John Sayers' Recording Studio Design Forum Archive

Hello All.

I'm building a small production/mix room at the end of my garden in Wimborne, Dorset in the UK. I don't have much space but am lucky to have a blank slate to work with, so can build whatever I want within my budget which I am hoping to keep to below £15,000.

My studio will be used for:
• Music production and mix-downs, predominantly of Drum’n’Bass, Jungle, Dub, Reggae, Glitch-Hop, Techno and House.
• Recording and rehearsal of dj sets, streaming dj mix radio shows with occasional vocal announcements and idents.
• Occasional vocal recording, amplifier / cabinet recording, using microphone reflection filters
• 95% of the time it will be used by myself solo, occasionally with 1-3 collaborators working with me.
• 3 days a week I will be using the studio as a home office.
• A long cupboard will run down one side of the building. This will be used for household storage.

The basic floor plan of the ICF structure is attached below. This just shows the interior and exterior structure dimensions not the interior wall dimensions. Interior room shape and finish is being worked out and designed by a friend who has built several studios. All my drawings show a rectangular room, which will not be the case for the finished studio, which will probably have an interior wall layout that follows Mr.Sayers recommendations as shown in 'basic studio shape'. All furniture will be on wheels so the dj setup can be easily manoeuvred into the sweet spot.

Drawings also show a concrete block structure, but the design has since changed. I'm planning to build the external structure from ICF. I figure this will give me a helpful amount of mass and also give me good thermal insulation. The ICF section dimensions will be 5cm interior expanded polystyrene / 15cm core / 10cm exterior expanded polystyrene (image attached). I'm planning on a decoupled slab so the interior floor slab is decoupled from the slab under the icf walls. The construction will be airtight and I will fit an MVHR unit with acoustic baffles.

I'm just wondering if anyone has used ICF to build a studio and if it is a suitable choice over say, Brieze blocks, possibly filled with sand?

I've been looking at studio build photos on this forum and see that new build studios tend to go for concrete block construction. I'm wondering if this is because concrete blocks will provide better sound isolation than ICF? Or if it is because ICF is lesser known? I would be really keen to hear from anyone who built their studio from ICF, to know how it performs and to see construction details.

Please take pity on me for my poor drawing skills I have squeezed these in alongside raising a 7 month old baby who has only just figured out how to fall asleep on her own I am just a hippy festival dj who has somehow managed to buy a house with enough space at the end of the garden to build a bass cave!

Thanks very much!

Hi there " Hagopm", and Welcome!

• A long cupboard will run down one side of the building. This will be used for household storage.

That's the room on the left, with the external door? No problem, but you also show shelving in the walls INSIDE the room! If you want to produce decent mixes in your room, then it must be symmetrical: the left side must be the mirror image of the right side. If not, then you ears hear different things, and you subconsciously try to "compensate" in the mix. Also, the area between the mix position and the speakers will undoubtedly require acoustic treatment. So there will be no place to have shelves, cupboards, or things like that on the side walls.

Interior room shape and finish is being worked out and designed by a friend who has built several studios.

Your friend has just built several studios, or he has he also designed several studios? It's not the same thing, and there are many details in the layout that suggest he does not have experience in acoustic design. For example, he has the speakers aimed across the short axis of the room, instead of down the long axis, and he should have warned you about the problem with symmetry and shelves. Your model also shows the sub in the middle of the front wall, but that's a bad position. It should be offset to the left or right. There's also no bass trapping, and the door is in one corner. Lots of mistakes that an experienced studio designer would not make.

All my drawings show a rectangular room, which will not be the case for the finished studio,

Why? What's wrong with a rectangular room? And if it is not rectangular, what shape would it be? Square?

All furniture will be on wheels so the dj setup can be easily manoeuvred into the sweet spot.

And how will you deal with the cables? There will be a bunch of cables connecting the mix position to the rest of the world.... what will you do with those when you "wheel the desk" out of the way?

I figure this will give me a helpful amount of mass and also give me good thermal insulation.

Have you done the math to ensure that you will have the right amount of isolation at the right frequencies? "Figuring" things is not the same as "figuring out with math"...

The ICF section dimensions will be 5cm interior expanded polystyrene / 15cm core / 10cm exterior expanded polystyrene (image attached).

You say it has a lot of mass, but how much? What is the surface density of that? What about the acoustic characteristics?

I'm planning on a decoupled slab so the interior floor slab is decoupled from the slab under the icf walls.

Is that necessary? You don't seem to need a lot of isolation... Don't get me wrong! It's GREAT to do that, and it can help, yes, especially for studios that need very high levels of isolation.... but it's also extra work and extra expense, so considering your very, very tight budget, you might want to look for ways of saving money.

I will fit an MVHR unit with acoustic baffles.

OK, but that's just HRV: what will you use for the actual temperature and humidity control? Some type of mini-split system, I imagine? Also, which make and model of MVHR unit includes acoustic baffles? What type of insertion loss do you get from that unit, and is that enough to match the isolation of your walls, floor, ceiling, windows and doors?

I'm wondering if this is because concrete blocks will provide better sound isolation than ICF?

Yes. Isolation depends on only four main physical properties: Mass, stiffness, decoupling, and cavity damping.. Of those, concrete has much higher mass and stiffness than ICF, and the decoupling and damping will be the same in both cases, from your wall design. ICF might be better in the region below MSM resonance, but if you design your wall right, that will be outside of the audible spectrum in any case, so it's not an issue.

Please take pity on me for my poor drawing skill

I'd suggest keeping your camera field-of-view angle to something ore realistic. Right now, you have it way too high. Something in the range 35° to 45° gives a reasonably realistic view, similar to what you'd actually see with your own eyes (unless you happen to be a fish.... )


- Stuart -

Soundman2020 wrote:Hi there " Hagopm", and Welcome!

• A long cupboard will run down one side of the building. This will be used for household storage.

That's the room on the left, with the external door? No problem, but you also show shelving in the walls INSIDE the room! If you want to produce decent mixes in your room, then it must be symmetrical: the left side must be the mirror image of the right side. If not, then you ears hear different things, and you subconsciously try to "compensate" in the mix. Also, the area between the mix position and the speakers will undoubtedly require acoustic treatment. So there will be no place to have shelves, cupboards, or things like that on the side walls.

Totally agree. I think I will revise the interior layout so that there is a sofa behind the desk and I will put shelves / cable racks above the sofa. These should help diffuse the sound as well.

Interior room shape and finish is being worked out and designed by a friend who has built several studios.

Your friend has just built several studios, or he has he also designed several studios? It's not the same thing, and there are many details in the layout that suggest he does not have experience in acoustic design. For example, he has the speakers aimed across the short axis of the room, instead of down the long axis, and he should have warned you about the problem with symmetry and shelves. Your model also shows the sub in the middle of the front wall, but that's a bad position. It should be offset to the left or right. There's also no bass trapping, and the door is in one corner. Lots of mistakes that an experienced studio designer would not make.

My friend has designed and built two studios. His father is a sound engineer who has designed several studios and he will be working out the interior wall sizes and orientations. Neither of these chaps have had any input on the layout drawings I uploaded. These are drawings I made to help me work out what I want in the room and where. The speakers are pointing down the short axis because I want to be able to look to my right and look out the window of the studio to my garden. Having a view on the outside world is important to me and I am willing to compromise on the sound quality of the room to have this. I do intend to have bass traps. Thanks for the suggestion on sub location.

All my drawings show a rectangular room, which will not be the case for the finished studio,

Why? What's wrong with a rectangular room? And if it is not rectangular, what shape would it be? Square?

By this I mean that the drawings show parallel walls & parallel ceiling and floor. The interior walls of the finished studio will not be parallel. I just don't yet know the angles so haven't drawn them in.

All furniture will be on wheels so the dj setup can be easily manoeuvred into the sweet spot.

And how will you deal with the cables? There will be a bunch of cables connecting the mix position to the rest of the world.... what will you do with those when you "wheel the desk" out of the way?

I do almost all my production and mixing in the box so there will be very little gear with cables running off the desks I don't own much hardware, and what I do own will plug straight into the protools interface I intend to use. I plan to have a stage box available for each desk so if there are lots of cables, they all combine to one single chunky cable.

I figure this will give me a helpful amount of mass and also give me good thermal insulation.

Have you done the math to ensure that you will have the right amount of isolation at the right frequencies? "Figuring" things is not the same as "figuring out with math"...

This is a VERY good point and one I will raise with the acoustician who designs the interior. Thank you for raising this.

The ICF section dimensions will be 5cm interior expanded polystyrene / 15cm core / 10cm exterior expanded polystyrene (image attached).

You say it has a lot of mass, but how much? What is the surface density of that? What about the acoustic characteristics?

Also something I need to work out. I enquired with a couple of guys who built studios from ICF and they are both very happy with the results.

I'm planning on a decoupled slab so the interior floor slab is decoupled from the slab under the icf walls.

Is that necessary? You don't seem to need a lot of isolation... Don't get me wrong! It's GREAT to do that, and it can help, yes, especially for studios that need very high levels of isolation.... but it's also extra work and extra expense, so considering your very, very tight budget, you might want to look for ways of saving money.

Good point and since discussing a decoupled slab with a few builders I have dropped it from the design. Neither of the guys I mention above used one for their ICF studios.

I will fit an MVHR unit with acoustic baffles.

OK, but that's just HRV: what will you use for the actual temperature and humidity control? Some type of mini-split system, I imagine? Also, which make and model of MVHR unit includes acoustic baffles? What type of insertion loss do you get from that unit, and is that enough to match the isolation of your walls, floor, ceiling, windows and doors?

Another good point. I intend to have freestanding oil filled electric radiator for heating. I may use clay boards for the ceiling as clay has excellent hygroscopic properties. I don't intend to have any active cooling, this is not usually necessary in the UK for a well insulated building with good ventilation. The MVHR unit does not come with baffles, I will build them myself. The unit i've chosen is designed for properties up to 90 sqm so I'm sure it will be able to handle the extra load of a few right angles. I have a friend who is a ventilation engineer and I will show him my final MVHR layout design before building. I've never heard of insertion loss, I've looked it up and it seems to refer to a loss of signal power in telecommunications devices. How does it relate to ventilation?

I'm wondering if this is because concrete blocks will provide better sound isolation than ICF?

Yes. Isolation depends on only four main physical properties: Mass, stiffness, decoupling, and cavity damping.. Of those, concrete has much higher mass and stiffness than ICF, and the decoupling and damping will be the same in both cases, from your wall design. ICF might be better in the region below MSM resonance, but if you design your wall right, that will be outside of the audible spectrum in any case, so it's not an issue.

Please take pity on me for my poor drawing skill

I'd suggest keeping your camera field-of-view angle to something ore realistic. Right now, you have it way too high. Something in the range 35° to 45° gives a reasonably realistic view, similar to what you'd actually see with your own eyes (unless you happen to be a fish.... )

- Stuart -

[/quote]

Thanks for all your suggestions!

I will put shelves / cable racks above the sofa. These should help diffuse the sound as well.

Not very much, to be honest. Diffusers are usually carefully designed to provide smooth, even, broad diffusion between an upper and lower frequency limit, as needed by the room, either in 1D or 2D, as needed. Do some research on QRD, PRD, Schroeder, Skyline, BAD and similar diffusers, and you'll get a better idea.

That said, your room is way too small to be able to use diffusion. You are limited to absorption alone.

The speakers are pointing down the short axis because I want to be able to look to my right and look out the window of the studio to my garden.

So you prefer visuals over acoustics in your room? In other words, you are more concerned about how your studio looks, then about how it sounds? Beauty over accuracy?

Long story short: There is a very basic concept in acoustics called the "Haas Effect". If your ears hear the direct sound from the speakers, followed by a reflection or echo of that same sound within a period of less than about 20 ms and at a similar level, your brain is incapable of figuring out that it was, in fact, an echo. Instead, it will identify that sound as having come from a different direction than it really came, and having a different frequency and phase curve from what it really was. In other words, you will be unable to determine the actual frequency response, and the actual direction. This is not something that you can learn to recognize, and learn to deal with: It is a physical limitation of the way our ears and brains are built. In order to avoid this problem, you must design your room such that the earliest reflections that reach your ears arrive later than 20ms after the original direct sound, and 20 dB quieter. You cannot do that if your speaker are firing across the short axis, as that places your head way to close to the rear wall.

In addition, with your current layout, your head will be in the geometric center of the room, which is the worst possible location for both modal issues and also SBIR. There is no worse location that the center of the room.

So, if you want your control room to be usable to actually turn out good mixes that translate well, then you should turn it around such that the speakers are firing down the longest possible path, and such that your head is NOT at 50% of the room depth, nor 25% either. About 38% is the theoretical best location.

Having a view on the outside world is important to me and I am willing to compromise on the sound quality of the room to have this

Well, that's your call, of course, but most people who go to all the huge expense in time, money and effort that is involved in building and tuning a studio, actually do want it to be as good as it possibly can be acoustically as their very first priority. Otherwise, they'd just sit in their living room and mix looking out the window, and save a lot of hassle, while still turning out the same mediocre mixes as they would in a mediocre studio.

By this I mean that the drawings show parallel walls & parallel ceiling and floor. The interior walls of the finished studio will not be parallel.

And once again I ask the same thing? Why do you NOT want to have parallel walls? You do understand that it's a myth, right? Since you are consulting with people you claim have already built a couple of studios, you should already know that there is no acoustic reason to have non-parallel walls in a studio? They have already explained to you that the only reason to do that is to avoid something called "flutter echo", but that in order to do that (get rid of flutter echo) the walls need to be angled at least 12°, which wastes a huge amount of space in a room, and that flutter echo can be eliminated in much simpler ways? They did tell you this already, right?

I just don't yet know the angles so haven't drawn them in.

As mentioned above, the aggregate angle must be at least 12° if you wanted to do that to control flutter echo. Splaying your walls by 12° will remove a LOT of space from the room, which would be a terrible thing: the room is already very, very small, and removing even more air volume would be a huge mistake. Take a look at specifications for critical listening rooms, such as ITU BS.1116-3 and EBU TECH-3276, and you'll find that the recommended minimum floor area is 20m2, and the reference volume for all acoustic calculations is 100 m3. Now compare that to your room, and you'll see that you cannot afford to lose any area or volume at all.

This is a VERY good point and one I will raise with the acoustician who designs the interior.

If you are allowing the acoustician to design ONLY the interior, then you have already made another huge mistake: The acoustician also needs control of the wall locations and angles, the isolation system, and the HVAC system. They all work together as a single whole.

Good point and since discussing a decoupled slab with a few builders I have dropped it from the design. Neither of the guys I mention above used one for their ICF studios.

Smart move.

I intend to have freestanding oil filled electric radiator for heating. I may use clay boards for the ceiling as clay has excellent hygroscopic properties. I don't intend to have any active cooling, this is not usually necessary in the UK for a well insulated building with good ventilation

Correct, it's not usually necessary for a usual building in the usual UK, but that's not your case. You are building a studio, which is very unusual building. It will be perfectly sealed, absolutely air-tight, twice over: Two complete hermetic seals. No air will be able to get in or out, except the air that comes in through your HVAC system. Since the relative humidity in the UK is pretty high most of the time, and since you need to get that down to 40% RH all the time, you need some method of controlling humidity. And since the very act of removing humidity from the air is a warming process and requires a cooling process to go with it (because the air has not only a sensible heat load but also a latent heat load), you need some type of equipment that is capable of doing that. In addition to the humidity coming in from outside, there's also the humidity emitted by your own body: In every single breath, you expel water vapor. If you don't deal with it, not only will the humidity inside be too high, it will also be rising continuously, until you end up with condensation on the walls.

The unit i've chosen is designed for properties up to 90 sqm so I'm sure it will be able to handle the extra load of a few right angles.

Nope. There is no relationship at all between the two! That's like saying "My car is able to hold 9 liters of refrigerant in the radiator, so I am sure it will be able to go 120 km/h on the freeway". Two different things. No relationship.

Your duct and silencer system resists the flow of air through it. This is known as "static pressure". The amount of resistance depends on several factors, but basically the total length of the system, and the internal surface area and cross sectional area, and changes in direction. You need to calculate this, not guess at it. The fans in the HRV unit are designed to be able to handle up to a certain static pressure, and this will be stated somewhere in the specifications. This is mostly independent to the air flow rate and the air flow velocity. In fact, the specs for the HRV should give you table with a range of air flow situations for several possible static pressures. You will notice that as the static pressure gets higher, the flow rates and flow speeds get lower, and if the static pressure of your system is higher than what the HRV can handle, the blades will suffer from airflow stall, and will generate more turbulence than actual air flow, since the will be incapable of moving air against such high resistance. The motor will be overloaded, will overheat, and will eventually fail, as will the motor bearings.

It's that simple. You have to do the calculations and check all the numbers and specs to make sure that the unit really is suitable for your situation. If not, you are inviting disaster.

I've never heard of insertion loss, I've looked it up and it seems to refer to a loss of signal power in telecommunications devices. How does it relate to ventilation?

Insertion loss in refers to how much acoustic isolation the silencer box produces. In other words, how much it attenuates or reduces sound levels of the air flowing through it. I'm surprised that you could not find anything about this, since the very first Google hit I got when searching for "HVAC silencer insertion loss", is this one: http://www.engineeringtoolbox.com/noise ... -d_81.html and the second one is this: http://www.enoisecontrol.com/wp-content ... itions.pdf There were many others too...

I have designed several studios for customers in the UK, similar to what you are trying to do, and I'd suggest that you should probably hit "reset" at this point, and go back to square one. I'd suggest that you start by buying and thoroughly studying two books: "Master Handbook of Acoustics" by F. Alton Everest (that's sort of the Bible for acoustics), and "Home Recording Studio: Build it Like the Pros", by Rod Gervais. The first one will give you the basics in acoustics that you are currently lacking, and the second one will give the basics of studio design and construction. Once you have worked your way through both of those, and fully understand them, then you'll be ready to start designing your place.

- Stuart -