SIMO Studio Design

Dear all, Simone here. This is my first post, even though I've been browsing around the forum for quite a while now and have to say that I'm amazed by the amount of information available and the general high level of competence of its members. Thank you so much for taking the time to kindly share your knowledge with all of us. It's fantastic and very much appreciated! I was wondering whether I could ask you a few questions. I am in the process of building my own studio at the end of my rear garden here in London (England). At present, where the studio will be, there is a wooden outhouse suspended onto brick columns. This, starting from next week, will be completely knocked down and a new structure - made with dense concrete blocks (circa 440 x 215 x 100 mm), proper foundations, wooden roof and concrete floor - will take its place. There will also be a small WC on the left-hand corner at the opposite side of the entrance. Our garden boundries onto neighbour's gardens. This means that noise won't be "too" critical but obviously I would like to keep leakage to its possible minimum in order to avoid any issues. The budget I have will allow me to hire a company to build the "external shell" only, so I will be doing the internal construction myself. The studio will be used both for my own productions, and to record/mix external clients (a producer that I regularly work with is into Rock bands...just to give you an idea of the kind of noise that I need to contain). It will be based around a Pro Tools rig with a small control surface and (maybe) I'll try to get a cheep Mackie desk (or similar) for monitoring. I haven't got money for a proper AC system yet, so I was looking for a portable one (here's the link for what I have in mind (one of the first three ones): http://www.airconco.com/portable-air-conditioners) which I reckon should be enough given the area that it has to condition. After the outer building is done, the budget left for the internal construction is around 7000-8000 UK sterling, but obviously I'd like to save as much as possible to allocate some of it to buy some more equipment (mics, preamps, etc.)... BUT Acoustics will always come first! I'm totally new in designing a recording studio as such, but both for necessity and for fun I'll give it a go. I have attached an idea of how I was thinking of sub-dividing the internal space so I could obtain a Control Room and a Live Room. There is also a slight modification of that plan with the addition of a small booth... I'm not entirely convinced by this second option, because I'm afraid that the booth would be to small (reducing even further the already not big live room - as seen on the first option). Maybe it would be more sensible to have one "decent size" room instead of two small ones. I could always use screens to separate sound sources if needed, couldn't I? The pics were in scale 1:100 (1cm = 1m)... but I'm not sure what they became after I re-dimensioned them in order to fit in the maximum dimension allowed by the Forum of 750 pixels Width. The proportions obviously are still there though ! I'm also digging into Scketch Up in order to have a better vision of what the 2D plan will actually look like and I'm getting totally addicted to it ! :-) ... I will post that as well as soon as I finish, but I'm going to wait for your comments first, in case I'm taking this idea too much in the wrong direction. ... so here we are with my first batch of questions: 1) I'm convinced of the advantages of flush-mounting the speakers in a small (and maybe not-so-acustically-perfect) environment, avoiding the rear wall reflections....but, how difficult would it be to change speakers at a later stage? I have a pair of Mackie HR824's - which I'm quite used to - but I'd like to have the option to be able to upgrade to better quality ones in the future. If it won't be possible to replace the speakers at later stage, would you suggest I build the speaker case anyway (with the measurements of the model I am thinking to upgrade to) and "temporarily" close the cavity (or maybe fill it in with insulation)? too mad / complicated? :-) 2) At what angle should the two sliding doors between control room and live room be? in my drawings they are at a 6 degree angle... would that be enough to avoid / reduce reflections between them? 3) If I build a step at the rear of the control room, how should I fill in the space underneath? Do I use the same principle as I do in treating the walls / ceiling? 4) I've still got some Auralex foam... both Wedgies (http://www.auralex.com/acoustic_studiof ... oam_4w.asp) and corner LERND "bass traps" (http://www.auralex.com/bass_traps_lenrd ... _lenrd.asp) that I used in my old nearly cubic room to minimize all the problems that you can imagine coming from such a shaped environment. They did a decent job in that specific case, but in the new studio I would prefer to keep the space clear from visible foam... Would I be able to use / recycle the Auralex Wedgies perhaps in the Acoustic Hungers (both side of the Fiberboard) instead of the usually used insulation material? ... or would I better sell the lot on eBay and get some cash to finance more conventional materials? 5) I would also like to recycle the two windows that are present in the existing construction, which are standard ones. In my drawing I'm totally "bypassing" and using them just to get the light through and planning to use two thick glass windows at an angle on the "inner construction". Is this an unnecessary exaggeration? Would I be able to still get a "decent" isolation by using double (or even a triple) glazed windows in the inner room (with the additional advantage of being able to open the windows on a sunny day and get fresh air in... and maybe being even a cheeper option)? Has anyone ever tried this and had any success? 6) Having a concrete floor suggests to me that I shouldn't need a floating floor (as it won't act as a "flanking path"), right?... but the question is: If I want a wooden floor, shall I just lay down the underlayer and then the wood on top of the concrete (as you would do in your house) - or - Do I need to have an extra layer of "material" between the concrete floor and the underlayer (and then wood) ? Any suggestions / comments / criticisms are very welcome ! I hope I have respected the Forums rules including all the information required and didn't repeat treats already discussed elsewhere, if not I apologize in anticipation as to waste your time is my last intention! Many thanks and hope to hear your tips soon Ciao ! Simone

Him Simone, and welcome! It's good to see a newcomer who reads the rules and does a great job of sticking to them. Great first post!. First, it looks like you have a pretty decent basic plan, just some details need ironing it.

I'm convinced of the advantages of flush-mounting the speakers in a small (and maybe not-so-acustically-perfect) environment, avoiding the rear wall reflections....but, how difficult would it be to change speakers at a later stage?

If you search the forum, you'll find a thread by Barefoot (I think!) with a design for doing just that: He created a large center panel in the soffit which can be removed and replaced with a different one, to accommodate various sized speakers. You just need to make it larger than the largest speaker you ever expect to use, and you'll be fine.

2) At what angle should the two sliding doors between control room and live room be? in my drawings they are at a 6 degree angle... would that be enough to avoid / reduce reflections between them?

To me, it looks like that angle is rather more than 6°! I may be wrong, but it looks more like 12°. But anyway, the minimum angle you want is 6° each side (12° total), and the actual angle depends on what you do with your speaker / soffit / mix position geometry. Currently you have yours at 60°, but if you increase the angle of intersection of the acoustic axes of your speakers (as you probably will need to do! see below...), then you also need to increase the splay angle of your walls in order to have a good reflection free zone. But having a bigger angle than you need does no harm, so if you like your current 12° angle, then stick with it. That would be good enough up to about 90° speaker axes intersect angle. The same is true of the ceiling: that also needs to be angled at 12°.

3) If I build a step at the rear of the control room, how should I fill in the space underneath? Do I use the same principle as I do in treating the walls / ceiling?

What kind of "step"? Do you mean a small platform for the sofa, or something liek that? If so, then build it like a drum riser.

Would I be able to use / recycle the Auralex Wedgies perhaps in the Acoustic Hungers (both side of the Fiberboard) instead of the usually used insulation material?

I don't know how well they'd work on hangers, but a better use might be as part of a cloud, or part of your bass trapping, or part of first reflection point treatment. They probably aren't thick enough to be really effective, but you could still use them along with mineral wool or fiberglass insulation, maybe as a "sandwich" layer or something. To deal with the "ugly factor", you could cover them with cloth.

I would also like to recycle the two windows that are present in the existing construction, which are standard ones.

That probably wont work. Ordinary window glass is too thin to be of much use in studios, and also isn't laminated. Best glass for studios is thick laminated glass. The exact thickness will depend on your wall construction, since you need to keep the surface density constant over the entire surface.

planning to use two thick glass windows at an angle on the "inner construction"

Yep! Thick laminate glass is what you need. What do you mean by "at an angle"? Are you talking about angling each pane of glass downwards slightly, or left-right slightly? If so, that has no acoustic advantages at all (despite myths and legends to the contrary that you might see oozing around the internet), and in fact it will decrease your isolation. For best isolation, the two panes of glass in a window should be parallel and as far apart as possible. Angling them always reduces isolation, all other things being equal. You might want to angle them a bit to avoid annoying lighting reflections, but not for acoustics. Even then, it might be better to carefully think out your lighting plan to avoid such reflections in the first place.

Would I be able to still get a "decent" isolation by using double (or even a triple) glazed windows

Triple glazed? NEVER! That's a three-leaf system, which is a bad idea in a studio (unless it is extremely thick glass, with large air gaps between). Stay well away from anything that has three leaves. Normal double-glazed windows probably won't do the trick either, as once again the glass is too thin, and the panes are too close to each other, to give you good isolation, especially at low frequencies.

(with the additional advantage of being able to open the windows on a sunny day and get fresh air in

An operable window is probably not a good idea: For proper MSM isolation you need total air-tight seals in both leaves. That's very hard to achieve with an operable window.

I haven't got money for a proper AC system yet, so I was looking for a portable one (here's the link for what I have in mind (one of the first three ones): http://www.airconco.com/portable-air-conditioners) which I reckon should be enough

Those portable units are usually VERY noisy, and in any case, I don't see how you can use it without cutting a huge hole in your excellent hermetically sealed 2-leaf MSM wall, to poke the air hose and drain pipe out of.... Search the forum for HVAC, to look for the best way of doing this, but probably a min-split system would be the best way to go, and that won't cost you much more than the unit you have in mind. (Or at least, where I live there isn't much difference in price: that might be different where you live). You will also need a roper ventilation duct system with silencers, as part of your HVAC, but that goes without saying, no matter what type of air con you use.

Having a concrete floor suggests to me that I shouldn't need a floating floor

Exactly! In fact, you almost NEVER need a floating floor, anywhere. Doing one right is really hard, and really expensive. You could blow your entire budget just on doing a floating floor... In any event, you do not need one at all, since your floor will be thick reinforced concrete slab on grade. There is nothing better than that! A large chunk of dense mass, damped by the entire planet underneath it.... hard to beat that!

If I want a wooden floor, shall I just lay down the underlayer and then the wood on top of the concrete (as you would do in your house

Yup!

Any suggestions / comments / criticisms are very welcome !

1) You need to fix your speaker geometry! Right now, it looks like you have your mix position at the 50% point of the control room (front to back). Worst possible spot! The ideal is at 38%, but it doesn't have to be exact, so don't beat yourself over the head trying to nudge things around by millimeters to get there. It's just the theoretical best spot. If you can get close, then you are fine. But 50% is bad. 2) Also, your CR appears to not be symmetric: your right wall is parallel to the outer leaf, but the left wall is not. You should fix that, probably best down by splaying your right inner-leaf to match your left. You absolutely do want to have a perfectly symmetrical CR, or at the very least the front half needs to be symmetrical. 3) You also need to fix the wall between your CR and LR: Right now that wall is coupled in several places, and you will have very poor isolation. Each room needs to be independent, totally decoupled from the other. Build it as a 2-leaf wall, where one leaf belongs to the CR and the other leaf belongs to the LR. The ceilings must be independent too: The LR ceiling rests ONLY on the LR inner-leaf walls, and the CR ceiling rests ONLY on the CR inner-leaf walls. There must be no mechanical connection at all between the two rooms (inner-leaves), nor must there be any connection between the inner leaves of the rooms, and the outer leaf, which is the shell of the building in your case. Anyway, those were the issues that I happened to notice at first glance. Others might find other things, but those are the glaring "biggies". - Stuart -

Stuart i have a question that may relate to the topic here, Why are we to angle glass to avoid standing waves, but not the double walls? wouldn't you expect that in a room within a room build (or any double wall) that the two walls should not be parallel? is because you're essentially dealing with two inner surfaces of insulation (facing each other) in each wall and not straight drywall? whereas with Glass you have a perfect flat surface and thus standing wave potential? thanks

maxgraham wrote:

Why are we to angle glass to avoid standing waves, but not the double walls?

You are not. Angling surfaces does not reduce the number of standing waves. It does make standing waves to be difficult to model, predict the frequencies and locations of the modes. Predictably, Andre

Max and Simone - it's not necessary to angle sliding glass doors. I used to think it was but I don't angle them now. a couple of suggestions.

Stuart i have a question that may relate to the topic here, Why are we to angle glass to avoid standing waves, but not the double walls? wouldn't you expect that in a room within a room build (or any double wall) that the two walls should not be parallel? is because you're essentially dealing with two inner surfaces of insulation (facing each other) in each wall and not straight drywall? whereas with Glass you have a perfect flat surface and thus standing wave potential?

Adding to what André and John said about not needing to angle glass or walls, the way I understand it (which might be wrong) is that angling the walls does not get rid of the standing waves: it just moves them around. The room will still have modes, but they will be harder to figure out. You can no longer do it with simple math if the walls are not parallel. But having said that, I'm not sure if you are talking about "walls" or "leaves". To clarify the jargon, for me a studio "wall" is practically always an MSM system composed of two "leaves" with a damped air gap between them. Each "leaf" is the sum total of all massive surfaces that contribute to that side of the wall, including the drywall itself, the window glass and the door panels that belong to that leaf, as well as all of the associated framing and sealing. So if you talk about a "wall", to me that means you are talking about the entire tuned two-leaf MSM construction that separates and isolates one acoustic space from another acoustic space. In that case, the space between two walls is the room itself, while the space between two leaves is the cavity inside a single wall. (I hope I'm explaining this clearly, because after reading it over, it sure ain't so clear to me, and I'm the guy that just wrote it!!! :) ) Anyway, I think you might be talking about the cavity between the leaves, rather than space inside the room, so that's what I'll assume from here on. If the two leaves of a wall are not parallel, then all basically what happens is that the MSM system will be tuned to a range of frequencies defined by the maximum and minimum gap, instead of a specific frequency as you'd normally get with parallel leaves. I may be wrong here, but logically I would expect that the result would be to "smear" the MSM resonant frequency, and hence broaden the dip in the transmission loss curve for that wall, while also flattening it out a little. So the dip will not go as low, but will be much wider. In other words, you won't have quite so much low-frequency reduction in TL, but you will have reduction in TL happening over a wider range of frequencies. The dip isn't so sharp, but is now wider. (Not sure if I'm making sense). That may or may not be a good thing, depending on where the highest part of that dip falls. If it gets too close to the lower end of the audible range, then it compromises isolation, but if it stays far away from the lower end, then it should improve isolation, since the dip itself isn't as low. That's just my own theorizing: I may be wrong. Maybe André or John can comment more on that. Getting to the point: If the TL dip is still there but smeared out due to the angled leaves, then obviously the standing waves in the cavity did NOT disappear : They are still there, but now there are more of them going around at different angles, doing all kinds of different things all over the place, making it harder to predict mathematically what is going on. The angle doesn't get rid of them: it just "moves" them to different locations. I guess you could say it is kind of like splaying walls to get a "reflection free zone" around the mix position. That does not actually stop reflections from getting to the mix position at all: They still get there eventually, but delayed enough in time and attenuated enough in intensity that they are no longer a problem. Or another analogy would be parallel walls vs. no parallel walls for resonance: Making walls non-parallel does not get rid of resonance in the room: it just changes the characteristics of the resonance. You cannot get your RT60 time down to zero just by tilting and splaying the walls of your studio at weird and wonderful angles. All you will achieve, at best, is changing the "timbre" of the resonance, but it will still be there. Long story short: There are pros and cons to angling walls, leaves, and windows. It all depends on how you do it, and what you are trying to achieve. Like john said, you don't NEED to do it, since parallel works just fine (and is easy to calculate, easy to build). So if you DO do it, then you should be well aware of WHAT you are doing, WHY you are doing it, and what the outcome will be. If you don't want to go to all that trouble of figuring it out, then just stick to parallel: it makes the math easier, and also makes the construction easier. Anyway, that's my long, meandering, convoluted and meaningless waffle on the subject, which I'll probably find just as unintelligible as you just did, when I wake up tomorrow morning and read it back to myself! :) - Stuart -

sorry Stuart, you are confusing walls. He's referring to the wall of the live room being parallel to the wall of the control room NOT the walls IN the control room. If those walls CAN be parallel why can't the doors? get it?

Ahhhh!!! The penny drops! Yep, I see what you are saying. Apples and oranges. I gotta get some sleep, and stop pretending I'm awake enough to post coherently.... :!: - Stuart -

goodnight - yeah the view unread posts is cool isn't it :)

Dear Stuart and John, Thank you very much for taking the time to reply and make suggestions... very kind and much appreciated ! I love the Barefoot idea for the speakers case (i found the thread here, if anyone else needs it: http://www.johnlsayers.com/phpBB2/viewtopic.php?t=718)... I'll try to implement that into my design. Thanks Stuart for pointing it out to me! Sorry, I realized that I posted a version of my drawings showing the sliding glass doors between CR and LR NOT angled (but a previous version with them still drawn parallel)... and that has created some confusion. The two "lateral walls" of the Control Room ARE actually angled 12º and the ceiling will be angle 12˚ as well (at least past the mix position). What I was wondering was whether I needed to angle the two sliding glass doors between each other or not, but John has already made it clear that it is not a necessity. Thanks Stuart for the suggestions re: - how to build the small platform for the sofa - how the Auralex wedgies can be recycled - the most appropriate HVAC system to consider - advising me NOT to implement operational windows in my design and for the correct type of glass to be used (laminated) - avoiding me the grief of building an unnecessary (and expensive) floating floor ! ... I'm still a bit confused about a couple of things, so wondered if i could ask for clarification: - what do you mean by "the exact glass thickness will depend on your wall construction, since you need to keep the surface density constant over the entire surface" ? How do I calculate that? - you said that there is no acoustic advantages in angling each pane of glass in the window, but I notice that on "The Recording Manual" on John's website he states "The two sheets of glass must be at an angle to each other else the two sheets will interact in a resonate sympathy and the sound reduction properties will be reduced. You can angle the glass as in the following drawing but don't forget that the glass can also be angled in the horizontal plane as well as the vertical plane". Maybe I misunderstood what you meant? ... obviously, if I can get away with NOT splaying the glasses ..... it will make my life SO much easier :-) What do you suggest? I have moved the mix position to around a 35-38 % point (front-to-back) and de-coupled the Control Room with the Live Room (in order to make them mechanically disconnected), as you suggested. Now, the (new) question is: what angle of intersection of the acoustic axes of my speakers would be appropriate (for the moment I left them as they were (60˚), waiting for clarification)? you said that it can go as far as 90˚ (considering a 12˚ wall splaying on both sides of the CR), but won't this compromise the stereo image of the reproduced sound from the speakers? Also, about the Control Room symmetry : I though that just the inner leafs needed to be symmetrical to each other - for a good sound reflection spread - and that the space between leafs in different walls (in my case between the left and right walls) could be different... Obviously I was wrong, as you pointed out, so I changed that on my design as you can see in the new pics posted here. That actually make sense, because if it's true that the air gap between the two leaf acts as a "spring", its action won't be the same on both side of the CR, right? John: Thank you so much for your kind suggestions! Just a quick one: where you pointed out on my design that "double doors not required here"... they were actually not meant to be double doors But double "glasses" (angled between each other) on the wooden internal structure and the big openings were actually the "normal" windows present in the outer brick shell... sorry for my unclear design :-). Do you still think that I won't need a double glass, but just one laminate glass there will do the trick ? Also - to finish off - I promise :-) - I love the addition of another ISO booth... my only concern is: won't it be "too small" ? and being the window between this ISO and CR on the "mix position line", won't it make the sound from the speakers radiate "unbalanced" (for lack of a better word to describe it) as the left side is Glass and the right side is wood (Slot resonators)? Thank you so much again for you time ! Have a good day Ciao! Simone

Yes Simone - only one layer of glass is needed. I was just suggesting a vox booth there instead of where you have it, not an additional vox booth. I put it there so you had sight line to it which is important IMO , the window won't make any difference to the symmetry.

- what do you mean by "the exact glass thickness will depend on your wall construction, since you need to keep the surface density constant over the entire surface" ? How do I calculate that?

The idea is that you want the density of the wall, in terms of kilograms per square meter of wall area (or maybe pound per square foot, if you are back in the 18th century still.. :) ) to be roughly the same at all places on each leaf. So if it turns out that you used enough drywall, green glue, and whatever else to get to (for example) 15 kg/m2 for the leaf itself, then you should get glass that also works out to about 15 kg/m2. If you were to get less dense glass, then you have created a weak point in the wall, since where the window is, the density drops (and thus the MSM frequency goes up, you lose isolation, etc.). If you were to use higher density glass, then that's not an issue really . . . Except that you wasted a lot of money on it, because thick laminate glass glass ain't cheap! How do you calculate it? Look it up on the tables of densities of common building materials! :) There are tables the give you the figures for numerous types of building materials, or you can probably ask the manufacturer, too. Glass is several times more dense than drywall, so your glass will not be as thick as your drywall. I can't give you exact figures, because it all depends on what type of drywall and glass you use, but it isn't hard to figure out. EG. If your glass is three times the density of your drywall, and you ended up with two layers of 15mm drywall, then you have a total of 30 mm of drywall, so you only need 10mm glass to maintain the same density. That's just an example!!!

- you said that there is no acoustic advantages in angling each pane of glass in the window, but I notice that on "The Recording Manual" on John's website he states "The two sheets of glass must be at an angle to each other else the two sheets will interact in a resonate sympathy and the sound reduction properties will be reduced.

John wrote that book a long time ago, and like he said above, he used to think that it was necessary, but now he doesn't. Acoustic science is advancing all the time, and what used to be just kind of "assumed" might get proven incorrect, or incomplete, later on. I don0t want to put words in John's mouth, but I'm guessing that's what happened here. It use to be a "generally accepted rule" that you should angle glass (and years ago, everyone DID do it), but today it is now known that you get better isolation by keeping the glass parallel and putting damping (fiberglas, mineral wool, etc) around the interior frame to deal with the resonance. It works better like that. You can also use two slightly different thickness of glass (one on each leaf), if you are concerned about having the panes themselves resonating at the same frequency.

obviously, if I can get away with NOT splaying the glasses ..... it will make my life SO much easier :-) What do you suggest?

The issue is this: Isolation in an MSM wall depends mainly on the mass of each leaf, and the air gap between the leaves. A smaller air gap reduces isolation severely, while a arger air gap increases it nicely. So if you angle your glass, then obviously you have to make the gap SMALLER at one edge of the glass. Thus, at that edge you have thrown away depth, and thrown away isolation. EG, if you have a 6 inch air gap, but you angle the glass down to 2 inches on one edge, you have given up a lot of isolation across the entire surface of your glass, and thus created a weak point in your entire wall. If you keep the glass parallel, then you keep the entire isolation that you started with, no compromises. Of course, if you really do want to angle your glass, you can compensate for the isolation lost due to the angle by using much thicker glass, but then your cost goes up.... Designing a studio is a juggling match! Fiddle here, fiddle there, play with thicknesses, distances, materials, prices, and then yell and scream as nothing works out the way you want.... :) So really, it's up to you. If you can design your lighting so that you wont get annoying glare and reflections on the glass as you look through it, then great! Use parallel glass in your windows. But if there is no way you can keep glare off the glass, and "glaring glass" is a deal-breaker for you, then go ahead and angle it, but make it thicker to compensate, and talk even more nicely to your bank manager...

Now, the (new) question is: what angle of intersection of the acoustic axes of my speakers would be appropriate (for the moment I left them as they were (60˚), waiting for clarification)? you said that it can go as far as 90˚ (considering a 12˚ wall splaying on both sides of the CR), but won't this compromise the stereo image of the reproduced sound from the speakers?

Yes, but it shouldn't hurt too much, and might even help: it widens your image a bit, which some people find useful, but the effect isn't that great until you get past 90 degrees (I don't have a paper I can point to about that: it's just judging subjectively myself. Maybe André has a link to a paper somewhere? He has a link to every paper ever written on acoustics, I reckon!!!!). So it's no big deal. The other effect you get from the greater angle is that your sweet spot is "squashed" a bit, but once again that shouldn't be an issue. Once again, its a compromise-juggling-act: In a small room the optimum 60° equilateral triangle geometry often doesn't work out, so you adjust it a bit, sacrificing something to get something else. You sacrifices a bit of squashed spot and a bit of wider image in order to get a usable room! I thinks that's a reasonable sacrifice!!! :) By the way, the "38%" position is where you EARS go, not where the axes intersect: the will intersect a few inches behind your head. Maybe you already knew that and took it into account, but it it doesn't hurt to remind you.

I though that just the inner leafs needed to be symmetrical to each other - for a good sound reflection spread - and that the space between leafs in different walls (in my case between the left and right walls) could be different...

Yes, you are actually correct, not wrong! But I think you are looking at the wrong part of your diagram as being the "inner leaf"! The spacing between leaves can vary (as long as it is still deep enough at the thinnest point to still give you the level of isolation that you need), so that's not an issue. and you are correct about that. But you seem to be confusing the inner leaf on the right side of your CR with the acoustic treatment on the right side of your CR, which looks like it might be a slot wall on your diagram(?). At least, I see TWO frames on that side of the CR, both angled at 12°, so I'm assuming that one is the inner leaf and one is treatment. If not, then maybe you could explain better what those two are. Also., why do you have two frames there, and only one on the left wall? Maybe if you could post a complete SketchUp mode it would be easier to see what is what.

where you pointed out on my design that "double doors not required here"... they were actually not meant to be double doors But double "glasses" (angled between each other) on the wooden internal structure and the big openings were actually the "normal" windows present in the outer brick shell... sorry for my unclear design :-). Do you still think that I won't need a double glass, but just one laminate glass there will do the trick ?

THREE-LEAF!!! THREE-LEAF!!!! DANGER!!!! DANGER!!! RED FLAGS!!!! RUN FOR THE HILLS!!!! THE SKY IS FALLiNG!!!! :D I think what John was saying there is that seeing you already have one pane of glass on the existing outer leaf, then you only need one more pane of glass on your new inner leaf, in order to complete your 2-leaf MSM system. If you were to put that third pane in there, angled or not, it would create a three-leaf system, which would REDUCE your isolation through the windows (and therefore reduces the isolation of your entire studio). You need to learn the Studio Builder's Mantra: repeat after me, one thousand times: "2-leaf good, 3-leaf bad! 2-leaf good, 3-leaf bad!". (You also seem to be missing a leaf around your bathroom and vocal booth... I only see one leaf there.) My guess is that John called them "doors" because they could be either doors or windows on your diagram, since it is a top view, not a 3D mocel. Hard to tell without a SketchUp model! (hint, hint!!!).

won't it make the sound from the speakers radiate "unbalanced" (for lack of a better word to describe it) as the left side is Glass and the right side is wood (Slot resonators)?

I think so. It goes back to your symmetry issue again! You need to fix that. A slot wall is a tuned resonator that absorbs certain ranges of frequency and reflects others. It also acts a bit like a diffuser. A glass door doesn't do any of that: it just reflects. So you need to figure out if you are going to get rid of the slot wall on the right of the CR, or fiddle with the glass doors so you can get a slot wall on that side too. For my studio design, I started out with glass doors like you, since I like the idea of good sight lines, but then I figure out (like you will, shortly!) that my room is too small to fit in sliding glass doors and also slot walls and also first reflection point treatment, so I ended up with plain old wood doors from CR to LR, small windows, absorption at the reflection points, and slot walls below and above, wherever I can shoe-horn them in. You might want to consider doing something like that, too. - Stuart -

Hi, Thanks John and Stuart for the clarifications. I made a few other small changes: 1) got rid of the second frame on the right side of the CR 2) moved the mix position (yes, considering my ears) at around 38% (front-to-back) 3) angled the speakers another 6˚ (they are now at 36˚) 4) angled the bass traps at the rear of the CR another 6˚. I did this to avoid that the surface of the rear bass trap on the Right was parallel to the surface of the front speaker on the Left (and the same obviously on the opposite side). Not sure if that is an exaggeration, but considering that angling them another 6˚ won't imply any additional cost I thought why not?! :-) 5) got rid of both ISO booths as I'm trying to contain costs :-( and so compromise as much as I possibly can. Time for me now to get cracking with the Sketch Up model, so it will be much easier to communicate and see where I am at. For the moment Thank you again so much for your time and precious advice! Have a good day Simone

Looking good from here! One question: What is the "blue line" thing across the front of the bass traps and also the speaker soffits, and in a few other places? - Stuart -

Soundman2020 wrote:

it widens your image a bit, which some people find useful, but the effect isn't that great until you get past 90 degrees (I don't have a paper I can point to about that: it's just judging subjectively myself. Maybe André has a link to a paper somewhere? He has a link to every paper ever written on acoustics, I reckon!!!!). So it's no big deal.

Sorry, I do not know or have any papers detailing the effect of changing the speaker angle. As you wrote in the last sentence quoted, the effect, from empirical data is minimal. 60 degrees is the classic subtended angle. The biggest advantage to using it is that is an internationally accepted standard. Standardized, Andre edited 10.04.1 to correct HTML

Hi there, Quote: One question: What is the "blue line" thing across the front of the bass traps and also the speaker soffits, and in a few other places? It's just to indicate the cloth finish, to differentiate it from the Slot resonators (brown lines) Thanks Simone

That's what I suspected: So it should NOT be on your speaker soffits then! The panels of your speaker soffits should be very solid, and very massive. Thick plywood, MDF, HDF, even concrete. But not just cloth over insulation. The purpose of a soffit is to act like an infinite baffle, so it needs to be solid, large and flat. Floor to ceiling, if you can. (Or at least, from the ceiling almost down to the floor, if you plan to use the space behind the lower part of the soffit for bass trapping) - Stuart -

Sorry, I do not know or have any papers detailing the effect of changing the speaker angle....

Wow! That must be a first! :) Seriously, I'm not surprised: I looked all over for information on speaker angles a while back (when we were talking about the maximum recommended tilt angle), and found very little. Another good thesis subject for a student of acoustics! I've been meaning to ask you another question about angles, André: Do you have any idea where the RFZ 6 degree / 12 degree splay angles come from? Any mathematical background on that? I guess there must be, and probably an equation or two to go along with it, but I haven't been able to find much. It just seems to be one of those things that everybody repeats, but nobody gives the underlying reason. Any idea where I should look for more info on that? - Stuart -

Great Thanks so much for the tip Stuart. much appreciated! I will change it straight away Sir :-) Simo

Hi there, sorry I've been quiet for a while.... I just been very busy helping out digging the foundations for the outer brick building where the studio will be. And 26m of foundations perimeter, 1/2m wide and 1.6m deep is quite a bit of earth to dig out :-). I've also been spending the rest of the time figuring out how to use SketchUp and have finally come up with a 3D model of my plan, which should help to understand how everything is layed out. Unfortunately, my SketchUp file is 28MB !! (so... far too big to be post it here) and I haven't figured out how to re-dimension it. Any idea as to why that is so big or how to change the file size? Anyway, in the meantime I have posted some screen pictures of the various layers, hoping that will be enough for now to see the 3D model and help you in eventually answering my questions. As you can probably see I took lots of inspiration from the John's very useful "Small Studio" SketchUp model that I found on this forum. Hiding and showing its different layers helped me a lot on figuring out several doubts that I had, but I still have a few questions for you :-) 1) using John's "Small Studio" design as a guide, I didn't put put any "material" behind the Slot Resonators (like for instance an MDF panel)... but I thought that the cavity behind a resonator must be sealed to an airtight container (like a bottle)? Should I put an MDF layer on the back of the Slots then (after the Slats, the Fibreglass layer and the air gap) ? 2) Similarly to the above, should another wood layer be placed also on the REAR of the Stud walls (opposite side of the MDF layer...the one that in my design is red in the CR and blue in the LR)? (at the moment there is no extra layer !). 3) If the answer of the two above questions is "Yes", what DEPTH should these MDF (or similar) layers be? the more the better (to increase the wall mass)? Would, say, a 2cm depth be reasonable? 4) Back onto the Slot resonators: In my design I place them at 20mm, 15mm, 10mm and 5mm intervals (again inspired by John's "Small Studio" design). Would this work, or was the pattern in John's design particular to his specific room dimensions? The room dimensions I have are very similar to his. In addition, should I also vary the SLAT WIDTH (as well as the SLOT width) and the SLAT DEPTH? ... if so, how? freely? or the 20mm, 15mm, 10mm and 5mm "pattern" could be repeated with the SLAT WIDTH and DEPTH as well? 5) lastly, browsing on the forum I saw various studio designs with flush-mounted speakers that have a "port" on the top of the speaker soffit. How should this port be done? Are its dimensions related to the type of speaker you are using ? I'm asking this because if it DOES depend upon the speaker dimensions, if I plan to follow the "Monitor Flush Mounting Method" suggested by Barefoot, the PORT dimension should also change too when upgrading to a different set of speakers, right? ... and that wouldn't be the easiest thing to do..... maybe I better get a set of monitors I'm happier with BEFORE building the speaker soffit (with port) and stick with those speakers (!!). What would you recommend? Well, that's it for the moment. Thank you very much in anticipation! looking forward to hearing you advice! Hope you had a great Easter weekend Ciao Simone

Simone - in sketchup go to Window/model info/statistics and click purge all. Save and check the new file size. Where you refer to MDF in your plan it's supposed to be cloth stretched over a timber frame. All the live room slot resonators go out to the wall in depth - you should do the same with the right hand slot in the control room.

Hi John, Thanks so much for your quick response! I followed your indication re: reducing the size of the file. The file has gone down from 28MB to 7.3MB... a lot less but still too big to post it here ! (??). When I talk of MDF yes, I mean that its supposed to be the timber with the cloth stretched over it. I don't know what you mean when you say that "the resonators go out the wall in depth" - sorry John. Is it maybe that I have to build a deeper frame for the length of the Slats in order to allow space for an air gap? but should I also "close" its rear to get an air-tight construction? Would it be possible for you to elaborate at all if its not too cheeky? All the very best Simone

Hi there, after lots of head scratching I finally managed to reduce the size of the SketchUp file up to 828 KB !! I just made a Component every single time I was repeating something more than once, eliminate any "eye-candy" stuff that was just making the file bigger for no reason (like instruments, equipment in racks, door handles and everything else that didn't serve the purpose of this matter at all), and more importantly (i think) I replaced all the texture/materials with plain colors. So here is attached the SketchUp file of my project (it has been compressed as the maximum file size that can be uploaded is 500KB!... it's a .ZIP - so just double click on it at it should expand to its normal size). Please note that at the moment the speaker soffit is not correct (being my Mackie - and possibly (in the future) the Genelec 1031 - an active speaker). I will update it to the Barefoot design as soon as I can and post a new updated SketchUp File). Hope you can find the time to have a look through it and help me getting an answer for the questions listed in my previous post. Thank you very much ! Ciao Simone

this is what I mean

Got it ! Thanks a lot for that John - that's very kind of you ! (It was actually like that on my first drawing and than it's gone missing somewhere along the way) :-) I obviously misunderstood some suggestions - anyway, back on track ! I will do some more homework and I will post a new SketchUp file as soon as I updated the resonators in the CR and designed a proper speaker soffit. Grazie !! Ciao Simo