New studio/house build including John’s small studio design

Hi, this is my first post and I am hoping to get some experienced thoughts on a new studio/house build. I am new to building studios, but, not new to recording, performing and working in professional studio. Please be nice and as informative as possible. I will try to be at all times too! I have talked to John briefly over email and he is aware that I am hoping to incorporate his existing and awesome small studio design into a new house build. The studio design is unchanged from John’s design and planning for the studio and house build are currently underway. I have been reading and researching John’s studio forum and the web for approximately 6 months prior to this post. Note that John did suggest putting the studio door on the office wall to make more room for the lounge behind the desk. However, I am hoping to leave the design as it is to keep things as simple as possible, to keep the studio entry outside of the main house, to keep the small galley office as clear as possible. In addition my existing lounge will fit as indicated and at least one person sitting on the lounge should be sitting in a centred listen position. I may open up the final studio in the future to external clients and friends, but, the main purpose is to allow me to record my own compositions, mix, master and rehearse. There is a chance that I will need to record live drums, but, not often. If drums were involved in a rehearsal then it would be a stripped down kit, ie, kick, snare, brushes and hats. I am allowing for about a 115db maximum loudness. I am currently working with an architect, my girlfriend and the builders to finalise the house design. So after all that, how loud do I want to be? I mostly compose with VI’s that are blended with live guitar, bass and vocals. But, I would like to think that I could record a live drum kit so up to 115db without any complaints coming from outside of the studio (my girlfriend and the neighbours!). All up I am aiming to achieve 65db of isolation for the final studio. Unfortunately, I can’t get any loudness readings, as there is only land at the moment. But, I will post the background noise levels on the block as soon as I can. Design information and files: The design is John’s small studio (known as Scott's Studio). Next are some further details and then questions at the end. Thanks in advance! SLAB AND CONDUIT The studio will be on a concrete slab. I am note sure how thick at this stage (I can find out I guess), but, at least as thick as the garage and to Australian standards. I would like to run a series of independent conduits under the slab so that I can later surface mount everything inside the LR and CR. Also, I would like any and all wiring for power, cat-6 and HVAC to be installed as part of the initial slab,outer-leaf and external window part of the build if possible. At this stage I am thinking there will be 8 separate conduits as follows: 1. Power to the CR + Power for LED lights in CR 2. Power to the LR + Power for LED lights in LR 3. Ethernet to the CR 4. Power to the A/C in the CR 5. Power to the A/C in the LR 6. Air to/from the A/C in the CR 7. Air to/from the A/C in the LR 8. Audio between the LR and CR HVAC PREP I can see 3 options for the A/C part of the HVAC and I am mentioning this now as it does impact on the outer-leaf stage of the build. Each has pros and cons and many unknowns due to my inexperience in this area: 1. I am aware that John has recommended the Daikin Ururu Sahara before due to its added fresh air and humidity functions. This is my preferred choice and the 2 units would be located in the LR above the window and above the lounge in the CR. The internal operating noise levels for the Daikin Ururu Sahara are quoted at 39db/23db (H/SL). 2. Another option would be a Daikin multi-split with one outside unit feeding, 2 independent, wall surface mounted units. The model here would probably be a Daikin FTXS20KVMA. Its sound operating levels are quoted as 38db/25db/22db (H/L/SL). There is also a version of the Daikin multi-split that has a humidity function, but, there is no model that also offers fresh air. 3. The 3rd option would be to incorporate the studio A/C into the house A/C. This would allow for the A/C power conduit run to be dropped from the studio plan and also the conduit and plumbing of the air send and return pipes under the slab. But, it would still leave issues. For example, I don’t understand at this point how to go about getting A/C vents through the outer and inner-leaf sections that would be impacted. Please see the question at the end about the shape of the air gap above the studio to better understand why. There would be no specific humidity function as far as I can tell. There would also be no specific fresh air function. I can visualise and understand how options 1 and 2 above would be physically patched/built through the outer-leaf (slab) so that they can be installed surface mount style in the LR/CR, ie, within the inner-leaf’s of each room. This is not the case for an incorporated studio + house ducted system For the ventilation part of the HVAC, I was thinking, that if fresh air can’t be delivered as part of the A/C then I could consider something like 2 x Aeropack’s (http://www.acoustica.com.au/aeropac.html) in the LR/CR. Air extraction would be handled by an extractor fan, located in the garage, toward the top of the laundry wall and connected to piping to extract stale air from both the LR and CR. I aim to use a silencer of some kind to ensure this exhaust is quiet and will also have to eventually get the piping through the inner-leaf/air gap/outer-leaf. I am still researching the air extraction system and would love to get ideas from the forum. OUTER-LEAF AND STUDIO CEILING STRUCTURE Our architect has designed the studio around the garage with a shared Colorbond skillion roof set at an 8 degree angle. I am hoping that it will be possible to make the part of the slanted skillion roof that is over the studio floor space the outer-leaf for the studio. In other words, I hope it will be possible to create an effective outer-leaf by having a mass of Colorbond + any under-roof sealing sheets and linings + 2 x 16mm sheets of Frychek, ie, all bound together and functioning as an outer-leaf. This skillion roof does raise some questions and they are asked toward the end of this post. Assuming the above will work, then I still need to understand the air gap beneath this outer-leaf. The garage and studio will be on a slab that is on the ground. I am planning for the 4 walls of the outer-leaf to be single 110mm solid brick. Although a bit out of scope, I will later render the inside of this outer-leaf brick wall with render to seal it, then have a 100mm air gap filled with 30kg/m2 mineral wool before I get to the outside of the inner leaf. The inner-leaf’s for the LR and the CR will both be 100% de-coupled from each other and from the outer-leaf too (ie room within a room). The inner-leaf’s will be built inside out with 2 x 16mm Frychek Gyprock (with Green Glue seals) followed by 2x4 studs that will be mineral wool filled and then material finish on the very inside. Also, as previously mentioned I will be following the exact dimensions and details as outlined in John’s design for this room. LAMINATED EXTERIOR WINDOW For the outer-leaf part of the LR fixed window, I am hoping to use a 13mm laminated glass window that will be purchased in its frame ready to install. Then, after the window part of the outer-leaf, there will be an air gap of at least 140mm (mineral wool filled) and then another laminated glass window, but, this inner-leaf one will be 15mm thick. But, I would prefer to keep the focus on the outer-leaf design at this point. I really hope to get that right and then follow John’s internal directions as closely as possible to tackle the inner-leaf and internal fitout. QUESTIONS AM I best to go for 2 x Daiken Ururu Sahara units, 1 x a Daikin multi-split or work out how to get the studio and house A/C all bound together into a single ducted system? Also, as alluded to above, is it possible to run the pipes and power for A/C in conduit under a slab so that inside A/C units can be surface mounted inside the inner-leaf? If this is possible is it sensible given that the A/C piping would at least in part be under slab in conduit and difficult to service? If this is common practice and not crazy, then where would the conduit exit the slab for the air and power runs to be in the best position for surface mounting inside the inner-leaf. For example, would the conduit exit, just inside the inner-leaf Frychek, to allow for the shortest possible runs to the A/C units above. Then, as part of the final finish, I was thinking that mineral wool on the inside of the inner-leaf and finally a material cover would hide all wiring and plumbing. Am I thinking correctly? Does, anyone have any working knowledge of the Aeropac units? Are they quiet? Could they run at the same time as A/C without the result being too loud? Am I mad to consider running A/C and a fresh air ventilator from a noise perspective when I could get both functions from a Daikin Ururu Sahara? Do I really need 2 x A/C units at this point? For example, could I run the required conduit to add one to the LR later if I end up opening the studio up to external clients and just install 1 x A/C in the CR in the short term, still add the exhaust to both the LR and CR and essentially leave the doors between the LR and CR open most of the time? Any thoughts on this? What is the best way to go about fixing the 2 x sheets of Frychek to the underside of the Colorbond. Also, what is the best way to go about ensuring that the 4 studio brick side walls meat and seal with the Frychek/Colorbond to create the entire outer-leaf. Will a final ceiling height of 2478mm be ok when considering acoustic performance (not isolation) and the final treated dimensions of the LR and CR as depicted in John’s Sketup design file? What do I have to watch out for to make sure that the builders for the home seal the 13mm external outer-leaf window is installed correctly for isolation and the elements? What is the best window frame material aluminum, uPVC or timber? I believe that the inner and outer-leaf windows need to be set at an angle in the horizontal plane? What is the best angle here? BUDGET My total budget for the build is $15-20K AUD. Hopefully, more like $15K, but, I’m guessing it will be higher. That budget does not include the slab and conduit work, outer-leaf materials (wood+Frychek+green glue for this bit) + not the extermal window + labour and associated consumables. Those parts will be added to the dreaded mortage that is pending. So, the budget will need to cover, the purchase and installation of the HVAC system (A/C, fresh air and exhaust), the purchase and installation of powerpoints, ethernet wall plate and cat-6 cable, LED lights and switches, an engineered wood pre-finished wood floor above the studio slab floor, 2 x laminated glass sliding doors between the LR/CR, 1 x dual entry door with air gap and all seals (hopefully 2 x laminated glass if the budget stretches that far). Also, all the wood, Frychek Gyprock, mineral wool, green glue, cloth material and other consumables like screws, nails etc etc that will be required to build and finish the LR/CR inner-leaf’s. Then there will be the builder's labour component. As a guide I have found the following rough retail prices online for the more expensive items that I have to cover in my budget. I could not find prices for 13mm and 15mm laminated sliding or glass doors. But, I hope to source the 2 x sliding and 2 x swinging doors for no more than $6,000AUD. • 2 x Rinnai Ururu Sarara = 2 x 1,728 = $3,456AUD • Green Glue/QuietGlue ($352AUD for 12 tubes versus about half that price for QuietGlue) • Frychek Gyprock (I will need about 130-140 square metres not including the outer-leaf ceiling that is not part of this budget). 16mmx1200mmx3600mm is $45.05. So at a rough guess about $1,500AUD • Engineered floor boards at approximately $25 per square metre will add up to about $500-$600AUD Thank you to everyone who read all that and got to this point. It sure is a lot to get through! I also hope that this first post is ok.

Congratulations on your planning so far Ben! I am in a very similar situation to you - planning using John Sayer's Small Studio design as the basis. I am sure far more experienced members than me will offer advice and as my plans are so similar to yours I will watch this thread closely. I hope to use the Daikin Sarara also as it offers fresh air which most don't. I too would like to start with one unit in the CR first to see if it works well enough for my needs. With your under slab wiring I notice you don't have power or audio cabling going to your speaker soffits - I am planning to do this as one of my only uses of under slab ducting. Regards Jim

Hi Jim, Thanks for support! We met with the owner of the building company yesterday and we still appear to be on track which is great. Some of the numbers around $ for the whole project are a bit scary, but, the builder is confident at this stage that he can do what I have asked. You are right that there is currently no plan for conduit for soffit power and audio. I am hoping to power the speakers via the surface mounted power points that will be behind the desk. The audio runs were just going to go across the floor behind the desk and then around the the back of the speaker. Those two cable runs I had been thinking would sit in and behind finished material/wool and then be covered by board so that they are not seen running up the wall. I had hoped to have these runs set up so that they can be serviced if required, but, I assumed at least at this point that I could do all that successfully as part of the inner build. Please feel free to critique this less than specific answer Ddo you think that I really should have the conduit? If so now is the time for me to decide. Also, the most important issue at this point seems to be the outer-leaf ceiling. I'm really hoping to get some experienced advice in that area. Specifically, assuming a skillion roof as depicted with an 8 degree slope and at least 2700mm of height, can I expect a sandwich of Colorbond followed by the roof lining/insulation blanket (amidst internal wood beams) and then 2 layers of Frycheck Gyprock to perform reasonably well as an outer-leaf? Inside that there would be a 100mm air gap filled with 30kg/m2 mineral wool and then the inside out rooms exactly as per John's design. As per the original post I am aiming for 65db of isolation. Any help or guidance in this area would be awesome in helping me to wrap my head around any questions that come back from the builder. He is currently, absorbing my initial conduit diagram and costing the Frychek Gyprock for the ceiling. Please note that there could be a further minimum of 100-200mm of height above the 2700mm finished height that has been quoted from the perspective of no studio, ie, the garage door is 2700mm high from top of slab to top of door, so there is some more height up there I just don't know exactly how much at this point. There will also be more than than the minimum height available due to the skillion. In other words if you were standing and looking at the garage door the amount of space above the garage door increases with the 8 degree skillion angle as you look from the left most side wall across the garage door to the right most side wall. I can request that minimum height and maximum height from the builder/architect.

Hi, With the end of the year approaching planning is still underway. If anyone on the forum does have any information to impart on my initial post then that would be great! Thanks again.

Hi Ben, and welcome! :) I must have missed your initial post for some reason, since I don't recall it at all. Sorry about that! :oops:

in summary I’m planning to get the house builders to do the studio slab (with conduit under the floor for power, audio, ethernet, hopefully HVAC too and also any wiring, piping and cabling complete ready for the internal fitout),

That's actually a pretty mart thing to do, as it simplifies the isolation of all your cabling very much. The only one of those that cannot go in the slab, is HVAC. The ducts are way too big for that.

the outer-leaf consisting of 110mm solid brick and one 13mm laminated glass window,

Sounds good so far!

I would like to think that I could record a live drum kit so up to 115db

That's a fairly accurate estimate for a typical drum kit played normal-to-loud.

without any complaints coming from outside of the studio (my girlfriend and the neighbours!)

... :D It would be good to put numbers on that!

With all that in mind, I am aiming to be at most 50db outside the studio wall falling to about 40db - 38db over 3 - 4 metres.

50 dB at 1 m from the wall (standard distance) should theoretically give you about 44 at 2m, and 38 at 4m, give or take a bit. However, reality is often not as good as theory, especially if there are other things around that could guide or focus the sound, so I'd guesstimate around 42 dB at 4m from your wall. But then there's the issue of how you measure that: A-weighting and C-weighting will give you very different readings for drums. Noise regulations are normally expressed as "A", which is good for you since "A" is less sensitive to low frequencies. But "C" is more similar to how people perceive sound, so it could turn out that you would meet the legal requirements for your area, but still disturb your neighbors with the low frequency "thump-thump-thump" of kicks and snares...

I trust that this is not an unreasonable goal.

It's not unreasonable, but it's also not easy to reach. Taking 115 dB inside and knocking it down to 50 outside means you need 65 dB of TL. That's not easy to achieve in a typical home studio. Not impossible, but it requires very careful design, and very careful attention to detail in the actual building stage, since even tiny "insignificant" gaps and imprecision can have major effects, at such high levels of isolation.

then a 20-40km/hr sealed road

Do you get traffic noise from that? Vibrations? What type of vehicles? (just cars, or also buses, trucks, farm equipment, etc.).

I am working through inner-leaf research, but, again, the focus of this initial post is on the outer-leaf, slab, external window and HVAC prep. Any thoughts about things that need to be done now to avoid impacting later parts of the build, inner-leaf etc would be greatly appreciated!

Make sure that outer leaf has as much mass as possible on it: specify the heaviest bricks you can find (highest density), and specify that the mortar joints must be done very carefully, very consistently, zero gaps, no entrained air, no holes, etc. Then render the face of that wall to add even more mass, and also to act as a seal on the bricks. Then paint the render, to seal that too. Your outer leaf needs to be as solid, massive, rigid and sealed as you possibly can make it.

6. Air to/from the A/C in the CR (orange line) 7. Air to/from the A/C in the LR (orange line) ... (please set me straight if I’m being dumb!)

OK, you asked for it! That part is "being dumb". The rest is fine. Your HVAC ducts will be very much larger than can fit in a slab. Probably about 20 to 25cm. So unless you want a 50 cm thick slab, leave out the HVAC ducts! :)

1. I am aware that John has recommended the Daikin Ururu Sahara before due to its added fresh air and humidity functions.

Well, yes, it brings in fresh air, but then what? Where does the STALE air go? Your room is inside a double-hermetically perfect seal.... In a normal house, there is plenty of air leakage through gaps and cracks, but not in your studio. You need a duct to get the stale air out too. Plus, when John suggests those Daikin units, I'm pretty sure he's talking about control rooms, where there is not much physical exercise going on, not live rooms, where there can be plenty of physical exercise going on. That makes a big difference to the amount of fresh air you need, as well as the cooling and dehumidifying capacity. There's a lot of calculation that goes into HVAC, and you really should do that, to figure out how much air you need to bring in, and how fast.

I don’t understand at this point how to go about getting A/C vents through the outer and inner-leaf sections that would be impacted.

Exactly. That's a big issue, especially in your case, where you need major isolation. The way you accomplish that is with "silencer boxes", which are basically just large wooden boxes with baffles arranged inside, and lined with duct liner. It's more complicated than that, but that's the basic concept. You need one silencer box on each leaf penetration.

There would also be no specific fresh air function.

I'm not sure what you mean by that. There WILL be very specific fresh air requirements, that you calculate as part of your HVAC design, based on the number of room changes per hour that you need, which in turn is based on room occupancy and physical activity.

I was thinking, that if fresh air can’t be delivered as part of the A/C then I could consider something like 2 x Aeropack’s...

Hmmm.... sounds strange.... They say "Outside noise is absorbed by Aeropac’s highly efficient acoustic absorber." Unfortunately, absorbing sound does not isolate! So either their marketing guy used the wrong words there, or the claims are rather suspect. I'd suggest you ask for the full report on just how well that things isolates, with the results of the tests conducted in a reputable independent acoustic test lab. If they can't (or won't!) give you that, then that should be the end of your conversation with them. If they do give it to you (and hopefully they will), then post it here, and we'll take a look. But I have to say I'm rather skeptical of those claims!

hope it will be possible to create an effective outer-leaf by having a mass of Colorbond + any under-roof sealing sheets and linings + 2 x 16mm sheets of Frychek, ie, all bound together and functioning as an outer-leaf.

If it is all sealed properly and well built, that could indeed be the basis of your outer leaf. However; there is way, way less mass in that than there is in a brick wall, and one of the basic points of acoustic isolation is consistency in surface density around the entire studio. If four sides have a surface density of 250 kg/m2 while the fifth side only has 36 kg/m2, take a guess which path the sound will take?

I assume that I will lose 100mm airgap between the outer and inner leaves

For the steep amount of isolation that you need, the gap will be much, much bigger than that. I didn't do any calculations on it, but I'd guess that you'd need a gap of about 30cm or so, at least. Especialy with the very low mass on the outer leaf roof.

The inner-leaf’s will be built inside out with 2 x 16mm Frychek Gyprock (with Green Glue seals)

Just a correction in semantics: Green Glue is not a sealing compound: it is a visco-elastic polymer compound that never hardens, and is applied in such a manner that it cannot and will not seal between the two layers. It merely acts as constrained layer damping between the layers, in order to greatly improve low frequency isolation.

after the window part of the outer-leaf, there will be an air gap of at least 140mm (mineral wool filled) and then another laminated glass window,

Ummm.... I'm not sure that you want to fill the air gap between your window panes with mineral wool! :shock: Mineral wool is not very transparent, and you'd have a hard time seeing through it.... :)

QUESTIONS

I think I already covered most o that above, but there's a couple of additional points that I'll add here:

What is the best way to go about fixing the 2 x sheets of Frychek to the underside of the Colorbond.

Nails or screws into the supporting structure. Whichever your local building code allows. However, if that were my place, I would forget the tin roof and go with an acoustically better asphalt tiles roof. I would put down a few layers of 21mm marine grade plywood or OSB, with Green Glue between them, then the underlay, then the tiles. Four layers would get me to around 60 kg/m3 surface density, then another two layers of 5/8" drywall from below, using the "beef up between the joists" technique, plus the GG, the tiles themselves and the underlay, and I'd be getting pretty close to 100 kg/m3. Still only about 1/3 to 1/2 the mass of the brick wall, but in the ball park for the level of isolation you need, provided that there is also a large air gap between the roof and the ceiling.

Will a final ceiling height of 2478mm be ok when considering acoustic performance (not isolation) and the final treated dimensions of the LR and CR as depicted in John’s Sketup design file?

With acoustics "more height is always better", but 247.8 cm is not bad.

What do I have to watch out for to make sure that the builders for the home seal the 13mm external outer-leaf window is installed correctly for isolation and the elements? What is the best window frame material aluminum, uPVC or timber?

The best things is to NOT let the builder do it! Call in a glazier that specializes in studio windows, or at least has done a few of them successfully. Once again,m you are aiming for very high isolation, so you can't afford to take chances. The glass must be very carefully sealed all around, with three seals: one on each side of the pane, and one along the edge. The glazier might do the separately, or he might do them all at once, as a single seal. I prefer separate.

I believe that the inner and outer-leaf windows need to be set at an angle in the horizontal plane? What is the best angle here?

That's actually a myth, but unfortunately one that is propagated around the internet regularly. You do NOT need to angle your glass, either vertically of horizontally, for acoustical reasons, and in fact doing so will REDUCE our isolation. However, you still might need to angle the glass to prevent glare from lighting getting in the way of your view through the glass. If that's the case it would be better to re-design the lighting, if possible, so that there is no glare on the glass.

• Green Glue/QuietGlue ($352AUD for 12 tubes versus about half that price for QuietGlue)

Ummm... 12 tubes wont get you very far! You need two to three tubes PER SHEET of drywall.... (well, OK, per PAIR of sheets, to be more exact) You'll probably need at least half a dozen cases of GG. But you can figure it out by taking the total number of sheets of drywall you'll be using, and multiplying by 1.5

• Frychek Gyprock (I will need about 130-140 square metres)

That's about 50 sheets. So you'll need about 75 tubes of Green Glue. - Stuart -

Hi Stuart, Thank you for your reply and welcome! :D I'm sorry that I have taken so long to get back to you. All I can say is that Christmas and the new year kinda got in the way! I trust you had some time to do as you please over the end of year break.

That's actually a pretty smart thing to do, as it simplifies the isolation of all your cabling very much. The only one of those that cannot go in the slab, is HVAC. The ducts are way too big for that.

As advised I will only place audio, power and ethernet conduit runs in the slab. Can I safely assume that I will be able to drag/draw a finished DB25 cable through the conduit after it is fixed in the slab? This would require the internal diameter of the conduit to be approximately 60mm to allow for about 5mm extra width to get a 54-55mm wide DB25 cable through. Also, is it ok to bring the power for the surface mounted lights through the same conduit that will also house the power run for the power points? I was thinking that I could run the light power cables up inside the material covered finished inner wall and then surface mount them. Otherwise I would need to drop them down through the inner leaf ceiling and seal as well as possible to not lose any isolation.

without any complaints coming from outside of the studio (my girlfriend and the neighbours!) ...> It would be good to put numbers on that!

Over the break my sound meter arrived and I was out on our new block during a very windy day. The slow C level readings on that windy day ranged between 50-65db. I hope to be out on the block again soon on a peaceful day to get better background sound level readings.

50 dB at 1 m from the wall (standard distance) should theoretically give you about 44 at 2m, and 38 at 4m, give or take a bit. However, reality is often not as good as theory, especially if there are other things around that could guide or focus the sound, so I'd guesstimate around 42 dB at 4m from your wall. But then there's the issue of how you measure that: A-weighting and C-weighting will give you very different readings for drums. Noise regulations are normally expressed as "A", which is good for you since "A" is less sensitive to low frequencies. But "C" is more similar to how people perceive sound, so it could turn out that you would meet the legal requirements for your area, but still disturb your neighbors with the low frequency "thump-thump-thump" of kicks and snares

That all sounds very promising!

It's not unreasonable, but it's also not easy to reach. Taking 115 dB inside and knocking it down to 50 outside means you need 65 dB of TL. That's not easy to achieve in a typical home studio. Not impossible, but it requires very careful design, and very careful attention to detail in the actual building stage, since even tiny "insignificant" gaps and imprecision can have major effects, at such high levels of isolation.

I hear you! I just hope that my planning and implementation will be up to the task. When I get to the inner room build I will most likely work alongside a contracted builder.

Do you get traffic noise from that? Vibrations? What type of vehicles? (just cars, or also buses, trucks, farm equipment, etc.).

No there is no significant traffic and zero heavy traffic as the block is part of a high conservation area within a state forest. There are other homes, but, our block only has an immediate neighbour on one side. They will be approximately 4 metres away. The other 3 sides of the property are bound by low speed roads and there is only 1 neighbour on the far side of those roads in one direction. The other 2 sides are bounded by forest reserve that can not be developed. They are public, state forest reserve.

Make sure that outer leaf has as much mass as possible on it: specify the heaviest bricks you can find (highest density), and specify that the mortar joints must be done very carefully, very consistently, zero gaps, no entrained air, no holes, etc. Then render the face of that wall to add even more mass, and also to act as a seal on the bricks. Then paint the render, to seal that too. Your outer leaf needs to be as solid, massive, rigid and sealed as you possibly can make it.

Yes, I am researching heavy (dense) bricks at the moment and will discuss the motar needs with the builders and engineer in about 2 weeks time. I had planned on rendering the inside of the outer leaf and then painting the render once dry after reading the information and following a few builds on this excellent forum. Will this extra external rendering requirement add a little more mass and help to seal the outer leaf a bit more than if no render was used on the outside? I will talk to the builder and engineer about brick density. Boral and Austral Bricks are 2 big suppliers here in NSW Australia. The following URL has tech specs for Austral Bricks: http://australbricks.com.au/nsw/getatta ... e.pdf.aspx On page 2 there are 2 bricks that I think may be what I am after and I was hoping to get clarification that they have the required density. The first is their Dry Press solid brick 230mm x 110mm x 76mm with density of 211.5kg/m2 including mortar and the second is called a Through Wall 76 230mm x 150mm x 76mm with density of 236.2kg/m2 with mortar, but, that second one does not seem to be totally solid (yet it seems to have a higher density, perhaps due to the extra 40mm of width?) Do either of those two bricks sound ok? Or is one better than the other and do they have the kind of density I should be aiming for or is a higher density possible with another type of brick?

OK, you asked for it! That part is "being dumb". The rest is fine. Your HVAC ducts will be very much larger than can fit in a slab. Probably about 20 to 25cm. So unless you want a 50 cm thick slab, leave out the HVAC ducts!

Thanks! I did think that HVAC in the slab was likely to be a bridge too far and more than a bit silly :oops:

Well, yes, it brings in fresh air, but then what? Where does the STALE air go? Your room is inside a double-hermetically perfect seal.... In a normal house, there is plenty of air leakage through gaps and cracks, but not in your studio. You need a duct to get the stale air out too. Plus, when John suggests those Daikin units, I'm pretty sure he's talking about control rooms, where there is not much physical exercise going on, not live rooms, where there can be plenty of physical exercise going on. That makes a big difference to the amount of fresh air you need, as well as the cooling and dehumidifying capacity. There's a lot of calculation that goes into HVAC, and you really should do that, to figure out how much air you need to bring in, and how fast.

I now realise that I did leave out of my plan an extractor fan. I will plan to have 1 or 2 extractor fans depending on whether the CR and LR can share 1 fan or if 2 separate fans are required. I assume that silencer boxes are also required here as the ducting out of the CR and LR will need to punch through both the inner and outer leafs. I also assume that it will be better to not have those punch holes inline with each other, ie, the exhaust ducting would turn 90 degrees and run a distance parallel to the air gap between the leaves before turning 90 degrees again and exiting through the outer leaf? The holes will also need to be sealed as well as possible with acoustic caulk? Is that correct? I hope so :?: In the past I have felt tired in studios when I knew I should not feel tired and guess that this feeling was due to low fresh air. I will talk more with available HVAC specialist around my way to better understand the amount of fresh air required for both the CR and LR and how best to achieve that. I have also been reading the forums about silencer boxes and their design.

I'm not sure what you mean by that. There WILL be very specific fresh air requirements, that you calculate as part of your HVAC design, based on the number of room changes per hour that you need, which in turn is based on room occupancy and physical activity.

Sorry my bad, I'm probably just a bit confused here regarding fresh air. I am struggling to understand why most splits do not draw fresh air through while ducted systems apparently do? That is why I was interested in the Daikin Ururu Sahara (along with its humidity function). Are not all AC units a system whereby hot air is cooled outside of a room and then pumped through to the room that requires cooling? Assuming that is correct what is different between split and ducted AC such that the ducted brings fresh air into the room (and if so how much) whereas the split does not bring fresh air? I assume that ducted must be bringing more than 15% fresh air thus making it more attractive for studio use than the Daikin Ururu Sahara? :?: I will be stearing clear of the Aeropac's at this point.

If it is all sealed properly and well built, that could indeed be the basis of your outer leaf. However; there is way, way less mass in that than there is in a brick wall, and one of the basic points of acoustic isolation is consistency in surface density around the entire studio. If four sides have a surface density of 250 kg/m2 while the fifth side only has 36 kg/m2, take a guess which path the sound will take?

I understand and will think a lot more about the outer leaf ceiling.

For the steep amount of isolation that you need, the gap will be much, much bigger than that. I didn't do any calculations on it, but I'd guess that you'd need a gap of about 30cm or so, at least. Especialy with the very low mass on the outer leaf roof.

Ok. If the outer leaf ceiling was closer to a surface density of 250 kg/m2 then would the required air gap come down a bit and would the larger air gap need to be completely filled with mineral wool too to achieve the required isolation?

Ummm.... I'm not sure that you want to fill the air gap between your window panes with mineral wool! :shock: Mineral wool is not very transparent, and you'd have a hard time seeing through it.... :)

Ooops ... I mean that mineral would enclose/fill all but the window part of the air gap :mrgreen:

However, if that were my place, I would forget the tin roof and go with an acoustically better asphalt tiles roof. I would put down a few layers of 21mm marine grade plywood or OSB, with Green Glue between them, then the underlay, then the tiles. Four layers would get me to around 60 kg/m3 surface density, then another two layers of 5/8" drywall from below, using the "beef up between the joists" technique, plus the GG, the tiles themselves and the underlay, and I'd be getting pretty close to 100 kg/m3. Still only about 1/3 to 1/2 the mass of the brick wall, but in the ball park for the level of isolation you need, provided that there is also a large air gap between the roof and the ceiling.

Ok, so if the studio plan was exactly the same as it is now except it was a basement studio then would it be easier to achieve higher isolation for the outer leaf ceiling, for example, higher than 100kg/m3. I have read a fair bit on the forums about adding mass to the underside of floors between the bearers using 2 or more layers of Frychek, green glue between layers and then acoustic caulk to seal around all edges. Many of these examples also seem to finish this "bulking" up of the underside of the outer leaf with mineral wool. If a basement style approach like this was more likely to achieve better isolation for the outer leaf, then it is not too late for me to work with the architect to modify the plans. We have played around with other configurations for the entire design prior to getting to the current layout and can re-jig the layout at no further expense to us. Getting the outer leaf ceiling as "right/correct" as possible to achieve maximum isolation in a sensible and tried and true way is something that it very important to me. I would be prepared to work with the architect to do this even if it delays the build. I'll also be budgeting for a lot of green glue to dampen between layers! If anyone on the forums has a recommendation for the best place to source cost effective bulk green glue then I would be very appreciative. I will also talk to our builders to see if they have access to good prices. Thanks again Stuart I really appreciate your input !!!

Considering the attached image, can I safely assume that I will be able to drag/draw a finished DB25 cable through the conduit after it is fixed in the slab? This would require the internal diameter of the conduit to be approximately 60mm to allow for about 5mm extra width to get a 54-55mm wide DB25 cable through.

DB25 is pretty big, and not too flexible, so you'll need to keep your curves very broad, very large radius. I would go for something bigger than 60 mm for a 55 mm cable. But are you SURE you mean 55mm? That's a massively thick cable! What do you need that for? Just curious. Whatever it is, maybe it would be better to convert it to a CAT5 signal, and just run CAT5 cable all over? Much thinner, more flexible, easier to handle.

Also, is it ok to bring the power for the surface mounted lights through the same conduit that will also house the power run for the power points?

Technically, that's fine, but there might be strange electrical code restrictions on running power and lighting circuits in the same conduit. Better check your local code.

Otherwise I would need to drop them down through the inner leaf ceiling and seal as well as possible to not lose any isolation.

... unless you build your ceiling "inside-out"... or use proper surface-mount ducting, such as Legrand.

The slow C level readings on that windy day ranged between 50-65db. I hope to be out on the block again soon on a peaceful day to get better background sound level readings.

Probably some of that was wind noise on the mic itself. Seems a little high, although certainly possible.

Will this extra external rendering requirement add a little more mass and help to seal the outer leaf a bit more than if no render was used on the outside?

Yep!

Do either of those two bricks sound ok?

They both sound fine. The render will add a few more kg to that.

I will plan to have 1 or 2 extractor fans depending on whether the CR and LR can share 1 fan or if 2 separate fans are required.

Right! I would go for separate fans, one for each room, so you can control each individually, as needed. It's never a good idea to drive two ducts from one fan either, unless they have identical static pressure drops: Else you get one branch taking all the air, and the other none.

I assume that silencer boxes are also required here as the ducting out of the CR and LR will need to punch through both the inner and outer leafs.

Right again. For the type of high levels of isolation you are looking at, you probably need silencers on EACH leaf. In other words, your CR intake duct has a silencer outside the outer leaf, and another silencer inside the inner leaf: Ditto for the CR exhaust duct. Duplicate for the LR. Yeah, that a LOT of plywood, and a lot of work, but to get high levels of isolation, that's the only way.

I also assume that it will be better to not have those punch holes inline with each other, ie, the exhaust ducting would turn 90 degrees and run a distance parallel to the air gap between the leaves before turning 90 degrees again and exiting through the outer leaf?

You could do that, if your air gap is REALLY big: But often there isn't enough room in the gap for that. Ducts are huge. It's usually easier to just put a flexible coupling across the gap, with a silencer box on each side. It can be done the way you suggest, and I often try to use ceiling space for that, but it takes careful planning.

The holes will also need to be sealed as well as possible with acoustic caulk? Is that correct?

Oh yes! Hint: you might as well buy shares in the acoustic caulk company, since their stock will rise as soon as you start buying enough caulk to do your project! :)

Sorry my bad, I'm probably just a bit confused here regarding fresh air. I am struggling to understand why most splits do not draw fresh air through while ducted systems apparently do?

Most split systems are intended for typical homes or offices, where there is plenty of ventilation through the usual "leaky" designs. But studios are a rather special case, since they are sealed absolutely air-tight, twice over, so there is no natural ventilation at all. True ducted systems with an air handler are designed to take in fresh air and add it to the recirculated air, while also exhausting the same volume of stale air to the outside world. The entire purpose of a mini-split system is to divide the typical old-style window air conditioner into two parts: the compressor (which is noisy) then goes outside, while the condenser (which is basically just a radiator with a fan to blow air through it) is very quiet, and goes inside. The only thing joining the two unites is a couple of copper pipes for the coolant, and an electrical cable. Plus usually a drain pipe, for the condensate. So you can have the two units a long way apart, and only small holes in the wall to pass through the pipes and cables. But not fresh air. The older style window units did also have fresh air vents on them, because the two units were combined into one that occupied a huge hole in the wall or window. But with mini-splits, the hole is tiny, and there's no fresh air (except on a very few units, and even then it is only a token amount of fresh air).

Are not all AC units a system whereby hot air is cooled outside of a room and then pumped through to the room that requires cooling?

Nope! In ALL air conditioned units, hot air is drawn from the room itself, cooled, then returned to the room. The heat is removed by "pumping" it outside. It works like this; You basically have two radiators, one inside the room, the other outside the room (even in the old window-style units it is done like this). There's copper pipe joining the two radiators in a continuous closed loop, and there is a phase-change fluid sealed into the system. Part of the time that fluid is liquid, and part of the time it is gas. There's compressor in the loop as well. The compressor sucks in the fluid in its gaseous state, compresses it so it becomes a hot liquid, passes it through the radiator on the outside of the room, where it cools down a bit, then passes it through an expansion nozzle inside the pipe, where it turns from liquid back to gas, and therefore gets very cold, very fast. So that icy cold gas passes through the radiator inside the room, where warm room room air is passed through the radiator, so it becomes cool and the gas in the radiator warms up, where it goes back to the compressor, and the whole cycle repeats. So in all systems you have two radiators, where one of the is cooling down the room air while the other is heating up the outside air. Air inside the room stays inside the room, and just passes over the condenser radiator, while air outside the room stays outside and just passes over the compressor radiator. With old style window units, all of this is contained in one physical box, with half outside and half inside, AND ALSO a vent flap that allows some limited amount of fresh air to get through into the room. But that's just an "extra". The reason for separating the two radiators and NOT mixing inside air with outside air, is efficiency as well as the sometime huge differences in temperature between inside and outside. You normally want the temperature in the room at about 20°C, but the temp outside might be +40°C or it might be -40°C, or anywhere in between: If you brought outside air in at +40, you'd have to cool a huge volume of air inside the room by a very large amount, all the time, but if you keep the hot air outside, then the room air is only going to need a little bit of cooling every now and then. And if you bring in lots of -40 air from outside, then you are going to need to heat a huge volume of air to get it to +20. By keeping the room air separate from the outside air, you only need to compensate for the slight increases and decreases in room temperature as they occur, instead of wasting massive amounts of energy. It's the exact same principle as your refrigerator: The concept is identical, with one radiator outside dumping he heat, another one inside doing the cooling, and a compressor between. As long as you keep the door closed, it can keep the inside very cool all day while drawing very little power, but if you leave the door OPEN, then it cannot keep it cool at all, since it does not have the ability to cool the huge extra volume of air. So all units work the exact same way (even refrigerators), by circulating room air through the cooling radiator, outside air through the compressor radiator, and pumping the phase-change coolant fluid between the two units. The ONLY difference with a min-split is that the two parts are not longer contained in the same physical box: they are now "split" into separate boxes, joined by the coolant pipes.

what is different between split and ducted AC such that the ducted brings fresh air into the room (and if so how much) whereas the split does not bring fresh air?

Actually there is no difference at all! :) A ducted system is also a split system, where there is a "heat pump" unit outside (the compressor and its radiator), and an "air handler" unit inside, and they are connected by coolant pipes and electrical cables. The principle is identical. What does change is that the air handler is inside a duct, and that duct branches out to feed many rooms. Then each room has a "return" register that goes into a return duct, with all those return ducts eventually joining together and arriving back at the air handler. So it's identical to the mini-split in concept, except that a ducted system handles several rooms at once, while a mini-split only does one room. The difference comes in with the fresh-air intake and stale-air exhaust. Part of the ducting does bring in a controlled amount of fresh air from outside, and dumps the same amount of stale air to the outside world. In some cases, those two streams of air (intake and exhaust) also go through a heat exchanger, to recover some of the heat being wasted overboard, which helps to deal with the problem of the huge temperature differences I mentioned above. For example, in very cold climates where the outside air being sucked in is at -20°C or some such, while the inside air being dumped is at +25°C, both streams go through a heat exchanger that transfers the outgoing heat to the incoming air, but without mixing the two streams. It's basically an "air to air" radiator. You can warm up the intake air greatly before adding it to the system, and save huge amounts on your heating bill. But that's probably not an issue where you live! The same applies when you have +40° air outside coming in, and you are dumping +20° air going out. The heat exchanger transfers some of the heat in the incoming air to the out going air, so the outgoing air gets hotter while the incoming gets cooler. So you don't need to waste energy cooling down 40° air, probably only +30° air.

I assume that ducted must be bringing more than 15% fresh air thus making it more attractive for studio use than the Daikin Ururu Sahara?

You need to bring is as much fresh air as is required to replace the air that is "used" by the people in the room, plus a bit more because the exchange is not 100% efficient. Air is "used" in several sense, such as the oxygen being depleted and replaced by carbon dioxide, as well as the humidity being increased by breathing, sweating, etc., and also various unpleasant odors being added to it. So you have to remove that "used" air at the same rate it is being produced, or faster. So you need to know how many people will be in the room, and how hard they will be working, to figure out how much air the will be "using". It's one thing to have a single person sitting at the console, doing nothing more strenuous than listening and occasionally moving a fader, and it's entirely another thing to have half a dozen hot sweaty musicians banging out their very best impression of a troop of wildly mad baboons destroying a perfectly good set of musical instruments! The lone guy mixing is hardly using any O2 at all, butting very little CO2 back in, and very little humidity. The troop of baboons is doing their best to outdo the entire world production of CO2, and pumping out Niagara falls worth of humidity. Very different cases. Each needs very different fresh air circulation requirements, and very different heat and humidity handling. The biggest problem of all is when the troop of baboons suddenly joins the lone mixer in the control room, to listen to the results of their efforts: suddenly you have a system that was having to handle a minimal load being forced to handle a maximum load, and it has to adapt in minutes. Meantime, the system in the CR that was working overtime, suddenly has nothing at all to do, so it too needs to adapt fast. If not, then you end up with condensation running down the walls...

Ok. If the outer leaf ceiling was closer to a surface density of 250 kg/m2 then would the required air gap come down a bit and would the larger air gap need to be completely filled with mineral wool too to achieve the required isolation?

You need to start working with the equations to figure that out, if you want to fully understand what you are doing. Or you can just look at the published data (such as that found in the Canadian IR research papers, or the huge technical library of the BBC) and find a construction that meets your needs. But yes, in general, if you increase the mass on one (or both) leaves, then you can reduce the size of the air gap and still get the same total isolation. That said, the absolute minimum gap is about 4" (10cm): Below that and you are into "diminishing returns" territory, where the mass you need to add takes up more space than the air gap you are saving!

Ok, so if the studio plan was exactly the same as it is now except it was a basement studio then would it be easier to achieve higher isolation for the outer leaf ceiling, for example, higher than 100kg/m3.

Assuming that the floor above can carry such a heavy dead load, then yes.

I have read a fair bit on the forums about adding mass to the underside of floors between the bearers using 2 or more layers of Frychek, green glue between layers and then acoustic caulk to seal around all edges.

Right. You need to copy the same concept (but maybe not with the same procedure) for getting more mass on your roof.

Many of these examples also seem to finish this "bulking" up of the underside of the outer leaf with mineral wool.

The wool is not there to add more mass: it is there to act as acoustic damping in the air gap. It damps the resonances that form between the two leaves, as well as the actual MSM resonance itself, and other things too. Without it, you lose a lot of isolation. It does basically the same job as the chock absorbers on your car: Take those off, and you still have a nicely sprung ride (the springs are still there!), but you'll be bouncing up and down all over the place in six different ways, since there is nothing to remove the resonant energy from the system. Each bump in the road that your tyre hits introduces a different resonance into the tyre-spring-car system (ie, the Mass-Spring-Mass system), and since there is nothing to stop that resonance, it just carries on vibrating and resonating. The job of the shock absorber is to damp that resonance. The mineral wool does the exact same job inside your wall. The tiny amount of mass it adds is negligible, and not it's real purpose.

If a basement style approach like this was more likely to achieve better isolation for the outer leaf, then it is not too late for me to work with the architect to modify the plans. We have played around with other configurations for the entire design prior to getting to the current layout and can re-jig the layout at no further expense to us. Getting the outer leaf ceiling as "right/correct" as possible to achieve maximum isolation in a sensible and tried and true way is something that it very important to me. I would be prepared to work with the architect to do this even if it delays the build.

Are you saying you could move the entire studio underground, into a basement? If so, that would be a very real, very good possibility, for several reasons, and could greatly simplify your isolation. Or are you saying that you want to use the same approach as used in basements, and apply it to your roof? That will also work.

I'll also be budgeting for a lot of green glue to dampen between layers! If anyone on the forums has a recommendation for the best place to source cost effective bulk green glue then I would be very appreciative. I will also talk to our builders to see if they have access to good prices.

I'd suggest contacting the Green Glue company directly, and ask for a list of distributors in our area. Or if there aren't any, then ask how you can get it shipped to you. By the way, I'd still suggest changing the design slightly: the right rear wall of your control room does not need to be angled like that. It's a bit misleading on John's model, but that isn't even a wall back there! It's a bass trap... It is just framing with fabric on it and mineral wool behind... :) - Stuart -

Hi Stuart, Thanks again for your reply, the wealth of very very useful information and great analogies that have really helped, especially regarding HVAC. I will also chase down the Canadian IR research papers and BBC information and hopefully that information will make some sense ... :wink: I will keep this reply short, other than to say that I am seeing the engineers and builders in the next 24 hours and we have already adjusted the house design so that the same studio design will now be under the house. It will not be in a basement as such, rather, the land slopes away by about 2-3 metres over the 30 metre length of the block. So, the same studio will now be under the home, enclosed by a solid brick outer leaf on slab. The de-coupled inner rooms will then be built as per John's design. Though I do hear you about the CR bass trap. The engineer is already aware that I will want to "beef up" the sub floor above the studio and he is factoring that into his load calculations. There will be a finished height from slab to bottom of the joists of 2750mm (before the inner room) and the preliminary drawings of the changes has a further 320mm above that 2750mm from the bottom of the joists up to the top of the floor above. The area above the studio is to be kept wire/pipe/cable free to make the "beefing up" as easy a possible. I am hoping to have a final finished height of at least 2400mm (assuming a 300mm air gap), but, I would prefer to have as much height as possible. I would love to think that a 100mm air gap and a finished height of 2600mm would be possible if I am very very careful and fastidious about the build within the brick outer leaf. But, that's all a long way off at the moment! The other thing I should clarify is that I already have 2 x crimped Mogami DB25 to 8 male XLR snake cables. The 55mm that I was referring to is the width of the DB25 connector. It would be great if I did not have pull my cables apart, ie, carefully pull/draw the DB25 end through conduit of a suitable diameter from the LR to the CR. Otherwise, I guess I could always carefully disassemble the 8 XLR ends and pull/draw that end of the cable through the conduit. But, I would prefer not to disassemble if possible. Thanks again for the great information. As soon as I have an updated floor plan and elevation I will post it and respond to any other answers above.

The area above the studio is to be kept wire/pipe/cable free to make the "beefing up" as easy a possible.

This might save you quite a bit of time, money and hassle: Don't beef up! If you are building this place from scratch, then you do NOT need to beef it up from below! Instead, just put down three layers of OSB for your sub floor on top, and you are done... :) "Beefing up" is for situations where the house is already built and you have no way of adding stuff more mass on top of that floor, since that would raise the floor level and mess with doors, furniture, steps up/down, etc. But if you are building the place from the ground up, then just design it with those joists set a bit lower to start with (to compensate for the floor thickness), slap on three layers of sub-floor (eg: 3 layers of 16mm plywood, OSB, etc.) and you are finished. No beef-up necessary. Stagger the joints between layers, seal the joints carefully as you go, even use Green Glue between layers if you really need major isolation, and that's it. It sure beats beefing-up, which is a major pain, slow, boring, expensive, etc.

we have already adjusted the house design so that the same studio design will now be under the house. It will not be in a basement as such, rather, the land slopes away by about 2-3 metres over the 30 metre length of the block. So, the same studio will now be under the home, enclosed by a solid brick outer leaf on slab.

Cool! That makes a lot of sense. Solves a lot of potential issues, and probably makes the entire thing cheaper too. Good move. Just make sure that the brick is plastered, to seal it well.

2750mm from the bottom of the joists up to the top of the floor above. The area above the studio is to be kept wire/pipe/cable free to make the "beefing up" as easy a possible. I am hoping to have a final finished height of at least 2400mm (assuming a 300mm air gap), but, I would prefer to have as much height as possible. I would love to think that a 100mm air gap and a finished height of 2600mm would be possible

I think we can do better than that! :) There's two techniques that allow you to improve your ceiling height. One is called "interleaving", where you basically have the ceiling joists for your new room set in between the floor joists coming down from above, so that your new ceiling drywall is just a cm or two below the bottom edge of the floor joists. The two sets of joists don't touch each other, of course, but basically you are using the space between each pair of floor joists above you, to place the ceiling joist for your room below. Not sure if I'm explaining that: if not, I'll do a sketch for you. The other technique is "inside out" construction, where you build the ceiling the "wrong" way around: drywall on top, joists underneath. For a normal room, that would be terrible, ugly, etc, but for a studio it is a God-send: You need huge amounts of treatment in the ceiling anyway, so why not put it between the joists, and put the drywall above, instead of below? Here too the drywall can sit just a couple of cm below the floor joists above you, and acoustically speaking, the drywall IS the boundary of the room. If you build your ceiling the conventional way (joists on top, drywall below) then you still need to add your ceiling treatment below that, so you lose maybe 10 to 20 cm for that, but if your drywall is on top of the joists then the treatment can end flush with the joists. ... :) Not sure if I explained that one clearly either: It's 3:20 AM right now, and my rain ain't workin' 100% Firing on only 3 cylinders, I think.... Anyway, if you need more details on those techniques, just yell and I'll sketch something for you. With either of those two techniques, you can gain quite a few cm of ceiling height. For free! Final drywall height can probably be around 2700, with a bit of luck... 8)

ps ... do you drink beer ??? we have a great local craft brewery over here at http://www.murraysbrewingco.com.au I think I will owe you some

Cool! :) It might be a bit pricey to ship it to where I live though! I'm half way around the world from you... I did used to live not too far from you (relatively speaking), in Wollongong, many, many years ago, when the universe was younger and the stars were brighter... But now I'm a little further away. Shipping beer to Chile is probably out of the question! However, the thought is certainly appreciated! :thu: - Stuart -

Hi Stuart, Thanks again! This is now an edited post after meeting with the engineer yesterday. I really hope I am not being too much of a pain by asking a few more questions and removing the ones that were here about 12 hours ago as I don't think they are as relevant now. The changes should hopefully stop very soon! Anyway, after our meeting yesterday, the engineer has suggested that the outer-leaf walls be built with 150mm wide concrete bessa blocks that get filled with concrete after they are laid to make the wall completely solid. He also suggested that conduit can be run down through the gaps in the blocks prior to filling them with an elbow type join at the bottom coming up under the slab just inside the inner-leaf wall. He said that power for lights and power points will be ok in the same conduit in our area. There would still be 4 conduit runs all up. 1 for for power and light to the LR, 1 for power and lights to the CR, one for cat6 and the last a bit different as it will not be in the wall rather just the slab for the audio run between the LR and CR. The floor plan for the studio will not change. The reason for this block idea is to ensure that downstairs can carry the weight of upstairs while also keeping costs under control. It turns out that until now he had been thinking that downstairs would be brick veneer. As soon as I understood that meant a wood frame inside a single skin brick wall to support all the weight, I asked how we could go about just having a dense, heavy-mass, single skin wall for the outer-leaf without any extra framing etc. Thus the concrete filled bessa block idea above. He also said that by using these blocks it removes the need to retain the land around the downstairs area thus saving some money and also that it brings other options for the outer leaf ceiling above the studio into play. Specifically, he said that by the time 3 layers of OSB, green glue, acoustic caulk and bearers and joists are are factored in and installed you may as well have poured 120mm of concrete for the outer leaf ceiling as that would probably be more cost effective and definitely isolate better. In addition he also thinks that all that can be done less trades to also save a bit more on labour and that there will be no engineering issues to span the studio space as it is not large. So, I guess I am hoping to now ask the following couple of questions :roll: 1. Firstly, the whole wall and ceiling outer leaf would definitely be strong enough to hold all the weight with the above suggestion. But, does all of the above sound sensible, practical and correct from a studio design perspective? ie, does this sound like a good way to have a consistent, heavy mass, outer leaf around all 6 surfaces of the studio space and still get power and internet into the inner leaf without having to punch through and lose some isolation? If it is also turns out to be more cost effective when compared to other solutions then that would be an added bonus. 2. Assuming all the above block and concrete outer leaf idea is ok then can I still have only a small air gap between the inner and outer leaf ceilings? And how small can this air gap be, eg, 20mm, 30mm, 40mm or more? The old plan had 320mm between the upstairs space and the studio. We will need 17mm of that for finished flooring and underlay upstairs and then there is 120mm of suggested concrete beneath that leaving 183mm. The engineer mentioned some kind of supporting layer for the concrete to be poured onto, but, I do not remember what he said that was nor how much height space that will take. But, I am reasonably sure that it will not take more than the remaining 183mm. With any luck the air gap can be within that left over 183mm too leaving the full 2750mm of height downstairs for inner leaf and finished floor construction. So, after building the inner leaf ceiling inside out (2 x 16mm of Frychek Gyprock + 90mm x 45mm framing) and adding 17mm of engineered wood flooring to finish, I hope to have at least 2750 - (2 x 16) - 90 - 17 = 2611mm finished height inside the studio. If I get a bit more because some of the 183mm mentioned above is left over after air gap and whatever is supporting the concrete pour then that would be a bonus.

Hi again, This weekend I spent some time learning how to use Sketchup. A big thank you to Stuart as your advice and knowledge is absolutely invaluable. Thank you many times over! 1. Based on the tape in Sketchup, the inner leaf framing rises approx 262mm (including 32mm of Frychek not shown) above the 2750mm high brick/concrete outer leaf wall as shown in the pictures below. The outer leaf ceiling is not shown and the real outer leaf height will be 2750 + 320 = 3070mm. That extra 320mm of height above the 2750mm outer leaf wall separates the studio space from the lounge room upstairs. I will need approx 20mm of that for flooring in the lounge room and 120mm for the concrete outer leaf ceiling that has been proposed by our engineer. That leaves approx 180mm of which some further height will be lost by whatever is used to support the 120mm concrete pour and the air gap that will separate the inner and outer leaf ceilings. I hope to have at least 100mm of the 180mm left over. In summary those height calculations are: 2750 + 320 = 3070mm (total height) 3070 - 20 -120 - 20 = 2910mm (inner leaf height = total height - flooring height upstairs - concrete outer leaf ceiling thickness - air gap) 2910 - 262 = 2628mm (maximum studio height = inner leaf height - inner leaf ceiling height - studio finished wood floor height) So, if the height of the material that supports the 120mm concrete pour (after form work has been removed) is less than 48mm I hope to have a finished height inside the studio of approximately 2580mm-2600mm at the sides of the studio rising a further 200mm or so to the peak at the centre. 2. In the pictures the green HVAC is meant to indicate air in and the red HVAC air out. I am also assuming that I will be able to run the duct in the air gap between the inner and outer leaf walls. That air gap is 100mm and I have used 80mm ducting in Sketchup. I hope that will be enough diameter to move the required air in and out. I have also simply guessed at the size of the silencer boxes inside the studio. I will adjust these after reading more about sizing on the forums and talking to HVAC specialists in the real world. I am also not showing how the HVAC ducting connects up outside at the back of the studio as that will be under the house. I am assuming that this task will not be too complex, there will also be easy under-house access and I am not worried about how this will look aesthetically as no one will be able to see this from outside of the home. It is also possible that this ducting may terminate outside at the side of the studio/house depending upon the best location for the condenser unit and extractor fan/fans. 3. I have drawn 4 yellow conduit runs that have internal diameters of 30mm and I hope to place them in the outer leaf walls and under the studio slab. As above, after talking to our engineer I am hoping to use bessa blocks for the outer leaf walls that are filled with concrete. The aim is to run the conduit prior to the slab being poured and the blocks being filled. I am also assuming that an electrician will be able to feed the required light, power point and cat6 cable through this conduit so that lights, power points and internet can be surface mounted later within the inner leaf structures. The conduit near the window is for cat6, the one near the door is for HVAC controls, light switches, lights and a power point, the other one in the CR is for power points and the one in the LR is for lights and power points. As above I aim to surface mount everything. 4. There is also one, green, 60mm internal diameter conduit run between the CR and LR. I will surface mount one 16 channel, combo jack, audio patch bay in the LR. The patch bay has two DB25 outputs and this green conduit run will hold two 8 channel, DB25 to male XLR snakes. 5. I have increased the length of the CR by approximately 1 metre as our engineers plans (to be posted by the end of this week when they are available) had some extra length available. When I checked the height, length and width after adding the extra length I could not find any obvious multiples. 6. I have left most of John's internal treatments in place at this point, except I did remove the treatment around what has now become the front of the studio where the window is located. I have also increased the width of the entry door to be 1200mm and flipped the direction in which the doors open. This door flip and extra length is aimed at giving me a bit more width for the mixing desk/rack, a bit more space for a lounge opposite and a bit more space in general within the CR.

I really hope I am not being too much of a pain by asking a few more questions and removing the ones that were here about 12 hours ago as I don't think they are as relevant now. The changes should hopefully stop very soon!

Questions is what we are here for! But please don't edit your thread to remove old questions: They might not be relevant, but they do still document your entire build process, including your original line of thinking and how it changes as you learn more and start refining the design. That can be useful information for others that follow your thread in the future.

Anyway, after our meeting yesterday, the engineer has suggested that the outer-leaf walls be built with 150mm wide concrete bessa blocks that get filled with concrete after they are laid to make the wall completely solid.

That would be excellent.

He also suggested that conduit can be run down through the gaps in the blocks prior to filling them with an elbow type join at the bottom coming up under the slab just inside the inner-leaf wall. He said that power for lights and power points will be ok in the same conduit in our area. There would still be 4 conduit runs all up. 1 for for power and light to the LR, 1 for power and lights to the CR, one for cat6 and the last a bit different as it will not be in the wall rather just the slab for the audio run between the LR and CR. The floor plan for the studio will not change.

That's all fine. No problems there.

Specifically, he said that by the time 3 layers of OSB, green glue, acoustic caulk and bearers and joists are are factored in and installed you may as well have poured 120mm of concrete for the outer leaf ceiling as that would probably be more cost effective and definitely isolate better.

Absolutely! He's thinking things through well, and arriving at the right conclusions.

1. Firstly, the whole wall and ceiling outer leaf would definitely be strong enough to hold all the weight with the above suggestion. But, does all of the above sound sensible, practical and correct from a studio design perspective? ie, does this sound like a good way to have a consistent, heavy mass, outer leaf around all 6 surfaces of the studio space and still get power and internet into the inner leaf without having to punch through and lose some isolation? If it is also turns out to be more cost effective when compared to other solutions then that would be an added bonus.

Yup! Perfect.

2. Assuming all the above block and concrete outer leaf idea is ok then can I still have only a small air gap between the inner and outer leaf ceilings? And how small can this air gap be, eg, 20mm, 30mm, 40mm or more?

The air gap should never be less than about 100 mm, as that tends to push the MSM resonant frequency too high. However, do make sure you are measuring the gap correctly! Some people get confused about the gap between the block wall and the inner-leaf FRAMING, but what you really should be talking about is the gap between the block wall and the LEAF, which is the drywall itself. So assuming you use 40mm x 90mm studs, then a gap of just 10mm between the block and the stud frame will give you a 100mm air gap. That assumes that you are building conventionally, of course: if you build "inside-out" then you need the 100mm air gap first, then the drywall, then the stud framing comes after that. So do be aware that, for the purposes of acoustics, the term "air gap" refers to the distance across the cavity from the surface of block wall to the surface of the drywall.

As soon as I tried to draw and lock in what I have been thinking and planning over the last few weeks I realised that there is always more to learn,

Yup! :) Welcome to the world of studio design. No matter how much you learn, there's always more that you still need to know...

things keep popping up that I had not considered.

Then you are doing it right! :!:

That air gap is 100mm and I have used 80mm ducting in Sketchup. I hope that will be enough diameter to move the required air in and out.

Ummmm.... don't look now, but this is something that you can't "hope". It is another of those "things that keep popping up ". And this is a biggie: You have to calculate that diameter... And you do that based on your room occupancy, room-changes-per-hour, air-flow volume, air velocity, etc. You need to keep the air speed at the registers under 300 feet per second (fps) while also supplying the right number of cubic feet per minute (CFM) of fresh air for the room. That's how you determine duct size. And you also need to consider that all of your ducts must be lined on the INSIDE with 25mm of duct liner, so a duct 80mm wide actually only has 30mm of space for air to move, since you lost 25mm on the left and 25mm on the right for the liner...

I am also not showing how the HVAC ducting connects up outside at the back of the studio as that will be under the house. I am assuming that this task will not be too complex,

:lol: Murphy guarantees that it will ALWAYS be far more complex then you ever imagined! Murphy hates studio builders...

5. I have increased the length of the CR by approximately 1 metre as our engineers plans (to be posted by the end of this week when they are available) had some extra length available. I am hoping this was not naive and that this extra length does not introduce any significant mode issues?

Welcome to room ratios! Plug your numbers in here, and see what you get: http://www.bobgolds.com/Mode/RoomModes.htm Use the final internal dimensions of the inner-leaf, measured from hard surface to hard surface, as seen from inside the final finished-but-not-yet-treated room.

When I checked the height, length and width after adding the extra length I could not find any obvious multiples.

Multiples are just a small part of it. Multiples only tell you about axial modes, but there are also tangential modes and oblique modes, and they are all important when calculating your modal spread.

I am guessing that is most likely because John's excellent design does not really have much by way of parallel walls being opposite?

Parallel walls are part of it, yes, but but not for the reasons you think. You can have a great room with parallel walls if it is well designed, and you can have a lousy room with angled walls if it is poorly designed... :) John uses those angles because he bases many of his designs on the RFZ principle, which is something you should look into, since you are using it too, but not necessarily doing it correctly... To be very honest (brutally so!), I would suggest rotating the orientation of your room 90° left, such that it faces the booth, and making it rectangular. With the shape and dimensions you have now, your head will be too close to the rear wall when it could be much better located. In general, for a small room it is much better to have the speakers firing down the longest dimension of the room, rather than across the shortest dimension. So I would try doing that: make the room rectangular, and face it towards the left. Some other things to keep in mind: your head should end up about 38% of the room length (front wall to back wall), your speakers should be angled at about 30° inwards and aimed such that the imaginary acoustic axis from each speaker grazes just past your ear, and the two axes intersect about 30 or 40 cm behind your head, roughly. the speakers should be set up so that their acoustic axis is 1.2m above the floor. That should get you started! - Stuart -

Hi Stuart, Thank you so much again for all your experience, wisdom and suggestions. I had hoped that my posts would get shorter, but, alas this one is not so. I have prefixed new questions with >>>> to hopefully make them a bit easier to spot. First, I am really pleased that our engineers suggestions for the external-leaf will work! I feel as though the outer-leaf design and planning is getting close to being final such that my partner and I can move forward confidently with the rest of the house plans knowing that the inner-leaf design is also closer to being complete and will eventually be a reasonable acoustic space. I have added the relevant parts of the updated plans that we received last night directly below: The last issue that I am guessing will impact upon the locking down the outer-leaf is what to do with the main studio door after rotating the inside of the CR by 90 degrees. Given that the CR is not a large space, ie, it is approximately 15m2, this rotation did introduce some issues for door placement. After starting to read about RFZ design I will need to balance maximising the CR interior space against space lost due to splayed walls. I have adjusted the floor plan in SketcUp and have attached some updated images that I hope you can critique when you get a chance :) To solve the door issue I would like to use a sliding door as this will not intrude into the room and will still allow for a large opening for loading in and out. I also plan to place the desk, computer and rack gear on a workstation surface (http://www.mrack.com.au) that will be on wheels so that it can be easily moved to the side to allow larger items to be loaded into the live room, ie, a kick drum, double bass or biggish amp. I have also placed the desk and chair so that the listening position is at 38% of the room length. Please note that the angled wall between the LR and CR meant that I have drawn a different/larger soffit mounting structure. If built like this the speakers would still both be set at 30 degrees and I am hoping (there we go more hope!) that by carefully placing the speakers to still be at the same height (1200mm as per John's original design) and also the same depth, that a suitable, centred, symmetrical position will still be possible when sitting at the 38% point. >>>> Is it ok to have two differently sized soffit constructions as depicted? >>>> Also, can I ask if you think I can successfully place glass sliding doors to the CR (as depicted above) in conjunction with the changes to the studio orientation and still complete the inner-leaf construction to obtain a quality acoustic RFZ design? After searching and reading the forums for "RFZ" or "Reflection Free Zone" I understand that monitor speakers are best set at 30 degrees and soffit mounted. In addition, for smaller rooms, as you have suggested above and on the forums, the monitor speakers are best oriented to be firing along the long axis of the CR with the rear wall having a balance of absorptive and diffusive properties such that early reflections are delayed by at least 20ms and their level reduced by 20db when compared to the direct sound from the speakers. In smaller rooms it may only be possible to achieve a 15ms delay and a 10db reduction. >>> Am I right that my small CR space is likely to require walls that are more absorptive as opposed to diffusive? Either way, reflection is to be minimised as much as possible? >>>> Assuming the answer to the last question is yes, should I be concerned about the double-pane, glass sliding doors between the CR and LR and the additional set of sliding doors that I have added to CR in the the new layout? I am guessing that the answer to the last question is yes (especially for the sliding entry added to the CR) as the doors will introduce reflections. to counter this I would like to use a thick, heavy, porous, pleated, acoustic curtain on a track and pull this across the CR sliding entry door to minimise any reflections from the left monitor speaker from hitting the glass and then bouncing around. Will a quality acoustic curtain work to reduce reflections or am I being naive? As above I am really trying to maximise the internal CR space (ie no inward swinging door) while also minimising reflections and maximising the acoustic performance of the space. I am planning to use engineered timber over the floor's concrete slab, so that will be another reflective surface. Other than the 2 sets of sliding doors and wooden floors, I plan on placing as much absorbing material as possible and required to the inner-leaf under side ceiling and inside out walls. Also with all the above in mind can I expect to achieve a reasonable sound for the CR if it is more like 15m2 rather than 30m2? I have read that 30m2 is considered to be a minimum area, but, I will definitely not have that much space. Even if I turn this design into a single room design and accept a combined LR/CR I will still not achieve 30m2? I did read comments on the forums where you have said that others have been successful with smaller CRs that were well designed and built. >>>> Another question that comes to mind is what RFZ framing is required and how best to build that framing to angle the rear wall and the wall opposite the CR sliding door to maximise the amount of usable space in the CR and also achieve a good RFZ and acoustic result? Do I need to angle the back wall at all? >>>> I did read about a minimum of 12 degrees being required for effective walls and when I place the SketchUp protractor on John's SketchUp file it seems clear that 12 degrees features in most angles aside from the 30 degree set soffit mounts. But, I am a bit concerned about how much space will be lost in the CR if the back wall and the wall opposite the entry are set at 12 degrees. Can I ask what you would recommend and do to achieve maximum space and good RFZ principles if this was your room? eg would small circa 30 degree angled framing in the last 2 corners of the CR work well and still leave a flat surface for the lounge on the rear wall and a flat surface opposite the sliding door, or, should I be looking more along the lines of building a longer slanted wall on the wall opposite the sliding door that goes from the soffit speaker structure (the edge furthest from the LR sliding door) up to the rear wall set at 12 degrees. This would be similar in orientation to the slot resonator wall that can be seen in the LR. Should I also be looking to also have smaller angled framing in the last corner of the CR to avoid any 90 degree corners? Or is some other kind of combination more sensible? Finally, I guess I should ask is there a good resource or book that discusses how to go about building custom RFZ framing structures that achieve the required timing and decibel reductions based on known room dimensions?

The air gap should never be less than about 100 mm

Thanks for clarifying the airgap. The ceiling and walls of the inner-leaf will be built inside out and there will be 100mm air gap between the inside of the walls and ceiling to the frychek fixed to the outside of the inner-leaf framing. I will also locate and talk to HVAC specialists to make sure that I can get enough air exchange in and out of both spaces. On another note, thanks for the room ratio calculator. I ran the dimensions as best as I could for both the CR but not the LR as it has not changed from John's original design. The width of the CR was fairly easy to measure at 3250mm. But the ceiling does not have a consistent height as it is at a 12 degree angle and so too is the wall through to the LR. I was not sure if there is an algorithm or some sort of averaging I should be using to accurately average the room length and height to be more accurate. So, I ran the room calculator on both the maximum/middle/minimum height (2500mm/2657mm/2880mm) and maximum/middle/minimum length (4252mm/4420mm/4593mm). The results are below as PNGs. The nearest known ratio reported as 1 : 1.25 : 1.6 for the middle and maximum distances and 1 : 1.26 : 1.59 for the minimum distances. >>>> The main thing that I noticed that appears to be an issue is that the middle and maximum measurements had the following fail "1.1w / h < l / h < ((4.5w / h) - 4): Fail" all other measurements were listed as pass and I hope that the predominant green frequency spans and some yellow at the very low end ie about 37/39Hz-53/65Hz are not critical? The graphs did not seem to be too far being a "good" curve and did not seem to have any major bumps as per the example "bad" graph. Compared to the results of a bad room with 10 foot in all directions these results seem more likely to be better than bad? Given my limited understanding will these dimensions be workable? Again please know that I am truly appreciative for all of your assistance and advice!

Hi, I thought I would post a quick update. As of last week we have design approval to move forward and our plans are now on to mine subsidence. We do not expect any major issues there are no known subsidence issues in the immediate area. The nest step is submitting all of our plans and documents to the council to get a DA (development application) approved and to obtain a CC (construction certificate). We believe that could take up to 8-9 weeks. With any luck we will ready to get underway by mid May. That's all for now, Ben

Hi, Another quick update. With any luck we will have the final plans along with our geotechnical report at our local Council just after Easter.

I'm really looking forward to seeing this move forward, Ben, so I hope you can get all your red tape sorted out, without too many hassles. - Stuart -

Hi Stuart, Thanks for checking up on me! First to the conduit runs. I will definitely have the cat-6 cable run in it’s own conduit to supply ethernet to the CR. CONDUIT QUESTION 1: Am I right that I should have a separate conduit run for power that is destined to be used by music equipment, e.g., the desk, computer and outboard in the CR and amps and powered mics in the LR? CONDUIT QUESTION 2: Is it ok to run 3 separate power runs in the same conduit, i.e., one for HVAC, one for lights and the other for general non music gear power? This would happen twice, once for the CR and then again for the LR. CONDUIT QUESTION 3: How far away should the cat-6 conduit/cable run and dedicated audio power conduit/cable runs be from the HVAC/light/general conduit/cable power runs to avoid any possible interference/noise issues? Next the dreaded HVAC background and questions! First, to recap, I know that I need fresh air in, stale air out and temperature and humidity control. I’ll address fresh air and stale air part of my evolving plan first followed by a few questions. For each room (i.e. LR and CR) I will have a fresh air intake and a stale air out take. The air out will be active, i.e., there will be an exhaust fan connected to a silencer box (both of which are on the outside of the outer leaf). The silencer box will be connected to ducting that runs to an air register located on the inside of the inner leaf. The air register, ducting, silencer box and fan will all be mounted as high as is practical given that hot air rises. I will most likely build my own silencer boxes as part of the inner leaf build using information on the forums. The CR exhaust air register will be placed high on the wall near the heat generating gear. So for each of these stale air exhaust runs I will need to punch through and acoustically seal around the inner leaf to install the air registers, connect ducting with an adapter/connector to the air registers, mount and run ducting in the air gap back to adapters that go through the outer leaf (again acoustically sealed) and the connect to the silencer boxes which in turn connect to the exhaust fans. Then I believe the fresh air runs can be passive because they can rely on the pressure difference between the interior rooms and outside world to draw fresh air back in. Still I will again need 2 fresh air runs. One for the CR and one for the LR. Each will have 2 x air registers + 2 x ducting and adapters + punch through and acoustically seal around the inner and outer leafs. For all 4 runs I will have at least one 90 degree turn in the ducting to assist with damping noise. HVAC QUESTION 1: I assume I also need a silencer box on the outside of the outer leaf at the end of each fresh air run as well? HVAC QUESTION 2: I have only allowed for a 100mm air gap between the inner and outer leaf walls so the exterior ducting diameter will need to be a maximum of 100mm or approximately 4”. This may be an issue for flow rate/fan strength/noise? How do I go about knowing if I can have 4” diameter fresh air in and stale air out ducting? If this diameter is an issue then can I simply have two exhaust and two fresh air runs per room to get the necessary exchange? Or would a larger exhaust fan and a single run provide enough power to draw stale air out without creating a major noise issue? Also, there may be a bit more air gap space in the roof air gap to accommodate larger diameter ducting so this may be another way to get larger diameter ducting for air exchange. If the fresh air in and stale air out ducting does end up in ceiling air gap then is it ok to have the air registers mounted in the inner leaf ceiling as opposed to the inner leaf walls? The LR and CR cubic dimensions and air exchange rates (3 per hour) are below. HVAC QUESTION 3: If ducting diameter and available air gap space allow for it what type of acoustic insulation should be present in the ducting itself? I am guessing that noise could easily build up along the duct run even with a silencer box at one end? Air exchange rate CR dimensions in feet: Length = 16 Width = 11 Height = 9 LR dimensions in feet: Length = 7.5 Width = 11 Height = 9 From reading the forums I believe that I am aiming to achieve 3 exchanges per hour (i.e. every 20 minutes). This URL provided a calculator: http://www.csgnetwork.com/airexchangecalc.html Based on this calculator, my studio’s cubic dimensions and 3 exchanges per hour. I got the following results: CR Enclosed area = 176 square feet Enclosed volume = 742.5 cubic feet Complete air recycle in = 20 minutes Hourly air volume = 2227.5 cubic feet CFM fan requirement = 37.125 CFM Quantity of target fans required = .371 LR Enclosed area = 82.5 square feet Enclosed volume = 1584 cubic feet Complete air recycle in = 20 minutes Hourly air volume = 4752 cubic feet CFM fan requirement = 79.2 CFM Quantity of target fans required = .792 Now for heating, cooling and humidity control. I am concerned about setting up the A/C so that all components that may need servicing can be accessed. One initial HVAC consultant suggested fixing part of the A/C to the underside of the outer leaf, but, once the inner leafs are built I would never be able to get to this part of the A/C for servicing. This fact was of little concern to the HVAC consultant! I really can’t get this part wrong. So, I am considering either 2 x Daikin Ururu split rated at 2.5kW or 1 x Daikin multi split with 2 x interior units each rated at 2-2.5kW. Both these models have 4-4.5 star ratings out of 5 where 5 stars is the most efficient. I am guessing that the multi-split will be cheaper as there would only be one outdoor unit. Both these options seem attractive as they do not require ducting and have similar inside noise. The Ururu lists inside noise as 39dB/23dB for cooling and heating at 41dB/25dB and the Daikin multi splits are 38dB/22dB for cooling and 39dB/25dB for heating. The only major difference I can see is that the Ururu also offers some fresh air. Both offer humidity control. I am comfortable switching off the A/C as required for open mic recording. As I am aiming to use splits that will be switched off during recording, separate, silenced active/passive exhaust/fresh air systems will be essential to maintain fresh air exchange all the time. So this fact seems to negate the need for the Ururu’s fresh air component. Eitherway, if the CR or LR were to get too uncomfortable or humid during a long recording session then the only option would be to take a break and turn on the split for a while. HVAC QUESTION 4: Stuart can you envision any major issues with the above HVAC plan? I do aim to find an experienced HVAC contractor to verify exchange rates and other technical aspects prior to then sourcing and installing. I guess I’m really asking if there is anything obvious missing on a conceptual or practical level from your point of view? Thanks! Also, I am hoping that the required piping runs from outside through the outer leaf and then into the inner leaf are installed with the most robust materials and in the most reliable way to minimise the need that they would need servicing in the future. Finally, If anyone on the forums knows of experienced HVAC suppliers and installers in the Newcastle, Central Coast or Sydney areas of NSW who can provide expert services to supply and install a HVAC system inline with the above information then I would be very appreciative if they could post their information.

Hi Stuart, Thank you again for your advice to date. If you do find some free time to set me straight regarding the questions in my last post that would be awesome. I am also starting to call HVAC suppliers around my local area to seek advice and to find a supplier that I trust so that I am ready when the builders get to the point that they are preparing the studio slab and later the walls.

hey Ben, great looking build you've got planned here :D I haven't had time to read through it entirely but it looks like you're ticking all the right boxes from the start. I'll be following along as it progresses :thu:

Hi Steve, Thanks for the encouragement. With any luck we should get going within the next 4 weeks (fingers crossed). Stuart if I can trouble you to look over my last couple of posts when you have some spare time I would really appreciate it. It would be great to know that my posts over the last couple of months do not contain any major errors, omissions or miscalculations. Also, I spent a few hours today updating my Sketchup file. I have added the splits where I think they will sit and adjusted the HVAC. I'm hoping to have two stale air and two fresh vents in the CR and one stale air and one fresh air vent in the LR (this can be doubled to two of each if advice indicates that this would be sensible). The stale air HVAC run will be connected to a silencer box on the outside of the outer leaf and then that to an extractor fan. Am I right that I can have a single stale air run for both rooms provided that the extractor fan used has enough power to draw the correct amount of stale air out to achieve air exchange. I am relying on negative air pressure inside the CR and LR to pull fresh air back in via the fresh air runs. I am also going to add a split to both the LR and CR that also adds a little extra fresh air too, e.g., a Daikin Ururu Sarara. In fact after reading the Daikin site again (http://www.daikinaircon.com.au/daikin-s ... lit-system) and also vakis's comment toward the bottom of the following thread (http://johnlsayers.com/phpBB2/viewtopic ... 4&start=90) I was wondering if one of these units in each room in conjunction with the red stale air active exhaust lines (in my pictures) would be enough. Do I really need a passive fresh air system as well as the Daikin Ururu Sarara's given that both my CR and LR are really quite small. If squared up the CR would not be larger than approx 4600mm (L) x 3500mm (W) x 2500mm (H) and the LR is at least half that size. I will speak to HVAC specialists locally very soon, but, if I can get a clear preliminary answer that would be great. I also expanded the conduit runs that I will have placed in the outer leaf and under the studio slab. I have uploaded a screen shot to explain what I hope is my final plan. Essentially, for the conduit I am now aiming to have a power conduit run in the LR and the CR (for power and lights), a cat6 conduit run into the CR, a conduit run for audio between the LR and CR and finally 2 under slab conduit runs to get audio to the soffit mounted speakers. Also a separate conduit power run on the other side from the cat6 run and away from the audio runs to bring power to the audio equipment. Can I also check if I should be concerned about one of the soffits being larger than the other one. This happened as a result of the suggestion to rotate the interior fit out by 90 degrees to ensure that the listening line was down the longest part of the CR. Please note that both set at 30 degrees and the speakers are centred so that the final listening position at the desk will be symmetrical, i.e. the listeners head will be centred between the left and right speakers and the speakers will be at the same distance and angle from the listener.

Hey Ben. Sorry for the delay: I had completely missed your thread! :oops:

CONDUIT QUESTION 1: Am I right that I should have a separate conduit run for power that is destined to be used by music equipment, e.g., the desk, computer and outboard in the CR and amps and powered mics in the LR?

You need a separate circuit for your gear, at least one and perhaps more than one. ONLY gear should be on that circuit; not lights, HVAC, utility plugs, etc. I normally run one conduit to each electrical box from the distribution panel, but you should check what your local electrical code allows/requires.

CONDUIT QUESTION 2: Is it ok to run 3 separate power runs in the same conduit, i.e., one for HVAC, one for lights and the other for general non music gear power? This would happen twice, once for the CR and then again for the LR.

I guess you cold do that, but I'm not sure why you would want to! They will all be locate in different places, so it would seem far more logical to run one conduit for each.

CONDUIT QUESTION 3: How far away should the cat-6 conduit/cable run and dedicated audio power conduit/cable runs be from the HVAC/light/general conduit/cable power runs to avoid any possible interference/noise issues?

The general recommendation here is to run all your electrical power circuits across the tops of the walls, and all your low-voltage signal circuits at the bottom. If the even need to cross over each, then the crossing should be done at 90°.

The silencer box will be connected to ducting that runs to an air register located on the inside of the inner leaf.

I normally try to put the silencer box right at the wall penetration, and arrange it so that the end of the silencer box pokes through the wall and has the register on the end of it.

Then I believe the fresh air runs can be passive because they can rely on the pressure difference between the interior rooms and outside world to draw fresh air back in

Correct.

For all 4 runs I will have at least one 90 degree turn in the ducting to assist with damping noise.

If your silencer boxes are well designed and properly built, that isn't necessary.

HVAC QUESTION 1: I assume I also need a silencer box on the outside of the outer leaf at the end of each fresh air run as well?

For high isolation, I put a silencer box on each wall-leaf penetration. In other words, at every point where a duct goes through a leaf, there is a silencer. In some cases you can build a single silencer that fits between the leaves, with one end penetrating the outer lea and the other the inner leaf.

This may be an issue for flow rate/fan strength/noise?

What matters most is the velocity of the air flow as it comes out the register: it can be flowing much faster inside the ducts, if necessary. Flow at the register should be no more than 300 fps, preferably lower.

If ducting diameter and available air gap space allow for it what type of acoustic insulation should be present in the ducting itself?

All ducts should be lined on the inside with 1" duct liner.

From reading the forums I believe that I am aiming to achieve 3 exchanges per hour (i.e. every 20 minutes).

Sounds a bit on the low side. It's normally about 2 to 3 times that: http://www.engineeringtoolbox.com/air-c ... d_867.html

One initial HVAC consultant suggested fixing part of the A/C to the underside of the outer leaf,

:!: :roll: Ummm... Nope! So in order to service it, you'd have to break down the wall? Maybe you should look for another HVAC guy... .) All of your HVAC mechanical should be accessible, so it all should either be inside the inner-leaf or outside the outer leaf, but not hidden in the cavity. The only exception is if the cavity is wide enough, then you might be able to get away with having something mounted just next to a doorway, where you can access it from in between the two doors. Not ideal, but it can be done. Just make sure that there is enough space to get tools in there too, to disassemble it and reassemble it: For example, damper valves could go in there.

HVAC QUESTION 4: Stuart can you envision any major issues with the above HVAC plan? I do aim to find an experienced HVAC contractor to verify exchange rates and other technical aspects prior to then sourcing and installing. I guess I’m really asking if there is anything obvious missing on a conceptual or practical level from your point of view? Thanks!

I think you pretty much covered the major points with your questions! :)

Also, I spent a few hours today updating my Sketchup file.

Ummmm... there's a rather major, huge, big, enormous problem with that layout! The front of the CR is not symmetrical at all! symmetry is critical. If you imagine a line splitting the room down the middle, then the left side of that line should be a mirror image of the right side. Yours isn't. that should be the very first thing you correct. Without room symmetry, you don't have a usable studio.

Can I also check if I should be concerned about one of the soffits being larger than the other one.

Yes, that's part of the "major, huge, big, enormous problem" I mentioned: your soffits must be identical, mirror-images of each other.

This happened as a result of the suggestion to rotate the interior fit out by 90 degrees

You rotated the room CONTENTS, but not the room itself. You still need to correct that angled wall which is now at the front of your room, and make it flat again.

both set at 30 degrees and the speakers are centred so that the final listening position at the desk will be symmetrical,

It isn't symmetrical. The acoustics on the left will be very different from the acoustics on the right. I'd say that your first priority should be to fix that, then post the update for some more beat-down! :) - Stuart -

Hi Stuart, No worries at all! Your help is every much appreciated. I have started redrawing this evening and though I am close to finished I am a little slow in Sketchup so I hope to have an updated plan posted in the next day or so. I thought I'd also mention that I will place active exhaust and passive fresh air despite also using Daikin Ururu Sarara's (with their small amount of fresh air). That way there will always be fresh air even without the A/C running (i.e. when recording with open mice) or when cooling and/or dehumidification are not required and we all love fresh fresh air! I'll post again with an updated symmetrical CR very soon. Thanks again, Ben

Hi Stuart, I’m ready for my next beat-down :) I hope my time in Sketchup over the last days has been worthwhile. In the end the dimensions of the CR and LR have not changed, but, the pics below are essentially a complete redraw.

You rotated the room CONTENTS, but not the room itself. You still need to correct that angled wall which is now at the front of your room, and make it flat again.

The CR is now symmetrical (hopefully in a successful way too!). Please note that I am not showing the 2 layers of 16mm Frychek on the outside of the inner leaf nor the rock wool on the inside of the inner walls and ceiling. I also unfortunately have more questions! For completeness my measurements indicate that the inside inner leaf wall height for the LR and CR, from the top of the finished wood floor, will be approximately 2200mm rising to approximately 2600mm at the inner leaf ceiling peak. The full dimensions in summary are: CR = L (4921mm) x W (3110mm) x H (2200mm rising to approximately 2580mm) LR = L (1896mm) x W (3110mm) x H (2200mm rising to approximately 2580mm) I also re-checked the room modes. Given that I am leveraging much of John’s design for Scott’s studio the inner leaf ceiling is slanted at 12 degrees and thus I was not sure what height to use for the mode calculations. So I did three sets of mode calculations. One with lowest wall height at the edge 2200mm, one with the highest point at the ceiling peak 2580mm and one with the average height at 2400mm. Three passed and three had one of the three criteria marked as a fail. The room dimensions for the three that failed were:

LR modes 3.1165W x 1.8960L x 2.2000H Computed Information: Room Dimensions: Length=1.89 m, Width=3.11 m, Height=2.2 m Room Ratio: 1 : 1.15 : 1.64 R. Walker BBC 1996: - 1.1w / h < l / h < ((4.5w / h) - 4): Fail - l < 3h & w < 3h: Pass - no integer multiple within 5%: Pass Nearest Known Ratio: - "14) Derived from C. P. Boner (stylized ratio)" 1 : 1.25 : 1.6 RT60 (IEC/AEC N 12-A standard): 152 ms - ±50ms from 200Hz to 3.5kHz = 102 to 202ms - ±100ms above 3.5kHz = 52 to 252ms - <+300ms at 63hz = 452ms - 300<RT60<600ms RT60 (ITU/EBU Control Room Recommended): 123 ms - ±50ms from 200Hz to 4kHz = 73 to 173ms - <+300ms at 63hz = 423ms - 200<RT60<400ms Absorbtion to achieve ITU RT60: 182 sabins Volume: 12 m^3 Surface Area Total: 30 m^2 Surface Area Floor: 5 m^2 Surface Area Ceiling+Floor: 10 m^2 Surface Area Front Wall: 6 m^2 Surface Area Front and Rear Wall: 12 m^2 Surface Area Left Wall: 4 m^2 Surface Area Left and Right Wall: 8 m^2 Surface Area 4 Walls: 20 m^2 Surface Area 4 Walls + floor: 25 m^2 (sabins - front wall - carpet) / Left+Right+Rear wall: 42 % (sabins - front wall) / Left+Right+Rear wall: 77 % Schroeder Fc: 184hz Frequency Regions: - No modal boost: 1hz to 90hz - Room Modes dominate: 90hz to 184hz - Diffraction and Diffusion dominate: 184hz to 736hz - Specular reflections and ray accoustics prevail: 736hz to 20000hz Count (55.2-332hz) : Axials=13, Tangentials=54, Obliques=72 Count (55.2-100hz) : Axials=3, Tangentials=1, Obliques=0 Critical Distance (direct = reverberant field): 2.80m

CR modes 3.1165W x 4.2910L x 2.2000H Computed Information: Room Dimensions: Length=4.29 m, Width=3.11 m, Height=2.2 m Room Ratio: 1 : 1.41 : 1.95 R. Walker BBC 1996: - 1.1w / h < l / h < ((4.5w / h) - 4): Pass - l < 3h & w < 3h: Pass - no integer multiple within 5%: Fail (ratio3 = ratio1 * 2) Nearest Known Ratio: - "5) M. M. Louden: 1971: Best ratio as per Louden" 1 : 1.4 : 1.9 RT60 (IEC/AEC N 12-A standard): 210 ms - ±50ms from 200Hz to 3.5kHz = 160 to 260ms - ±100ms above 3.5kHz = 110 to 310ms - <+300ms at 63hz = 510ms - 300<RT60<600ms RT60 (ITU/EBU Control Room Recommended): 165 ms - ±50ms from 200Hz to 4kHz = 115 to 215ms - <+300ms at 63hz = 465ms - 200<RT60<400ms Absorbtion to achieve ITU RT60: 307 sabins Volume: 29 m^3 Surface Area Total: 56 m^2 Surface Area Floor: 13 m^2 Surface Area Ceiling+Floor: 26 m^2 Surface Area Front Wall: 6 m^2 Surface Area Front and Rear Wall: 12 m^2 Surface Area Left Wall: 9 m^2 Surface Area Left and Right Wall: 18 m^2 Surface Area 4 Walls: 30 m^2 Surface Area 4 Walls + floor: 43 m^2 (sabins - front wall - carpet) / Left+Right+Rear wall: 39 % (sabins - front wall) / Left+Right+Rear wall: 93 % Schroeder Fc: 142hz Frequency Regions: - No modal boost: 1hz to 40hz - Room Modes dominate: 40hz to 142hz - Diffraction and Diffusion dominate: 142hz to 568hz - Specular reflections and ray accoustics prevail: 568hz to 20000hz Count (40.1-253hz) : Axials=13, Tangentials=54, Obliques=72 Count (40.1-100hz) : Axials=4, Tangentials=4, Obliques=0 Critical Distance (direct = reverberant field): 3.50m

CR modes 3.1165W x 4.2910L x 2.5800H Computed Information: Room Dimensions: Length=4.29 m, Width=3.11 m, Height=2.58 m Room Ratio: 1 : 1.2 : 1.66 R. Walker BBC 1996: - 1.1w / h < l / h < ((4.5w / h) - 4): Fail - l < 3h & w < 3h: Pass - no integer multiple within 5%: Pass Nearest Known Ratio: - "14) Derived from C. P. Boner (stylized ratio)" 1 : 1.25 : 1.6 RT60 (IEC/AEC N 12-A standard): 210 ms - ±50ms from 200Hz to 3.5kHz = 160 to 260ms - ±100ms above 3.5kHz = 110 to 310ms - <+300ms at 63hz = 510ms - 300<RT60<600ms RT60 (ITU/EBU Control Room Recommended): 174 ms - ±50ms from 200Hz to 4kHz = 124 to 224ms - <+300ms at 63hz = 474ms - 200<RT60<400ms Absorbtion to achieve ITU RT60: 342 sabins Volume: 34 m^3 Surface Area Total: 64 m^2 Surface Area Floor: 13 m^2 Surface Area Ceiling+Floor: 26 m^2 Surface Area Front Wall: 8 m^2 Surface Area Front and Rear Wall: 16 m^2 Surface Area Left Wall: 11 m^2 Surface Area Left and Right Wall: 22 m^2 Surface Area 4 Walls: 38 m^2 Surface Area 4 Walls + floor: 51 m^2 (sabins - front wall - carpet) / Left+Right+Rear wall: 35 % (sabins - front wall) / Left+Right+Rear wall: 79 % Schroeder Fc: 134hz Frequency Regions: - No modal boost: 1hz to 40hz - Room Modes dominate: 40hz to 134hz - Diffraction and Diffusion dominate: 134hz to 536hz - Specular reflections and ray accoustics prevail: 536hz to 20000hz Count (40.1-239hz) : Axials=12, Tangentials=47, Obliques=60 Count (40.1-100hz) : Axials=4, Tangentials=4, Obliques=1 Critical Distance (direct = reverberant field): 3.60m

Please note the above dimensions are from flat surface to flat surface and do not consider any final room treatment (bass traps, Helmholtz resonators, RFZ walls etc). QUESTION 1: How concerned should I be about the above fales? In your opinion do I have a major problem or should I be able to address most of issues with room treatment? e.g., suitably tuned Helmholtz resonators and bass traps etc. With room treatment in mind, it is too soon to know exactly what will be used inside the LR and CR. QUESTION 2: Am I right that provided there are no major issues with modes and after conduit runs are in place, the inner leaf has been constructed, wiring is in place, rock wool has been applied to the inner leaf and the HVAC system has been installed, then the LR and CR behaviour can be tested and analysed to work out the best treatment to apply, e.g., bass traps, tuned Helmholtz resonators and ceiling clouds etc? i.e., add treatment after problem frequencies have been identified. With question 3 in mind I have shown bass traps in the LR and some Helmholtz resonator like panels too. But, these are really only in place to show that treatment is going to be required and the actual treatment is likely to be different after analysing the room response after the inner leaf is complete. Also, please excuse my dodgy duct runs, wiring runs and A/C piping runs. I am getting a bit better and a bit quicker in Sketchup but I have a long way to go. Given Sketchup’s vector ability I do wish you could simply drag a handle to rotate and also expand and drag curves in a more intuitive way rather than using a combination of tools and a lot of guesswork when it comes to angles and dimensions. Maybe I’m missing something? HVAC --------

I normally try to put the silencer box right at the wall penetration, and arrange it so that the end of the silencer box pokes through the wall and has the register on the end of it.

Ok. I would like to install silencer boxes that are similar to the one from this thread viewtopic.php?f=2&t=11508&p=96578&hilit=silencer#p96578.

What matters most is the velocity of the air flow as it comes out the register: it can be flowing much faster inside the ducts, if necessary. Flow at the register should be no more than 300 fps, preferably lower.

If I understand correctly, the exit diameter of the silencer (2x) is to be twice that of the entry (x) and the internal diameter will be the same as the entry (x). The inside will be lined with insulation duct liner or rock wool. Also the duct runs themselves will be lined with duct liner. I will also talk to the HVAC specialist that I choose about duct diameters, 1" duct liner and a maximum final air speed of 300fps. As discussed the fresh air in run will be passive (i.e. relying on the negative air pressure) and one silencer box will be mounted to the outside of the LR inner leaf and another for the CR inner leaf. These two boxes will connect to the air register that feeds air into the rooms. QUESTION 3: Can I double check that the two duct runs that connect to the two silencer boxes can themselves be fed from a single duct that is connected to the fresh air outside as shown in my drawings. The green boxes represent the fresh air run and red the stale air run. Given my Sketchup inexperience, please note that all HVAC ducting is not to scale and its location is as close as I could get to where it is likely to sit.

Sounds a bit on the low side. It's normally about 2 to 3 times that

Assuming the answer to Q2 is yes, then I will work with the final HVAC supplier to make sure that I get 6 complete air exchanges per hour. To achieve this I assume the HVAC supplier will need to be able to identify an extractor fan can extract 6 complete air exchanges per hour. That brings me to my next few questions. QUESTION 4: Have I got the red stale air silencer boxes positioned correctly? i.e., are they normally placed immediately above the stale air register in a similar wary to the fresh air ones?

For high isolation, I put a silencer box on each wall-leaf penetration. In other words, at every point where a duct goes through a leaf, there is a silencer. In some cases you can build a single silencer that fits between the leaves, with one end penetrating the outer lea and the other the inner leaf.

QUESTION 5: Ok. Would there be any point or increase in isolation if a metal silencer was placed inside each of the duct runs before they split? e.g., something like this product that you have mentioned before: http://www.electricsuppliesonline.com/6siforroduld.html and then have silencer boxes only at the inner leaf penetration? They don't seem to cost too much and would probably work out cheaper in time and material expense over additional outer leaf silencers. Power ———— I have changed my mind about running conduit down through the outer leaf for power and conduit. Instead I will place a separate meter box and fuses under the house on the back wall of the outer leaf (there is plenty of head room and access) and get the house builder/electrician to run light and power to this box (Also cat6 will be nearby too). Then when I get to the internal studio fit out I will run the studio wiring from this box. This means that I will punch through the outer leaf from behind the meter box. I will then run lights, power and cat6 in the air gap and punch through the inner leaf and acoustically seal a few times. I am hoping that if done well there will not be too much of an isolation loss.

You need a separate circuit for your gear, at least one and perhaps more than one. ONLY gear should be on that circuit; not lights, HVAC, utility plugs, etc. I normally run one conduit to each electrical box from the distribution panel, but you should check what your local electrical code allows/requires.

Thanks, I will also make sure that there is at least one dedicated power run just for gear and a separate run for HVAC and any utility power points. Lights will be separate again.

The general recommendation here is to run all your electrical power circuits across the tops of the walls, and all your low-voltage signal circuits at the bottom. If the even need to cross over each, then the crossing should be done at 90°.

In my drawing the yellow run is lights, red is power and blue is cat6. I have kept the cat6 run away from the power and lights as much as possible. I did place the red power runs low down, but, I will move these up to the top and then run down the walls as required. I have been in Sketchup most of the weekend and took screenshots before I realised! Power will be placed up and run down rather than the other way around. QUESTION 6: If I use shielded cat6 cable and shielded speaker cable will it be safe to run the cat6 cable along side speaker cable in the same conduit? I know that power and cat6 are an issue, perhaps audio and data are too? The reason that I ask is that I’m hoping to minimise the number of underfloor conduit runs. On that note I will still need 4 under slab, sub floor conduit runs. One to run audio to the left monitor speaker, one to the right monitor speaker, one to run audio between CR/LR and one to bring power up to the equipment. The under floor power conduit is red and the other 3 audio conduits are a deeper burgundy colour. The under slab conduit runs are approximate they are not to scale nor mm perfect as my Sketchup skills are a bit basic. I will be more precise when I meet with the builders over the next few weeks and we mark their locations exactly.

Wow! :shock: I think that must be the record for the longest post ever on the forum! :!: :) Naah, just kidding: I reckon some of my volumes have that beat... Seriously, that is looking MUCH better! Way to go with the SketchUp skills, too! Very nice. The first thing I noticed is the rather high angle of the speakers/soffits. They seem to be angled at even more than 45°, which is too much. What angle are they? 45 is pretty much the limit, and I would try to not even go that far, if possible. 30° is the "standard". I realize that you need a bit greater angle due to the size of the door, but you could maybe reduce the size of that door a bit, build out the doorway some, and reduce the angle.

... thus I was not sure what height to use for the mode calculations.

Use the average, but it's also good to look at the high and low, to get a better idea of what the room will be doing.

Please note the above dimensions are from flat surface to flat surface and do not consider any final room treatment (bass traps, Helmholtz resonators, RFZ walls etc).

That's correct! Room modes are ALWAYS measured from hard surface to hard surface, regardless of treatment. There's not much that treatment can do to change that....

QUESTION 1: How concerned should I be about the above fales? In your opinion do I have a major problem or should I be able to address most of issues with room treatment? e.g., suitably tuned Helmholtz resonators and bass traps etc.

Well, the good news is that you are failing in three different ways for the three different measurements! Of all were failing on the same test, that would be sad. The other good news is that the average for the CR passes, and the spread looks good either way, so I'd say you are OK with that. I wouldn't be too worried about the LR: That's fine too.

With room treatment in mind, it is too soon to know exactly what will be used inside the LR and CR.

CR will take pretty much "standard" treatment: superchunks in as many corners as possible, thick panels on first reflection points and the rear wall. Then do a REW test and see what else you need.

QUESTION 2: Am I right that provided there are no major issues with modes and after conduit runs are in place, the inner leaf has been constructed, wiring is in place, rock wool has been applied to the inner leaf and the HVAC system has been installed, then the LR and CR behaviour can be tested and analysed to work out the best treatment to apply, e.g., bass traps, tuned Helmholtz resonators and ceiling clouds etc? i.e., add treatment after problem frequencies have been identified.

Yes, but forget the "tuned Helmholtz resonators". Those are way harder to get right than the internet myth factories would suggest. First, modes are very narrow band resonance, so the tuning the device has to be very accurate. Second, it is hard to tune Helmholtz resonators accurately anyway, so the tuning has to be made variable such you can fine-tune it after it is built. Third, you have to locate the device at the correct position in the room, where the actual modal peak is. That usually turns out to be an impossible location. Forth, they have to be huge to be effective. The internal volume of the resonator needs to be about 1% of the room volume at least, to be effective. So imagine that you need to fight ten modes: are you willing to give up 10% of your entire room for large resonant boxes hanging at strange places around the room? :shock: They aren't much of an option, really. There are better ways of dealing with modes.

Sketchup’s vector ability I do wish you could simply drag a handle to rotate and also expand and drag curves in a more intuitive way rather than using a combination of tools and a lot of guesswork when it comes to angles and dimensions. Maybe I’m missing something?

Are you making individual items into components? If so, then they are very easy to rotate, scale and move. If not, then now would be a good time to do that!

If I understand correctly, the exit diameter of the silencer (2x) is to be twice that of the entry (x) and the internal diameter will be the same as the entry (x).

The internal cross sectional area of the box needs to be at least twice the cross-section of the duct, and the register should be at least as large as the cross section inside the box, but larger still if possible. Don't forget to allow for the "percentage open area" of the registers: just because it measures 10" x 10" does not mean that there is 100 square inches of open area.... the vanes and other internals take up a large percentage of that space....

The inside will be lined with insulation duct liner or rock wool.

Use proper 1" duct liner ONLY! Never use ordinary mineral wool or fiberglass. It will erode and shed fibers over time, and will also pick up dust like you wouldn't believe....

QUESTION 3: Can I double check that the two duct runs that connect to the two silencer boxes can themselves be fed from a single duct that is connected to the fresh air outside as shown in my drawings.

Yes and no.... That will only work if you balance the flows very carefully, and keep the room doors closed. As soon as you open a door, you provide alternative paths for air to get in and, and you might end up with one room not getting as much air as it should, while the other gets way more than it needs. It is better to have separate intakes for each room, if possible.

To achieve this I assume the HVAC supplier will need to be able to identify an extractor fan can extract 6 complete air exchanges per hour.

Yes, but he'll also need to know the static pressure of your complete HVAC system, end to end. Fans provide different flow rates when the are working against different static pressures. A fan rated at 250 CFM might only provide 190 CFM at a typical static pressure load, and 150 CFM at another static pressure.

QUESTION 4: Have I got the red stale air silencer boxes positioned correctly? i.e., are they normally placed immediately above the stale air register in a similar wary to the fresh air ones?

That looks fine for the LR, but for the CR I normally try to put the supply register as far back as possible and the return register as far forward as possible (or vice-versa), so there is flow along the entire room length.

QUESTION 6: If I use shielded cat6 cable and shielded speaker cable will it be safe to run the cat6 cable along side speaker cable in the same conduit? I know that power and cat6 are an issue, perhaps audio and data are too? The reason that I ask is that I’m hoping to minimise the number of underfloor conduit runs.

As long as all your cables are of the correct type, and shielded correctly, then you should have no problems. - Stuart -

Hi Stuart, Thank you so much yet again! I trust that all is well over in your neck of the woods. I am at work at the moment and will process your answer a little more thoroughly when I get home after a post work rehearsal. I am so pleased to learn though that the room dimensions appear to be ok and I will double check the speaker soffit angle very carefully as suggested. As for the build, we have had our DA and CC for a few weeks now. Our builder is ready to start excavating for the space that will be the downstairs studio as soon as the weather clears. Thursday this week is supposed to be clear and sunny and is penned in as the start day. As of today, ie Wednesday afternoon the rain has stopped and the sun is out. I do hope it stays that way! I'm also talking with the builder's electrician very soon to finalise the conduit diameters and location prior to pouring the slab. Thank you again for your valuable advice. I know it has been many months since I started this thread, but, the build is finally getting ready to start. I will certainly post pictures to track the work over the coming months.