John Sayers' Recording Studio Design Forum Archive

Hello community,

Greetings from Sao Paulo, Brazil, I 've been reading the forum for a while but I still have some doubts about my design. I am doing my best and putting a lot of effort at following the forum's rules and keeping this post both informative and concise.

INTRODUCTION
This is my studio's design (picture 1) it is in the planning phase and I need to start building the studio soon. I don't have spare rooms with decent acoustics dimensions and isolation so I will have to expand a room by breaking and building walls, at my design green means to build and pink means to break.

As a rap beat maker and edm producer, I am mostly concerned about the control room since I don't record instruments very often, however, I plan to record vocals and guitar more often, and I would appreciate tips on how to do this right in the control room. My main goal is to have a place with decent acoustics that I can produce rap beats, edm and to mix and master.


ISOLATION
I live in a quiet place and the control room is already mostly isolated since it is surrounded by a bathroom, a wine house, the garage and the basement, therefore, I am not that concerned with acoustic isolation here.


WALLS/FLOOR/CEILING
The existing front and the back walls are masonry 20cm thick cement, the left side wall and half of the right wall are going to be drywall. This drywall is standard, composed by 2 gypsum plates filled with either rock wool or fiberglass layer between them. The floor is vinyl and the ceiling is plasterboard. Should I use rock wool or fiberglass? Is vinyl any good?


VOCAL BOOTH
I am going to turn this triangle shaped corner at the bottom right of the room (picture 2) into a vocal booth by closing the corner with drywall/removable panel. How would you do this? Visual communication between the vocal booth and the control room is important.

One of the vocal booth's walls (bottom right) has holes so I need to seal it. (picture 3) How would you do it?
The dimensions are 2.15m by 2.6m (cathetus of the right triangle). Do you think this vocal booth has a good shape and size?


COLUMN
There is a 17cm x 9cm cement column inside the studio, is that a huge problem? I didn't post pictures because I didn't break the walls yet. If that is a real deal breaker I could build the studio in another part of my house, but I would have to sacrifice I very useful room.


DIMENSIONS
The control room is small but it has a good ratio, within bolt area, the modes are well distributed, and it is far better than my last location.
The CR dimensions are: 4.50m x 3.50m x 2.45m (14.8ft x 11.5ft x 8.1ft)

I could increase the width up to 3.80m, but if I do, the modal distribution worsens a lot, about 2 axial modes overlap, and if I increase to something in between 3.50 and 3.80 it gets even worse. Another reason for not increasing the width is that the column would be further away from the side wall (not sure if that is a problem). Would you go for 3.50 or 3.80?


LISTENING POSITIONING
I will be facing the wall that has a door, this way I would be far away from that column, in my mind that would mitigate the symmetry issues/extra reflections caused by the column. Does that make sense? John said the area around the listening positioning must be symmetrical. Another reason for this position is that I would have a better view of the vocal booth. I am following the 38% guideline as well (actual position: 35.5%).
The drawback is that the right speaker would be very close to the door, but I am fine with that.


TREATMENT
I plan to treat the room with broadband absorption panels at the first reflection points and at most of the back wall, using 5cm air gaps between the panel and the wall, what material and density do you recommend? I am also putting those panels at the column to reduce reflection, is that a good idea?

I am going to use bass traps at the corners of the room, except the front wall corners, since there is a door at the right front corner. I am putting a sofa on the back wall, and maybe a bookshelf. Is this treatment ok? I also plan to use aurelex free room analysis for more input. I know this treatment is too basic but for now, that is what I am planning, I might improve it later though.


ALTERNATIVE DESIGN
If this design is too small for a decent sound and, as said before, if the column is a real deal breaker, I could build the studio in another part of my house, but I would have to sacrifice a useful and more important room, and this might decrease my house's value a little bit, so the stakes are higher.

This alternative design is 4.78m by 3.90m by 2.49m, has 4 cement walls, plasterboard ceiling, tile floor, longer RT60, the modal distribution would be worse but it is a bigger room and most important, it doesn't have a column inside the room. I could add a vocal booth but it would be noisy and there would be way less visual communication between rooms. This design is the last case scenario because I don't want to sacrifice a useful room.

I am looking forward to your input, thanks for your time,
Gustavo

Hi Gustavo, and welcome!

Greetings from Sao Paulo, Brazil,

I love the food in SP! It's been a while since I was there last, but I've eaten some of the best steaks ever in SP. Picanha, con caiprinha.... Mmmmmm!

The floor is vinyl

OK, but what is under that? Being Brazil, I imagine that you have a concrete slab for your sub-floor?

Should I use rock wool or fiberglass?

Where? Either one of those is fine. If you use mineral wool, then look for stuff that has a density of around 50 kg/m3. If you use fiberglass, look for stuff that has a density of around 30 kg/m3.

Is vinyl any good?

Vinyl is fine for your floor, as long as it is laid over something solid, hard, flat, and massive, such as concrete.

I am going to turn this triangle shaped corner at the bottom right of the room (picture 2) into a vocal booth

It's going to be very small! You will need a lot of treatment in there, and it will have to be rather dead, acoustically.

by closing the corner with drywall/removable panel.

I would not use drywall on anything removable. Drywall is brittle, and easily damaged. It is not very strong, and it would not stand up to repeatedly removing/replacing it. I would suggest using a sliding glass door to partition off that booth.

One of the vocal booth's walls (bottom right) has holes so I need to seal it. (picture 3) How would you do it?

Fill them with mortar, then plaster over both sides.

There is a 17cm x 9cm cement column inside the studio, is that a huge problem?

It could be a problem, depending on how big it is, but with suitable treatment the effect can be reduced. It's behind your head, which is good, and you don't need isolation, so it is probably OK.

I could increase the width up to 3.80m, but if I do, the modal distribution worsens a lot, about 2 axial modes overlap, and if I increase to something in between 3.50 and 3.80 it gets even worse. Another reason for not increasing the width is that the column would be further away from the side wall (not sure if that is a problem). Would you go for 3.50 or 3.80?

I'm not seeing the problem you mention. I don't see any axial mode overlaps at 3.8m. Which axials are you referring to? What frequency?

To be honest, I don't see anything wrong with 3.80: It's still a good ratio, and increased area and volume are worthwhile. Your floor area increases from 15m2 to 17m2, and your room volume increases from 38m3 to 41m3, so I wold go with the larger size. Unless I missed something in the modal calculator!

I will be facing the wall that has a door, this way I would be far away from that column, in my mind that would mitigate the symmetry issues/extra reflections caused by the column. Does that make sense?

Another reason for this position is that I would have a better view of the vocal booth. I am following the 38% guideline as well (actual position: 35.5%).

That's fine. No problem. But obviously your drawing is not to scale! The place where you show the desk and "head" seems to be more like 20% in that image...

I plan to treat the room with broadband absorption panels at the first reflection points and at most of the back wall, using 5cm air gaps between the panel and the wall, what material and density do you recommend?

For the firs reflection points, use fiberglass at around 30-40 kg/m3, and make it at least 100mm thick, with an air gap as big as you can afford behind it, if possible. For the rear wall, you want better low frequency response so you0ll need a lighter insulation, around 20-30 kg/m3 for fiberglass, or 40-50 kg/m3 if it is mineral wool. Make that at least 150mm thick, and with an air gap as well, if you can. You will need to cover some or most of that with plastic, to prevent it from sucking out all the highs, and also to help keep the fibers from coming ount into the room.

You will also need a ceiling cloud.

And don't forget that you will need absorption panels on the front wall, directly between the wall and the speakers. The rear corner of the speaker should be just touching the front face of the absorption panel. Make it 100mm thick fiberglass.

I am also putting those panels at the column to reduce reflection, is that a good idea?

Yes. You will need to wrap that column all around with fairly thick absorption, at least from about 50cm above the floor up to about 50cm from the ceiling. You can experiment with the thickness to get it just right: start out with 50mm, listen carefully and test with REW. Then try adding a second layer to make it 100mm, and listen/REW test. The try 150mm, and once again listen/REW test. You might also need to fine tune it with strips of plastic. You need to balance that just right so that the pillar seems to be "not there" acoustically, in the sense that it does not adversely affect the room symmetry.

I am going to use bass traps at the corners of the room, except the front wall corners, since there is a door at the right front corner.

There are twelve corners in a room, not just four...

I am putting a sofa on the back wall, and maybe a bookshelf.

Sofa is good, but not a bookshelf. There won't be enough space for the bookshelf in any case, as the entire rear wall will be covered in thick insulation, with large bass traps in the corner...

Is this treatment ok? I also plan to use aurelex free room analysis for more input.

Don't waste your time.

I know this treatment is too basic

Right! That's why it's not worth using their service. The results only apply to their specific products, and it's a simple "one size fits all" recommendation that they produce. Your room is not a "standard" room, and needs a more detailed solution.


Your basic idea is good, but there's some things you are not considering yet. HVAC, for example: You need ventilation and cooling and dehumidifying: You do live in Sao Paolo!


- Stuart -

I love the food in SP! It's been a while since I was there last, but I've eaten some of the best steaks ever in SP. Picanha, con caiprinha.... Mmmmmm!

The food here is really great! I just realized you are from Chile, I am going to Atacama in July!

Being Brazil, I imagine that you have a concrete slab for your sub-floor?

Exactly

Where? Either one of those is fine.

At that paragraph, I was talking about the insulation inside the drywall.

You will need a lot of treatment in there

Are bass traps and thicker panels necessary at the vocal booth? I would prefer acoustic panels since I can make them. Regarding acoustic panels, it is easier for me to use air gaps than to increase the thickness of the panels since I have some spare shelves attached to the wall that could be used as a hanger for the panels, providing an air gap up to 20 cm.

To be honest, I don't see anything wrong with 3.80: It's still a good ratio, and increased area and volume are worthwhile. Your floor area increases from 15m2 to 17m2, and your room volume increases from 38m3 to 41m3, so I wold go with the larger size. Unless I missed something in the modal calculator!

I've decided to go for 3.80

Fill them with mortar, then plaster over both sides.

I am reluctant to completely fill all of them with mortar because I could use a few of those holes to help with ventilation

HVAC, for example: You need ventilation and cooling and dehumidifying

I am from the state of SP but the city is in the suburbs, which are colder. That room is naturally cool, the sun doesn't reach there and there is good ventilation from the outside at that area of the house. I could leave the door open when I am not using the studio, plus I have one of those "portable air conditioners" (it looks more like a fancy fan), I am going to wait to see if I would really need HVAC.

Gustavo

I love the food in SP! It's been a while since I was there last, but I've eaten some of the best steaks ever in SP. Picanha, con caiprinha.... Mmmmmm!

The food here is really great! I just realized you are from Chile, I am going to San Pedro de Atacama in July! Looking forward to have some ceviche con pisco!

Being Brazil, I imagine that you have a concrete slab for your sub-floor?

Exactly

Where? Either one of those is fine.

At that paragraph, I was talking about the insulation inside the drywall.

It's going to be very small! You will need a lot of treatment in there, and it will have to be rather dead, acoustically.

I thought vocal booths were supposed to be small and sound dead, what would be a regular/ideal area of a vocal booth?
Are bass traps and thicker panels necessary at the vocal booth? I would prefer acoustic panels since I can make them. Regarding acoustic panels, it is easier for me to use air gaps than to increase the thickness of the panels since I have some spare shelves attached to the wall that could be used as a hanger for the panels, providing an air gap up to 20 cm.

To be honest, I don't see anything wrong with 3.80: It's still a good ratio, and increased area and volume are worthwhile. Your floor area increases from 15m2 to 17m2, and your room volume increases from 38m3 to 41m3, so I wold go with the larger size. Unless I missed something in the modal calculator!

I've decided to go for 3.80

Fill them with mortar, then plaster over both sides.

I am reluctant to completely fill all of them with mortar because I could use a few of those holes to help with ventilation

HVAC, for example: You need ventilation and cooling and dehumidifying

I am from the state of SP but the city is in the suburbs, which are colder. That room is naturally cool, the sun doesn't reach there and there is good ventilation from the outside in that area of the house. I could leave the door open when I am not using the studio, plus I have one of those "portable air conditioners" (it looks more like a fancy fan), I am going to wait to see if I would really need HVAC.

Gustavo

I thought vocal booths were supposed to be small and sound dead,

Nope! That's just the way they end up in most home studios, due to lack of space, but a vocal booth should not be small, and should not sound dead. The only reason that small booths sound dead, is because there's no other option! If a room is very small, then the ONLY possible way to treat it in order to make it usable, is to make it dead. That's part of the way the laws of physics work, unfortunately.

what would be a regular/ideal area of a vocal booth?

Maybe 3m x 4m, or something like that. Here's one that I designed a few years back:
That one has variable acoustic panels on two of the walls, so you can adjust the acoustic response of the room.

Are bass traps and thicker panels necessary at the vocal booth?

Very much! If not, the the room will sound "boomy" or "thuddy! or "hollow". The smaller a room is, the more bass trapping it needs to get well balanced acoustic response. That's why really small rooms MUST sound dead.

I am reluctant to completely fill all of them with mortar because I could use a few of those holes to help with ventilation

Then you wont have any isolation! Which means the room would be useless as a vocal booth. Vocal booths need good isolation. If you leave holes in the wall, then the mic will pick up all o the outside noises, and your neighbors will be annoyed by the singing and music coming out through the holes....

I am from the state of SP but the city is in the suburbs, which are colder. That room is naturally cool, the sun doesn't reach there and there is good ventilation from the outside in that area of the house. I could leave the door open when I am not using the studio

Sorry, but that just is not a practical plan at all. In order to get isolation, the room MUST be sealed, totally air tight. If air can get out, then so can sound. If the room is sealed air-tight, then whoever is in there will use up the oxygen very quickly, and fill the room with CO2. The temperature and humidity will go up, and it will be very uncomfortable in there, very fast. You cannot have a well isolated vocal booth with no ventilation.

I am going to wait to see if I would really need HVAC.

Then you are making a big mistake, because by the time that you get to that point, where you can see if you need it, it will be too late to actually install it! At that point, you will have to break down the walls you just built to make space for the silencer boxes and ducts...

- Stuart -