Planning design of a full recording studio/ Now building...

Hi there ! What a marvellous resources this forum is, there is so much info i get confused ;-). First i would like to specify that english is not my primary language, so you may read some weird things from time to time. OK here is my situation. Intro I am a recording engineer/musician located in the Region of Montreal, Quebec, Canada, i have record and mix music for TV, Records, film in 5.1, Live sound, Live recording. In recent years i have slow down a bit, and this old dream of bulding my own studio re-appeared. Although I have a great experience in sound i've never actually built or design by any extent a recording studio. So let's assume i don't know anything about studio acoustics. Location/Surroundings I am currently in the designing process. i am planning to built a full recording studio. I plan to use this studio for project ranging from basic demos to full record production including mixing, arranging and post work. Most album project i do are Hard Rock music with very powerful drummers. The "shell" in wich i am planning to built already exist, it's a 10 years old woodworking workshop used by the previous owner, see Photo.1. The "future studio" is located on a 56700 sq.ft. terrain surrounded by forest, the closest neihbors are bout 400ft south side, the nearest streets is a dead end and is about 100ft east side, and this "future studio" is about 85ft from my house north side. All of this is about 90KM away from Montreal... i don't think i will hear the city rumbling ! Eventough neiboors are far i don't want to disturb the quiet peace of nature's pace. Photo.1 The building This 8.090 X 7.700 X 3.085M (or L26'6" X W25' X H10'3") (interior dimension) construction was made on a +/-5" concrete slab, with NO footing, by that i mean that the slab rest on about 1ft of crushed rocks at ground level, there is no underground structure whatsoever. Exterior is white PVC (read ugly) And are made as follow : PVC - Vertical Forens - Black Paper - OSB 5/8 - 2X6 with mineral wool - Vapor barier - horizontal Forens . Exept for the ceilling wich is finished 1/2 Gypsum board, Interior is unfinished with one half division see fig.A, the 2X6 exterior walls are all exposed vapour barier with horizontal forens at every 16", exept for the north-east corner where there is a masonery wall with fireplace (very nice).Floor are on raw concrete, no paint. Heating insulation is present in all walls (R-20)and roof (R-12). For windows,doors, beams location of the actual building see fig.A. The roof is all steel sheats, with a 5ft (at it's peak) attic. Fig.A Budget I am quite good at constructing/renovating and i plan to do all the work myself. That would keep the cost down. This project will be done by phase. Assuming there is no problem with structure or dimension of the actual shell, my first step would be to built the control room, with a 3000$ budget as a start. Since for me this is a long run project, spending 20000 over say five years is justifiable and worth it for what i do. ( i won't go into electro-magnetic floating room...;-) And this won't be a Prime International Commercial studio anyway). BUT that said i need to have a control room ready by June/July of this year. The studio Now for this future Studio. After weeks of trying to use the space i had with no satisfactoy results. I came to the conclusion that the shell needed to be bigger, i was a bit discouraged, primary by the $ factor. Then i was leaded to your forum and i began to see studio with smaller spaces. Then I came across the "corner room Studio" and i tough i was a great ideas. So Fig.B is a scaled down re-arranged, grealty modified version of this to fit the actual shell dimension. All walls would be made of 2X4 steelstud, spaced 24"o.c. filled with Roxul Safe'nSound Rock wool. Then with of one layer of 5/8" + another layer of 1/2" Firecode gypsum board. Sealed at their perimeter with acoustic sealant. The air space between walls would go from a minimum of 0.284M to 0.704M max. variable. I am not sure if should use RC channels. If someone think that doesn't make sense please tell me so, that is why i post all this anyway. It is my understanding that materials are one thing, how they are assembled is another, i am very, very, very picky on this in everything i do. Fig.B Questions/Questions... At this stage my troubled mind outputed these questions 8-) : 1a.Are those dimension realistics or acousticly correct? (Specifically the control room See Fig.C) 1b.Should i have a bigger control room at the expense of smaller recording room ? Fig.C 2a.Are the cavities between the walls of the control room and the other rooms need to be sealed ? (See Fig.D and E) 2b.Is there a problem if they are sealed, will i lose something ? Fig.D Fig.E 3.Do i need to finished the walls of the shell before i actually bulit the studio walls. (My understanding is No but i want to make sure) 4.Can someone clarify this : In a lot of studio design i have seen on this and other sites a lot of peoples use free field references monitor in a soffit manner, i don't get it. I always though that free field (near field-mid field) speaker were calibrated and made to be used on a stand otherwise you skew the frequency response.And if you want soffited speaker you need to buy some that were design to be so. Any monitor front ported or not will have bass radiating behind it and was measured and designed taking that in consideration. I need really some light on that issue. Thanks ---------------------------

1a.Are those dimension realistics or acousticly correct? (Specifically the control room See Fig.C) The average length vs. front width is approx. 1:1.34, with a ceiling height of around 4.8 M it's one of the optimum ratios. 1b.Should i have a bigger control room at the expense of smaller recording room ? Depends on your working style; if you do a lot of solo (one man creation) stuff, a larger CR would be better. If you record bands live, then the Live room should be larger. 2a.Are the cavities between the walls of the control room and the other rooms need to be sealed ? (See Fig.D and E) No, they're actually better if NOT sealed but allowed to "breathe" into each other - just make sure any sound has to pass through mass-air-mass to get to the other space. 2b.Is there a problem if they are sealed, will i lose something ? See above. 3.Do i need to finished the walls of the shell before i actually bulit the studio walls. (My understanding is No but i want to make sure) Depends on what you mean by "finish" - structurally complete, or painted, or?? You can't get to them to change anything once the inner walls are up. 4.Can someone clarify this : In a lot of studio design i have seen on this and other sites a lot of peoples use free field references monitor in a soffit manner, i don't get it. I always though that free field (near field-mid field) speaker were calibrated and made to be used on a stand otherwise you skew the frequency response.And if you want soffited speaker you need to buy some that were design to be so. Any monitor front ported or not will have bass radiating behind it and was measured and designed taking that in consideration. I need really some light on that issue. http://www.johnlsayers.com/phpBB2/viewtopic.php?t=766 That explains the main difference between speakers designed for soffit mount and those NOT - some offer switches built in to compensate. Genelec has about the best info on this of any manufacturer http://www.genelec.com/support/flushmount.php but several of our members can attest to the sound quality they've gotten by soffiting Mackies, KRK;s, Dynaudios, etc... Steve

Thanks for answering Steve !

1a.Are those dimension realistics or acousticly correct? (Specifically the control room See Fig.C) The average length vs. front width is approx. 1:1.34, with a ceiling height of around 4.8 M it's one of the optimum ratios.

When you say 4.8M for the ceiling do you mean Meters ? the Plan i have provied indicate a ceiling height of 3.123Meters, that is more than a 2Meters difference with the dimension you are refering to, or about 7fts.

3.Do i need to finished the walls of the shell before i actually bulit the studio walls. (My understanding is No but i want to make sure) Depends on what you mean by "finish" - structurally complete, or painted, or?? You can't get to them to change anything once the inner walls are up.

By finish i mean a closed wall with gypsum board, not an exposed vapor barrier wall as they are right now see Photo.2 below. I guess structurally complete would be the right expression. To put it another way, is it better to leave those walls as they are and built the inner walls leaving an air gap between the two. Or is it better to "close" them before building the inner walls ? Sorry if this is confusing. Photo.2

1b.Should i have a bigger control room at the expense of smaller recording room ? Depends on your working style; if you do a lot of solo (one man creation) stuff, a larger CR would be better. If you record bands live, then the Live room should be larger.

Well i do both, i guess i will have to compromise, however being stuck in a closet is not my idea of a great day at work.... In our previous discution you mention there might be problem with the door of the CR, what exacly are you refering to ? (symetry, reflections...)

Your average dim's for the room are about 3.7 M wide, 4 M long, 3.1 M high; these are averages since splayed walls are involved. Using those averages the Bonello distribution of modes is quite favorable, with no potential problems indicated. This is NOT to say you won't still need treatments in the room, only that they won't be in vain. On your outer walls, you do NOT want another leaf of mass besides the outermost one and the innermost one; air space and insulation between these will make up your mass-air-mass barrier for best isolation. If your outer shell isn't already heavy mass, you may want to increase that before building the inner shells; check out Sharward's thread in Construction for more, probably around page 5 to 10. Also, you only want ONE vapor barrier in a building and in your climate it goes to the inside; so you will want to replace that foil-faced insulation with UN-faced, and put the foil faced stuff with the foil against your first layer of INNER wallboard. The door problem I referred to is just that your existing door doesn't seem to be in the right location for the plan you've adopted... Steve

Thanks Steve About my control Room dim's, originally i tried to fit my CR into a H1/W1.28/L1.54 ratio. And i used the exel spreadsheet called "modes1" that i found somewhere on this forum, it is actually as it's name implies a room mode calculator but it gives a wider choice of ratios from wich to start. Is there other calculator available that will do calculation with splayed walls/ceiling ? ..does that exist at all ? Just what i needed to know on my outside walls structures but wasn't sure about, and thanks again for the vapor barrier placement.

Ok. Here's an updated floorplan with a slightly bigger control room. I have moved the control room door a litte (doors and window are not to scale but the rest is ) any thought john ? thanks to all.

No splayed wall modal calculators exist that I'm aware of; I know for sure that I'm not gonna be whipping one out anytime in the forseeable future (don't like wearing those funny jackets with the really long sleeves and buckles :? ) (IOW, it's not even vaguely simple to calculate something that complex) Your new plan looks good... Steve

OK here's a more detailed version of my floor plan for the control room. Windows size are subject to change. Getting close....

Here's the hopefully last update of my floor plan Control room and whole studio. I have move the entry door and machine room, wich give me more space and a place to put the WC. With that design i achive perfect symetry in the control room. I am quite happy with it. Now the only things that remains undefined are the windows dimension on both sides of the control room. HVAC and electric plans are on the way , construction will begin as soon as i have moved the dreadfull post where i want it to be. I'd really appreciate some feedback from you guys. Thanks Tons of pictures to come ....

Your CR is gonna have some early reflections off the side walls; right speaker, left wall and vice versa will reflect to the mix position. Not a major deal, just so you know about it. You can build a couple extra portable absorbers, and place one on each side about where the windows are, and only while mixing... Steve

Thanks for pointing that out Steve, i was aware of that but i tought that since sound reflected from the window was comming out of the speaker at 50 degres angle or so, it was not that of a problem, but now that i am writting it.... (':oops:') . i would prefer not to have to use removable absorbing gobos. So how about that : Is this a good idea or a big Nono, of course the other window in the other room would follow the same angle. If that is a not a good option i can still move the window, it is a lot easier on paper indeed.... Also your reply made me realise that the two hi freq absorber on the rear walls were also misplaced by 300mm or so. quote of the day : One day i will actually put a nail somewhere... Thanks

Did you think of these reflexions? Good luck, Dirk

Dirk - the side walls are OK when you set the speaker radiation at 30 degrees (the projection angle of the upper mids and highs.) It's the rear walls in the last drawing that are going to be the problem. cheers john

Hi John ! Sorry if this is obvious, but what exacly would be the problem with the rear walls ? Did you mean the big blue triangle (Bass trap) at the back, wich is parralell to the front wall ? If i get you right about speaker radiation, i do not need to angle the windows on both side like i did in the "crtl-room-window-angle.gif" graph right ? Thanks

John Sayers wrote:

Dirk - the side walls are OK when you set the speaker radiation at 30 degrees (the projection angle of the upper mids and highs.) It's the rear walls in the last drawing that are going to be the problem. cheers john

John, I am not getting it and would like to understand. Could you explain a little? Thanks, Dirk

Hi Dirk It's always nice to have some feedback from other user of this forum, i did know about the reflexion you showed in your graph, the reflexions comming out of the right speaker you draw get absorbed by the yellow pad on the back wall you see on my drawing, the other from the left speaker... well i was just too lazy to update my drawing with absorber in the corner ;-). But thanks for pointing it out. I am a bit puzzled too with John's last post, i am anxious to know what exacly he is refering to.

OK - there are two factors here. The first is the directivity of speakers. The midrange and tweeter speakers in a standard system are directional. In other words they don't radiate in 360 degrees (unlike the woofers) The main power output of these speakers is generally recognised as being around 30 degrees, after that they roll of. look at the angles emanating from the speakers in this plan and you can see what I mean by the 30 degree radiation angles. The second factor is the rear reflections that are going to come off the rear slot resonators in your cr reflexion.gif. If these reflections are under 20 msec from the original the two are going to mix together and confuse the ear. If they are greater than 20msec the ear will separate them and treat them as two individual sources, no confusion. I'm not sure of your exact measurements but it looks to me like these rear reflections will be under 20msec thus causing imaging confusion. BTW sound travels at approx 1ft/msec. cheers john

Hi John I did know about the 30 degres span and frequency diffusion but not about the time relationship of reflected sound vs direct sound, i doubted there was something there, but i didn't have the crucial parameters to calculate it (forgive my innocence). As i see it : The rear wall reflections problem is located between 105 and 98 degres from the speakers. I made the calcuation as my modest contribution to this forum, i hope it is not too confusing (see graph below): (D1)Distance from speaker to mix position at 90 degres =2.121M (D2)Distance from speaker to rear wall at 101 degres from speaker (worse case)=4.345M (D3)Distance from mix position to rear wall reflection at 101 degres from speaker (worse case)=2.169M So the calculation for the distance sound has to travel from speaker to wall to mix position would be D2+D3= (D4)6.514M And since we're calculating time arrival of reflections vs direct sound = D4- D1= (D5)4.393M Speed of sound = 344M in 1sec D5 = 4.393M in ?sec 4.393M / 344M = 0.013sec or 13ms I am well under 20ms.... I am in deep S%*T John !?(':shock:') Let's pretend for now that i can't lenghten my CR. What would be my best option ? 1-Put some angled deflector/diffuser where there would be reflection in the 30 degres span? 2-Put absorbing rear walls patch where there would be reflection in the 30 degres span, and use what's left as slot resonator ? 3-Built a combo resonator/absorber for the rear walls ? (If such thing is possible) 4-Get to the highest bridge and throw myself down ? ;-) Thanks

well - why not run the slots down the side walls around your doors and windows. cheers john

The words of thruth came from man of wisdom... so simple yet so true ! So, i put the slots on each side, and make the rear walls dead, right. Now if i do that, my only concern is... (snare roll please...) you guess it : Space ! Originally I was planning to use what i called the "Inverted wall" technique for the rear walls as you describe it in the graph below from the SAE site. Although it is a compromise as far as soundproofing is concern that technique would still be viable for the side walls me thinks. Anyway that is not much space, i need to go back to the drawing board for this one. Regards

kewl topic guys :) :)

Well it's been a long time since my last post. I have finally settle to go on with my last drawing. Lots of things have been done since then .I have been very very busy lately. I'll post lots of pictures soon. As we speak all the control room walls are up on a U-Boats floated floor. I am now in the process of adding layers on those new walls. Here's how everything is done so far. My floor is made of 2X3 joist floated on U-Boats at evey 12" at the perimeter and 16"o.c. for the inner surface. All cavities filled with Roxul Safe'n sound.And to top it all ,one layer of 5/8plywood so far, more later. My walls are made of 2X4 studs at 24"o.c. filled with 3" Roxul Safe'n sound, as we speak they are covered by one layer of 5/8 gypsum board caulked at their perimeter (using the foambacked rod technique). The walls are resting on Etafoam (thermal isolation product, i did not used that as a decoupler but rather as a sealer) , and screwed to the floor. All walls framing are not touching each other, and gypsum leaves are not touching adjecent walls or ceilling or floor. The walls are held in place using a DIY bracket made of steel and EPDM rubber (photos to come).There is a 3/8 space between the top of the walls and the actual ceiling. Good job so far but now i am facing a new questions that keeps me awake at night :shock:. How in Hell will i make my angled ceilling hold in place ? see fig.A below. The actual ceiling is 8mm(1/2) gypsum board fixed on forens at every 16"o.c. wich is nailed diretcly on the Roof joist. i didn't want to take off the gypsum board because it keeps rodents that gets in the attic from getting in ! ( i am not talking of one or two...). And i do have some concern about adding weight to the existing ceilling. Well i am stuck, i really need some advise here on how to make this ceiling, without compromising what i have already done.

This thread now continues in the construction forum Here : http://www.johnlsayers.com/phpBB2/viewtopic.php?t=6792