Octagonal small Studio plans for Studio in Thailand

Greetings everyone, I luckily enough came across this forum today , as we are preparing to go into the final planning phase of our Studio build and we'd love to have these plans looked over by the experts. Over the next few months my friends and I, will be building a small Studio on Ko Phangan Island in the South of Thailand. The studio will be primarily used for electronic dance music production. We are fortunate enough to have the opportunity to be able to build our room from scratch. Therefore it has been my aim over the last few months, to come up with a design that will optimize the RFZ and generally minimize reflections. Our other main consideration is that we must soundproof the room as much as possible, as it will be located in populated area. I became interested in the Octagonal designs of many hi end control rooms ,and their use of architecture as a prime element in controlling reflections. We have access to very reasonably priced building materials and also a highly skilled building crew (who have built most of our houses there); so the extra cost/work element of this Octagonal design is fortunately not really an issue for us. I found this design on the Auralex website, which I am assuming is a tried and tested design based on their R&D . Please also note that the ceiling is planned to be sloping from 8 feet to 10 feet at the back. The Acoustic treatment inside the room, is planned to be a combination of Ethan Winer's # 703 & # 705 Basstraps at varied thickness and 2" Broadband and Hi Frequency Panel Absorbers along the sides and ceiling , mainly around the RFZ. Before we go ahead with the final planning , I would greatly appreciate any feedback from the forum regarding these following questions.: 1) Do you think this design is worth the extra construction effort ,in regards to the Acoustic environment it will create being sufficiently superior to say a rectangular room of the dimensions of 6m.40cm by 5m.31cm by 2m.59cm height.? If the Acoustic benefits this design are not considered sufficient enough to warrant the extra time and work etc, then what dimension rectangular room would be recommended ? ( our land area is 10meters by 10 meters.) 2) Do these dimensions supplied by Auralex "hold water" as being the ideal proportional ratio for a room of this size and shape.? 3) Any suggestions regarding the actual construction method (pls note the MDF/#705/Plasterboard sandwich proposed for the "inner" wall construction. 4) With the goal of achieving a near to perfect as possible RFZ, are there any design flaws in these plans that look like they are either unnecessary or perhaps even detrimental to this goal ? 5) Due to the Island lifestyle and fierce daytime heat, most Studio work will be done mainly in the evening and night...We would like the room to be quiet enough as to be able to continue late into the night without concern for disturbing our neighbors. Does this dual Breezeblock construction look sufficient enough, as to be able to contain music production in the 90db-100db ballpark ( loudish) 6) Any comments, suggestions, critiques are welcomed and will be greatly appreciated.

1) Do you think this design is worth the extra construction effort ,in regards to the Acoustic environment it will create being sufficiently superior to say a rectangular room of the dimensions of 6m.40cm by 5m.31cm by 2m.59cm height.? If the Acoustic benefits this design are not considered sufficient enough to warrant the extra time and work etc, then what dimension rectangular room would be recommended ? ( our land area is 10meters by 10 meters.)

What is the construction of the outer shell? This could make a difference in this answer.

3) Any suggestions regarding the actual construction method (pls note the MDF/#705/Plasterboard sandwich proposed for the "inner" wall construction.

A lot of this depends on what the construction of the outer wall. It is possible that you could have 3 different air spaces and you only want one. You could have what is called a triple leaf, or even a quad leaf wall which is progressively worse for stopping sound transmission. 4) With the goal of achieving a near to perfect as possible RFZ, are there any design flaws in these plans that look like they are either unnecessary or perhaps even detrimental to this goal ? Depending on your monitors (if you have already purchased) you might want to think about flush mounting them in the wall.

5) Due to the Island lifestyle and fierce daytime heat, most Studio work will be done mainly in the evening and night...We would like the room to be quiet enough as to be able to continue late into the night without concern for disturbing our neighbors. Does this dual Breezeblock construction look sufficient enough, as to be able to contain music production in the 90db-100db ballpark ( loudish)

I'm not sure what breezeblock construction is so I can't answer this, maybe someone else can.

6) Any comments, suggestions, critiques are welcomed and will be greatly appreciated.

I think I'll be able to answer after I do some research into what breezeblock construction is. :D

Ok, I now know what breezeblock is :D Is the structure already built, or are you building it? What is the ceiling construction? Your proposed wall would create a triple leaf wall, not a good idea. (or would this not be a problem with the mass of the cinder blocks? Others chime in PLEASE)

Thank you Eric for your reply. I will address your questions: The proposed plan calls for an Inner wall comprising of 1/2" Plasterboard/ 4inches of #705 fiberglass (contained within the wooden framing joists) and then sealed with 1 inch thick MDF boards all around. Then around this sandwich wall , will be an inner 10 cm Breezeblock wall which will be flush up against the MDF,( also acting as a secure surface for the Inner walls to be bolted onto) . The idea behind having this secondary inner Breezeblock wall in addition to the main outer wall, was to increase strength ( we occasionally get Typhoons ) and mainly to aid in the soundproofing equation by creating an air space ( perhaps this is overkill though as you mention?) So if this arrangement creates a non desirable triple leaf air pocket then please could you elaborate further as to what would be a better layout of walls/materials etc.. Also Eric, what are your thoughts on the actual Inner room shape and dimensions? The Inside ceiling is planned to be constructed from the same Plaster/ #705/MDF sandwich as the side walls , then a flat concrete slab will be laid over the top of the entire structure(due to the angle of the sloping ceiling the air space between the inner ceiling and this slab will be triangular , ranging from about 2feet to a few inches above the rear end of the ceiling...Many thanks for your time..

The building is not yet constructed ( planned to begin construction in 2 weeks) , hence my enthusiasm at getting these proposals looked over by the forum's members who have both the experience and knowledge in the Studio planning dept., that we are unfortunately lacking. BTW , Monitors are already purchased and are Adam's A7 X's with a Sub 8

The proposed plan calls for an Inner wall comprising of 1/2" Plasterboard/ 4inches of #705 fiberglass (contained within the wooden framing joists) and then sealed with 1 inch thick MDF boards all around. Then around this sandwich wall , will be an inner 10 cm Breezeblock wall which will be flush up against the MDF,( also acting as a secure surface for the Inner walls to be bolted onto) . The idea behind having this secondary inner Breezeblock wall in addition to the main outer wall, was to increase strength ( we occasionally get Typhoons ) and mainly to aid in the soundproofing equation by creating an air space ( perhaps this is overkill though as you mention?)

As Eric suspected, there are several problems with that plan, not just multi-leaf. You want only ONE air space between the inside of the room and the outside world. You have at least two. ' MDF - 1/2" plasterboard - 4 inch air gap - MDF " and then "breezeblok wall" and then "outer wall". What is the "main outer wall" made of? But then you also say "up against the MDF,( also acting as a secure surface for the Inner walls to be bolted onto)" That implies coupling, and therefore flanking. Frankly, that's a very confusing method of construction. And it is not "overkill", as you thought, but rather "underkill". This is not intuitive, but you have too many layers of wall in there for it to be effective. That will make the wall isolate LESS than it would have if you built it as a simple two-leaf structure. This is explained in many places on this forum, so if you search for terms like "three leaf" and "two leaf" and "MSM" you'll be able to find out why this is a bad idea, as Eric says. I'd suggest that you try to simplify your structure to have your outside main wall tough enough to withstand whatever problems Nature might give you, but built as a single, massive leaf (concrete, brick, block, etc.) with no air gaps. Make it very tough. Then inside that you build your second, inner-leaf, which can be a simply stud frame with drywall on only ONE side. Or if you really want to use MDF, then put MDF on only one side of the studs, and drywall directly over the MDF. But do NOT put anything on the other side of the studs, as that would create a 3-leaf system again, which is bad. A couple of other issues I see there: - Instead of 1/2" drywall, use 5/8": it has more mass, is more rigid, and in general is better for sound isolation. - 705 is bit too dense for that application. 703 would be better. Or mineral wool with a density of roughly 48 kg/m3, or fiberglass insulation with a density of roughly 32 kg/m3. - You do not need the 2" hardwood "tunnel" where your sound-lock doors are. It is creating a flanking path, and should be removed. You can just cover that gap with cloth, or something like that. - You also show "breezeblock" surrounding that hardwood tunnel: You cannot do that. It creates a direct flanking path from inner leaf to outer leaf.

Also Eric, what are your thoughts on the actual Inner room shape and dimensions?

Personally, I think you are wasting space in the front and rear corners by cutting them off like. The space could be better used for bass trapping in the rear, and soffit mounts up front. I have seen that octagonal shape many times before, and always wondered why anyone would waste so much useful space in a studio that is already small. I don't understand the reasoning behind that. So my suggestion would be to re-think the design as a two-leaf system, not a 3-leaf system. If you have structural concerns regarding the forces of nature, then consult a structural engineer to find out how to build the outer shell strong enough to withstand that as a single leaf, then design the inner shell with simpler 4-sided geometry (either as a rectangle or with splayed walls if you are aiming for an RFZ design concept), also as a single leaf. I would also plan to soffit-mount (flush-mount) your speakers.

BTW , Monitors are already purchased and are Adam's A7 X's with a Sub 8

Good choice! :) - Stuart -

Thank you Stuart! Invaluable advice..So it seems as though we'd be far better off in pursuing a rectangular room shape ( approx 8mx5.6mx3.6m was what I have been considering as an option to the Octagon) and then Bass trapping the corners front and back and soffit mount the monitors. So only a single outer wall constructed from 10 cm cinder blocks, cement rendered all for strength and to seal off the fairly porous cinder blocks..is this a fairly good approach? What would be the advisable air gap (if any) between the inner wall frame work ( open backed as you advised> without the MDF) and the inside of the outer cinder block walls ?

So it seems as though we'd be far better off in pursuing a rectangular room shape

Either rectangular or with splayed walls, which help with several issues (RFZ, flutter echo, aesthetics, etc.). Both options work well. Some folks prefer rectangles, others prefer angling the side walls for the benefits that provides.

and then Bass trapping the corners front and back and soffit mount the monitors.

Bass trap the rear, soffit mount the front. Yes, you can use some of the soffit space for bass trapping too, but it's not quite the same as the simple bass trapping in the rear.

So only a single outer wall constructed from 10 cm cinder blocks, cement rendered all for strength and to seal off the fairly porous cinder blocks..is this a fairly good approach?

Yes, if your structural engineer says that that's safe and suitable, then sure. But 4" cinder blocks doesn't sound very thick or tough to me. Maybe that should be a bit thicker? Also, after you finish the cement render, you still should paint the inside cement surface before you put up the inner leaf. Cement is porous too, and that needs to be sealed to give the wall the correct acoustic properties so that it isolates well.

What would be the advisable air gap (if any) between the inner wall frame work ... and the inside of the outer cinder block walls?

Absolutely! You MUST have an air gap! That wall is a tuned system, and the air gap is a necessary part of tuning it. That's how it isolates: by being tuned to a very low frequency, below the range of human hearing. If the air gap is too small, then the tuned frequency is too high. You should have at least 4" or air gap, minimum, preferably 6" (or even more, if you have the space). The bigger the gap, the better the isolation. You also need to put some form of insulation in that gap, at least 4" of 703, mineral wool, or fiberglass. - Stuart -

Once again thank you Stuart for your excellent and practical advice. If we were to splay the side walls , what sort of angle would be advisable ? (is there an exact angle that is optimal in reduction of problems you outlined) . Will go for the thicker 15cm blocks and paint the inside as you advise. Also maintain a 6" airgap all around the Inner structure. You mentioned filling this air gap with #703 fiberglass insulation..do you mean the entire space or just a layer on the inside wall. Also, by filling this airgap with the #703 , would that then render unnecessary the #703 insulation planned for in between the framework of the Inner room walls? Would you recommend a sloping inner ceiling ( say from 10 feet up to about 12 feet ). On top of the walls will be a 10" of solid concrete cap.

Splaying walls: It should be whatever amount you need to keep first-order reflections reflections away from your mix position, if you are planning on an RFZ design, but at least 6 degrees for each wall (total of 12 degrees MINIMUM). If you angle the ceiling, then the same rules apply: angle it enough to keep first-order reflections away from the mix position, but at least 12 degrees. If these angles (min. 6° on walls, 12° on ceiling) would waste too much space in your room, then you can just use those for the front half of the room, and then straighten them out at the rear, to leave them parallel.

You mentioned filling this air gap with #703 fiberglass insulation..do you mean the entire space or just a layer on the inside wall.

As much as you can afford, and as much as your local building code or fire code allows! Filling the entire cavity could give you (theoretically) as much as 16 dB of extra isolation, as compared to no fiberglass at all. But filling the entire cavity could be expensive, so make sure you have at least 4" in there, all around. - Stuart -

Remember too that there is quite a variance between quality of these breeze blocks depending on what is used as the aggregate and whether it is aerated or not. For this constuction you want an aggregate of fine sand or similar so that the blocks are very dense and heavy. So check the quality. Also up 'til now no mention has been made of the proposed foundation ...?

Thanks Stuart and Brian..From the information I have been gathering from this and other forums, it's looking the best way to go will be a rectangular room, so now it's a case of fine tuning the dimensions.. [quote="Soundman2020"] As much as you can afford, and as much as your local building code or fire code allows! Filling the entire cavity could give you (theoretically) as much as 16 dB of extra isolation, as compared to no fiberglass at all. But filling the entire cavity could be expensive, so make sure you have at least 4" in there, all around. Fortunately Thai made semi rigid rock wool with a density of around 48 kg/m3 , is not too expensive therefore we should be able to fill the entire 6" gap all around ( would this also enhance the interior sound, i.e act as one encompassing bass trap?) Will be looking into finding denser cinder blocks this week, however I have a feeling that only the lighter porous ones are available here. If we can only find the lighter bricks, what would you suggest regarding treatment of the inner and outer sides of the wall ?.....(3/4"Plywood cladding on the inside and 1" of cement render outside? ) The foundation will be a 10" thick concrete slab, poured with internal steel re bar , raised 3 feet of the ground on brick pylons ( for flooding prevention)

In regard to the blocks, many suggest filling the hollow chambers of the blocks with sand as the wall is being built. You could also render both sides after they are built with a dense cement coat on the outside, plaster on the inner side. The foundation sounds interesting. I'll just assume you've got a static engineer to calculate loading and stress.

So due to many discoveries , realizations and invaluable help from this forum and others, we have finally decided to go with a more simple rectangle..Here is the mock up of the 'plan B' proposed room.. Any comments regarding the frequency band (800 hz-3500 hz) of the Skyline diffusor and also it's placement.? ( this is what I dialed into the calculator to produce the matrix that I will be constructing it upon) I don't want the room too bright,.. I just want there to be a dash of life and space to the mid range.. thanks...

Soundman2020 wrote:

...You should have at least 4" or air gap, minimum, preferably 6" (or even more, if you have the space). The bigger the gap, the better the isolation. You also need to put some form of insulation in that gap, at least 4" of 703, mineral wool, or fiberglass.

I would like to clarify if the 6" air gap should be filled at least with 4" insulation or if the insulation should be add to the minimum air gap of 6"? As i understand the 6" air gap should be filled with 4" 703 insulation, so the area where is nothing only air is 2"... And a big thank you to Stuart who explained the inner leafes in interrelation with an outer wall/leaf very traceable :) Aaron

What if he made his doubled his block wall and filled the cavities with sand? Would that make a stronger structure?

Thank you Aaron for your input..I have a question regarding the best method of constructing the layers of the inner walls, for optimal low freq. absorption and good STC figures. Option A shows the (rendered) 6" Cinder Block wall, then a 7" inch air gap stuffed with 6" fluffy type fiberglass, the framing wall containing 703 fiberglass between the joists . I am not sure whether to place 1/2" of MDF as well as the 1/2" of plasterboard. The reason why I was considering MDF here was only for added structural strength of the framework . Yet if an extra solid layer here is not advisable in regards to acoustics ,then I will construct the walls as in option B-without the MDF. My aim is to make the actual walls as similar to Bass traps as possible, and I am not sure how low frequency transparent 1/2" of MDF will be.( perhaps it will reflect certain frequencies back into the room? ) Also would anyone recommend using FRK 703, foil facing towards the room, instead of plain 703 in this postion.?

I am not sure whether to place 1/2" of MDF as well as the 1/2" of plasterboard. The reason why I was considering MDF here was only for added structural strength of the framework . Yet if an extra solid layer here is not advisable in regards to acoustics ,then I will construct the walls as in option B-without the MDF.

Yes, you can add MDF for structural strength. You can also use plywood or OSB instead of MDF. Use whatever is less expensive in your area. If you do that, then the wood (MDF/plywood/OSB) goes on first, up against the studs, then you add the drywall on top of that. BUT! Don't use 1/2" materials: they are too light, thin, and flexible. It is better to use 5/8" materials, for the better isolation properties.

My aim is to make the actual walls as similar to Bass traps as possible, and I am not sure how low frequency transparent 1/2" of MDF will be.( perhaps it will reflect certain frequencies back into the room? )

Careful there! Are you building bass traps (panel traps) or are you building an MSM isolation wall? Those are two different concepts! Yes, there is one theory about building walls as bass traps, but if you do that you will NOT have good isolation for your studio. If you need good isolation AND good bass trapping, then you should build your MSM isolation wall first, in the manner you already describe, and THEN build your panel traps afterward, in the room itself. The construction of these two concepts (isolation wall and bass-trap wall) LOOKS very similar, but they operate very differently. In both cases you are creating a tuned resonant cavity in the wall, but for different purposes and in different manners 1) For an isolation wall (MSM), you MUST tune that frequency to be way below the lowest frequency that you need to isolate. For example, if you want to isolate the entire range of human hearing, then the MSM wall should be tuned to 10 Hz. or below, That will force it to block energy transfer through the wall at all frequencies above 14 Hz, it will block quite well above 20 Hz, and will block very well above 30 Hz. But that is NOT a bass trap. It is tuned too low to trap bass. 2) For a bass trap wall (panel trap, membrane trap), you also tune the wall to a certain frequency, but in this case you tune it to the frequency that you want to trap. For example, if you want to trap kick drum frequencies, then you'd tune your wall to around 80 Hz, very roughly. That will make the wall vibrate at 80 Hz, thus absorbing that frequency (and the frequencies just above and below) very well. It will absorb up to about 110 Hz, and down to about 65 Hz. BUT: That wall will be TERRIBLE at isolating the room! It will not isolate at all for any frequency below 110 Hz, will only start isolating reasonably at 160 Hz, and will isolate well at 240 Hz and above. In other words, even voices could be audible through that wall. CONCLUSION: Don't confuse the two concepts. Yes, in both cases the way you build it is the same, and just from looking at the wall they will look very similar. The difference is on the design of the wall: What frequency it is tuned to. That frequency is determined by the total mass (surface density) of the materials on each side of the wall, and by the distance between them. In other words: you cannot do with things with the same wall. Either you can have an MSM wall that isolated ("soundproofs") your room well, or you can have a bass-trap wall, but you cannot do both at once. If you DO want to do both, then you need to build BOTH the MSM isolation wall, AND the bass trap (panel trap), as two separate devices. But if you do that, then you MUST do it very carefully, taking into account that the two devices will be nest to each other, because that automatically creates a three-leaf system, which is complicated to design... So I'd suggest that you think about this carefully, and do the calculations carefully, to make sure that you get both good isolation and also good bass trapping. - Stuart -

Many thanks once again Stuart :D ..And to answer your questions:-The wall's main purpose will be a MSM isolation dual leaf.. The inside of the room will be treated extensively with panel bass traps, mid-high panels, cloud etc. I was just curious to see if i could augment the internal acoustic treatment with the actual wall construction itself, and you have very clearly explained the concepts of each and the wisdom in keeping the two functions separate. So by going with the 3/4 " of MDF nailed directly against the studs- then another 3/4 drywall on top of that- could you please explain further the MDF's benefit to the MSM?. Would the MSM be just as efficient, with say no MDF and just a layer of 5/8 drywall? Also does the air gap of 7" with 6" of rockwool insulation seem sufficient enough to you to "tune" the absorption frequency to below the 15-10 hz? ..Can you recommend any modifications to the plan that would enhance low frequency isolation.? Is there a method of calculating this mathematically?

So by going with the 3/4 " of MDF nailed directly against the studs- then another 3/4 drywall on top of that- could you please explain further the MDF's benefit to the MSM?. Would the MSM be just as efficient, with say no MDF and just a layer of 5/8 drywall?

The MDF just adds more mass to the wall, which is GOOD! As you add mass to a "leaf" (one side of the wall), then that brings down the MSM resonant frequency. So a layer of 3/4" MDF plus a layer of 3/4" Drywall is going to be more than double the mass of a single sheet of 5/8" drywall. Much better isolation, plus the advantage of extra structural integrity, plus one more advantage that you might not have considered: nailing surface. If you have that MDF (or plywood) all around the room, then you can nail or screw the treatment anywhere you want it in the room! You are not restricted to just the places where you have studs. That is also very useful.

Also does the air gap of 7" with 6" of rockwool insulation seem sufficient enough to you to "tune" the absorption frequency to below the 15-10 hz?

One layer of 3/4" MDF plus one layer of 3/4" drywall over a 7" air gap filled with insulation gives you an MSM resonant frequency of 19 Hz. So the wall will start isolating at about 26 Hz, will isolate reasonably well above 38 Hz, and very well above 57 Hz. That's pretty good. There aren't very many musical instruments that produce sounds at those low frequencies, so unless you are mixing for movies with earthquakes and canon fire, that should be good. You say that your primary work will be electronic dance music, so you are probably OK, as long as your music doesn't have a huge amount of very low frequencies in it. Adding another layer of drywall and increasing the gap to 8" improves things: 15 Hz resonance, isolation starts at 21 Hz, good at 31 Hz, very good at 46 Hz. That's all theoretical, of course: reality might be different, depending on the actual materials and how well you build it! :)

Can you recommend any modifications to the plan that would enhance low frequency isolation.?

If you add more mass to the wall (extra layers of material) or increase the size of the air gap, or both, that brings down the resonant frequency.

Is there a method of calculating this mathematically?

For your case (single leaf against a concrete block wall) you can use the simplified form of the equation: f = 60 ( SQRT (m x d) ) Where: m = the surface density of the leaf, in kg/m2 d = the size of the air gap, in meters That's if you have no insulation in the cavity (air gap). If you DO have insulation, then you need this equation: f = 43 ( SQRT (m x d) ) - Stuart -

Can't thank you enough Stuart!..you have been immensely helpful. I will follow you advice by increase both wall density and the airgap by an inch or two..

hello, i am just following this thread with a lot of interest. One second question came up to me as Mr ban sabaii wants to drill mdf on studs and then add drywall. Are there benifits if he would decouple the mdf/drywall mass from the studs? There are interesting spacers out there that would ensure the air gap and fixing the wool. I found a youtube vid here: http://www.youtube.com/watch?v=Bf5syq09 ... re=related best regards Aaron

Are there benifits if he would decouple the mdf/drywall mass from the studs?

No. No benefit at all. He is building a proper MSM system, where the inner leaf is already entirely decoupled because it is built on a separate stud frame that is not attached to anything else (except the floor). So it is already decoupled. Trying to decouple again is pointless. That would be like taking your garden hose into the swimming pool with you, to try to get you "wetter" than the water already made you! Once you are wet, then you are wet. Once you are decoupled, then you are decoupled. Those clips are intended for walls where there is only one stud frame with drywall on both sides. In that case, they do work well to decouple the drywall on one side. But that's not the case here. - Stuart -

ah ok, i understand. Thanks to clear up this point :)

We will also be creating a 15cm "well" around the inner part of the concrete slab before it's been poured; effectively isolating the inner floor from the outer slab where the B/block wall will be built upon.( apart from the small doorway area) Stuart , could you please advise us upon the best way to deal with : a) The doorway and doors(s):-should we have an inner door flush to the studio walls , and an outer door built into the brick walls, or just the one door on the inside wall ? How should the 20cm airgap be treated in this small doorway area- bricked off or finished with the drywall / MDF sandwich as part of the inner wall? b) We will be installing a wall mounted Air Conditioning unit with an external heat exchanger unit as per typical on the island..Any precautions or considerations with the way it's installed /position & placement etc ? Also I'm concerned about the ducts we'll need in order to handle the stale air exhaust...Will these ducts effect the isolation characteristics of the room at all , and if so, what is the prescribed way of building them to reduce this effect? many thanks ....