Mid-Size Studio Design

Hello all - I am in the process of purchasing a building that I will be converting into a recording studio. It is a concrete base, metal wall building that has been mostly finished on the inside - sort of room-within-a-room style. It has previously been used as a church and is laid out as such. The great thing is that I have been to several concerts that were held here, as well as rehearsed here with several bands in the area, and despite being in a residential area, the building is pretty far from the nearest homes (and on a hill); and there have never been any noise complaints (most noise really only gets out the front door, which will be replaced). The rehearsals have been two electric guitars, loud drums, loud bass, vocals through a PA, etc. My goal is to be able to record all such instruments here - I would love for the main room to remain big enough to potentially be able to record a full band live off the floor in the future. I will be doing the bulk of the construction work myself with the help of a few friends (and a friend I have that is an electrician by trade). We are all extremely handy and myself and one friend used to do construction work together. Definitely would like to know what people think of splitting the main room into a live room/control room and what kind of layouts/measurements to use, as well as treatment, etc. Obviously I would rip up the carpet - is a bare concrete floor the least bit desirable to use until I can fund some sort of wood flooring? What kind of door would be ideal to replace the main (french glass) door? I can't spend a ton of money on design, but would like to do what I can to get this space right - if anyone has suggestions of designers to get into contact with I would surely appreciate it. Thanks for looking! -Ben

Hi Ben, and welcome! :) That's a nice big space you have there! I'm jealous! :)

Definitely would like to know what people think of splitting the main room into a live room/control room and what kind of layouts/measurements to use, as well as treatment, etc.

The space is definitely big enough that you cold do that, yes. You could have a nice sized control room and a live room good enough for a band. You might even have space for a separate drum booth and/or iso booth.

Obviously I would rip up the carpet - is a bare concrete floor the least bit desirable to use until I can fund some sort of wood flooring?

Ripping up the carpet is a very smart idea! Contrary to popular belief, carpet is not good in studios. And the bare concrete floor is an EXCELLENT surface for a studio! Both the live room and the control room could have just plain concrete floors, if the rest of the room is treated correctly. You don't even have to lay wood flooring ever, if you don't want to. And if you do, then just put down ordinary laminate flooring: that's also a great surface, acoustically.

What kind of door would be ideal to replace the main (french glass) door?

You say the place is already built as a room-in-a-room, so you really need two doors there, back to back, one in the inner-leaf and one in the outer-leaf. They should both be very heavy, solid-core doors. Not foam core, not hollow core: just solid core. And they need good seals all around all the edges. It would help if you could post some photos of the place as it is now, so we can get a better handle on what you are facing. - Stuart -

Hi Stuart - thanks for the reply! I'm attaching a few pictures I took of the space - there's a small stage and a sound booth in the main room that will go away pretty easily. Thanks alot for the info you've already posted. Look forward to hearing any more thoughts you might have! -Ben

I'm not seeing much evidence that it really is built as proper "room-in-a-room" construction. Are you sure about that? I only see ordinary walls, ceiling and doors. I also don't see any HVAC in there, which implies that you'll need to set aside some budget for that. You can't have a well isolated studio without HVAC! And the lack of HVAC is another sign that it isn't built as room-in-a-room. - Stuart -

Stuart - thanks for the replies. I probably mis-used the term "room-within-a-room". The interior space is built separately from the outside - it's a metal walled building on the outside, and they built the interior structure within that with pretty much only doors touching both. It does have heat and air. As stated in my OP, I am not concerned about isolation at all, except for isolating each room from one another. I would love thoughts on where/what shape I should split the main room into a live room/control room setup, as that's the only major change I'm looking to implement, aside from significant acoustic treatment.

If you take a look at several of the build threads on the forum, you'll find several where your type of situation is discussed, and that should set you on the right track. The "search" feature here is not fantastic, and a bit quirky, but it should lead you to threads that are going in the right direction.

As stated in my OP, I am not concerned about isolation at all, except for isolating each room from one another.

Unfortunately, you can't isolate them from each other without also isolating them from the outside world. That's just the way physics works: it would be nice if you could do that, but the way sound propagates and the methods available for stopping sound, just don't allow that to happen. You can't bypass the laws of physics, unfortunately. Your most economical solution is a fully-decoupled two-leaf MSM solution. There are other solutions, but they will cost you more money to build, and/or take up more space... - Stuart -

Soundman2020 wrote:

And the bare concrete floor is an EXCELLENT surface for a studio! Both the live room and the control room could have just plain concrete floors, if the rest of the room is treated correctly. You don't even have to lay wood flooring ever, if you don't want to. And if you do, then just put down ordinary laminate flooring: that's also a great surface, acoustically.

Stuart, if you allow one stupid question I´ve been wondering about: On a plain concrete floor without any insulation, won´t you get cold feet all the time? I´m seriously asking. Been wondering about this for a while ^^ By the way: Welcome Ben! You have a really nice place to build a studio there :wink:

On a plain concrete floor without any insulation, won´t you get cold feet all the time? I´m seriously asking. Been wondering about this for a while

Well, if you walk around the studio with no shoes on, then yes, you might get cold feet! :) But jokes aside, in some countries this might be more of a problem that in others. In very cold climates, it would be an issue. If you are concerned about it where you live, then just lay laminate flooring, with a suitable layer of insulation between that and the concrete, as specified by the manufacturer of the flooring. - Stuart -

I know I'm effectively resurrecting this thread from the dead - haha. Stuart - after much contemplation (and some readings of F. Alton Everest and Rod Gervais), I have come to agree with your conclusion - and I feel I should apologise for being so averse to your suggestions thus far. Here is where I am at thus far: I have deconstructed the stage and sound booth elements that were present and removed the carpet from all rooms. I had a 'friend-of-a-friend' work me up a design for a control room for a pretty affordable price. However, I'm not entirely sure this design is all that great now that I have spent some more time reading, and attempting to use the online mode calculators which I only partially understand. I have spoken with a couple 'big time' designers who more or less agree that this could be better, but they are all so far out of my price range by a long shot. I am posting the current ideas here and would be stoked if some of you much more knowledgeable people would be willing to take a look and maybe give me some thoughts or ideas of things to do or change. the following is a view of the trapping that he spec'd out - there are 3 bass trap clouds, and everything on the Control Room wall that is white would be fabric covering absorption.

Anxious to hear some thoughts....also, my copy of the Master Handbook of Acoustics has gotten lost in the mail.... :cen:

With some helpful suggestions on the Gearslutz acoustics forum by jhbrandt, I have updated at least the control portion of the design, here is where it is at now:

Expanding on some of the ideas I've been given, I took a stab at a basic idea for the live room as well today... I'm also attaching the Sketchup file. Things to note: The windows are a little weird; I'm not very good with sketchup and it was a fight to even get them there, so I pretty much just put in enough info to be able to get dimensions off of them later if this winds up being the design that I use. Also, the ceiling height is 12'. The walls will not be touching it I don't think, but in sketchup I just stuck with 8' for ease of layout and to save time. https://www.dropbox.com/s/6s4h8l4uzb8a0rh/Bearded%20Fox%20Design%20Updates%204.skp - had to attach the file this way, as it is too big for the forum allowance, and I have already purged the file of all unnecessary components.

I know I'm effectively resurrecting this thread from the dead - haha.

No problem! Just blow the dust off a bit, and give it some fresh air and sunshine!!! :)

Stuart - after much contemplation (and some readings of F. Alton Everest and Rod Gervais), I have come to agree with your conclusion - and I feel I should apologise for being so averse to your suggestions thus far.

No problem there either! The good thing is that you did more research, and came to the right conclusions. Sorry about the delay in responding: I've been on vacations, and it seems that not too many others have been replying to threads! :(

However, I'm not entirely sure this design is all that great now that I have spent some more time reading, and attempting to use the online mode calculators which I only partially understand.

It looks a little square-ish to me. It seems to be an RFZ-based design, but there's only the bare bones in there: not enough to go on at all. The outer-leaf wall (the one facing the big room) does not need to be angled, either: that can run straight across, to simplify construction. The inner-leaf wall (facing the CR itself) is fine with angles for RFZ, but those angles have to be carefully calculated to confirm that there really are no reflections at the mix position, and to do that you need to know the exact location of the speakers in the walls, and the type of speaker. None of that is shown in the diagram, so it's hard to say if it is correct or not. But overall, to my eye, that CR seems to be too short: I would make it longer (or not so wide), and base it on a good ratio.

the following is a view of the trapping that he spec'd out

That construction at the front of the ceiling looks to be overly complex, and isn't necessary. Also, the speakers appear to be mounted way too high in the soffits. Standard height (according to ITU, EBU, AES, etc) is 1.2m above the floor. Note that the number refers to the acoustic axis of the speakers, not the top or bottom of the cabinet! Those mains are way higher than that. Also, the little speakers on stands are too LOW: they are behind the console! The cloud is too small for a room that size, and seems to be angled too much. Normally about 15° is good (not less than 12°, but the room geometry dictates the best angle).

there are 3 bass trap clouds,

Are they bass traps, or are they clouds? It's hard to do both at once! :)

everything on the Control Room wall that is white would be fabric covering absorption.

Then it seems to be way too absorbent: it will be too dead. EBU specs are very specific on the decay times for each frequency band, and with that much absorption all at the same frequency, it will be too dead.

I have updated at least the control portion of the design, here is where it is at now:

The layout has improved, but you turned it sideways! It is no longer facing the live room: you'll end up with a sore neck like that, from having to turn your head 90° left every few seconds, to see the live room, then back again, to see the console. You also lost your soffits! :shock: Soffit mounting your speakers is probably the single best thing you can do for your room, since it eliminates all of the artifacts associated with speakers being close to walls. I would suggest rotating the CR back to face the LR, and putting soffits in again.

I took a stab at a basic idea for the live room as well today...

Looks good! But with a room that long, angling the entire side wall eats up a lot of space at the far end. Instead, you can angle part of the wall out, then angle the rest back in again for the same overall result. Or you could just leave them parallel and use suitable treatment, to reduce flutter echo. What is the design goal for the live room? Do you want it very live, or very dead, or one section more live with another section more dead? Or maybe even variable acoustics, so you can adjust as needed for each session? I saw that you added the HVAC unit, which is a good start, but there's a lot more you need to do for your complete system. Ducts, silencers, dampers, registers, and a mountain of calculations... :) Is that rectangle marked "HVAC unit" showing the location of the air handler? - Stuart -

Soundman2020 wrote:

The layout has improved, but you turned it sideways! It is no longer facing the live room: you'll end up with a sore neck like that, from having to turn your head 90° left every few seconds, to see the live room, then back again, to see the console.

Hey Stuart! Glad to talk with you again! Good to have some other thoughts... The Control room positioning was based on a recommendation from JH Brandt. With those dimensions, which he also offered up, It could only really fit in the space sideways without wasting a whole lot of space otherwise. While I sort of hesitate for it to be faced like that, it does make for good sight lines into the booth as well as the live room - though I don't know how much use the booth will see. However, during tracking, I would be using the computer mostly anyways - so not nearly as much twisting around? Maybe I'm just trying to justify working with what he's offered, as I can't afford a designer at this point (I have gotten several quotes and all have been pretty far out of reach).

Soundman2020 wrote:

You also lost your soffits! :shock: Soffit mounting your speakers is probably the single best thing you can do for your room, since it eliminates all of the artifacts associated with speakers being close to walls. I would suggest rotating the CR back to face the LR, and putting soffits in again.

JHBrandt's recommendation was to start with a basic rectangular room (for the semi-predictability of the room modal behavior, I think) and then add within it. I haven't started working on any sort of treatment - I could add soffits within the rectangle, though - right? :shock:

Soundman2020 wrote:

Looks good! But with a room that long, angling the entire side wall eats up a lot of space at the far end. Instead, you can angle part of the wall out, then angle the rest back in again for the same overall result. Or you could just leave them parallel and use suitable treatment, to reduce flutter echo.

you and John (JHB) both came to the same conclusion - the angling wastes a lot of space. I'll be redo-ing the walls parallel and work on treating them.

Soundman2020 wrote:

What is the design goal for the live room? Do you want it very live, or very dead, or one section more live with another section more dead? Or maybe even variable acoustics, so you can adjust as needed for each session?

Definitely on the more lively side of things. Most of my work has been done in larger live spaces and I like to use mobile gobos to control the liveliness into mics if I have to. Pretty fond of that way of working.

Soundman2020 wrote:

I saw that you added the HVAC unit, which is a good start, but there's a lot more you need to do for your complete system. Ducts, silencers, dampers, registers, and a mountain of calculations... :) Is that rectangle marked "HVAC unit" showing the location of the air handler?

That's the air handler, yeah. It is already present and came with the building. If you look in the pictures in my second post, you can see in the last one (building3.jpg) how the air runs along the wall/ceiling corner in the ISO - which is shared with the long wall of the live room. Once you see it in that picture it makes a little more sense when you look at the picture of the large room w the pews where you can see the vents all along that long wall sort of higher up. My plan *currently* would be to remove the vents (since the drywall on that side would be removed anyways, and then use flex duct/silencers/etc to bring the air from there into the live and control rooms via the new wall layers. Haven't pieced together how I would do the same thing in that ISO room, but I would attempt something similar in there. Does that make sense? I'll admit to being a little stressed about the whole thing. The only recommendations I've gotten since I've started work on this again have been from JH, which I am super thankful for, but it is hard to know what is 'best' and what I am capable of sorting out on my own (for example - knowing how much and what kind of treatments to use - I have gotten some hints, but am still working on trying to piece that all together - it is feeling like a struggle on my end). Anyways - I am super glad you've taken the time to comment! Thanks so much. I look forward to more, hopefully! -Ben

Updated Image.

so - i'd said (now that i know where the bathrooms are :)) that the overall layout is good but i don't see how you get into the large isolation room unless you're taking out one of the bathrooms... and even then you should have a door which makes that feasible rather than have to exit the building... on the small isolation booth in the live room - i'd skip that or make something much bigger with sliders opening into the live room so you can use all of the space when needed. agreed that using smaller angled treatments along the walls in the live room will preserve space, and depending on what those are, you could add some variability in the space (a good thing). on the CR - one of the questions is what type of monitoring system are you using (in one drawing it looked like some nice mains in the soffits) in the others you have freestanding and smaller speakers. if you are going for the larger ones in the soffits that would be good :)

gullfo wrote:

i know this sounds like we're stepping back a but but maybe if you can provide a detailed and labelled SU file which has the rooms as they are including ducts, pipes, bathrooms, doors, windows, etc without any pre-conceived studio bits in it, that would help me because i'm a bit lost (as you've noted) about what rooms are what, and what doors you can use or not etc. it's important to have these details to make the most of the space. otherwise it becomes more of a guessing game as new details emerge...

... :oops: You're quite right. I'll get right on that. Thanks so much! -Ben

here's one idea while you're doing that...

Glenn - thanks so much for that! Looks pretty rad. I tried to make two different Sketchup files, one simpler and one complete, but I still could not meet the small size requirement to upload directly here. So I am just going to attach a download link to the Complete one - I have tried to be as comprehensive as possible, so as to help avoid further confusion. What you see here is pretty much exactly as the building is right now. One note: I have not yet measured the locations of all the HVAC vents, so what are in the file are guesses - fairly random, but a decent representation of what they are like. I am hoping to get to the building this week to make those measurements. I also have no idea of the spacing of the joists and studs, so they are all over the place as I am not good in sketchup yet and was only worried about them being representative. https://www.dropbox.com/s/2xhwi731kzpeb ... mplete.skp Let me know if the link doesn't work, etc. Thanks so much!

gullfo wrote:

on the CR - one of the questions is what type of monitoring system are you using (in one drawing it looked like some nice mains in the soffits) in the others you have freestanding and smaller speakers. if you are going for the larger ones in the soffits that would be good :)

Sorry for missing this.. I've gone back and forth on this. But soffits would be a much better choice. I will very likely go with JBL LSR 6332s, as I have used them before and they are similar to my current nearfields- the older LSR28Ps, which I love.

Also - and this question is for anyone - one thing that has confused me on here is how I see a lot of designs where the RFZ is being created with the massive inner leaf. If you are splaying the walls of the actual inner structure of the room, that means that room mode calculators are mostly useless, right? How do you decide on dimensions for your room then? I have been searching here for a while and can't seem to find much. Most of the info I read in books or on other sites points to making the room structure itself a rectangle with good ratios and treating the inside of that. MHoA talks about ratios, and touches on the unpredictability of modes in a non-rectangular room, but when he talks about the RFZ design philosophy doesn't mention anything about ratios or room dimensions. A soffit has to have significant mass, and will be a part of the RFZ angling.... I don't think I'm getting how that all fits together.

As far as I understand. if you angled one or more walls will make the room ratio invalid and Online Room mode calculator won't be usable because it's not rectangular. You'll need Acoustic modeling software to calculate room mode of none-rectangular room. Example (Joe Egan's STUDIO design by John Sayers) On the other hand If you keep room rectangular but treat first/early reflection away from mixing spot and Prevent sound wave bouncing back and forth. I Believe doing this way room ratio still valid. Example (Design by John Sayers) Lets analyze this plan Front wall: Flush mounting Speakers. Basically they act as Corner Bass Absorber and mount speaker in them. They are treatment not angled wall so it doesn't change room's shape. Side walls: Slat resonator walls. They're just air sealed space and still let air through the space via those gaps between slats. they should be made and tuned to absorb low-mid and let high still alive that's why I believe it's angled. Rear wall: Hanging acoustic hangers and cover with Fabric. Those angle are false walls just to hide those hangers behind it. It might not look like rectangular but behind those Timber, Cloth and slat finished the room's still rectangular with built-in acoustic treatments. So, I think room ratio still valid. BTW I believe 2nd picture (Plan3.jpg) is not pure RFZ design. I think it's combination of several designs which are RFZ, Non-environment and LEDE. All these three designs require Quite a lot of space to build RFZ design normally side walls and ceiling should be angled to reflect sound away from mixing spot and diffuse at rear wall like Egan's Studio. You'll need very large room to angle side walls and sit at least 4.12m (which is almost 14feet) away from rear wall because diffuser behind mixing engineer's seat. LEDE design (Live End Dead End) Normally this design should Absorb front part of the room to stop early reflection and leave rear part reflective/diffusive to prevent the room from being too dead (but some said you can do another way around Dead End Live End). same as RFZ Listening spot should be quite far away from rear wall Non-environment design uses a lot of space to make wide band absorber to side, rear and ceiling using Acoustic Hangers and cover them with Cloth to create false wall. Small rooms can't build to meet these requirements because of space. So, this is why it need a little combination to build small control room. This is what I understand, Please correct me If there are any mistakes. Cheers - Ken

If you are splaying the walls of the actual inner structure of the room, that means that room mode calculators are mostly useless, right? How do you decide on dimensions for your room then? I have been searching here for a while and can't seem to find much.

It is confusing, isn't it, Ben! Like most things about acoustics, actually... :)

A soffit has to have significant mass, and will be a part of the RFZ angling....

Basically, yes it does have an effect, but the questions to ask are "how big is the effect?" and "does that matter?". OK, think of this scenario: Think of a text-book perfect rectangular room with absolutely perfectly parallel walls, perfectly perpendicular, plumb and square in all senses. So obviously you can easily calculate the ratio and predict the modal response very accurately. But what happens if one of the walls is angled by just 0.1°? That's a tiny, minute fraction of an angle. Does it make a difference? If the wall is 5 meters long, that means that one end is just 9mm out of square. Clearly, that isn't going to make any real difference to the calculations, and the modal response will be practically identical to the "perfect" room. Sure, in theory the axial modes associated with that wall don't exist any more, and the tangentials and obliques will be at different frequencies, but in reality the change is so slight that you'd never notice, and even the most sensitive acoustic measurement would hardly see any difference. Why? Well sound waves are huge, with respect to the size of the difference. Even the shortest waves (at 20 kHz) are still twice as big as that tiny change, but the short waves are of no interest to us in calculating modes anyway: You only really need to worry about frequencies below 300 Hz for most rooms, meaning waves of about 1 meter long and longer. That's more than a hundred times bigger than the slight difference caused by that tiny angle. For such long waves, the axial modes are still there, and the tangentials and obliques have only shifted by a fraction of 1 Hz. In other words, no change at all. So clearly, angling the wall slightly has no effect. But what about for a bigger angle? An angle of 1° for a 5 m wall is a difference of 9cm at that far end: Still very small with respect to the size of the wavelengths we are talking about. At an angle 10°, however, there's a large difference: one end of the wall is nearly 90 cm further away than the other end, which is comparable to a full wavelength at 300 Hz, so yes, that's substantial and will cause noticeable changes in the room response: definitely no axials on that wall now, and the tangentials and obliques are off by many Hz. However, consider this: for big angles, the axials that would have been there for a non-angled wall, are now tangentials! The didn't go away: they just morphed into a different type of mode. Now, here's where it gets interesting: if instead of assuming that there is a 90 cm shift from one end of the wall to the other, you take a different viewpoint and assume that there is only a 45 cm at each end with respect to the CENTER of that wall, well then things aren't so bad! One end of the wall has tangentials and obliques that are higher in frequency than the center, while the other end has tangentials and obliques that are lower in frequency. So if you use the AVERAGE dimension of the room, instead of one corner or the other, then your calculations will only be off by half of what the error would have been, and even then the errors average out! Some are higher, some are lower. So what you have done is to move your perspective, and now your calculations are still accurate for the center frequency of the modes, with errors spread out broadly going both ways, but the errors are 50% smaller. So, as Everest says in MHoA, you can take the average dimensions of the room and still get a reasonable idea of how the room will behave, using only basic room mode calculators. The result will not be accurate, of course, but it can still give you an idea of how the room will behave. The error will be proportional to the difference between the two ends of the wall. Now let's add another ingredient to the mix: If you splay only one wall (for example, the front wall), well, that has NO EFFECT AT ALL on modes that do not touch the front wall! The vertical modes between floor and ceiling are unaffected, the horizontal modes between the side walls are unaffected, and all tangential modes that don't touch the front wall are not affected. So you have only changed SOME of the modes in the room by angling one wall. For the other walls (that are still parallel), the modes are the same. The only modes that are different are those associated with the wall that you changed. So once again, most of the data shown by a simple calculator is still valid: If you ignore the modes associated with the changed wall, then all the rest is perfectly accurate. So, the basic conclusion is that you can still use a room mode calculator when you have soffits on your front wall, even though they are heavily angled, and massive. You just take the average length of the room and use that in your calculations, and the overall picture won't be too far from reality. In fact, you can also do another calculation for the shortest side of the angled wall, and a third calculation for the longest side, to get an even better idea of what changes and how much it changes by angling. If all three calculations turn up good ratios and no red flags, then you are good to go. Finally, above the Schroeder frequency of the room and below the lowest modal frequency (length axial), modes aren't even a problem worth worrying about: you only need to be concerned about the range between the lowest mode supported by the room, and the Schroeder frequency. Actually, I'd adjust that say up to about twice the Schroeder frequency, since there's a lot of overlap between the regions. So for a room 5m long, 4m wide and 3m tall (arbitrary dimensions, pulled out of the air as an example), you'd only need to worry about what happens between 34 Hz and about 220 Hz, absolute maximum. So, the final answer to your question is: Yes, you can still use a room mode calculator to approximate what the modal behavior of the room will be like, but it will not be accurate. It can give you a rough idea of how the room will respond, but that "rough idea" is still good enough to be useful, in most cases. Now, having said all that, there are two other points here: 1) You don't need to go overboard trying to find the "perfect" dimensions for your room! There is no such thing as a perfect ratio: There are only "less good" ratios and "better" ratios. And in reality, the difference between a fantastic ratio and a so-so ratio is not going to be noticeable in the end, once the room is finished and properly treated. So don't go crazy trying to adjust your walls by millimeters or small fractions of an inch, just to try to tweak the ratio! The idea with ratios is simply to stay away from the really bad ones, get close to one of the many good ones, and leave it at that. 2) Mode calculators only predict how the room will behave it you build it perfectly, from perfect materials. Since it is impossible to do that anyway, your room will NOT behave the exact way that the predictions say it will! There is no such thing as an acoustically perfect material to make your walls out of, the air temperature, pressure and humidity in the room will be different from "standards", and it is impossible to build the room with sub-millimetric precision on all sides, so the actual room will be different from the planned and predicted room. Therefore the only sane way of dealing with room modal behavior is to measure how the room is actually behaving, after you finish building it, then plan your treatment based on that. In other words, after you have all the walls, windows and doors in place, before doing any treatment, then do an acoustic analysis of the room using REW, and based on what REW shows you, decide how you will treat it. Then, after you install each group of treatment, do another measurement with REW to make sure that that device had the effect you wanted, as well as to see how it might have affected the room in other ways, and to see what still needs to be done. That's the logical, intelligent method of designing a control room: Approximate on paper, measure in reality, and treat accordingly. - Stuart -

Stuart - that explanation is amazing. I remember reading some of that in MHoA, but it must not have stuck - easy to get overwhelmed with all the info in the book. Both of you - thanks! This has been super helpful. I am going to try and work on some ideas combining the things that you all have said based on my earlier ideas, and post them later. :idea: -Ben

Front wall: Flush mounting Speakers. Basically they act as Corner Bass Absorber and mount speaker in them. They are treatment not angled wall so it doesn't change room's shape.

Actually, soffits have hard, solid, massive front faces, and they do change the room dimensions and modal behavior.

Side walls: Slat resonator walls. They're just air sealed space and still let air through the space via those gaps between slats. they should be made and tuned to absorb low-mid and high still alive that's why it's angled.

Slot walls do many things at once, and the overall effect depends on several factors. For example, if the perforation percentage is high (above about 20%), then they act like a perforated panel broadband absorber, but for low perforation percentages (less than about 5%) they act like a series of individual Helmholtz resonators. In which case, they are pretty good reflectors across most of the spectrum, and really should be considered in room mode calculations too, at least for the upper end of the range of interest (around the Schroeder frequency).

BTW I believe 2nd picture (Plan3.jpg) is not pure RFZ design.

It might be, or might not be, depending on how the slot walls were built.

I think it's combination of several designs which are RFZ, Non-environment and LEDE. All these three designs require Quite a lot of space to build

In reality, RFZ is just extensions or modifications of the original LEDE concept, and NER has the same goal, so all true RFZ rooms also show aspects of LEDE and NER. The room depicted in Plan3.jpg isn't long enough to use diffusion on the rear wall, which is why I imagine that John used hangers there. But then again, John is a big fan of Tom Hidley, so that probably explains that! :) Both RFZ and NER originated with Tom.

RFZ design normally side walls and ceiling should be angled to reflect sound away from mixing spot and diffuse at rear wall like Egan's Studio. You'll need very large room to angle side walls and sit at least 4.12m (which is almost 14feet) away from rear wall because diffuser behind mixing engineer's seat.

You can do it in much smaller rooms, if you angle the surfaces accordingly. I've achieved a pretty good approximation in a room measuring only 4.3 long, 3.2 wide and 2.2 high (at the longest, widest and highest points). Interestingly, Tom, John and others (even myself) design RFZ rooms without using too much in the way of tuned diffusion on the rear wall. It's not needed, and can create problems of its own, especially if there is a couch back there. - Stuart -