Home Studio Build - Advice and Direction Required

Hello, I am based in Cape Town, South Africa. I have a comprehensive studio setup but no where to put everything at the moment. Recently I have been fortunate enough to be given a space/room to convert into a studio and make use of for the next 10 years at my folks place, provided that a passage way is left to provide access to and from the garage. (you will see what I mean in my diagrams.) The room is an old garage that was converted into an entertainment room, so all the surrounding walls are brick cavity walls with plaster and the walls leading to the lounge and garage (top and bottom) are fire walls - so they are bricked all the way up past the ceiling. The flooring is ceramic tile and there is a 2.23m window at the top right hand side (which can be covered if need be). and there is about 10cm of "think pink" general fibre glass insulation in the ceiling. The entrance is a separate entrance from the road (the house has two entrances). The room with out partitions is 5.7mLx5.4mWx2.66mH my budget is around $1500-$2000USD - Im not sure how prices are relative to other countries between South Africa and there. We have local manufacturers for a lot of the materials (isover - previously owens corning) As mentioned earlier a wall needs to be created in the room to provide for the passage way to the garage - so that wall is variable back and forth, and then a wall to partition the room for the control room and the small live room for tracking vocals, drums and guitar which I would like a window between. I used the ideal room ratios to try and get a room that was the ideal size as you will see in my idea image. I am unsure of a few things in my idea. Are my partitions and dimensions OK? Please let me know if you there there is a better way to go about this Should the wall partitioning the house from the new rooms (long wall) and between the control and live room be cavity walls, (2 layers sound board, isulation, gap, insulation, sound baord) - is it necessary to do walls along the perimeter (against the plastered cavity walls) of the control room and live room Do the new walls need to be angled at all and where and by how much? will it be necessarry to do a floating floor and celing? How much acoustic treatment will be required for the live room? should it be more, less, the same as the control room, in this case? I tried my best to give you some idea of what I am working with, I am no expert in the field but I have tried my best to do as much research as possible - I understand that this isnt going to be cheap if it needs to be done properly, but I am hoping with your expertise you will be able to guide me with the most efficient way to go about it - perhaps even giving ideas on how to build it in phases - like including floated floors or ceiling at a later stage etc. Any way, I would love to hear your thoughts. Please let me know if there are any details I may have left out - measurements are in meters BTW Thank you!!

Floating floors and walls and ceilings are to prevent that drum kit from making the rest of the house crazy. I don't know how bad it is in the current situation. How much noise can you make before people start to get mad? I would not worry to much about room ratio's as long as the dimensions of different partitions are not to close. New walls are if they are not for isolation a cosmetic matter. And walls need not to be angled, in fact angling walls only makes the room smaller and that is not good.

bert Stoltenborg wrote:

Floating floors and walls and ceilings are to prevent that drum kit from making the rest of the house crazy. I don't know how bad it is in the current situation. How much noise can you make before people start to get mad? I would not worry to much about room ratio's as long as the dimensions of different partitions are not to close. New walls are if they are not for isolation a cosmetic matter. And walls need not to be angled, in fact angling walls only makes the room smaller and that is not good.

Thanks for the Reply Bert. At the moment I dont record drums here because it will be too loud and drive people crazy - So I would like to build this so that the studio room can track Drums, Vocals, and Amped guitars without annoying the people in the house or the neighbors. I found out now that the rooms perimeter walls are not cavity walls but are 22cm (9inches) double brick walls with plaster (So same thickness as cavity wall with out the cavity, which I think is better for isolation from what I have read and the sound does not rezonate within the cavity) and according to these STC ratings the wall should provide an STC of 58 with no treatment http://www.concreteconstruction.net/Ima ... 340735.pdf The Floor is also Solid concrete on a concrete foundation with ceramic tiled floor So I am wondering if my main focus should be on Floating the floor of the studio, the ceiling and just acoustically treating the Main Brick/Concrete walls and not worrying about the plaster board insulation walls? (Unless I angle the walls - which you will see in my new diagrams) Regarding your mention about the room dimensions and wall angling - I have made the studio room a bit bigger and the control room as I think there needs to be a bit more space in the studio I dont understand why Splaying the walls dont need to be angled, when in all the studio plans on here the walls are angled - I cant help but feel it will help improve things if it is constantly shown in diagrams. The angled walls make my studio a bit bigger but because of the symmetry needed in the control room it eats up a bit of space there. I have created two new possible reworkings how how I could lay things out are there any problems with this? My main questions at this point are: • do my diagrams look OK in terms of room dimensions? • Should I leave out angled walls despite it being in most studio layouts? • Is floating the floor in the control room and the studio necessary - also considering that the floor is solid concrete should I just focus on the studio room? or both control and studio? • When Floating the floor is it necessary that the walls are standing on the floor or can they be next to the floor? • The ceiling looks like its going to be a big cause for leaking - Should I focus on isolation of the ceiling for the studio and control room? • The insulation in the walls - the only place Ive seen density and thickness mentioned is here http://johnlsayers.com/Recmanual/Pages/STC%20Chart.htm where 25km/m2 and thickness of 125mm thickness is mentioned - we have this http://www.isover.co.za/sites/isover.za ... _sheet.pdf which comes in 75mm 24km/m3 - which I will use per wall layer (75mmx2 = 150mm) - is this ok or which should I be using between my walls for insulation instead and does batts/rolls matter? (please see wall diagrams in latest post) • Do I need to worry about isolation on the perimeter walls and if so, is 1x12mm layer of plaster board enough? (please see wall diagrams in latest post) • On the walls adjoining rooms (House-to-Studio or Studio-to-Control room) is 4 layers of 15mm Plasterboard over-kill? Should I be using different thickness when doubling up like 12mm on 15mm? (please see wall diagrams in latest post) Im sorry for so many questions I would appreciate it if someone could read each carefully and answer each, as this will clear up a lot of uncertainty I have at the moment - I also dont want to go crazy and spend more money that I have to, I would like to save where I can and don't want to do things unnecessarily Thank you very much, Regards, Sean

Here is a diagram I have created showing How I plan to build the various walls I adapted the daigrams a bit as I wont be using the extra 4" for slot rezonators, as I have aready made acoustic panels and bass traps which I will mount to the walls

A 25 cm brick wall reduces popmusic about 42 dB, and over here they use the house music spectrum as popmusic is produced more bass heavy in de recent years, reducing the isolation to about 39 dB. So if you mix at 85 -90 dB there is 46 - 51 dB left outside. Over here 25 dB is permitted, and at night 15 dB. STC doesn't consider low frequencies so it's not very reliable in this situation. A decoupled cavity wall of 2 x 125 mm and a wool filled gap will outperform such a single wall as does a well designed decoupled light weight wall in front of the existing wall. You should calculate the transmission loss of all the soundpaths, then you can decide what constructions you need, else you have a fair chance you create an imbalanced isolating shell. If you know what to do you can design something with proper decoupling. Angling walls makes predicting standing wave patterns virtually impossible. If you like the looks of such walls you can better make false, acoustically transparant walls with absorption behind. There is from a physics point of view absolutely no reason to angle walls to get better acoustics I am aware of. :D

Hi there "Anna_Logue" (I love the pun in your screen name!!! :thu: ) Welcome to the forum.

my budget is around $1500-$2000USD

I imagine that was supposed to read "$15,000 to $20,000"? (1500 wont go very far at all to do what you want!) :)

Im not sure how prices are relative to other countries between South Africa and there.

I used to live in the RSA, many years ago (East Rand, back when that was still in Transvaal... :) ), so I have a vague idea of costs. You should be OK at the high end of your budget.

that wall is variable back and forth, and then a wall to partition the room for the control room and the small live room for tracking vocals, drums and guitar which I would like a window between.

You only have about 30 m2 to play with, so that's going to be a tight squeeze, especially considering that some of that space is not usable! In reality, you only have about 20m2 of usable space. That's going to be REALLY tight. Have you considered doing a single room, instead of two rooms? Would that work for you?

Should the wall partitioning the house from the new rooms (long wall) and between the control and live room be cavity walls, (2 layers sound board, isulation, gap, insulation, sound baord) -

Both NO and YES! I'm not trying to be cryptic, but that's the only right answer. The issue is that you cannot view that wall as a single, isolated, independent wall that isolates the studio from the house. It does not. Rather, it is part of the isolation SYSTEM that isolates the entire studio, both to the house and also within itself (I'm assuming two rooms here). So that wall needs to be designed correctly along with all the other walls, doors, windows, and ceilings, since they all work together to create a complete system. The whole is greater than the sum of its parts. If you take away any one part of that system, then the entire system dies. If you change or modify any one part, then you will have to modify several other parts to compensate. Isolation is a system, not a wall.

is it necessary to do walls along the perimeter (against the plastered cavity walls) of the control room and live room

The same answer applies here: Yes, No, Maybe, Certainly. It all depends on one single number: how much isolation you need, in decibels. Once you have decided on that number, then you can decide on how to build your walls such that they will give you that number.

Do the new walls need to be angled at all and where and by how much?

I guess I'm not being very much help here, but once again the answer is "yes, no". You can angle them ("splay" them) if you need to do that for your room design concept, or you could decide to NOT angle them if you go with a different room design. As Bert pointed out, splaying walls wastes space, and you don't have much space to start with, so you are probably limited to room philosophies that do not require splayed walls. So RFZ, CIS and NER concepts are probably not available to you, even though they all make for fantastic control room acoustics.

will it be necessarry to do a floating floor and celing?

Floating floor: definitely not. Decoupled ceiling: most certainly yes.

How much acoustic treatment will be required for the live room? should it be more, less, the same as the control room, in this case?

Ummmm... can I say it again? "Yes, no, maybe, more, less, the same, some, lots". It isn't possible to answer that question, since we don't have enough info to go on! However, do keep in mind that small rooms need a lot of treatment. The smaller they are, the more treatment they need: Very small rooms, need a ton of treatment, while large rooms can get away with much less. For control rooms, the requirements are laid out by a number of good specification documents, and there are simple "rules of thumb" for calculating roughly how much treatment it will need, and where to put that treatment, and what frequency ranges it should treat. That's because the frequency response and time-domain response of control rooms are tightly defined: it's a known factor how it should sound, and they key point is "neutral". It must not add or subtract anything from the sound of the speakers, in either the frequency domain or the time domain: it must just basically "do nothing" to the sound. No "coloration". It must produce that makes you think the room is not there at all, or (since that's actually impossible) it must fool your brain into thinking that it is not affecting the direct sound coming out of the speakers. But for the live room, it can sound any way you want it to sound! Some people like a very live, ringy, tinny, room, others want a dead, dull, "thuddy" room... others want a variable room, where they can change the acoustics as needed. That's up to you.

So I would like to build this so that the studio room can track Drums, Vocals, and Amped guitars without annoying the people in the house or the neighbors.

Great! That provides some parameters to work with: you will be LOUD! We are talking about upwards of 110 dB peak in the LR. Now we need to know the other side of the equation: how quiet do you need to be, on the other side of the wall? How many decibels do you need to get down to, in order to "not drive people crazy"? There's two things wrong with that assumption: 1) Treatment will have practically no effect on isolation (they are two different things), and 2) STC tells you nothing at all about how well the wall isolates for loud rock music (as Bert already mentioned). STC is an old system, from many decades back, and was originally designed to provide a single-number system for rating how well walls isolate SPEECH, as well as typical house and office sounds. Deep thumping rock, rap, techno, dance, disco, etc. music was NOT even around back then, so it was never considered in STC. The method for producing an STC number for a given wall does not even consider the bottom two and a half octaves of the musical scale, nor does it consider the top two and a half octaves. So it is a useless system for talking about studio isolation. I can build you a wall rated at STC-50 that does a lousy job of isolating rock music, and I can build you another wall rated at only STC-40 that does a much better job of isolating loud rock music. You should not try to use STC to decide on isolation for studios. Instead, look at the TL ("transmission loss") which gives you a more useful picture, but for the best understanding, look at the actual TL curve, which shows you how much isolation you are getting in each frequency band. Publications such as IR-761 and IR-582, as well as IR-169 and BRN217 give you that information. You can also calculate it yourself, using the equations for mass law, as well as for tuned MSM walls. Also, the document you mentioned is about reinforced concrete walls, but you say yours are brick: so it is not applicable. You can't extrapolate from one type of construction to another. My guess would be that you'll be getting about 45 dB of isolation (TL) from the walls you have, but that does not consider the ceilings, doors, windows or HVAC system. Take those into account, and it is probably more like 40.

The Floor is also Solid concrete on a concrete foundation with ceramic tiled floor

Excellent! Nothing better!

So I am wondering if my main focus should be on Floating the floor of the studio,

Why do you want to float your floor so badly? Bert already pointed out that you don't need to do that, but let me see if I can help you to figure this out for yourself. Read this: viewtopic.php?f=2&t=8173 And this: http://prorecordingworkshop.lefora.com/ ... n-mistakes Then look at this for the final nail in the coffin: http://archive.nrc-cnrc.gc.ca/obj/irc/d ... /ir802.pdf OK, now that we have that out of the way: you only need your walls, your ceilings, your doors, your windows, and your HVAC system. They all need to work together to provide the isolation you need.

and just acoustically treating the Main Brick/Concrete walls and not worrying about the plaster board insulation walls?

... in which case your total isolation would be down to something in the region of 35-40 dB, roughly. Is that enough?

Regarding your mention about the room dimensions and wall angling - I have made the studio room a bit bigger and the control room as I think there needs to be a bit more space in the studio

There ALWAYS needs to be more room in an studio! :) That goes without saying. It's really hard to have a home studio that is "too big"...

I dont understand why Splaying the walls dont need to be angled, when in all the studio plans on here the walls are angled

Because as Bert said, splaying your walls wastes space, and you don't have much space! Sometimes, with careful design, you can minimize the lost space. Sometimes you can't. It all depends on the existing space, the needs, and the budget.

I cant help but feel it will help improve things if it is constantly shown in diagrams.

That's sort of like looking through a transportation vehicle catalog, and saying: "I cant help but feel it would improve my car if I had 18 wheels and a huge trailer behind me, because that's what I see in all these photos, everywhere I look"... :) OK, lets' take this logically. There are three reasons why you might want to splay your walls. 1) Because you want to get rid of flutter echo. That works. If you splay one or both walls across the room such that the total splay angle between them is more than about 12°, then you don't have any more problems with flutter echo. Or you could just put simple simple panels on the non-splayed walls, and get the same effect much cheaper, and without wasting any space. 2) Because you really want an RFZ design concept for your room, or maybe NER or CID, or another similar concept. All of these rely on the shape of the room itself to create certain acoustic conditions inside, namely keeping first-order reflections away from the mix position. 3) Because it looks cool! Those are the only three valid reasons why you should splay your walls. For me, #2 is the ONLY one that makes any sense. If you do want an RFZ room, then that takes a lot of very careful design work, in order to make it happen correctly. It is nowhere near as simple as "Well, I'll just jog this wall over a bit, like I see in the photos, and it will all work just fine!" No it won't. RFZ design is very specialized, and requires a lot of thought, analysis, checking, and double-checking. The angles have to be exactly right, and are different for each and every room. You certainly could do an RFZ design (I sort of specialize in designing RFZ rooms, since it works so well when done right), but it's going to take a lot of learning for you to get to the point where you can do it yourself. Yes, they do look great, and yes I'm a firm believer that RFZ rooms make excellent control rooms with great accuracy... but I also know that it ain't easy to get it right.

The angled walls make my studio a bit bigger but because of the symmetry needed in the control room it eats up a bit of space there.

... and the angles are wrong in both cases... :) In acoustics, angles are important: VERY important. If you are going to angle your walls, then you need to start ray-tracing your reflections to see where they go for each frequency band, then calculate flight times and distances and attenuation and diffusion and phase cancellation and SBIR and all other things that make acoustic design so much fun! You can't just throw in any old angle and hope it works: it wont. Angles need to be calculated and checked by ray-tracing, then the results checked against the parameters for an RFZ room, to make sure it is going to work. John's rooms are mostly RFZ design, which is why they have splayed walls. Not because they look good, but because John carefully figured it all out to make the room sound correct, as well as look nice.

• Is floating the floor in the control room and the studio necessary

No. See above links.

should I just focus on the studio room? or both control and studio?

Build a drum riser for the LR. That's all you need.

• When Floating the floor is it necessary that the walls are standing on the floor or can they be next to the floor?

Both ways work, but they are very different scenarios. If you float the entire room, that implies a huge amount of mass, so the resilient mounts will be very different from those used for floating only the floor. In both cases you do have to tune the entire isolation system well, so that the floor or room really does float, and isolates all the way down to the design frequency. So you have to get your spring deflection correct (both static and dynamic), so you'll need to correctly deal with the dynamic compressive modulus, the compessive stiffness, the compressive stress, etc. in order to get the transmissibilty at resonance down as low as possible, while also getting the actual resonant frequency down to at least an octave below the lowest note you need to isolate, and ensuring that the air resonance is also under control, and ensuring that you have enough damping at the correct frequencies to keep it all under control... The math and design skills needed to successfully float an entire room are not for the faint hearted! Plus, there's the issue of budget: I don't think you have enough budget to float your floors... If you double your budget, that would be about right...

• The ceiling looks like its going to be a big cause for leaking - Should I focus on isolation of the ceiling for the studio and control room?

No. You should focus on isolating the two complete inner-leaf rooms from each other, and also from the outer-leaf shell. To do that, you need to ensure that the mass (surface density) on each leaf is consistent, all the way around, and that the air gap between them is large enough to provide the resonant frequency that you need. It sounds complicated, but in reality it isn't that bad. Basically, each room has to be built as a stand-alone structure, usually a wood or metal stud frame, that consists of four walls plus that ceiling. That structure has drywall (gypsum board) on only ONE side of it, all around, and that is your inner leaf. The inner-leaf cannot be allowed to touch any part of the outer leaf: it stands independently, all on its' own. It's that easy.

The insulation in the walls - the only place Ive seen density and thickness mentioned is here

If you are using fiberglass insulation then it needs to be around 30 kg/m3. If you are using mineral wool insulation, then it needs to be around 50kg/m3. It needs to be as thick as possible, such that it completely fills the air gap between the inner-leaf and outer-leaf, or at least fills it as much as is allowed by you building code.

• Do I need to worry about isolation on the perimeter walls and if so, is 1x12mm layer of plaster board enough?

The question itself is invalid for a proper MSM system. You'll see why once you look into it ... :) It's like asking: "Do I need to use a leash on my goldfish when I take it for a walk?".. 8) :lol: Since you'd never actually do that, the question makes no sense...

• On the walls adjoining rooms (House-to-Studio or Studio-to-Control room) is 4 layers of 15mm Plasterboard over-kill? Should I be using different thickness when doubling up like 12mm on 15mm? (please see wall diagrams in latest post)

What you need is consistency. The surface density of your outer leaf should be roughly the same all around. The weakest part of it should still have enough surface density to provide the correct MSM resonant frequency, when taking into account the size of the air gap and the amount of insulation in it. It's not complicated. In summary: you are not looking at the isolation system from the correct perspective. You first need to understand how a fully decoupled 2-leaf MSM system works, then you'll be able to design the isolation correctly. I'd suggest that you buy two books: "Master Handbook of Acoustics" by F. Alton Everest, and "Home Recording Studio: Build it Like the Pros", by Rod Gervais. They will give you the background information you need in order to understand the concepts, and then you can start the actual design process based on valid assumptions and valid concepts. Right now, your "angled" version of the CR is wasting a lot of space, is barely good for reducing flutter echo in one dimension only (the one where you don't need it anyway...), and it does not create an RFZ design either. Your speakers are over the desk :ahh: , the mix position is wrong, the treatment appears to be insufficient, the room is not acoustically symmetrical, the isolation is incomplete and won't work very well, access paths are questionable, sight lines are questionable, usability is questionable, there is no provision for HVAC, there is no provision for electrical or signal cabling, and you won't be getting STC-58 out of that, even if STC was a good system for describing isolation. I'm not trying to be harsh or trash your hard work that went into the designs! Not at all. I'm simply pointing out what needs to be fixed, and what you'll need to know in order to fix them. The whole point of this forum is to provide constructive criticism for members, and that's what the above is intended to be. You do have a reasonably usable space, and a reasonable budget, and you could get a decent small home studio in there, with good isolation and good acoustics, just not in the way you are going right now. - Stuart -

:D Maybe you should warn people for the pictures of very small controll rooms stuffed with diffusers in the Master Handbook, Stuart.

Hi Stuart,

Hi there "Anna_Logue" (I love the pun in your screen name!!! :thu: ) Welcome to the forum.

Haha, yes, I thought it was quite fitting. Good to speak to a fellow South African, or previous one! Thank you, I really appreciate you taking the time to get back to me and at least trying to touch on all of my questions where it was possible given my low level of understanding. I understand that my ignorance, ideas and understanding at this point (and probably for a lot longer) may seem like an insult to the world of professional acoustic design and implementation, but I am a novice and I am willing to learn, so thank you for welcoming me here, and I appreciate your feedback. I hope that through here I will be able to get to implementing something professional I can be proud of.

You only have about 30 m2 to play with, so that's going to be a tight squeeze, especially considering that some of that space is not usable! In reality, you only have about 20m2 of usable space. That's going to be REALLY tight. Have you considered doing a single room, instead of two rooms? Would that work for you?

I Have considered it but I am just not sure about how to go about it and how I should lay everything out to get the best results - With the single room design it would probably need to have an isolation booth for vocals. I have drawn an idea of how I think might work? Do you have a better suggestion or tips of how you would go about partitioning and layout in the case of a both a double and single room design to really get the best use out of my space constraints.

The issue is that you cannot view that wall as a single, isolated, independent wall that isolates the studio from the house. It does not. Rather, it is part of the isolation SYSTEM that isolates the entire studio, both to the house and also within itself (I'm assuming two rooms here). So that wall needs to be designed correctly along with all the other walls, doors, windows, and ceilings, since they all work together to create a complete system. The whole is greater than the sum of its parts. If you take away any one part of that system, then the entire system dies. If you change or modify any one part, then you will have to modify several other parts to compensate. Isolation is a system, not a wall.

Regarding isolation and the wall structure, I think I have a better understanding of what you mean now with regards to a 2-leaf MSM system - I can see how my drawings were not indicative of this - so I have redrawn it below so that the 2nd leaf (new wall) is separated from the 1st leaf (existing wall)

is it necessary to do walls along the perimeter (against the plastered cavity walls) of the control room and live room

The same answer applies here: Yes, No, Maybe, Certainly. It all depends on one single number: how much isolation you need, in decibels. Once you have decided on that number, then you can decide on how to build your walls such that they will give you that number.[/quote] OK I think I have a better understanding of what needs to be achieved in terms of db - so if a drum kit is 100db and mixing levels are around 83-90db and with the accepted level at night time being 15db, means I would need to get the level down by about 85db - with the existing walls providing around 40db of attenuation, that leaves around 45db of attenuation required of isolation - so looking at the http://archive.nrc-cnrc.gc.ca/obj/irc/d ... /ir761.pdf document it now becomes apparent that the biggest challenge lies with low frequency attenuation. I think it would be possible to get to an acceptable level using the first leaf as the brick wall and the second leaf as steel studs, with a resilient channel, 2 layers of 16mm Gypsum with fiberglass 75mm 24kg/m3 insulation in between? The wall between the house (Passage) and the CR and LR (or just single control room) I dont have 40db attenuation from the brick walls so at a level of 15db at night with playing drums at 100db or monitoring at 83db leaves a need for 68-85db attenuation - with the proposed wall design shows that I would be getting getting around 30-60db attenuation in the low-mid ranges and 60-80db in the upper mid ranges which is quite worrying? - I guess the cheaper solution is that I have to not play drums and turn it down at night!? perhaps I can add more layers of gypsum?

Do the new walls need to be angled at all and where and by how much?

I guess I'm not being very much help here, but once again the answer is "yes, no". You can angle them ("splay" them) if you need to do that for your room design concept, or you could decide to NOT angle them if you go with a different room design. As Bert pointed out, splaying walls wastes space, and you don't have much space to start with, so you are probably limited to room philosophies that do not require splayed walls. So RFZ, CIS and NER concepts are probably not available to you, even though they all make for fantastic control room acoustics.

Ok I get that if I splay the walls I am wasting space - and that its probably going to be more effective and efficient to just use acoustic treatment to solve this, so thats a bit of a relief - its certainly not because I want it to look cool - a RFZ would be my objective.

will it be necessarry to do a floating floor and celing?

Floating floor: definitely not. Decoupled ceiling: most certainly yes.

OK again, a bit of a relief about the floating floor - that will save me some pain and money - the ceiling I will do decoupled in conjunction and the same as the 2nd leaf - 2 layers of gypsum and insulation

OK, lets' take this logically. There are three reasons why you might want to splay your walls. 1) Because you want to get rid of flutter echo. That works. If you splay one or both walls across the room such that the total splay angle between them is more than about 12°, then you don't have any more problems with flutter echo. Or you could just put simple simple panels on the non-splayed walls, and get the same effect much cheaper, and without wasting any space. 2) Because you really want an RFZ design concept for your room, or maybe NER or CID, or another similar concept. All of these rely on the shape of the room itself to create certain acoustic conditions inside, namely keeping first-order reflections away from the mix position. 3) Because it looks cool! Those are the only three valid reasons why you should splay your walls. For me, #2 is the ONLY one that makes any sense. If you do want an RFZ room, then that takes a lot of very careful design work, in order to make it happen correctly. It is nowhere near as simple as "Well, I'll just jog this wall over a bit, like I see in the photos, and it will all work just fine!" No it won't. RFZ design is very specialized, and requires a lot of thought, analysis, checking, and double-checking. The angles have to be exactly right, and are different for each and every room. You certainly could do an RFZ design (I sort of specialize in designing RFZ rooms, since it works so well when done right), but it's going to take a lot of learning for you to get to the point where you can do it yourself. Yes, they do look great, and yes I'm a firm believer that RFZ rooms make excellent control rooms with great accuracy... but I also know that it ain't easy to get it right. and the angles are wrong in both cases... :) In acoustics, angles are important: VERY important. If you are going to angle your walls, then you need to start ray-tracing your reflections to see where they go for each frequency band, then calculate flight times and distances and attenuation and diffusion and phase cancellation and SBIR and all other things that make acoustic design so much fun! You can't just throw in any old angle and hope it works: it wont. Angles need to be calculated and checked by ray-tracing, then the results checked against the parameters for an RFZ room, to make sure it is going to work. John's rooms are mostly RFZ design, which is why they have splayed walls. Not because they look good, but because John carefully figured it all out to make the room sound correct, as well as look nice.

I agree, and the only reason I would want to angle the walls is for acoustic purposes and not because they look cool - I just want to get the best possible sounding room, I must be honest that now that you have explained it like that, it seems like its a massive undertaking to get it right - I think as you say it would be cheaper to go with acoustic absorption to create an RFZ room

• Is floating the floor in the control room and the studio necessary

No. See above links.

should I just focus on the studio room? or both control and studio?

Build a drum riser for the LR. That's all you need.

Ok cool, thats good news, ill just call the matt that the drum kit is on, a drum riser! :D

• The ceiling looks like its going to be a big cause for leaking - Should I focus on isolation of the ceiling for the studio and control room?

No. You should focus on isolating the two complete inner-leaf rooms from each other, and also from the outer-leaf shell. To do that, you need to ensure that the mass (surface density) on each leaf is consistent, all the way around, and that the air gap between them is large enough to provide the resonant frequency that you need. It sounds complicated, but in reality it isn't that bad.

Got it - how do I determine the size of my air gap required? does this come down to the resonant frequency? How does one go about deciding on their rezonant frequency? so because the focus is on isolating the inner leaf walls and that their mass is consistent all the way around, does this consistency apply to the ceiling to or can the ceiling be less mass than the walls? It seems to me like the ceiling does not have the same mass as it does not have the brick walls behind it like the wall leaf's

Basically, each room has to be built as a stand-alone structure, usually a wood or metal stud frame, that consists of four walls plus that ceiling. That structure has drywall (gypsum board) on only ONE side of it, all around, and that is your inner leaf. The inner-leaf cannot be allowed to touch any part of the outer leaf: it stands independently, all on its' own. It's that easy.

Got it

• On the walls adjoining rooms (House-to-Studio or Studio-to-Control room) is 4 layers of 15mm Plasterboard over-kill? Should I be using different thickness when doubling up like 12mm on 15mm? (please see wall diagrams in latest post)

What you need is consistency. The surface density of your outer leaf should be roughly the same all around. The weakest part of it should still have enough surface density to provide the correct MSM resonant frequency, when taking into account the size of the air gap and the amount of insulation in it. It's not complicated.

The perimiter walls are the concrete walls the built wall will be the weakest part as you mention - you say it should have enough surface density to provide the correct MSM rez freq - how do I determine that so i can determine the air gap size and amount of insulation - I think this ties into one of my questions above.

Right now, your "angled" version of the CR is wasting a lot of space, is barely good for reducing flutter echo in one dimension only (the one where you don't need it anyway...), and it does not create an RFZ design either. Your speakers are over the desk :ahh: , the mix position is wrong, the treatment appears to be insufficient, the room is not acoustically symmetrical, the isolation is incomplete and won't work very well, access paths are questionable, sight lines are questionable, usability is questionable, there is no provision for HVAC, there is no provision for electrical or signal cabling, and you won't be getting STC-58 out of that, even if STC was a good system for describing isolation.

OK I think i have to do with out the angled walls - it seems like its a bit beyond me and Im feeling a bit overwhelmed with what is required to get that right. I think as you say I can get the same result by using acoustic absorption.The speakers are on decoupled stands - the desks back corners are cut off which gives it more space - there was just no way to illustrate that. I dont understand why my mix position is wrong or why my treatment is insufficient - ( I have absorbers on all the reflective and flat services in the reflection zone the bass traps are all 6" 705 and the wall absorbers are 6" 703, ceiling corner bass traps are also used around the room and a cloud above the mix position 4" 703 (all each)

I'm not trying to be harsh or trash your hard work that went into the designs! Not at all. I'm simply pointing out what needs to be fixed, and what you'll need to know in order to fix them. The whole point of this forum is to provide constructive criticism for members, and that's what the above is intended to be. You do have a reasonably usable space, and a reasonable budget, and you could get a decent small home studio in there, with good isolation and good acoustics, just not in the way you are going right now.

All-in-all I hear what you are saying and I really appreciate you taking the time to explain and point things out to me and provide me the references that you have - I feel like I do have a better idea in some aspects, but in other aspects I feel like I've been told that everything I am doing is wrong but not how to make it right - so I get the "what" but I would really like to know more about the how - I feel like with a few bits of solid direction, we could probably get there, I'm feeling a bit in the dark as to the building blocks or "This-there-like-that" I also understand that you don't want to just spoon feed people and its about learning and researching :) but Id really appreciate some pointers - And I do appreciate the fact that you just replied in any case, and thank you for your insights, I really do appreciate it and it has put me a bit more on track!

Good to speak to a fellow South African, or previous one!

Australian, actually, but I lived in the RSA for many years back in the 70's and 80's. Believe it or not, I actually lived in Hillbrow for a couple of years, back when it was a decent place to live, and you could still walk around the area any time of day or night without getting mugged every few meters... :(

really appreciate you taking the time to get back to me and at least trying to touch on all of my questions where it was possible given my low level of understanding. I understand that my ignorance, ideas and understanding at this point (and probably for a lot longer) may seem like an insult to the world of professional acoustic design and implementation,

Not a problem at all! That's exactly what the forum is for: helping out others.

have drawn an idea of how I think might work

You could do it that way. It's probably about as good as you can get, even though the room does get narrower behind you, and the booth thingy messes up your symmetry pretty bad...... Hmm... This is one of the many design trade-offs you have to consider with home studio design: Does it make more sense to have a single larger room, with better overall volume but kinks in the walls and problems with symmetry? Or would it be better to have a smaller room with no kinks and good symmetry? It's a case of "six of one, or half a dozen of the other".... Maybe the best would be to go with two rooms, but maximizing space with non-splayed walls. Make the CR a bit wider, to get better volume and ratio: If your final internal dimensions are 4.13 (L) x 2.97 (W) x 2.31 (H), that's about as good as you could hope for in that size space.

Regarding isolation and the wall structure, I think I have a better understanding of what you mean now with regards to a 2-leaf MSM system - I can see how my drawings were not indicative of this - so I have redrawn it below so that the 2nd leaf (new wall) is separated from the 1st leaf (existing wall)

:thu: yep, that's the idea!

with the accepted level at night time being 15db,

:shock: :ahh: 15 dB is the legal requirement where you live? That's impossibly unattainable... Go to the middle of the most remote desert you can think of, and check the level at midnight with no wind... that will still be louder than 15 dB, by a wide margin. Bert lives in the Netherlands, which has some extremely strict laws it seems. So check with your local municipality to find out what your local legal restrictions are. Most places these days seem to have night-time limits of around 40 dB, which is still pretty hard to reach, or even to measure accurately, but bureaucrats do seem to like imposing impossible laws on people!

I would need to get the level down by about 85db

In theory, yes, but in practice... no, you'll never get that much. Not unless you add a couple of zeros to your budget! :) The reason is simply that the decibel scale is logarithmic, not linear. Each time you increase your isolation needs by 10 dB, that make it ten time harder to achieve. A typical house wall (stud frame with thin drywall on each side, no insulation) will give you about 30 dB of isolation. It's relatively easy to increase that to 40 dB, by adding insulation in the cavity and using thicker drywall. But increasing isolation from 30 to 50 means that you need to block ten times more energy than going from 30 to 40. Increasing form 30 to 60 implies blocking one hundred times more energy (10x10). Going from 30 to 70 means blocking a thousand times more energy (10x10x10), and going from 30 to 80 means stopping ten thousand times more energy (10x10x10x10). To increase isolation from 30 to 80, you need to one hundred thousand times more energy than increasing from 30 to 40.... That's a daunting task, very, very hard to do. Very expensive. Most home studios can expect to get somewhere around 50 dB of isolation, maybe 60 or so if they are very careful about the design and build, and have a good budget, but getting beyond that is hard.

I think it would be possible to get to an acceptable level using the first leaf as the brick wall and the second leaf as steel studs, with a resilient channel, 2 layers of 16mm Gypsum with fiberglass 75mm 24kg/m3 insulation in between?

That should give you around 55 or so, yes. Maybe a little more.

with the proposed wall design shows that I would be getting getting around 30-60db attenuation in the low-mid ranges and 60-80db in the upper mid ranges which is quite worrying

That sounds about right, yes: Why is it worrying?

perhaps I can add more layers of gypsum?

That would help, yes. So would using Green Glue between the layers, as well as increasing the size of the air gap between the leaves. You could probably get it up to a bit over 60 like that.

its certainly not because I want it to look cool - a RFZ would be my objective.

You could do RFZ by soffit mounting your speakers, and that's a Good Thing, but it would reduce down the room volume... trade-offs... But still that would probably be better than angling the entire wall: less space wasted.

I must be honest that now that you have explained it like that, it seems like its a massive undertaking to get it right

Maybe I made it sound a bit too scary! It isn't that bad, with patience, and there are rules-of-thumb to guide you.

I think as you say it would be cheaper to go with acoustic absorption to create an RFZ room

You can't achieve true RFZ with absorption alone. The design concept itself is based on angling parts of the front of the room (but not the entire wall!). It can be done with just speaker soffits and additional angled bits...

ill just call the matt that the drum kit is on, a drum riser!

Ummmm.... Nope! :) A drum riser isn't hard to build, but it is a but more than a mat on the floor!

how do I determine the size of my air gap required? does this come down to the resonant frequency?

Yes. And mass. There are equations for calculating what the MSM resonant frequency of your wall will be, based on the mass (surface density) of each leaf and the depth of the gap between them, and the damping provided by the insulation in that gap. F=C [(m1 + m2)]^.5 / [(m1 x m2 x d)]^.5 Where: m1 and m2 are the mass of leaf 1 and leaf 2 (surface density, in kg/m2) d is the distance between the leaves (in meters) and C is a constant that is either 60 if there is no isolation in the gap, or 43 if it is filled with suitable isolation

How does one go about deciding on their rezonant frequency?

You should tune your walls such that the resonant frequency is at least an octave below the lowest frequency that you need to isolate. Bare in mind that at the resonant frequency you get no isolation at all, and only at 1.414 times the resonant frequency do you start getting isolation.

so because the focus is on isolating the inner leaf walls

The focus os on ensuring that BOTH of the leaves have enough mass, and the distance between them is sufficient.

and that their mass is consistent all the way around, does this consistency apply to the ceiling to or can the ceiling be less mass than the walls? It seems to me like the ceiling does not have the same mass as it does not have the brick walls behind it like the wall leaf's

The overall isolation of your room is only as good as the isolation provide by the weakest part. Think of this: if you sit in traffic down-town in your car with the windows closed, you have a reasonable level of isolation form the noise outside. But if you open your window, you no longer have any isolation. Even though the rest of the car around you is still isolating just as well as before, you still have no isolation because there's now a much weaker part: the open window. If you put a sheet of cardboard in the place where the window was, isolation would increase slightly, but not much, because cardboard has much lower surface density than glass... Apply that same situation to your ceiling: If that is any less isolation that the walls, then that's where sound will get in and out. What is up above you right now? What is the current ceiling made of, and what is above it? You might need to beef that up first, before doing your inner-leaf.

The speakers are on decoupled stands -

Yes, but they are over the desk, or close to being over the desk. With that situation, you will get reflections from the desk into your ears, as well as comb-filtering artifacts.

I dont understand why my mix position is wrong or why my treatment is insufficient -

The speakers should be tight up against the front wall (or rather, up against the panels that you have on the front wall), in order to push up the SBIR issues to the mid range, where they aren't so noticeable. If the room is 2.97m wide (see above), then each speaker should be 85cm from the side wall. And when I say that, I mean that the acoustic axis should be 86cm from the side wall, not the edge of the box. For most speakers, that means that the center of the front panel should be that distance from the wall. That would mean that the speakers would be 122cm apart from each other. Your chair should be set up so that your ears are about 155 cm from the front wall, and the speakers should be aimed such that the acoustic axes meet about 30cm behind your head. The acoustic axes of the speakers should also be about 12cm above the floor. That would be roughly the correct geometry.

I have absorbers on all the reflective and flat services in the reflection zone

... except you don't have a reflection free zone! And you can't create one with absorbers either. Even if you could, you don't have that: you are showing a window to the LR on the left wall, exactly where your first reflection point absorbers should be. You will need to move that window further back, so that it is no longer at the reflection point, then put absorber panels on the wall at that point. You could also consider combining the door with the window, in the form of sliding glass doors. Since sliding glass doors take up no space when they open (they don't swing into the room, like normal doors), that would also improve your live room accessibility.

the bass traps are all 6" 705

:shock: That's too dense for bass traps. Fine if you want to absorb high frequencies, but 705 is overly dense for bass frequencies. Also, 6" isn't enough: you are dealing with waves that are tens of FEET long... Do "Superchunk" traps in the corners, and make them from 703, not 705. Or even 701, if you can get it. It's even less dense than 703, so better for bass trapping.

but in other aspects I feel like I've been told that everything I am doing is wrong but not how to make it right

Well, it's not ALL wrong! And hopefully the above will help you get it right!! :)

I'm feeling a bit in the dark as to the building blocks or "This-there-like-that"

It would be nice if it was that easy, but small room acoustics is a vast subject, and all rooms are different. We can give you some basic pointers, rules of thumb, and a few equations to get you started, but if you really want your room to be great then you are going to need more than that. You need two books to get you on track, if you want to shoot for having a great studio: "Master Handbook of Acoustics" by F. Alton Everest, and "Home Recording Studio: Build it Like the Pros", by Rod Gervais.

I also understand that you don't want to just spoon feed people and its about learning and researching :) but Id really appreciate some pointers

spoon feeding is fine, and I really don't mind doing that with folks like you, who want to learn and are prepared to go the distance, and are willing to take advice. The problem is that some people who come here expect us to do it all, for free! You'd be surprised at the number of new members who post something like "I have an empty garage. Design my studio for me." You are not doing that, thank heavens, since you obviously did your homework before posting, and came up with a couple of reasonable designs, thought through fairly well, but lacking the acoustic refinements. So you'll find that folks here on the forum won't have any trouble helping you. :thu: :) - Stuart -

Soundman2020 wrote:

Good to speak to a fellow South African, or previous one!

Australian, actually, but I lived in the RSA for many years back in the 70's and 80's. Believe it or not, I actually lived in Hillbrow for a couple of years, back when it was a decent place to live, and you could still walk around the area any time of day or night without getting mugged every few meters... :(

really appreciate you taking the time to get back to me and at least trying to touch on all of my questions where it was possible given my low level of understanding. I understand that my ignorance, ideas and understanding at this point (and probably for a lot longer) may seem like an insult to the world of professional acoustic design and implementation,

Not a problem at all! That's exactly what the forum is for: helping out others.

have drawn an idea of how I think might work

You could do it that way. It's probably about as good as you can get, even though the room does get narrower behind you, and the booth thingy messes up your symmetry pretty bad...... Hmm... This is one of the many design trade-offs you have to consider with home studio design: Does it make more sense to have a single larger room, with better overall volume but kinks in the walls and problems with symmetry? Or would it be better to have a smaller room with no kinks and good symmetry? It's a case of "six of one, or half a dozen of the other".... Maybe the best would be to go with two rooms, but maximizing space with non-splayed walls. Make the CR a bit wider, to get better volume and ratio: If your final internal dimensions are 4.13 (L) x 2.97 (W) x 2.31 (H), that's about as good as you could hope for in that size space.

Regarding isolation and the wall structure, I think I have a better understanding of what you mean now with regards to a 2-leaf MSM system - I can see how my drawings were not indicative of this - so I have redrawn it below so that the 2nd leaf (new wall) is separated from the 1st leaf (existing wall)

:thu: yep, that's the idea!

with the accepted level at night time being 15db,

:shock: :ahh: 15 dB is the legal requirement where you live? That's impossibly unattainable... Go to the middle of the most remote desert you can think of, and check the level at midnight with no wind... that will still be louder than 15 dB, by a wide margin. Bert lives in the Netherlands, which has some extremely strict laws it seems. So check with your local municipality to find out what your local legal restrictions are. Most places these days seem to have night-time limits of around 40 dB, which is still pretty hard to reach, or even to measure accurately, but bureaucrats do seem to like imposing impossible laws on people!

I would need to get the level down by about 85db

In theory, yes, but in practice... no, you'll never get that much. Not unless you add a couple of zeros to your budget! :) The reason is simply that the decibel scale is logarithmic, not linear. Each time you increase your isolation needs by 10 dB, that make it ten time harder to achieve. A typical house wall (stud frame with thin drywall on each side, no insulation) will give you about 30 dB of isolation. It's relatively easy to increase that to 40 dB, by adding insulation in the cavity and using thicker drywall. But increasing isolation from 30 to 50 means that you need to block ten times more energy than going from 30 to 40. Increasing form 30 to 60 implies blocking one hundred times more energy (10x10). Going from 30 to 70 means blocking a thousand times more energy (10x10x10), and going from 30 to 80 means stopping ten thousand times more energy (10x10x10x10). To increase isolation from 30 to 80, you need to one hundred thousand times more energy than increasing from 30 to 40.... That's a daunting task, very, very hard to do. Very expensive. Most home studios can expect to get somewhere around 50 dB of isolation, maybe 60 or so if they are very careful about the design and build, and have a good budget, but getting beyond that is hard.

I think it would be possible to get to an acceptable level using the first leaf as the brick wall and the second leaf as steel studs, with a resilient channel, 2 layers of 16mm Gypsum with fiberglass 75mm 24kg/m3 insulation in between?

That should give you around 55 or so, yes. Maybe a little more.

with the proposed wall design shows that I would be getting getting around 30-60db attenuation in the low-mid ranges and 60-80db in the upper mid ranges which is quite worrying

That sounds about right, yes: Why is it worrying?

perhaps I can add more layers of gypsum?

That would help, yes. So would using Green Glue between the layers, as well as increasing the size of the air gap between the leaves. You could probably get it up to a bit over 60 like that.

its certainly not because I want it to look cool - a RFZ would be my objective.

You could do RFZ by soffit mounting your speakers, and that's a Good Thing, but it would reduce down the room volume... trade-offs... But still that would probably be better than angling the entire wall: less space wasted.

I must be honest that now that you have explained it like that, it seems like its a massive undertaking to get it right

Maybe I made it sound a bit too scary! It isn't that bad, with patience, and there are rules-of-thumb to guide you.

I think as you say it would be cheaper to go with acoustic absorption to create an RFZ room

You can't achieve true RFZ with absorption alone. The design concept itself is based on angling parts of the front of the room (but not the entire wall!). It can be done with just speaker soffits and additional angled bits...

ill just call the matt that the drum kit is on, a drum riser!

Ummmm.... Nope! :) A drum riser isn't hard to build, but it is a but more than a mat on the floor!

how do I determine the size of my air gap required? does this come down to the resonant frequency?

Yes. And mass. There are equations for calculating what the MSM resonant frequency of your wall will be, based on the mass (surface density) of each leaf and the depth of the gap between them, and the damping provided by the insulation in that gap. F=C [(m1 + m2)]^.5 / [(m1 x m2 x d)]^.5 Where: m1 and m2 are the mass of leaf 1 and leaf 2 (surface density, in kg/m2) d is the distance between the leaves (in meters) and C is a constant that is either 60 if there is no isolation in the gap, or 43 if it is filled with suitable isolation

How does one go about deciding on their rezonant frequency?

You should tune your walls such that the resonant frequency is at least an octave below the lowest frequency that you need to isolate. Bare in mind that at the resonant frequency you get no isolation at all, and only at 1.414 times the resonant frequency do you start getting isolation.

so because the focus is on isolating the inner leaf walls

The focus os on ensuring that BOTH of the leaves have enough mass, and the distance between them is sufficient.

and that their mass is consistent all the way around, does this consistency apply to the ceiling to or can the ceiling be less mass than the walls? It seems to me like the ceiling does not have the same mass as it does not have the brick walls behind it like the wall leaf's

The overall isolation of your room is only as good as the isolation provide by the weakest part. Think of this: if you sit in traffic down-town in your car with the windows closed, you have a reasonable level of isolation form the noise outside. But if you open your window, you no longer have any isolation. Even though the rest of the car around you is still isolating just as well as before, you still have no isolation because there's now a much weaker part: the open window. If you put a sheet of cardboard in the place where the window was, isolation would increase slightly, but not much, because cardboard has much lower surface density than glass... Apply that same situation to your ceiling: If that is any less isolation that the walls, then that's where sound will get in and out. What is up above you right now? What is the current ceiling made of, and what is above it? You might need to beef that up first, before doing your inner-leaf.

The speakers are on decoupled stands -

Yes, but they are over the desk, or close to being over the desk. With that situation, you will get reflections from the desk into your ears, as well as comb-filtering artifacts.

I dont understand why my mix position is wrong or why my treatment is insufficient -

The speakers should be tight up against the front wall (or rather, up against the panels that you have on the front wall), in order to push up the SBIR issues to the mid range, where they aren't so noticeable. If the room is 2.97m wide (see above), then each speaker should be 85cm from the side wall. And when I say that, I mean that the acoustic axis should be 86cm from the side wall, not the edge of the box. For most speakers, that means that the center of the front panel should be that distance from the wall. That would mean that the speakers would be 122cm apart from each other. Your chair should be set up so that your ears are about 155 cm from the front wall, and the speakers should be aimed such that the acoustic axes meet about 30cm behind your head. The acoustic axes of the speakers should also be about 12cm above the floor. That would be roughly the correct geometry.

I have absorbers on all the reflective and flat services in the reflection zone

... except you don't have a reflection free zone! And you can't create one with absorbers either. Even if you could, you don't have that: you are showing a window to the LR on the left wall, exactly where your first reflection point absorbers should be. You will need to move that window further back, so that it is no longer at the reflection point, then put absorber panels on the wall at that point. You could also consider combining the door with the window, in the form of sliding glass doors. Since sliding glass doors take up no space when they open (they don't swing into the room, like normal doors), that would also improve your live room accessibility.

the bass traps are all 6" 705

:shock: That's too dense for bass traps. Fine if you want to absorb high frequencies, but 705 is overly dense for bass frequencies. Also, 6" isn't enough: you are dealing with waves that are tens of FEET long... Do "Superchunk" traps in the corners, and make them from 703, not 705. Or even 701, if you can get it. It's even less dense than 703, so better for bass trapping.

but in other aspects I feel like I've been told that everything I am doing is wrong but not how to make it right

Well, it's not ALL wrong! And hopefully the above will help you get it right!! :)

I'm feeling a bit in the dark as to the building blocks or "This-there-like-that"

It would be nice if it was that easy, but small room acoustics is a vast subject, and all rooms are different. We can give you some basic pointers, rules of thumb, and a few equations to get you started, but if you really want your room to be great then you are going to need more than that. You need two books to get you on track, if you want to shoot for having a great studio: "Master Handbook of Acoustics" by F. Alton Everest, and "Home Recording Studio: Build it Like the Pros", by Rod Gervais.

I also understand that you don't want to just spoon feed people and its about learning and researching :) but Id really appreciate some pointers

spoon feeding is fine, and I really don't mind doing that with folks like you, who want to learn and are prepared to go the distance, and are willing to take advice. The problem is that some people who come here expect us to do it all, for free! You'd be surprised at the number of new members who post something like "I have an empty garage. Design my studio for me." You are not doing that, thank heavens, since you obviously did your homework before posting, and came up with a couple of reasonable designs, thought through fairly well, but lacking the acoustic refinements. So you'll find that folks here on the forum won't have any trouble helping you. :thu: :) - Stuart -

Hey Stuart, Thanks for the reply's - I decided to take the leap and purchase your recommended read - Home Recording Studio: Build it Like the Pros", by Rod Gervais - I am finding that a lot of my initial questions are being answered in here and so I just wanted to touch base and say thank you, I am going to read through this and them come back to you with further questions! :)

Soundman2020 wrote:

Good to speak to a fellow South African, or previous one!

Australian, actually, but I lived in the RSA for many years back in the 70's and 80's. Believe it or not, I actually lived in Hillbrow for a couple of years, back when it was a decent place to live, and you could still walk around the area any time of day or night without getting mugged every few meters... :(

really appreciate you taking the time to get back to me and at least trying to touch on all of my questions where it was possible given my low level of understanding. I understand that my ignorance, ideas and understanding at this point (and probably for a lot longer) may seem like an insult to the world of professional acoustic design and implementation,

Not a problem at all! That's exactly what the forum is for: helping out others.

have drawn an idea of how I think might work

You could do it that way. It's probably about as good as you can get, even though the room does get narrower behind you, and the booth thingy messes up your symmetry pretty bad...... Hmm... This is one of the many design trade-offs you have to consider with home studio design: Does it make more sense to have a single larger room, with better overall volume but kinks in the walls and problems with symmetry? Or would it be better to have a smaller room with no kinks and good symmetry? It's a case of "six of one, or half a dozen of the other".... Maybe the best would be to go with two rooms, but maximizing space with non-splayed walls. Make the CR a bit wider, to get better volume and ratio: If your final internal dimensions are 4.13 (L) x 2.97 (W) x 2.31 (H), that's about as good as you could hope for in that size space.

Regarding isolation and the wall structure, I think I have a better understanding of what you mean now with regards to a 2-leaf MSM system - I can see how my drawings were not indicative of this - so I have redrawn it below so that the 2nd leaf (new wall) is separated from the 1st leaf (existing wall)

:thu: yep, that's the idea!

with the accepted level at night time being 15db,

:shock: :ahh: 15 dB is the legal requirement where you live? That's impossibly unattainable... Go to the middle of the most remote desert you can think of, and check the level at midnight with no wind... that will still be louder than 15 dB, by a wide margin. Bert lives in the Netherlands, which has some extremely strict laws it seems. So check with your local municipality to find out what your local legal restrictions are. Most places these days seem to have night-time limits of around 40 dB, which is still pretty hard to reach, or even to measure accurately, but bureaucrats do seem to like imposing impossible laws on people!

I would need to get the level down by about 85db

In theory, yes, but in practice... no, you'll never get that much. Not unless you add a couple of zeros to your budget! :) The reason is simply that the decibel scale is logarithmic, not linear. Each time you increase your isolation needs by 10 dB, that make it ten time harder to achieve. A typical house wall (stud frame with thin drywall on each side, no insulation) will give you about 30 dB of isolation. It's relatively easy to increase that to 40 dB, by adding insulation in the cavity and using thicker drywall. But increasing isolation from 30 to 50 means that you need to block ten times more energy than going from 30 to 40. Increasing form 30 to 60 implies blocking one hundred times more energy (10x10). Going from 30 to 70 means blocking a thousand times more energy (10x10x10), and going from 30 to 80 means stopping ten thousand times more energy (10x10x10x10). To increase isolation from 30 to 80, you need to one hundred thousand times more energy than increasing from 30 to 40.... That's a daunting task, very, very hard to do. Very expensive. Most home studios can expect to get somewhere around 50 dB of isolation, maybe 60 or so if they are very careful about the design and build, and have a good budget, but getting beyond that is hard.

I think it would be possible to get to an acceptable level using the first leaf as the brick wall and the second leaf as steel studs, with a resilient channel, 2 layers of 16mm Gypsum with fiberglass 75mm 24kg/m3 insulation in between?

That should give you around 55 or so, yes. Maybe a little more.

with the proposed wall design shows that I would be getting getting around 30-60db attenuation in the low-mid ranges and 60-80db in the upper mid ranges which is quite worrying

That sounds about right, yes: Why is it worrying?

perhaps I can add more layers of gypsum?

That would help, yes. So would using Green Glue between the layers, as well as increasing the size of the air gap between the leaves. You could probably get it up to a bit over 60 like that.

its certainly not because I want it to look cool - a RFZ would be my objective.

You could do RFZ by soffit mounting your speakers, and that's a Good Thing, but it would reduce down the room volume... trade-offs... But still that would probably be better than angling the entire wall: less space wasted.

I must be honest that now that you have explained it like that, it seems like its a massive undertaking to get it right

Maybe I made it sound a bit too scary! It isn't that bad, with patience, and there are rules-of-thumb to guide you.

I think as you say it would be cheaper to go with acoustic absorption to create an RFZ room

You can't achieve true RFZ with absorption alone. The design concept itself is based on angling parts of the front of the room (but not the entire wall!). It can be done with just speaker soffits and additional angled bits...

ill just call the matt that the drum kit is on, a drum riser!

Ummmm.... Nope! :) A drum riser isn't hard to build, but it is a but more than a mat on the floor!

how do I determine the size of my air gap required? does this come down to the resonant frequency?

Yes. And mass. There are equations for calculating what the MSM resonant frequency of your wall will be, based on the mass (surface density) of each leaf and the depth of the gap between them, and the damping provided by the insulation in that gap. F=C [(m1 + m2)]^.5 / [(m1 x m2 x d)]^.5 Where: m1 and m2 are the mass of leaf 1 and leaf 2 (surface density, in kg/m2) d is the distance between the leaves (in meters) and C is a constant that is either 60 if there is no isolation in the gap, or 43 if it is filled with suitable isolation

How does one go about deciding on their rezonant frequency?

You should tune your walls such that the resonant frequency is at least an octave below the lowest frequency that you need to isolate. Bare in mind that at the resonant frequency you get no isolation at all, and only at 1.414 times the resonant frequency do you start getting isolation.

so because the focus is on isolating the inner leaf walls

The focus os on ensuring that BOTH of the leaves have enough mass, and the distance between them is sufficient.

and that their mass is consistent all the way around, does this consistency apply to the ceiling to or can the ceiling be less mass than the walls? It seems to me like the ceiling does not have the same mass as it does not have the brick walls behind it like the wall leaf's

The overall isolation of your room is only as good as the isolation provide by the weakest part. Think of this: if you sit in traffic down-town in your car with the windows closed, you have a reasonable level of isolation form the noise outside. But if you open your window, you no longer have any isolation. Even though the rest of the car around you is still isolating just as well as before, you still have no isolation because there's now a much weaker part: the open window. If you put a sheet of cardboard in the place where the window was, isolation would increase slightly, but not much, because cardboard has much lower surface density than glass... Apply that same situation to your ceiling: If that is any less isolation that the walls, then that's where sound will get in and out. What is up above you right now? What is the current ceiling made of, and what is above it? You might need to beef that up first, before doing your inner-leaf.

The speakers are on decoupled stands -

Yes, but they are over the desk, or close to being over the desk. With that situation, you will get reflections from the desk into your ears, as well as comb-filtering artifacts.

I dont understand why my mix position is wrong or why my treatment is insufficient -

The speakers should be tight up against the front wall (or rather, up against the panels that you have on the front wall), in order to push up the SBIR issues to the mid range, where they aren't so noticeable. If the room is 2.97m wide (see above), then each speaker should be 85cm from the side wall. And when I say that, I mean that the acoustic axis should be 86cm from the side wall, not the edge of the box. For most speakers, that means that the center of the front panel should be that distance from the wall. That would mean that the speakers would be 122cm apart from each other. Your chair should be set up so that your ears are about 155 cm from the front wall, and the speakers should be aimed such that the acoustic axes meet about 30cm behind your head. The acoustic axes of the speakers should also be about 12cm above the floor. That would be roughly the correct geometry.

I have absorbers on all the reflective and flat services in the reflection zone

... except you don't have a reflection free zone! And you can't create one with absorbers either. Even if you could, you don't have that: you are showing a window to the LR on the left wall, exactly where your first reflection point absorbers should be. You will need to move that window further back, so that it is no longer at the reflection point, then put absorber panels on the wall at that point. You could also consider combining the door with the window, in the form of sliding glass doors. Since sliding glass doors take up no space when they open (they don't swing into the room, like normal doors), that would also improve your live room accessibility.

the bass traps are all 6" 705

:shock: That's too dense for bass traps. Fine if you want to absorb high frequencies, but 705 is overly dense for bass frequencies. Also, 6" isn't enough: you are dealing with waves that are tens of FEET long... Do "Superchunk" traps in the corners, and make them from 703, not 705. Or even 701, if you can get it. It's even less dense than 703, so better for bass trapping.

but in other aspects I feel like I've been told that everything I am doing is wrong but not how to make it right

Well, it's not ALL wrong! And hopefully the above will help you get it right!! :)

I'm feeling a bit in the dark as to the building blocks or "This-there-like-that"

It would be nice if it was that easy, but small room acoustics is a vast subject, and all rooms are different. We can give you some basic pointers, rules of thumb, and a few equations to get you started, but if you really want your room to be great then you are going to need more than that. You need two books to get you on track, if you want to shoot for having a great studio: "Master Handbook of Acoustics" by F. Alton Everest, and "Home Recording Studio: Build it Like the Pros", by Rod Gervais.

I also understand that you don't want to just spoon feed people and its about learning and researching :) but Id really appreciate some pointers

spoon feeding is fine, and I really don't mind doing that with folks like you, who want to learn and are prepared to go the distance, and are willing to take advice. The problem is that some people who come here expect us to do it all, for free! You'd be surprised at the number of new members who post something like "I have an empty garage. Design my studio for me." You are not doing that, thank heavens, since you obviously did your homework before posting, and came up with a couple of reasonable designs, thought through fairly well, but lacking the acoustic refinements. So you'll find that folks here on the forum won't have any trouble helping you. :thu: :) - Stuart -

Hey Stuart, Thanks for the reply's - I decided to take the leap and purchase your recommended read - Home Recording Studio: Build it Like the Pros", by Rod Gervais - I am finding that a lot of my initial questions are being answered in here and so I just wanted to touch base and say thank you, I am going to read through this and then come back to you with further questions! :)