John Sayers' Recording Studio Design Forum Archive

Hi, this is my first post. I've tried a search but please point me to existing threads if I'm asking old old questions!

I'm building a soundproof room-within-a-room inside my house, the builder is experienced in soundproofing for studios but he doesn't know a lot about ventilation systems. Obviously I need to breathe.

The room is about 3.5 x 4.5m. Usually only me in there or one other person. The climate is not hot in the UK so I don't think I need aircon.
I am thinking of basically intake and outlet vents with acoustic baffling as much as possible, a fan on the intake.

I have read that I should get a bigger fan and use it on low power. What kind of fans would people recommend that I can find in the UK?
I've seen Fantech recommended on this forum but it doesn't seem to be very easy to find here.

Is it important whereabouts in the room the vents are located? ie low down, high up?

THANKS!

Hi. Please read the forum rules for posting (click here). You seem to be missing a couple of things!

the builder is experienced in soundproofing for studios but he doesn't know a lot about ventilation systems.

Then he's not very experienced in studios! Sorry. If he really did know a lot about building sound-proofed studios, then he would also know a lot about HVAC, becasue HVAC is a huge part of building studios...

The climate is not hot in the UK so I don't think I need aircon.

Yes you do. If you isolate your studio properly ("isolate" = correct technical term for "soundproof"), then that implies that you will build two very thick, very massive "leaves" around your studio, and both of them will be absolutely air-tight, as well as being surrounded by masses of thermal insulation. Heat will be trapped in there. Humidity will be trapped in there. Ventilation alone cannot deal with that, so you WILL need an air conditioner. That's a basic part of studios, everywhere. Your expert contractor should already know this! A few days ago I spoke to one of my customers who lives in Canada. He wants me to design his new studio after moving out of the place where he previously had his studio. He mentioned that in the old place that he had designed himself, he had had to install a large air conditioner, because it got too hot inside... when the temperature outside was -30 °C! So yes, you do need HVAC.

I am thinking of basically intake and outlet vents with acoustic baffling as much as possible, a fan on the intake.

Correct. Plus at least a mini-split, to control the temperature and humidity.

I have read that I should get a bigger fan and use it on low power. What kind of fans would people recommend that I can find in the UK?

Wrong. You should get the correct size fan for the job. To figure that out, you need to do some math: you need to figure out what the correct flow rate and flow velocity are for your room, based on the normal "rules of thumb", and you also need to figure out the static pressure of your duct system. Then you need to get a variable-speed fan that can produce about 20% more than the needed flow rate when operating into the static pressure created by your duct system.

Is it important whereabouts in the room the vents are located? ie low down, high up?

Yes it is important. The supply register should be located very close to the intake on the mini-split unit, which is usually high up on the rear wall. The exhaust duct needs to be located at the opposite end of the room, and usually where the air is warmest: so high up at the front of the room.


- Stuart -

Thanks for the reply.
I've edited my profile to add the location.
Room is approx 3.5 x 4.5m, I will check the height once I am inside.

I will qualify my comments about the builder: he is very experienced at doing the "building" part of building studios, ie. walls, floors, ceilings and so on.
He is not qualified to do any acoustic treatment and has advised me to ask someone else to sort our ventilation / ac.

It's a home studio in a first floor room, there won't be a drum kit or anything like that, and not even microphones very often, nearly all electronic and electric stuff but I would like to be able to play music at night without disturbing people so I think we are aiming for something like 70-80dB reduction.
First thing will be to strengthen the floor joists to make sure the structure of the house can take the extra weight, then fill the cavity below the floor with soundproofing materials. The room below is quite tall so we will hang a second ceiling below the exisiting ceiling and fill that cavity as well.

Then we'll build decoupled stud walls within the room, including a triple glazed window, ceiling on top of the walls, fill all the gaps with rockwool or similar.
Hang a pair of heavy doors with seals round them.

So I guess we need to include gaps for the aircon and build some kind of baffles to keep the sound from getting out.

Probably I am posting too early, just trying to find out information before I start so I don't have to tear anything out and re-do it.

So the main questions are:
please can you or anyone else recommend HVACs for this size of room and show me a link to help me install it whilst keeping the room isolated?
or recommend a company in South / west UK who are experienced in installing HVAC in this kind of application?
Thanks again.

so I think we are aiming for something like 70-80dB reduction.

It's doubtful that you would need that much. That's a VERY tall order, or a home studio. Even the best professional studios don't usually go to that extreme. A more reasonable goal for a home studio would be around 50 dB. But do some testing with a sound level meter, and also check your local noise regulations, to make sure. If you really do need 70 dB, it IS possible, but youare going to need one hell of a budget to accomplish that.

First thing will be to strengthen the floor joists to make sure the structure of the house can take the extra weight

Right. You will need to hire a structural engineer for that part. He's the only guy who can safely (and legally) design the floor structure.

...then fill the cavity below the floor with soundproofing materials.

Ummm... no, it doesn't work like that. Sorry. That's a common misconception, but there's actually no such thing as "soundproofing materials". There are METHODS and TECHNIQUES that can be used to get good sound ISOLATION, but "soundproofing" is impossible, and no material on it's own could do that, even if it were possible. Instead, you will need to create an isolation SYSTEM, that consists of several individual parts. Those parts do act on their own, individually, to a certain extent, but far more important that that, is how they interact together, as a complete system. Just putting "materials" under your floor will do zero to isolate. Instead your floor needs to be design as an isolation system that includes the floor deck itself, plus whatever is supporting that deck, plus a few other things None of those by itself is any use for isolating, but when put together correctly, they can provide a good amount of isolation.

The room below is quite tall so we will hang a second ceiling below the exisiting ceiling and fill that cavity as well.

... and that would create a "three-leaf system", which will REDUCE your isolation for certain frequency ranges. It will NOT improve isolation. Yes, I know that this is not intuitive at all, but it is the plain truth. Logically, you would think that if having one sound barrier helps a bit, and two sound barriers helps a lot, then three must help even more, but that simply isn't the case. There's lot of things about acoustics that are not intuitive at first glance, but once you understand the principles, it all makes sense.

Here's a diagram that shows the issue. This diagram is for walls, but the same principle applies to floors and ceilings too (as well as doors and windows): There are three parts to the diagram. The one on the left shows a typical situation where there is already one wall that consists of a stud frame with a sheet of drywall on each side, and somebody decide to build another identical wall right next to it, to get more isolation. A typical stud wall will get you about STC-33, and as you can see, adding the second wall increased that to about STC-44, which isn't very much! They DOUBLED the entire wall, and only get an 11 point increase. Not what you'd expect, intuitively.

The second image, in the middle, shows what would happen if, instead of building the second wall with drywall on BOTH sides, it would have been built with drywall on just ONE side. In other words, that system uses only THREE sheets of drywall, or 3 "leaves" in acoustic terminology, yet it gets over 50 dB of isolation! So with FEWERE barriers that wll gets MORE isolation! Definitely not intuitive.

The image on the right of that sequence shows what would happen if, instead of leaving the drywall on both sides of the original wall, they would have removed that drywall and put it over the drywall on the OTHER side of the studs, then built the second wall the same way: with 2 layers of drywall on only ONE side of the studs. So now there are only TWO barriers in that wall, yet the isolation took a steep jump, way up to STC-63! That third option has the exact same materials, and the exact same mass, and the exact same side as the first option, yet it is about one hundred times better at blocking sound. The ONLY difference is that there's just two leaves of mass on the best wall, as compared to 4 leaves on the worst wall, and 3 leaves on the intermediate wall.

Not intuitive at all, but very true. Supported by both acoustic theory, and also numerous real-world tests in acoustic laboratories, plus even more numerous actual studio builds, all over the world.

I could explain the technical reasons why it works like this, if you want. But the important point is that your floor needs to be designed like the third image above, with only two leaves, but you are currently planning to design it like the second image, with three leaves, which is a bad choice.

Then we'll build decoupled stud walls within the room,

Once again, refer to the above diagram: first you need to remove any drywall, plywood, OSB, MDF, or other paneling that might be on the inner face of the existing walls, then "beef up" the outer face of those walls with more mass. Then you can build the new wall, with drywall on only ONE side of the framing.

including a triple glazed window,

Very bad idea! For the same reason as above. Triple glazing gives you LESS isolation than a properly done studio window, which consists of TWO panes of glass (one in each "leaf" of the wall) separated by a large air gap.

ceiling on top of the walls,

Right! but once again, the same principle applies. Your entire ceiling and roof system must be two leaves, only.

fill all the gaps with rockwool or similar.

Right! But do make sure you get the right stuff! You can't just use any old insulation. It has to be the correct density for the job, and that density number is different for each type of insulation. One size does not fit all!

Hang a pair of heavy doors with seals round them.

RIght! One door in each leaf, for the same reasons as above.

So I guess we need to include gaps for the aircon and build some kind of baffles to keep the sound from getting out.

Yes, but it's a little more complicated than that.... HVAC is a very large part of studio design and studio construction. When I'm designing a studio, I often spend as much time on the HVAC system as I do on the entire rest of the studio! It's a big deal...

Probably I am posting too early, just trying to find out information before I start so I don't have to tear anything out and re-do it.

Not at all!!! Quite the opposite, in fact: it is NEVER too early to start posting, and even more important; IT is NEVER to early to start designing your studio, and planning. If you look around the forum, you'll find that the only studios that were built successfully, and worked great, are the ones that were based on extensive, careful, detailed design, spanning months. Those builders that didn't bother too much with design, or tried to cut corners, are the ones that ended up with flops, or never even finished their studios...

please can you or anyone else recommend HVACs for this size of room and show me a link to help me install it whilst keeping the room isolated?

You'll have to start working through the math for that! It's not a complicated process, but you'll have to do some learning first, then some calculating, then some designing. Basically, each room in your studio needs one fresh-air supply duct, and one stale-air exhaust duct. Both of those ducts must be dimensioned such that the air is flowing at the correct velocity, AND ALSO the correct rate at the point where it goes though the registers. If it is moving too fast (velocity too high) then the air flow itself will be noisy, and also annoying: you don't want a constant wind blowing on your head! And if the RATE is too low (not the velocity: the velocity can band should be very low, but the rate has to be correct), then you won't be getting enough fresh air into the room. So you start by calculating the total volume of air in the room, then figuring the correct rate by considering that you have to replace that entire volume at least six times per hour, preferably 8 times per hour, while keeping the velocity at the register to less than 300 FPM. Based on that you can dimensions our registers, your ducts, and your silencer boxes. You also need to know how much isolation you need so that you can figure out how to design the silencer boxes: more isolation requires more baffles and thicker wood, plus a longer box. You need one silencer box at each point where a duct goes through a leaf. Once you have all that, then you figure out the total static pressure that your system will create, then you search around for an HVAC fan that can produce the correct air flow volume at the correct velocity when facing that static pressure level.

That's just the ventilation side of things: you also need to dimension the actual air conditioner unit (usually a "mini-split" system in most home studios). You have to determine the sensible heat load and the latent heat load that your studio will produce, for both extremes: with many people in there playing hard on a hot summers day with high humidity outside, and also for just one person in there late at nigh in mid-winter with low humidity. So you do the math to see what BTU/Hr rating you need for those extremes, then look around for mini-split systems that have the right capacity, and can also produce the right flow rate/velocity for the re-circulated air.

That's a rough outline of the process. It's more complicated, actually, but that's the basic idea.


- Stuart -

Thanks for the detailed information.
I think I might spend some money on getting someone to design this for me rather than trusting the builder.
But I think it's likely he haas a firmer grip on this and it's just my understanding of it that's poor so I will have a good session with him and get him to show me plans & detailed descriptions.
The studios I worked in before that he had built were pretty good.

The studios I worked in before that he had built were pretty good.

Did he DESIGN them? Or just BUILD them? There's a difference. Studio design is a rather specialized discipline, somewhat beyond what a typical contractor would be able to do. There are some companies that design studios, then also build them, but they are DESIGNERS, not builders. Their primary services is the design, but then they want to build it for you too, to make sure it is done right, the way the designed it. On the other hand, a contractor's primary business is building things, not designing them. He might be a great builder, but if that's his specialty, that's what he should stick to. If his primary business is "building contractor" but he also does a bit of studio work on the side, I'd be concerned. However, if his primary business is "studio design" and he also does some building contracting on the side specifically for the studios he designs, then you are probably OK.

I hope you make the right choice, because to be very honest, getting the design right is rather important! Pretty much any good contractor who is willing to learn and follow instructions can build a studio, but the reverse is not true: "pretty much any contractor" cannot successfully design a studio, even if he has built studios before. Studio design is all about acoustics, sound waves, frequencies, wavelengths, decay times, absorption coefficients, angles, first refl

Here's a quick check: when you meet with the contractor, ask him 2 things "What the MSM resonant frequency of your wall design?", and "What the ITDG goal for the diffuse field?". If he stares at you blankly, blinking like a deer caught in car headlights, then you have the wrong guy to design it! (although he might be fine to build it). But if he can tell you those two numbers right off the bat, without even checking his notes (or Google...), then you are perfectly fine, and you probably have the right guy for designing your place.

I will have a good session with him and get him to show me plans & detailed descriptions

The plans and details might LOOK fine on paper, but it's the type of question (see above) that will reveal if he really knows what he is doing or not. He might show you beautifully detailed plans, with every stud and joist perfectly clear, but if he doesn't know what MSM frequency he designed it for, then he has no business designing studio isolation walls. If he doesn't know what the ITDG times or levels will be at the mix position, then he has no business designing the acoustics of the room.

Those are basic parameters of any studio design

Here's a couple of others for him:
"What height will the acoustic axis be at?"
"What room ratio did you use?"
"What is the basic room design concept?"

Sorry to sound so skeptical, but since I design studios for a living, I have a pretty good handle on how complex it is! Several times I have been hired by customers to re-design rooms that had already been designed by others, but the owner realized the design was not going to work. So I've seen this before, and I'm just waving some red flags for you, to put you on the alert!

- Stuart -

Thanks for the warnings.
No no he's a builder not a designer.
I'm neither claiming nor hoping that he knows a lot about designing. He is extremely familiar with the construction techniques involved.

That's why I am here looking for help, as well as contacting a few studio design consultancies for their input with a view to paying them to design it.
Right now, as far as "design" goes I just mean designing it to be an isolated / soundproof room. I am confident the room dimensions are OK so acoustic treatment / speaker / listening positions etc can come afterwards.

I am confident the room dimensions are OK so acoustic treatment / speaker / listening positions etc can come afterwards.

Sorry if I seem to be harping on the same point over and over, but no, they cannot. The ENTIRE design needs to be done now. You say: "The room is about 3.5 x 4.5m", which is about 15.7m2. The minimum recommended size for a control room is 20m2, so you are at only 78% of where you should be for decent acoustics. The Schroeder frequency for that room will be 138 Hz, which is rather high. That implies serious modal issues below that frequency, and moderate modal issues for an octave either side. That implies major treatment, which will need to be designed in to the room itself. For example, doors, windows and HVAC registers will need to be positioned at locations where they do not interfere with the treatment. If you just build the room now and hope to treat it later, you'll be in for an unpleasant surprise!

And the above assumes that you are talking about the final interior dimensions of 4.5 x 3.5: but that's not the case: it will actually be considerably smaller than that, since the isolation system will take up space. My rough guess would be final inner-leaf dimensions of around 4.1 x 3.1, which is only 12.4 m2, or 62% of minimum size. Treating such a tiny room is a big deal.

I'd suggest you should google the document "ITU BS.1116-3", download it, and take a close look at chapters 7 and 8: That defines the acoustic specifications for critical listening rooms, such as control rooms. Meeting those specs is not easy, even for a large room (more than twice hte size of yours), but for small rooms it gets increasingly harder. The smaller it is, the harder it is. It CAN be done: I recently completed the design for a customer in New Jersey for a room that is just 16m2, and it worked out quite well. But it was a major challenge to do that, and there's a HUGE amount of treatment in there.

speaker / listening positions etc can come afterwards

Once again, no they can't. Those are pretty much set in stone by the overall room dimensions, and the overall design concept. For example, if you choose the RFZ concept, then the locations of the speakers and listening position are cast in stone already, and you cannot move them if you screwed up with the isolation plan. So if you put a door in the wrong place, you'd have to rip it out and move it to the right place. Ditto with your HVAC silencers: if you messed up and put one where your rear-wall bass trapping needs to go, or where your soffits need to be, or where some other piece of important treatment needs to be, then you are screwed: You'll have to rip down the room to get access to the HVAC silencers (which are outside the room, not inside it), and move them to a location that does no interfere with the treatment.

In other words, what I'm trying to say is that all aspects of the room need to be designed at once: the entire room is an integral system. All parts of it work together. Optimizing that is what a designer does. If you have a designer telling you that you don't need to consider the layout and treatment of the room at the same time as the isolation and HVAC, then that's a problem. Your room will NOT be optimized. It's a very small room, so it MUST be optimized, if you want it to be a successful mixing environment.

That's why I am here looking for help, as well as contacting a few studio design consultancies for their input with a view to paying them to design it.

I'd suggest that you contact John Sayers himself, if you want to hire a great studio designer. He's one of the best in the business (which is why you are here, I'm sure! ). If John is too busy or unable to do your project for you, then PM me and I'll give you a list of designers that we trust. WARNING! Since you posted here publicly that you are looking for a designer, you will VERY likely be contacted by some of the unscrupulous predator wannabes that hover around the forum, for this exact purpose: They approach unsuspecting members, such as yourself, with wonderful offers of design services, ultra-cheap, ultra-fast, with amazing promises of spectacular results.... BEWARE! I'm aware of a few cases like that, and then I've been hired later by some of those customers that got scammed to "fix" the design, which usually means re-doing it completely. So "Caveat Emptor", as the saying goes: forewarned is forearmed. We ONLY recommend designers we trust, and those guys will NOT contact you, unsolicited. If you want to talk to them, then PM and I'll put you in touch with them. If you get an unsolicited offer here on the forum, ignore it, and please report it to me, so I can deal with it.

So contact John first, and if that doesn't work out, PM me. But whatever you do, don't allow yourself to be mislead into thinning that you can just do the isolation now then design the acoustics later. I mean, you CAN do that if you want, as long as you are happy with a mediocre studio. But it's far better to design everything together, with each part optimized to perform at maximum capability, and in harmony with all other parts. Isolation, layout, geometry, treatment, HVAC, electrical, lighting, etc. All parts at once: that's the only sensible, intelligent way to design a studio.


- Stuart -

Thanks for the advice once again.

Hi Nuromantix,

Welcome to the forum. Greetings from Lincolnshire! I just wanted to say that I too came to the forum thinking that the design I had for the my studio would be fine, but after reading 2 books and discussing the design here I drastically redesigned.
You can see my design thread's current progress here:
http://www.johnlsayers.com/phpBB2/viewt ... =1&t=21057

First of all. Don't build anything without designing your ventilation. I repeat, don't build anything without designing your ventilation. This will come and bite you the second you look at it. You will need silencer boxes in your build the size of which will boggle your mind, they will take 2 or 3 men to fit in place... And you need 4 of them. You won't have space for them, and you will stare blankly at your sketchup design for hours into the night slowly hating them a little more as each minute passes by, until finally... You will have squeezed them into a ceiling void or speaker baffle, or dropped soffit, or all three and with a sigh of relief realise... Your studio can now be... Suitable for humans.

Sorry if that seems crazy, but I'm serious, look at the pictures on my build thread for some ideas:
http://www.johnlsayers.com/phpBB2/viewt ... 10&t=21269

I calculate my requirements with Stuart's help on my design thread, if you need help working yours out look there.
I used: http://www.ductstore.co.uk for my ventilation materials.

I hope you will keep getting advice here and not discount this place as "snobby" or "over the top", because it really isn't. The people here want you to meet your needs. If you really know what they are, we will all help you and tell you what is achievable.

Thanks,
Dan

Well put Dan!!

Greg

- Stuart -

Thanks again, I'll check all the links.

Dan, thanks for the really useful links.
I think I am looking for a middle path where I don't do any building myself but don't buy the whole thing for a zillion pounds from a studio company.
My brother is a contractor used to project managing buildings and I have a sympathetic builder with a lot of studio experience and a contact who builds and installs ventilation baffles so I guess I will get a studio designer to help plan everything out with them and see if I can keep it under 25000!

nuromantix wrote:Dan, thanks for the really useful links.
I think I am looking for a middle path where I don't do any building myself but don't buy the whole thing for a zillion pounds from a studio company.
My brother is a contractor used to project managing buildings and I have a sympathetic builder with a lot of studio experience and a contact who builds and installs ventilation baffles so I guess I will get a studio designer to help plan everything out with them and see if I can keep it under 25000!

That sounds reasonable. Designs can be expensive though so don't be too shocked, a lot of work goes into them. If you're looking for a studio design private message Stuart and he'll get you in touch with John or another credible designer based on your budget. I wouldn't go with a studio designer based on them being local though. The design requires no site visit usually and can be arranged entirely over the internet. So pick the best designer you can afford and speak to them on the phone/skype.