Ideal control room shape: Main conclusions=confusion

I have been looking after most of studio designs for a while now, coming from suggestions thru forums around, or from dedicated simulation sofwares supports, or even from professional studios internet sites, in a way to optimize the space that i have for building a control room. I have studied most of technical aspects in theory, but now i am stuck between these 2 contradictions: 1) In big professional recording studios, studio shapes are often irregular...WHILE other people say that this kind of rooms is difficult for room modes predictions: Should i stay with parallel walls, or choose for hexagonal/octogonal shapes? 2) Most of optimisation softwares -as RPG Room Optimizer- consider the length of the room as the basis in getting front/backward placement, WHILE some of true professional studios have 'width' larger than 'length' (ex.http://www.davout.com/studioA/map.html): Is there any pro/con of that particular design? [Well, i had the conclusion that the design theory used for big recording studios isn't really the same, since the one adapted to most of our control room possibilities depends on the room space, which is often less... The thing is that in these big 'professional' recording studios, space available is often much bigger than in most project studios, and i know that room space allows much more adapted solutions, of course!]

kep in mind the room shape may be treatment and not solid walls. so the designer may have made the room rectangular based on mode analysis, space etc but then added a variety of treatments to create the desired RT60 times, flutter echo reduction, etc.. volume is king and makes up for a lot of less desirable (typically) configurations. so in a pro studio, yea, they might have a CR only 20 feet deep and 30 feet wide and 15 feet high :-)

1 - it is possible to try to predict room modes with really irregular shapes with computacional methods but it is a pain in the ass... for rooms with slightly splayed walls you can use the traditional method. There are some mathematical methods to predict the room modes taking in account the rigity of the modes (same rooms with different wall materials don't quite have the same modes). The question rectangular rooms vs slighty splayed vs hexagonal/octogonal shapes depends on the space itsel, the person doing the design and the philosophy behind it. Also depends in my opinion (this is just my opinion) if the speakers are placed into the walls or not. Control are not irregular shapes, they should be as symetrical as possible. Tracking rooms is another story. 2 - the reason for a wider room is to delay lateral reflections. This is the reason to have a room with a a large width.

Well guys, happy to see that some of you have replied ! I tended to think that my post was rather complex or something like that... ----Any your advices are really appreciated and useful--- Gullfo said:

kep in mind the room shape may be treatment and not solid walls.

Actually i was interested by studios shapes especially made hexagonal/Octogonal from the concrete step, as the layout, given from their site, do show.In these examples, each room shape is dependent on the next room shape, and so on. Andebrito said:

for rooms with slightly splayed walls you can use the traditional method

--So wouldn't that solution be the best compromise? (Easy method for room modes, but still no parallell walls)?

There are some mathematical methods to predict the room modes taking in account the rigity of the modes

--Do you know the method exactly? Is there a way to calculate that kind of things?

same rooms with different wall materials don't quite have the same modes

--Well, i talked wth 2 acousticians 2 days ago, and each of them got different points of view: One claimed that the modes were dependent on the wall materials, while the other (who finally seemed to convince the first), claimed that the strength of the modes were dependent, but not the room modes themselves

Also depends in my opinion (this is just my opinion) if the speakers are placed into the walls or not.

Do you talk about flush mounting? Then, How is it related to room shapes?

Control are not irregular shapes, they should be as symetrical as possible

I totally agree.But i thought about regular octogonal/Hexagonal shapes anyway.

the reason for a wider room is to delay lateral reflections

Ok, so i deduce it is ok if the reflection is more than 20ms, and, if its under, room size is not wider enough?

Nightmusic - the reason the control room you cited is that wide is to fit in that huge console and those wide speakers. Otherwise the room is a standard flush mount 5:1 system where the front of the room is angled to the speakers i.e 30 degrees. You will note that the finished room shape is not as per the "Plan" cheers john

Ok John, indeed that console is very huge, 80 inputs ! There's also the same kind of huge console in the Studio B http://www.davout.com/studioB/map.html http://www.davout.com/studioB/picture.html But there, the length/width seems to be rather equal (!), while it also has an octogonal shape. Would you have yourself any opinion about these Octogonal/Hexagonal room shape anyway? These shapes seems to be common for most of control rooms in big recording studios. 1) Then, should we follow these example in a way as possible, even for our project studios? Is it adaptable to smaller rooms? 2) If yes, is it so difficult to predict room modes with these shapes, or is there any plan ratio/angles that we would have to follow, given the height (for ex.), in order to get the best results (as we have ideal ratios for rectangular rooms)?

I know these methods but the formulas are heavy to use and if the room is rectangular or slightly splayed the differences are not that important and you can always make measurements after the room is built. The rigidity or the non-rigidity of the walls not only changes the frequencies where the modes occur comparing to the typical simple prediction formula but also you don't actually end up having zero pressure zones. The question is that I didn't notice that one of the reasons for that studio to have such a width was like John well refer: the size of equipment of the studio. Acoustically speaking delaying the lateral reflections can be beneficial as well. You can compute the room modes even taking in account the furniture of the room or for the strangest room you can possible imagine but you need special software for that which is not that easy to use :-)

Nightmusic wrote:

--Well, i talked wth 2 acousticians 2 days ago, and each of them got different points of view: One claimed that the modes were dependent on the wall materials, while the other (who finally seemed to convince the first), claimed that the strength of the modes were dependent, but not the room modes themselves Ok, so i deduce it is ok if the reflection is more than 20ms, and, if its under, room size is not wider enough?

the shape and materials will affect modes, but each octave will be affected differently. low octaves will behave poorly in rooms with wide spacing between modes or overlapping modes. the stronger the walls, the more the sound stays in the room. the more that stays in the room, the more treatments/trade-offs will be needed. sound and noise isolation and good sounding acoustics are anthitetical to each other... if the room is not deep enough (as in plan A) you need a dead back wall (which is what it looks like they did).

Would you have yourself any opinion about these Octogonal/Hexagonal room shape anyway? These shapes seems to be common for most of control rooms in big recording studios.

As I said - the front geometry is a standard 30 degree speaker system. The plans shown at that site do not reflect the actual room geometry. cheers john

Andebrito wrote:

I know these methods but the formulas are heavy to use -You can compute the room modes ... but you need special software for that which is not that easy to use

Would you have any link to these method/theory? Even if it is difficult to use, it should be very interesting to me anyway... Gullfo wrote: -

If the room is not deep enough (as in plan A) you need a dead back wall (which is what it looks like they did)

I understand there that early reflections would come mainly from the back wall, in that kind of room shape, isn't it? This would be the reason why there should be absorbing treatment there, while reflection coming from both sides may be easier to handle (if they are more than 20mm)? Am i catching it the right way? :roll: -

sound and noise isolation and good sounding acoustics are anthitetical to each other...

Yes i undestand and agree that point of view.If one wouldn't have to put any isolation to the wall, reflections and bad ones wouldn't occur as much in the room.The more one keep sound from going outside, the more the sound stays inside, and then room modes are stronger. John wrote: -

the front geometry is a standard 30 degree speaker system. The plans shown at that site do not reflect the actual room geometry

You're right John, i didn't noticed that the first time when i saw the plan.When compared to the pics, one can see there are extra space between,allowing next room adjustments shapes. Well, of course, now i understand that geometry, caused by the flush mounting speaker at 30° !!!! Then, the simmetry rule may lead the room to be hexagonal, as for the Studio B, right? So then comes one final question: Should this geometry (including 30° front walls) be made with solid wall (I mean double gypsumboard+Sheetblok for ex.), or just be considered as treatment part? (Gullfo wrote:the designer may have made the room rectangular based on mode analysis, space etc but then added a variety of treatments to create the desired RT60 times, flutter echo reduction, etc.. ) Because depending on that, room modes would change,right? here we are back to the choice/dilemna between 'rectangular rooms vs slighty splayed vs hexagonal/octogonal shapes', as Andebrito spoke about...

if you are starting from scratch I usually build solid splayed walls but if the room already exists and is rectangular I create the angled wall system using treatment - as Gulfo said. cheers john

Well John, All depends on what you describe as 'building from scratch'. The room already exists, but it is only concrete walls for the moment. Now i am about to build the isolation walls, with Mass-air-mass system. Then, should i use isolation walls as a way to angle walls, the way described above? (considering the isolation walls solid enough to use them, as starting points for room modes)...

Nightmusic - show us your building and we can go from there instead of you posting lots of "what if" questions! We are here to assist you in your project - not to become your personal audipedia. cheers john

Would you have any link to these method/theory? Even if it is difficult to use, it should be very interesting to me anyway...

It's on the Kuttruff book but I find these formulas just good for theoretical purposes, I wonder if anyone uses them,,,

I have attached the pic of the layout--- Everything here in nude,only concrete. I am about to install electricity and H/Vac, but still waiting for dedicating rooms purposes, before planning anything. That whole building is recovered with earth, instead on the right upper part, where there's the main entrance. So 2 main entrances are available, the one at the upper right ('basement' access), and the other at the down right of the layout, which is available by the top of the building, i mean by stairs. -Black lines stand for concrete walls. -Grey lines stand for concrete walls, but the ones that i intend to destroy. -Everything concrete is made with steel+cement. -Walls concrete blocks are all 22 cm width. -'Double parts' access between rooms, are supposed to become windows. -'Triple parts' access, stand for actual stairs (the bottom central room is lower 1m more than the others). -The other access are from bottom to top, regular access (supposed doors) -All heights are 3,02m, except for the central room at the bottom of the layout, which is built/digged lower 1m, with a consequent height of 4,08m. -All pink lines give main dimensions, clearer pink lines stand for inner dimensions(dimensions between different inner acces) I have to add isolations extra walls to that layout, using mass-air-mass double leaf principle.That isolation step is the one we are discussing, about the fact that these new inner room should follow particular shape, or not. I hope that layout would help you in comments or suggestions. Here's the layout of the place:

whats in the middle square? what type of building is this? are you sure the gray walls aren't load bearing?

The central room that i intend to destroy, doesn't bear any load, as walls don't go up the ceiling, off few centimeters. That central place is exactly the same as others, just concrete walls. I think that room was originally built as for an iso booth, for vocals for ex. I haven't told about the origin of that building yet: Actually it was built by the previous owner of the house, in order to become a recording studio! But it always stayed as is, thus it gave me an extra reason for buying the house, of course ! The two little grey squares on the down left/right of that central room, were supposed to handle flush mounting (big) speakers. My idea is to destroy all that part (all grey lines), in order to get much more space available, and get the freedom to manage it the way i want, for example for getting a bigger live room, or for creating optimized room modes configurations there, with adapted new rooms shapes. I hope all my explanations are clear enough, don't hesitate to ask me further.

maybe something like this? i adjusted some door sizes a bit and changed some of the window openings into doors as well. the long narrow room I'd just make into storage - put shelves on one side.

Well, Gullfo, you did that so quick !!! So...Your suggestion are really welcome, as i told you, the central room is eligible to become a control room. The only dilemna that i had, was about the 'higher' room (the main one on the right side on your layout), as it is 4,08m high: I didn't know if it would be better to use this room as an acoustic recording room (as you chose), or as a high-absorbing-sloped ceiling control room, as the one one can see in big professional recording studios :shock: Your appreciation there would be welcome ! Ok, so anyway i am back to the original question posted here: What about the angled wall as you designed, as octogonal control room...I mean, should i build these extra angled walls as the isolation leaf (mass-air-mass rule), or as treatment walls? In other terms, should i build these walls as massive as possible, in order to change resonances/room modes inside the room (non rectangular room)? Or should i build massive isolation walls, adjacent to the original walls (rectangular room design) first, and then add treatment angled boards on it? Thank you for that big help anyway!

i think you build them as treatment walls, you have plenty of concrete... i'd just extend that one wall on the CR front all the way across. with the 3m+ height in the CR, you can do a bit of a sloped ceiling. since you do have the 4m ceiling in that one room, i'd make that a killer drum room.

Gullfo wrote:

i think you build them as treatment walls, you have plenty of concrete

Do you mean that i don't have to build an extra massive isolation wall, in order to decouple the inner room from the outside one? (with mass-air-mass system)? Would that mean that i just have to add treatment walls directly on concrete walls? So Is the concrete part, considered enough for isolating sound transmission from one room to the other (live room-control room, for ex.)?

i'd just extend that one wall on the CR front all the way across

Do you mean the long way 9,74m?

since you do have the 4m ceiling in that one room, i'd make that a killer drum room.

With isolations added, it may go for 3,75m or something like that...So do you have a precise idea about the resonance of that kind of room? Do you know what kind of drum recording posible there? Is there a way to now the RT for that room? So many questions, sorry...

the treatment walls could be built inside-out to give you treatment and isolation. the center wall where your removing most of the box, extend the remaining wall across to complete the CR. without extensive design based on requirements it would be hard to compute the RT60 since you're going to build things in that space and that construction will vary. budget comes into play but some options would be to build reversible wall treatments to be able to adjust the characteristics.

the treatment walls could be built inside-out to give you treatment and isolation

Well, first let me be clear about some conceptions that i have , wereas i can get confused, if i'm wrong (well, cause i got confused with the terms 'inside-out'): 1) As i consider 'treatment walls', these kind of walls are a basis support for low/mid absorbers (often made with plywood, mineral wool and wood frame,with air caught), or for high absorbers (regular foam), and finally for diffractors/diffusors. So they are not made to be especially massive. 2) Isolation walls have to follow mass-air-mass rule, and the way i intended to build them is: steel frame>rockwool>gypsum(equivalent)>sheetblok>gypsum(equivalent), that wall being used as the second leaf of a 2 leaf system (in my case: concrete-air-drywall)-these walls have to be massive So if you share this (i hope so!), then you meant that i would better use isolation walls as support for treatments parts, so that have to build the isolation walls, in a way that will give the final room shape (octogonal, for ex.), keeping in mind treatments positions in the room?

the center wall where your removing most of the box, extend the remaining wall across to complete the CR

ok, so you if you mean using the whole length as the control room dimensions, wouldn't that room be too long (-10m), in regard of acoutic purposes (given the height/width)? Some calculation formulas leaded me to think that above 7m long , that room would loose its best acoustic properties (room modes complications and so on), or maybe all this theory should be related to a designer experience-as yourself, maybe- for that kind of situation?

some options would be to build reversible wall treatments to be able to adjust the characteristics.

That is exactly what i wanted to do. But my question was more precisely focused about knowing how 'large' that room would 'sound', in a better case when one don't put any absorbtions, given the dimensions of the room? I just would like to imagine how much that room would offer up to a 'killer' drum sound, as you said? I know this is subjective, but, in terms of music, could we say that this room would sound good for jazz recording? for deep-kick-drum led zep recording?... That subjective aspect leaded me to talk about RT60 for that room, cause i just wanted to go in a more objective direction with it for you explanations, as you can't see and feel in place how the room would sound like, and as i never built/used such a room before! Well Gullfo, please know that all your explanations are very-very appreciated. :D

just because they're inside out doesn't mean they don't have mass. adding another layer (resulting in 5/4 thick) of drywall would seem to be what you need + you already have concrete which i believe is already more dense than drywall construction. note that the treatment side of the inside out wall also works to reduce sound transmission so the outer wall has less work to begin with. :idea: your weak spots will be windows and doors. so if you spend about $8K EU per doorway, and another $15K EU for the windows, you can probably get reasonably close... :? if you look at my drawing - the front wall of the CR spans the entire center area - the existing wall doesn't - so extend that wall. just because its a "drum room" doesn't mean you couldn't put a grand piano in there... 8) plus if you keep the room somewhat on the live side, you can add the adjustable treatments to deaden it if needed. i'd take advantage of the height to add bass trapping overhead with a sloping false ceiling over which i would put a number of skyline diffusers. this would keep the room height around 3.25-3.75m and lively without harsh reflections. judicious use of wall and floor treatments to taste. additional bass trapping in the corners to tighten it up. here's a friend of mine's A studio built in an old church which has a lot of liveliness. http://www.thebarbershopstudios.com/cop ... om%202.jpg

i'd take advantage of the height to add bass trapping overhead with a sloping false ceiling over which i would put a number of skyline diffusers. this would keep the room height around 3.25-3.75m and lively without harsh reflections. judicious use of wall and floor treatments to taste. additional bass trapping in the corners to tighten it up.

Yeah that advice is very precious to me, man ! I think i will go for it !!!! Well, your friend's room is impressive ! Could you describe what kind of treatments here we have? 3 Diffusors on the front? Absorber in the rear? Well, also do you know how high is that room? :P You didn't really told me-or am i blind to see clear enough behind your words-, if i should keep my isolation wall concept (steel frames>rockwool>gypsums/sheetblock), and then look for a 2 leaf system, or should i consider that concrete is massive enough, so just add treatment on it?