John Sayers' Recording Studio Design Forum Archive

Hey there, I´ve been reading here for a long time and (I hope) I learned a lot. Thank you all for being here! After my last studio build project couldn´t happen, I have a new oppurtunity now:

My rooms (both 4,85m x 3,42m x 2,45m) are situated on the second floor of an office building. I will be recording voiceover and podcasts/audiobook lectures. This is the main purpose and I want to base the needed isolation only on that. Being able to record music will be an additional benefit, but there is no need for recording drums or bass amps. So it´s mainly about keeping the noise outside of the booth. The building is already pretty quiet, but I want to be safe to record undisturbed. Most noises I hear are coming from the hallway which is a bit busy with walking and chatting people and from time to time I can hear some rumbling on other floors. An additional 20db of isolation at 100hz should be enough. My idea is to build a wooden stud structure and put insulation between the studs. There will be no direct connection to the existing floor or walls by using neopren pads or something similar underneath the studs. Then I put 12mm gypsum board (15kg/sqm) on the studs inside of the booth. This would happen at the existing walls a (giving up door c), b (giving up/taking out door b) and c and at the ceiling (with insulation between the existing and the new ceiling). I think of a 10cm distance between the existing walls and the gypsum board. The fourth wall (facing the windows) would be a simple 2 leaf drywall. I could add more gypsum board later to gain more isolation if needed.

1. What do you think about this layout?

2. About the flooring: I think about putting a simple OSB flooring on neopren/MLV/rubber to decouple it against impact noise from footsteps on the hallway. Should the whole booth be standing on the new floor to use its mass or could I put in the floor later? I´m allowed to add 150kg/sqm. For door d, I think about a simple balcony door. Again - I don´t need that much isolation. In case of too much leakage into the control room, I could install another door inside the frame of the existing door (b), opening into the control room.

Thank you in advance for your input!

Silvan

Welcome KreuzZwerg,

KreuzZwerg wrote: An additional 20db of isolation at 100hz should be enough

.

Do you know your current isolation levels? The reason being, it's a lot easier to get from 30dB to 50dB then it is from 45dB to 65dB. Get yourself a good SPL meter (unless you already have one) and measure the levels in the room at the loudest times of the day.

KreuzZwerg wrote:My idea is to build a wooden stud structure and put insulation between the studs. There will be no direct connection to the existing floor or walls by using neopren pads or something similar underneath the studs. Then I put 12mm gypsum board (15kg/sqm) on the studs inside of the booth. This would happen at the existing walls a (giving up door c), b (giving up/taking out door b) and c and at the ceiling (with insulation between the existing and the new ceiling). I think of a 10cm distance between the existing walls and the gypsum board. The fourth wall (facing the windows) would be a simple 2 leaf drywall. I could add more gypsum board later to gain more isolation if needed.

Have you run the numbers on this to see if it will be enough/overkill? You may not need to float the walls, depending on the construction of the floor. Is it a concrete floor?

KreuzZwerg wrote:About the flooring: I think about putting a simple OSB flooring on neopren/MLV/rubber to decouple it against impact noise from footsteps on the hallway. Should the whole booth be standing on the new floor to use its mass or could I put in the floor later? I´m allowed to add 150kg/sqm. For door d, I think about a simple balcony door. Again - I don´t need that much isolation. In case of too much leakage into the control room, I could install another door inside the frame of the existing door (b), opening into the control room.

If the whole room was floating on the fllor you would need a lot "beefier" of a floor. usually a floated concrete floor would be great for floating the studio. If you were going with timber, you would need strong floor joists, sole/header plates, and ceiling joists, tying the room together as a cube, greatly increasing the structural integrity. You couldn't float the studio on insulation though, it would be too heavy. You would need to go with commercial springs/rubber isolation mounts.

The floor alone may be OK to "float" on insulation, but you really need the current isolation levels and construction details.

When it comes to doors and windows, the aim is to achieve similar isolation to your walls/floors/ceilings. If they are weak then the entire studio has weak isolation. You will need to run the numbers on your proposed doors/windows to see if they achieve the levels you need.

Other points:
Your control room doesn't need any isolation at all above your current levels? You haven't added anything in your drawing.
What about your HVAC? How will you breathe in your air tight room, or extract the humid air created by people's voices/perspiration and equipment, or moderate the temperature? There is no passive ventilation in an airtight room.

Dan

Thank you very much for your time Dan, it´s really appreciated!

Waka wrote:Welcome KreuzZwerg,

KreuzZwerg wrote: An additional 20db of isolation at 100hz should be enough

.

Do you know your current isolation levels? The reason being, it's a lot easier to get from 30dB to 50dB then it is from 45dB to 65dB. Get yourself a good SPL meter (unless you already have one) and measure the levels in the room at the loudest times of the day.

That is so true, sorry. I was measuring about 35 db(a) for the city noise with closed windows. I will have to measure how loud this chatter on the hallway is, but I don´t worry that much about it. I think I can convince my neighbours not to shout in front of my studio during recording sessions. I´m more afraid of their impact noise when walking.

KreuzZwerg wrote:My idea is to build a wooden stud structure and put insulation between the studs. There will be no direct connection to the existing floor or walls by using neopren pads or something similar underneath the studs. Then I put 12mm gypsum board (15kg/sqm) on the studs inside of the booth. This would happen at the existing walls a (giving up door c), b (giving up/taking out door b) and c and at the ceiling (with insulation between the existing and the new ceiling). I think of a 10cm distance between the existing walls and the gypsum board. The fourth wall (facing the windows) would be a simple 2 leaf drywall. I could add more gypsum board later to gain more isolation if needed.

Waka wrote:Have you run the numbers on this to see if it will be enough/overkill? You may not need to float the walls, depending on the construction of the floor. Is it a concrete floor?

I downsized my plan to 10mm drywall (11,5kg/sqm), still calculating with 10cm insulation and an additional 3cm airgap (due to not-to-remove skirting board which I didn´t mention before). I can´t imagine that won´t be enough for airborne noise, but it´s also the cheapest I can build. If it´s not enough, I could add another layer of drywall, maybe also using green glue. The floor is 10mm OSB on top of an old carpet. I am not sure about the material underneath, but it doesn´t seem to be very heavy. But I only assume that on how the footsteps sound. I´ll try to get the information.

KreuzZwerg wrote:About the flooring: I think about putting a simple OSB flooring on neopren/MLV/rubber to decouple it against impact noise from footsteps on the hallway. Should the whole booth be standing on the new floor to use its mass or could I put in the floor later? I´m allowed to add 150kg/sqm. For door d, I think about a simple balcony door. Again - I don´t need that much isolation. In case of too much leakage into the control room, I could install another door inside the frame of the existing door (b), opening into the control room.

Waka wrote:If the whole room was floating on the fllor you would need a lot "beefier" of a floor. usually a floated concrete floor would be great for floating the studio. If you were going with timber, you would need strong floor joists, sole/header plates, and ceiling joists, tying the room together as a cube, greatly increasing the structural integrity. You couldn't float the studio on insulation though, it would be too heavy. You would need to go with commercial springs/rubber isolation mounts.

The floor alone may be OK to "float" on insulation, but you really need the current isolation levels and construction details.

I´ll try to get them. But I guess I will go with only „floating“ the floor as good as possible. Am I wrong in assuming that the impact noise will already be less as soon as the floor carries the weight of the booth? Maybe they will allow me to lay a neopren mat on the hallway next to the booth when I record. Everything seems easier than floating the whole thing.

Waka wrote:When it comes to doors and windows, the aim is to achieve similar isolation to your walls/floors/ceilings. If they are weak then the entire studio has weak isolation. You will need to run the numbers on your proposed doors/windows to see if they achieve the levels you need.

I assume a triple-glass balcony door will do the job even better than a 10mm/10cm/10mm drywall. Or let´s say good enough for my purposes regarding airborne noise.

Waka wrote:Other points:
Your control room doesn't need any isolation at all above your current levels? You haven't added anything in your drawing.
What about your HVAC? How will you breathe in your air tight room, or extract the humid air created by people's voices/perspiration and equipment, or moderate the temperature? There is no passive ventilation in an airtight room.

Dan

I didn´t put any effort in the control room in this layout, it´s only for dimension. I´ve treated several control rooms and feel much more confident than about setting up a recording booth. For HVAC, I´ve found something on Youtube that looks promising.
https://www.youtube.com/watch?v=WrAMJpl ... e=youtu.be
(around 22:20)

I´ll add a new layout, including my idea of the ceiling. I can´t hang the booth ceiling from the existing ceiling, so it thought to put beams on the walls and then screw the drywall underneath it. The studs are 45*100mm, I think they can carry the weight.

Thank you again for thoughts on this

That ventilation system will not provide much insertion loss. There is no impedance mismatch or insulation in it. It just has a ton of flex duct making a lot of 180 degree bends which is only really going to increase your static pressure. So yeah, don't do it that way. There are many examples on the forum showing how to properly build HVAC silencer boxes and how to calculate your heat loss and static pressure

Greg

Gregwor wrote:That ventilation system will not provide much insertion loss. There is no impedance mismatch or insulation in it. It just has a ton of flex duct making a lot of 180 degree bends which is only really going to increase your static pressure. So yeah, don't do it that way. There are many examples on the forum showing how to properly build HVAC silencer boxes and how to calculate your heat loss and static pressure

Greg

Thank you for your reply, Gregwor!
Of course, we cannot know what the band means when they say their ventilation systems works fine, even with a whole band in the room. I just assumed that it´ll be enough for one person in my room then. I´ve watched a video where the fan they use (ECO dMEV) handles a very long flex duct with a lot of bends very well. I´ve tried to find something on this forum which could be suitable for my room, but haven´t really found something. Most solutions seem over the top to me. I´d rather have more breaks during a seesion and open the door every other hour than spending a ton of energy (and money?) in HVAC. So I thought this could be a way to go. But of course I´m grateful for better ideas! Is there a software tool/excel sheet to calculate heat loss and static pressure?

But of course I´m grateful for better ideas! Is there a software tool/excel sheet to calculate heat loss and static pressure?

Here is a static pressure calculator I built:

http://www.johnlsayers.com/phpBB2/viewt ... =1&t=21752

As for heat loss calculation, there are some basic rules you could find with a google search or using the search on this forum, I'm know there are a lot of threads that cover this.

Greg

Thank you, I'll have a look soon.

KreuzZwerg wrote:I´ve tried to find something on this forum which could be suitable for my room, but haven´t really found something. Most solutions seem over the top to me. I´d rather have more breaks during a seesion and open the door every other hour than spending a ton of energy (and money?) in HVAC.

What other methods are you planning on using for heating/cooling/dehumidifying? The silencer boxes are not only used for HVAC. They are used whenever you need a whole in the isolated assembly. That includes for basic passive ventilation or extractor fans. They are used to prevent you trashing your isolation by just cutting a giant whole in the wall. They also prevent the sound of air handlers/extractor fans entering the room and raising the noise floor.

Opening the door every few hours won't really help with cooling/heating a room. What will pull the air in and circulate it? You might hold it open for a minute or so and then close it. So your stale air hasn't moved. You need continuous ventilation. In a normal house this happens by people leaving doors open when it's stuffy. People don't just open a door and close it a minute later and get immediate relief.

The cheapest ventilation design you can get would be an extractor fan and 2 big silencer boxes. But this may not provide the isolation you require, that's why we always recommend 4 silencer boxes (2 per leaf. 2 for inlet, 2 for extract.) That way they're decoupled and the mass of the wall/ceiling is retained.

If you are installing a mini-split AC system to heat/cool/dehumidify the room, then you can just use an extractor fan on the outside of your studio and run it through 2 silencer boxes, and a corresponding passive inlet cut into the other end of the studio with 2 silencer boxes. The silencer boxes may cost about £/$/EUR 100 each, but they are the only way to maintain high isolation and actually have a comfortable studio. It may be a requirement by building regulations in your area even, as you are preventing all forms of passive ventilation. What if there was a problem with your door and it got jammed/stuck? You have no oxygen whilst waiting for a repair, you would have to break down your (very expensive) doors.

Dan

Waka wrote:

KreuzZwerg wrote:I´ve tried to find something on this forum which could be suitable for my room, but haven´t really found something. Most solutions seem over the top to me. I´d rather have more breaks during a seesion and open the door every other hour than spending a ton of energy (and money?) in HVAC.

What other methods are you planning on using for heating/cooling/dehumidifying? The silencer boxes are not only used for HVAC. They are used whenever you need a whole in the isolated assembly. That includes for basic passive ventilation or extractor fans. They are used to prevent you trashing your isolation by just cutting a giant whole in the wall. They also prevent the sound of air handlers/extractor fans entering the room and raising the noise floor.

Opening the door every few hours won't really help with cooling/heating a room. What will pull the air in and circulate it? You might hold it open for a minute or so and then close it. So your stale air hasn't moved. You need continuous ventilation. In a normal house this happens by people leaving doors open when it's stuffy. People don't just open a door and close it a minute later and get immediate relief.

The cheapest ventilation design you can get would be an extractor fan and 2 big silencer boxes. But this may not provide the isolation you require, that's why we always recommend 4 silencer boxes (2 per leaf. 2 for inlet, 2 for extract.) That way they're decoupled and the mass of the wall/ceiling is retained.

If you are installing a mini-split AC system to heat/cool/dehumidify the room, then you can just use an extractor fan on the outside of your studio and run it through 2 silencer boxes, and a corresponding passive inlet cut into the other end of the studio with 2 silencer boxes. The silencer boxes may cost about £/$/EUR 100 each, but they are the only way to maintain high isolation and actually have a comfortable studio. It may be a requirement by building regulations in your area even, as you are preventing all forms of passive ventilation. What if there was a problem with your door and it got jammed/stuck? You have no oxygen whilst waiting for a repair, you would have to break down your (very expensive) doors.

Dan

Thank you for your input Dan, really appreciated! I guess I'll go with the cheapest design you suggested, silencer boxes, one active fan, one passive outlet. I am pretty sure that will do the job. I can upgrade the ventilation system later if needed. The good thing about my place is that I can open windows and doors in both directions (draft?). So I can get a complete change of the air pretty quickly in every pause we make. At this point I don't worry about heating or active cooling.
I'll attach some pics of the progress.
Right now I am thinking about the rear wall in the control room. In front of the wall is a wooden structure that holds a second door, filled with 18cm of insulation. So it's a giant bass trap. I'd like to add some diffusion from the rear wall. Since I don't want to put more weight to the door hinge, I think of pyramid foam on the door. But the space to the sides can be treated properly. The total width of the wall is 3,4m, the listening position is 3m away.

I am considering two concepts, 1d diffusors or a scatter plate as a bass trap layover. As far as I could read, both are possible. A scatter plate would use less space and be easier to build (I am lucky to know skilled people with good tools). A 1d Diffusor should do a better job diffusing, but I have no idea how big the difference would be.
I'll also attach today's rew measurements. This is with additional bass Traps in the corners behind the window and broadband absorbtion an the early reflection sides. The ceiling (2,45m) is not treated yet, but there will be an absorber cloud.

Are there any pros or cons I'm missing considering scatter plate overlay VS 1d Diffusor?

Thank you all in advance.