height in both cases? If it is more than about 2.5m even for the lower option, then I wouldn't worry too much, but if it is a lot less than that, then I'd seriously consider raising it. There's also the question of studio objectives: if this is just a hobby studio, for your own use, then the higher ceiling might not be worth it. But if this is going to be a commercial facility, with paying customers laying down tracks in your drum booth, then I would highly recommend going as high as you can: your customers will thank you for that! A drum booth with a low ceiling is not going to attract paying customers too well.... Another option might be to go down, not up: have you considered digging the floor deeper in the drum booth? Digging down another 20cm before pouring the slab can make a huge difference, without affecting your roof construction.... - Stuart -

This room is purely for me to practise in a teach from. There is never a need to rehearse with other instruments and I won't be recording my drums. The only other sound source is a PA speaker which can be used to play over top of (but I can and do use headphones instead).

Then you are probably fine with the lower ceiling. But how low are we talking? What would be the finished ceiling height, with the lower option? - Stuart -

I decided to go with it. 31 courses is 2.65m 28 courses of brick is 2.44m ...It will feel more comfortable for me, and more inviting when taking clients/students in for lessons. etc. etc. so that question is answered. Thanks

That's a good decision, I reckon! Smart move. - Stuart -

How about some photos of how it is going? It's always a good idea to have a few extra pairs of eyes "watching over your shoulder", so to speak, and looking out for issues that you might not have noticed... - Stuart -

Soundman2020 wrote:

How about some photos of how it is going? It's always a good idea to have a few extra pairs of eyes "watching over your shoulder", so to speak, and looking out for issues that you might not have noticed... - Stuart -

Certainly Stuart, but like I said I have time up my sleeve. At the moment the final structural design is going through drafting. We won't have title until April. I'm guessing we will be moving in this time next year (Dec 2014). Then building of my practise room will commence. Thanks

Can you believe it's taken me this long to finally read your response and take the time to fully understand it? Thanks Stuart. So I am interested in running some numbers for myself. I would like to input some different options and see what amount of mass and spring will be optimal for me. I like to get down to the fundamentals, so I googled spring physics. I came up with Hooke's law. Is this the right one? I think so but it doesn't incorporate distance. f is frequency of oscillation about equilibrium position k is stiffness of spring m is mass f = (0.5*pi) * [square root of(k/m)] I don't know the stiffness of air but it will be the same in each comparison anyway. What are the equations I'm chasing? Do we just put in f = 10Hz as you mentioned that is pretty good? Again I'd like to try it with 5Hz and see how feasible that would be.

Here's a couple of equations for ya: Mass law (for single-leaf walls): TL(dB)= 20log(W) + 20log(f) -47.2 Where: W is the surface density of the leaf, and f is the frequency of interest Empirical real-world overall Mass Law transmission loss equation: TL = 14.5 log Ms + 23 dB (where: Ms = Surface Mass in lb/ft2 ) Resonance for 2-leaf MSM walls: F0=c[(m1 + m2)]^.5 / [(m1 x m2 x d)]^.5 C=43 for imperial, 1897 for metric m1, m2 = surface density of leaf #1, leaf #2 (pounds per square foot, or kg/m2, depending on "C") d=depth of air gap (inches or mm) For 3-leaf MSMSM walls: f+ = (1 / (2 x pi) ) x SQRT( (3.6 x Rho x c^2) / ( m x d ) ) f- = f+ / ( SQRT(2) ) Where: m1 = m3 = 1/2 m2 = m d1 = d2 = d Hope that helps! - Stuart -

It's been a while but now the house is past roof cover stage and I have taken measurements of the completed room and started building the sketchup model (attached). So my goal and understanding is (following the MAM principle) to build a room within a room to get the best sound isolation possible. 1) I should leave the finished rendered and painted wall alone, right? 2) how much space between the existing wall and the inside edge of the framing (including the leaves of gyprock) should there be? 3) I am right to be thinknig of designing and constructing something along the lines of: existing wall, gap, gyprock, green glue, gyprock, framing (with hat channels), gyprock, green glue, gyprock, right? OR should I be staggering the timber and putting more leaves (3, say). 4) for the connections with the floor, nothing special is to be done, except to ensure that it is completely sealed, right? 5) for the ceiling, I leave the existing ceiling as is, and build a lower ceiling to complete my room within a room, with a similar construction as the wall: existing wall, gap, gyprock, green glue, gyprock, framing (with hat channels), gyprock, green glue, gyprock, right? OR should I be staggering the timber and putting more leaves (3, say). I have been following the design shown with pdf_OL08-324.pdf at: http://www.greengluecompany.com/test-da ... ts_tid=All and the material on http://johnlsayers.com/Recmanual/Titles/Acoustics3.htm too in particular. Thanks for any help in advance. Just a reminder of purpose: this room is for me to practise my drums in, teach drums in, and not to record, or jam with other instruments in. I do have a single pa speaker to play along with music too.

1) I should leave the finished rendered and painted wall alone, right?

Yep!

2) how much space between the existing wall and the inside edge of the framing (including the leaves of gyprock) should there be?

As much as you can afford, but at least an inch, assuming conventional construction, or at least 5" if you are going with inside-out construction.

3) I am right to be thinknig of designing and constructing something along the lines of: existing wall, gap, gyprock, green glue, gyprock, framing (with hat channels), gyprock, green glue, gyprock, right? OR should I be staggering the timber and putting more leaves (3, say).

No. That would be a three-leaf wall, and would have poor low-frequency isolation. You only ever want two-leaves, not three. The existing wall is your outer leaf. So you only need ONE more leaf, not the two you mentioned there. That leaf is built as a stud frame with drywall on only ONE side, not both. It can either go on the side facing the room (conventional construction) or it can go on the side facing the wall cavity ("inside-out" construction). Both methods have their pros and cons.

4) for the connections with the floor, nothing special is to be done, except to ensure that it is completely sealed, right?

Correct. Run three beads of acoustic caulk under your sole plates before you nail them down: one bead down the center line of the 2x4, and the other beads about an inch either side of that. Then do another bead up against the edge after it is nailed in place, and one more bead under each layer of drywall. Did I mention that good eals are crucial, and that you'll be buying caulk by the truck load? :)

5) for the ceiling, I leave the existing ceiling as is, and build a lower ceiling to complete my room within a room, with a similar construction as the wall: existing wall, gap, gyprock, green glue, gyprock, framing (with hat channels), gyprock, green glue, gyprock, right? OR should I be staggering the timber and putting more leaves (3, say).

Once again, that would be a three-leaf system, and you only want 2-leaf: Assuming the existing ceiling is just one leaf itself (you should check that!) then your new ceiling is a frame that rests ONLY on the new inner-leaf walls, not touching any part of the existing building at all. Here too you can put the drywall either on top of the joists (inside-out construction) or below them, (conventional construction). Here too, there are pros and cons for both methods. And forget the resilient channel! You don't need it on the walls, and you don't need it on the ceiling. You only need it for cases where you cannot have a fully decoupled frame for the inner leaf. In that case, the resilient channel does the decoupling, but it isn't as good as having a separate frame, and you don't need both. If you have a decoupled frame, RC is not needed. - Stuart -