Inside out modules...

#1

Hey, all, first post here...

I've been trying to find a brilliant thread where Soundman2020 showed lots of photos of a ceiling joist grid before and after some heavy ceiling modules were lifted into place with a panel lifter. I'm thinking of having inside out modules for my build, but there are a lot of questions I don't want to bore the forum with, which I know would be answered if I could find the original thread. I did bookmark a lot of threads over a year ago on the johnsayers site, but I'm denied access to them, even though I'm perfectly logged in. Do they expire after a while?..

Anyway, if there's another thread someone can point to that relates to the above, it would be much appreciated! Cheers, kj

#2

Hi there "killerjoe", and welcome to the forum!

OK, you spurred me to action: I've been planning on doing an article on inside-out construction for a while, so I'll get working on that.

But if your question is specifically about inside-out ceilings, then this thread might be what you are looking for:

How to Build an Inside-out Ceiling for Your Studio (click here)

Let me know if that's what you need, and also if it doesn't cover your specific question. I'd be happy to update it.

Also, please do start a thread about your place! Not boring at all! That's what the forum is all about.

Stuart

#3

Ah yes, that's the one! Many thanks!

I can now show this to the architect, who was seemed unsure it was a good idea... I'll have a few questions, most can wait til your new article is unleashed, but for now, if my room is 7m x 4.6m, then how many joists (and what size) would I need to span the 4.6m ? If I was to have layers of compressed cement sheet and ply weighing 40kg/m2 for each module, how large could they be? And what are the lifting mechanism options?

#4

killerjoe wrote:Source of the post Ah yes, that's the one! Many thanks!

I can now show this to the architect, who was seemed unsure it was a good idea...

Understandable... Architects commonly don't understand studio acoustics very well... And an inside-out ceiling also makes his job a bit more complicated! It means doing things a different way that he's not accustomed to.

if my room is 7m x 4.6m, then how many joists (and what size) would I need to span the 4.6m ?

That depends to a certain extent on local regulations where you live. Structural regs vary from place to place, so you will need to get a local structural engineer involved, to make sure that what you are planning actually meets code, and will pass inspection.

It also depends on the total load that the joists must carry, of course. When you say 40kg/m2, is that just the sheathing, or did you include the weight of the joists themselves, and the insulation (both above and below), plus whatever else you plan to hang from the ceiling? Eg: ceiling cloud, lighting, cabling, decorations, acoustic treatment, etc. It's the total dead load that is used for the structural calculations. The type of wood that the joists are made from is also a factor. That said, as a rough estimate I would probably use sistered 2x8 or 2x10 joists spaced about 645mm (in order to have a module width of 600mm, which is half of the typical panel width of 1200mm, thus minimizing cutting and wastage). (Depending on regulations and load, it might be possible to do 2x8s... otherwise 2x10s). I would use either 2x3 or 2x4 framing for the actual modules, depending on how big they are.

But do not take those numbers as being Gospel truth, valid, safe, and accurate for your situation! Those are just rough estimates, based on generic calculations and typical wood species. To be certain, you would need to hire a structural engineer to do the math. Never do anything structural in your studio without consulting an engineer and getting him to sign off on it. Apart from anything else, your insurance would likely not cover anything, if something bad happened and there was no structural engineer's signature on the paperwork.

I would also suggest not using just fiber-cement board alone: it is brittle and unforgiving to work with. I would suggest putting a layer of MDF, plywood or OSB on top of the module framing first, then put the layers of fiber-cement board on top of that. If you need high isolation, you could also consider using Green Glue compound between the layers.

And what are the lifting mechanism options?

If you keep the modules small enough, then you can lift them with an ordinary heavy-duty drywall-lifter. As long as you check the load carrying capacity of the lifter, and your modules don't exceed that, then its a good way to do it. Another option is to use a pair of hand winches. A third option is to do what the client did in that sequence: use a car jack and steel poles, with some type of sturdy support structure. If you really wanted to get fancy, you could rent a small fork-lift. And if the modules are small enough, you can even do it by hand, as shown in one of the photos in that article.

But whatever method you choose, work safe! Make sure there is a secondary "something" safety measure, to stop the module falling if the main lifting device fails. Ropes, chains, wooden supports, etc. Anything that would prevent a module doing damage if it comes loose from the lifter. And of course, never stand directly under anything that you are lifting.

- Stuart -

#5

Hi Stuart, you suggested I start a thread about my build, so I may as well start it here. Disclosure - you know of my proposed build already, we exchanged a few posts over at John's site. I'm the guy that wanted to build on the 7th floor of an office building. Coming up to 3 years in this place now and have been working after hours (after people leave) because I can't do drums during the day until I soundproof a live room. Took a long time to get structural info about the building, and I've been waiting to see if I still want to go through with it the build, or keep going as I am. I've decided to bite the bullet recently and take the expensive risk of building the heaviest RWAR I can, as best I can, and see how loud I can go before I annoy someone. If it turns out I still can't do drums by day, then I'll still use it for everything else, and just do drums at night or weekends.

To refresh, the combined CR and Studio space is 14 m x 5m. The existing slab is 125mm reinforced concrete. There is glazing along the 14m north facade. The ceiling slopes from south to north - 3150mm down to 3025mm. There are annoying bulkheads along corners that will make
it tricky to elevate the inner ceiling. I have decided on the studio walls to have a density of 80kg /m2 with a ceiling of 40kg/m2 (cladding mass only). CR will have 40kg/m2 walls but not floating floor (just a damped deck) and no inner ceiling (perhaps a future RC dropped ceiling if required).

I have 5 bespoke heavy studio doors pulled from my last studio, as well as 2 large window boxes (2.76m x 1.32m each around 360mm deep). There are 2 panes of 10mm glass in each box. I used these in my last studio between CR and studio and they worked very well, despite the quadriple leaf! So I will use these again and only try taking out a pane from each box if I need more isolation b/n rooms.

There will be lots of fun, quirky fiddly bits with this build, and I am in the middle of working through some layout plans with an architect prior to submitting for permits etc. I had run my plans by an acoustic engineer, who has only done a few music studios (he mainly does gyms, hospitals, factories etc). He seems OK with my latest plans. I'll be swapping out the existing ceiling AC unit for wall mounts to do away with space hogging ducts etc. The SE has okayed the proposed loads. We have a building surveyor waiting in the wings, so the wheels are finally in motion.

But I just thought I'd run it all by you in case you spot something important that we're missing :cop:

I have plenty of diagrams and most of the usual information at hand to respond with incase you have questions, but let me just start with the basic proposed layout:

Pretty weird eh? I have strong reasons for why I want it like that, but happy to consider any of your thoughts, critiques, ideas etc.

#6

Hi Stuart, you suggested I start a thread about my build, so I may as well start it here. Disclosure - you know of my proposed build already, we exchanged a few posts over at John's site. I'm the guy that wanted to build on the 7th floor of an office building.

Cool! Lindsey, right? PrincePlanet? Wow! It's great to have you here!

I've decided to bite the bullet recently and take the expensive risk of building the heaviest RWAR I can, as best I can, and see how loud I can go before I annoy someone. If it turns out I still can't do drums by day, then I'll still use it for everything else, and just do drums at night or weekends.

That's great! Do you have your design for that finalized? I seem to recall that you were concerned about the glass exterior of the building back then, and also transmission through your floor to the offices below. Have you resolved all of that? If so, I'd love to see what you came up with.

I have decided on the studio walls to have a density of 80kg /m2 with a ceiling of 40kg/m2 (cladding mass only).

OK, as long as you are aware that this will make the ceiling your weak point: that's where you'll have the lowest isolation. And since sound spreads out once it gets through a barrier (low frequency especially), it's probable that the "leak" through the ceiling will also get out through the rest of the structure.

CR will have 40kg/m2 walls but not floating floor (just a damped deck) and no inner ceiling (perhaps a future RC dropped ceiling if required).

I would not recommend that: with no ceiling, there's not much isolation. I'm assuming that you mean your CR walls will go up to the roof slab (I'm also assuming that your ceiling is the building roof?). Any sounds in the building structure itself (motors, pumps, HVAC equipment, elevators, water pipes, etc) will be right there, in your CR, with no isolation. Are you OK with that?

There will be lots of fun, quirky fiddly bits with this build,

Yup! It's a studio, so there will be a ton of those!

I'll be swapping out the existing ceiling AC unit for wall mounts to do away with space hogging ducts etc.

So how will you get air into and out of the rooms? Wall-mounted mini-split condensers (AHUs) do not supply fresh air to the room, nor do they remove stale air: all they is recirculate the same stale air over and over, cooling it and dehumidifying it, but that's all. They don't do the "V" part of HVAC. I wrote an article about that, not too long ago. Not sure if you have seen it: viewtopic.php?f=16&t=141 I there, I explain some of the common issues with HVAC.

The SE has okayed the proposed loads.

Excellent! That was the big sticking point before, if I recall correctly: trying to get enough mass for good isolation, and also spreading the load to the load-bearing areas of the floor. I'm glad you got that sorted out. What frequency did you design your floor floating for, in the end? How much mass are you putting on that? Springs or pads?

But I just thought I'd run it all by you in case you spot something important that we're missing

I must say, it's looking a lot better than the early designs. I'm really glad to see that you took the advice to rotate the CR to face the LR. Smart move.

I do realize that this is just a rough sketch, but for the CR I would really, really, really recommend that you flush mount your speakers! Flush mounting (a.k.a. "soffit mounting") is about the single best thing you an do for any speakers, in any control room. It just gives you so many benefits all at once, with practically no down-side. You do have the space to do that correctly, so that would be my first and biggest suggestion.

Next, you now do seem to be allowing plenty of room for bass trapping at the rear of the room, which is great, but I'm not so convinced about the window in the middle of the rear wall. I suspect that is going to cause you problems with reflections back to the mix position. Do you really need that? If you want more natural light in the room, I'd suggest doing a larger window on the side wall, rather than at the rear. Or if you really must have something back there, then I'd suggest a pair of smaller, angled "slit" windows (tall and narrow), or maybe something else higher up, not at head height, where the reflections would not be so bad. In general, I try to reserve as much of the rear wall area as possible for treatment: In any control room, the rear wall is the biggest problem, and needs the most treatment. Sometimes, I wish I could cover 110% of that wall with treatment, because 100% just isn't enough...

I also get the impression that the console / mix position are a bit too far forward. It's hard to say from just that rough mock-up, but it looks that way.

Finally, the entry to the CR is a problem. A big one: It's right where the speaker, soffit, and treatment need to be. I would very much recommend moving that down the side wall, and leave the corner space for what it does best: acoustics. Also, doing a "two in one" sound-lock like that is going to have unexpected consequences: any time anyone needs to get into or out of the CR while there is a session going on in the LR, your isolation to the LR will disappear when that outer door is opened. Sound levels out in the rest of the building will rise quite a bit when that outer door is open, because it is the outer door for BOTH rooms, not just the CR. I would suggest having separate doors for the CR and LR. That sound-lock is also tiny: It won't be easy for musicians and technicians to get their gear and instruments through there. They already have to carry all their stuff up the stairs from the floor below (since the elevator does not reach your floor, IIRC), so it might not be so good to add an additional obstacle course at the end of the path, upon getting into the LR. I would suggest making that easier for them, with just a straight pair of back-to-back doors.

I have plenty of diagrams and most of the usual information at hand to respond with incase you have questions,

Great!

I already asked some stuff above, so maybe you could comment on that, then we can look at the rest of the design.

- Stuart -

#7

Hey, thanks for the response Stuart. Actually. before I respond to your questions, while it's fresh, I'd like to share with you if I may, a rather extraordinary meeting I had yesterday with someone you may be aware of. I won't mention his name here (perhaps in a PM?), but suffice to say he is one of the most experienced room designers / architects in Australia and has designed rooms all over Aus since the 70's. He seems to be the go to guy for radio and TV stations but has also designed many small studios, and, yes, even some on upper levels that have the same issues as my space.

Anyway, here's the news flash - "Forget about all that mass! "(he says...) "You don't need it, it's more about stiffness!"

His solution is to use isolation mounts creating a gap of only around 60mm filled with 60kg/m3 insulation. Then a frame with yellow tongue (19mm) canite (soft fibre board) / blue tongue (25mm). That's it! Just 117mm total height, and only 41.5 kg/m2 total density!. :ahh:

OK, OK, settle down.... I know all about the warnings of light weight floating floors. From yourself, Rod Gervais, Thomas Joujean etc etc... In fact, although my SE has permitted 150 kg/m2 for the floor, which I was going to have over a 100mm gap, I was worried this would be inadequate as I keep reading about how 250 kg/m2 (ie - a 100mm concrete floating slab) should be considered minimum!

This must sound crazy to you (as it does to me), yet this man and his credentials are hard to ignore. When I remind him of the apparent consensus regarding light weight floors he is adamant and dismissive and refers to it as "wanking"! ... He knows all his figures by heart. so for the "sandwich" and air gap he claims 40dBA STC (i know, why STC ? !!), and for the existing 125mm slab he cites 50dBA (plausible). He went on to explain how these both add up to total 80 dBA (not sure how that works out...). This along with the extra 5dB to be gained through the cavity and light suspended office ceiling on the level below would total 85dB. Now he estimates that the ambient background noise downstairs is 40dB (I actually measured it as 38.5 dB), so his reckoning shows that even a peak of 125dB from a drumkit will be reduced down the ambient level of 40dB, and hence not be a problem. He did say that he would create a section of the floor with a drum rise consisting of a similar gap and sandwich (my term, not his). When I cried "triple leaf!" he gave me the dirtiest look and just said don't believe the hype....

TBH, his worldliness and experienced tone reminded me of John Sayers from my talks with him, where he cares little for the theory of others and stands by his record, he claims a thousand projects with NO failures!!!

He uses the same "sandwich" for his walls and ceilings. and he seemed angered that I was led to believe I needed way more materials. He insisted layers of CFC was not a good option because it had no where near the kind of stiffness of yellow tongue.

Naturally, I have to be skeptical, and I'll look into his past and recent work, but he is highly recommended by Marshall Day in Melbourne, which, as you may know, seem to get the top tier Acoustic jobs in the country.

Stuart, I have seen you savage this kind of heresy in the past, but let's try to be respectful and find a way to investigate his claims fairly. Any thoughts?

#8

Anyway, here's the news flash - "Forget about all that mass! "(he says...) "You don't need it, it's more about stiffness!"

Wellll... I'd take that with a grain of salt!

He's right, of course... but only for frequencies below resonance, and at the coincidence dip (sort of).

In truth, different parts of the spectrum are controlled by different physical aspects. There are basically four regions of the sound isolation spectrum:

In each region, one aspect is dominant, while the others take a back seat. All of them play some role in all four regions, but for each region one of them is far above the others.

For frequencies below the resonant frequency of the barrier, it is, indeed stiffness that is dominant: it's the most important aspect, and paying attention to that will, indeed, get you greater isolation than increasing the mass.... Assuming, of course, that your wall (or floor) is so badly designed that the resonant frequency is within the audible spectrum!

For properly designed walls, where the resonance is at least an octave below the lowest frequency that needs isolating, stiffness isn't too much of an issue.

As you go up the spectrum, you get to the "resonance controlled" region, which is pretty much always the worst region for isolation: at resonance, the wall tends to have very, very poor isolation, and in some cases can have negative isolation... meaning that it actually amplifies sounds around those frequencies, making them louder. That is independent of stiffness or mass, to a certain extent: resonance is a very, very powerful thing, and overwhelms the other factors... which is why a well-designed wall, floor, etc. will have a resonant frequency below the audible spectrum, or at least below the lowest frequency that needs to be isolated.

As you go up the spectrum, you get to the next region, which is... ummm... well it is called "mass controlled"... and it just happens to be in the part of the spectrum that matters most: the low end, and mid range. The bottom half of the audible spectrum. As you can see, mass is the key in this region. Although stiffness and resonance also play a part here (damping too), mass is dominant. For this region (by far the most important for studio isolation), mass is what you need most.

As you move up higher, you get to the coincidence region, where stiffness once again plays a role... sort of... (but in a different manner, though), since we are talking about bending waves: Waves that move along the surface of the panel. However, if you look at the equations for coincidence, you'll see one curious factor: mass is involved! Or rather, density. And also the thickness of the panel. More dense materials do, indeed, have lower coincidence dips, but changing the stiffness here doesn't do much. And for the majority of studios, the coincidence dip is in a region that isn't too important, since it is pretty high up the spectrum, and already has pretty decent isolation, so the dip is not too much of an issue, usually.

Finally, above the coincidence dip, stiffness is the key factor again (along with mass). So if you need to isolated ultra-sonic sounds, then yes, worry about stiffness.

Summary: If you need to isolate frequencies way below the audible spectrum, or way above it, then stiffness plays a role. But if, like most studios, you need to isolate normal audible frequencies, then mass is key.

Even more simple: So if you need to isolate whale song and dog whistles, then fine: go with stiffness! Otherwise, go with mass.

He knows all his figures by heart.

I'm sure he does, but ask him for the actual proof: the written reports with the results from testing his method, done in reputable acoustic laboratories, showing that his claims are true. If he can't or wont, provide such data, and instead just insists that his own word is Gospel truth and cannot be questioned, then you should probably just walk away, regardless of his reputation.

so for the "sandwich" and air gap he claims 40dBA STC (i know, why STC ? !!), and for the existing 125mm slab he cites 50dBA (plausible). He went on to explain how these both add up to total 80 dBA (not sure how that works out...).

OK, so let me get this straight: He takes an STC number (which is not related to decibels), adds it to a TL value, and comes up with a prediction of 80 dBA isolation, for a STUDIO floor, where dBA isn't even the correct metric? Ummm.... That would be sort of like saying that when you peddle a bicycle at 40 revolutions per minute, and there's a tail wind of 30 km/h, you can add those two and discover that the total speed is 70 degrees Celsius... :shock:

That is every bit as logical as what he is saying.

An aside: you can't measure isolation in units of dBA! Only in dB. Because you are comparing two levels of something (in this case, two levels of dBA), so the results MUST be in plain old dB, not in dBA nor dBC. The simple fact of claiming that is isolation is measured in dBA indicates a basic problem with comprehension of decibels: what they are, and what they measure. Surprisingly, the plain decibel is not a measure of sound intensity at all! It is a measure of comparison. I could quite rightly say that Brisbane is about 6 dB further away from Melbourne than Sydney is from Melbourne, when measured in the same units of distance. Because decibels do not measure sound: they measure logarithmic differences. dBC and dBA are such measures of sound level, yes, and that's why there are subscripts on them: to indicate what things are being measured: But plain B with no subscripts, is just logs differences between numbers. I'm surprised that an acoustician would not understand decibels!

This along with the extra 5dB to be gained through the cavity and light suspended office ceiling on the level below would total 85dB.

So where are his calculations for the resonant frequencies? And the coincidence dip? I didn't see those. Considering that those are rather important in any estimate of isolation, it's rather important that he should include those.

Also, if what this guy says is true, then Galaxy Studios in Belgium wasted millions of dollars and many years, consulting with some of the best acousticians in the world, to build their place... when all they really needed was a few dollars worth of T&G along with Rockwool...

so his reckoning shows that even a peak of 125dB from a drumkit will be reduced down the ambient level of 40dB, and hence not be a problem.

Wouldn't that be loverly?

On the other hand, I'm surprised he didn't warn you that a sound present at the same level as the background noise, is very audible.... Try it yourself: set up two sound systems, each individually set to play at 70 dBC, by itself, but playing different music. Turn on one, and listen to the sound at 70 dB. Then turn on the other, which is also playing at 70 dB... can you hear the second one? Yup, you sure can! Even though each is playing at the same level, they are BOTH audible. So your 40 dB drums with a background noise of 40 dB will be quite audible. One would expect that an acoustician would know this!

In reality, depending on the type of sound, in order for one sound to be inaudible through another sound, it needs to be about 16 dB lower in level. As I said, that varies by sound type : for very similar, continuous sounds, the difference can be just a few dB, while for very different sounds, such as when one is intermittent and pulsating, you might need more.

This is partly to do with the the incredible ability of the human brain to "hone in" on certain sounds, even when louder sounds are present. There's a common explanation that you often see in texts on psycho-acoustics, often referred to as the "cocktail party" effect. If you are at a cocktail party with people talking all around you, all at roughly the same level, you'll find that you can "tune in" to specific conversations if you want to: You can "hear through" the background noise, and pick up something that is quieter than background: two people talking on the far side of the room, for example. Even though just comparing the actual sound levels would lead you to believe that it is impossible to hear that "distant" conversation at a lower level than ambient, in reality it is not only possible but very common.

It's not just about comparing numbers (not even if the numbers are valid!), but rather about understanding sound, and how people perceive sound.

Long story short: if you have a typical background office noise level (which is more like 50 dB, rather than 40, by the way, for a well designed office: 45 to 48 is the average), that is similar to pink noise with a slight band-pass filter boosting some frequencies: A typical constant, low level, all frequencies present: Then you superimpose varying sounds with transients, impacts, and beats (such as contemporary music), it will still be discernible if it is at the same level, and down to about 10 or even 15 dB below that level. So, if you measured 38 dB in the office down below you for normal conditions (which would be very quiet!) then your noise would have to arrive down there at a level of somewhere between 25 and 30 dB, in order to be "silent". Those are VERY low levels. It would be rather unusual for a typical office to have an ambient level below 40 dB. Just the HVAC alone should be producing more than that, for a well-designed office space. Add to that the typical normal office sounds, such as people, computers, photocopiers, phones, etc., and you get to around 45 for a quiet office, 50 for a more usual office.

TBH, his worldliness and experienced tone reminded me of John Sayers from my talks with him, where he cares little for the theory of others and stands by his record, he claims a thousand projects with NO failures!!!

How big of a grain of salt do you think you can find? Look at his own claims: He says he has built a thousand projects. Let's say he's been doing this for a typical career span of 30 years. That's 34 projects per year, or nearly three every month! One completed project every ten days, no weekends, no holidays, no vacations. In reality, there's about 240 working days in a year, so this guy turns out a completed acoustic project every 7 working days..... Ummm... I find that just a little hard to believe. Does that sound reasonable to you? You know yourself how long it takes one guy to do a typical studio project: you've been working on yours for 3 YEARS, and still don't have it even half finished. Nor even a complete design. Ask most acousticians or studio designers, and they'll tell you that it takes months to do the average large, full-facility design project, and even for a small home studio it takes weeks. Even if he has a team of a dozen acousticians working along with him, there's no way that claim is plausible. Most acoustical designers do just a handful of projects in a year: a high volume designer might do maybe ten or perhaps twelve in a year. There's no way that someone can churn out quality acoustic designs at four times the rate of anyone else. I'm not buying that. So at the very best, his "one thousand projects" claim is hyperbole. But more likely it is plain old male bovine excrement.

he cares little for the theory of others and stands by his record

So where is his record then? Ask him for that list of a thousand happy customers, and contact several at random... Ask him for the measured test results, that prove his claim. Oh right! He doesn't have any! Because he doesn't believe in measurements or science!

Short story: anybody can make claims. If there's no data to back up those claims, then they are pretty much worthless...

He uses the same "sandwich" for his walls and ceilings. and he seemed angered that I was led to believe I needed way more materials.

Yup. That often happens with people who can't prove their claims, when others are rightly skeptical, because the claims don't match science or reality.

Put it this way: if he really did have a magical combination of materials that provides 85 dB of isolation in a low mass, cheap, thin, package, that would be all over every acoustic, architectural, and engineering paper on the planet! It would have been tested in labs, theoretical work would have been done on it to predict performance, and it would be widely used in studios all over the world. It would be the single most talked-about "discovery" in years, in acoustics.

Stuart, I have seen you savage this kind of heresy in the past, but let's try to be respectful and find a way to investigate his claims fairly. Any thoughts?

Sure! The simple way to investigate his claims, is to do just that: Investigate! Get hm to provide the data that proves his "sandwich" actually does what he claims. If he doesn't have that data, then there's your first red flag. Hearsay is not evidence, especially when it comes from he himself personally! Subjective opinion is not evidence. Evidence means real, actual objective testing in a reputable acoustic test lab. It's not hard to do: there are several such labs in Australia. Most large universities have them, or have access to them. If this guy doesn't have the data, the ask him to produce the data by having his "sandwich" tested in such a facility. If he refuses to do that, and bristles at the mere suggestion that his "sandwich" needs testing, then there's your second red flag. If he won't do it himself, then persuade an acoustics student at one of the universities to do that as pat of his thesis. "Measuring the acoustic properties of unusual combinations of materials", or something. If the acoustics student laughs in your face when he sees the design for the "sandwich" you propose testing, that would be another red flag. And the final red flag would be the test results themselves....

Perhaps another way would be to take that list of a thousand successfully completed projects (which I can guarantee you wont have a thousand names on it!), and call a few at random, as I mentioned above, then actually go to several of them and do some testing yourself, along with an acoustics student to check that the tests are done right. Test, for example, twenty out of those one thousand, and check that they all get 85 dB isolation. Any that don't, are failures. Any that obtain isolation greater than predicted by theory, are successes. Compare how many failures vs. how many successes. One single failure invalidates his claim that he has had no failures. One single success (isolation greater than theory allows for), would catapult both you and him to the forefront of current acoustic research.

But really, it isn't your job to do that: In real science, it is the person making the claim that is required to provide the evidence, not others! In peer-reviewed science, claims are made, experiments are done, theory is proposed, by someone who thinks he has a justified reason for his claims. So he publishes all of that in a paper, for others to see. Then a whole bunch or other experts in the same field try to repeat the testing, check over the theory, conduct their own experiments, ... but not in an attempt to prove the claim RIGHT! Rather, they are trying to prove it WRONG. Because that's the only logical way to do science: test the claim, and see if it stands up. If it does, then new theory is needed to explain it. If it does not, then it is abandoned, discarded, and forgotten. (Except maybe for the radical faithful few, who desperately want to believe the claim anyway, due to vested interests, despite the evidence that it is not true....)

So there's a few ideas about how you could go about checking, if you really wanted to, but honestly the onus is not on you to do that: it is on him. He is the one making the claim, so the onus is on him to provide the data and theory to back it up. If he can't or won't, and "gets angry" at the mere mention of someone having the barefaced audacity to question His Eminence, then that's your filth red flag.

- Stuart -

#9

He said he'd get back to me with some local places to check out that he has designed. Hopefully a studio on an upper level that manages to keep drums and bass amps out of their lower neighbour's earshot...

As regards to your issues with the CR design, I'm aware of the many problems the east facing CR presents. Some are solved in this design:

However the biggest problems here are the sound blasts from the Studio and CR every time someone goes between rooms. A small air lock to the studio probably helps a little, and the CR could have a "dim" switch that attenuates the monitor amp every time the door opens... but the ingress/egress is inelegant...

Compare to my best design for the north facing design:

With this the traffic issue is solved. The sliders to the left of the CR lead into the lounge, which will not blast sound leakage to the hallway either. Sure, the lack of room depth is a challenge, but I have been mixing and mastering important projects these last 3 years from lounge area where the depth is even less, and the monitors right up against the front wall. I've EQ'd the monitors from my listening sweet spot until all my time honoured references sounded right, and I've had no problems. Sure, the playback is a little off outside the sweet spot, but not much worse than a treated room. At any rate, I ask the client to sit in my chair for critical mix calls, and all is well. (I've mixed a ton of highly successful records in my time and I know what world class rooms sound like, having worked in many both here and in the US, so I'm not clueless.) I'm not sure you know this, or would agree, but the best and most experienced guys in this biz know how to pull great sounds in imperfect rooms. Certainly a lot of the guys I know of.

For this and other reasons, my preferred option is still the wide room (north facing). Either way, the new guy advises that I should still put a 60mm high floating floor in the CR and suspend an RC ceiling taking up 80mm space. He claims any resonance is soaked up by the 60kg/m3 insulation. BTW, he has since confessed that the fibre wood (canite) part of the sandwich doesn't get used any more as he's never been convinced it is worth the expense or the 13mm space. He's not a fan of the "inside out" module, not just because of extra materials and expense, but more so because he feels 450mm centres (not 600) is a critical part of his stiffness-centric approach...

The other bombshell relates to the deflection of the mounts supporting the floating floors. He said I could always add more mass to the floor after the fact, even as much as double, without upsetting the working deflection range of the Embleton "blue" rubber mounts. If the spec worsens by doing this it would apparently be so slight as to be virtually insignificant.

John Sayers also used to make certain claims that defied the accepted practices, insisting that experience trumps any theory that is commonly touted. You obviously left his site a while back, but would you say you and he diverged in opinion about various practices? Would you dare to say that you had misgivings regarding some of John's methods (some which also refute common accepted "science")? Has he ever been "wrong" about anything? - any disappointed clients you know of? I understand if you'd rather not say, but it is interesting how some of the old school guys seem to thumb their noses at the Gervais / Newell books that seems to be accepted as the industry's "Bibles"...

#10

However the biggest problems here are the sound blasts from the Studio and CR every time someone goes between rooms. A small air lock to the studio probably helps a little, and the CR could have a "dim" switch that attenuates the monitor amp every time the door opens... but the ingress/egress is inelegant...

Can you move your doors on the CR outer leaf wall? I see you have two doors there, one of which will be blocked off. I'm guessing those are existing doors in the building itself? I would suggest just moving one of those to roughly the middle of the CR right side wall.

Compare to my best design for the north facing design:

There's lots more problems with that, to be honest! The East facing design is better.

the sliders to the left of the CR lead into the lounge, which will not blast sound leakage to the hallway either.

With the East facing design, you could also have doors in the rear wall. Not ideal, but possible with careful design.

On the other hand, you could just put sliders across between your speaker soffits, in the middle of the front wall: that gives you easy access between LR and CR. Simple, effective. Great sight lines, and you can still get good isolation.

I'm not sure you know this, or would agree, but the best and most experienced guys in this biz know how to pull great sounds in imperfect rooms. Certainly a lot of the guys I know of.

Sure you can! A good engineer can mix in a not-so-good room... But it is more tiring than mixing in a good room. There's more mental effort involved in "ignoring" the defects in the room. Even though it is mostly subconscious for an experienced engineer, it still takes effort to "listen through" the poor acoustics. So why make your life more difficult and more tiring? In a great room that only tells you the absolute truth, it is easy to get mixes that translate well with less mental effort, less fatigue. It's rather like the old original LEDE rooms: they were accurate for mixing, but mentally very fatiguing because the sound was not natural or pleasant. Hence, all those more recent modifications to and extensions of the LEDE concept, to keep the good part and get rid of the bad part, creating rooms that are even more accurate, but without the negative fatiguing.

So, absolutely, the best engineers can mix in a less than stellar room... but the average engineer can't...

Either way, the new guy advises that I should still put a 60mm high floating floor in the CR and suspend an RC ceiling taking up 80mm space.

For what reason, with regards to the floor? Assuming you'll be mixing at sane levels, around 80-85 dB, and the room is correctly treated, you might be able to get away without it. Yes, it would be better to fully isolate your CR with a properly floated floor, but you still have your building floor loading limit problem: that floating floor in the CR will add mass, which you will then have to subtract from the LR mass...

I do agree with the ceiling, though: you do need some type of isolated, decoupled ceiling up there.

He claims any resonance is soaked up by the 60kg/m3 insulation.

The purpose of insulation in a decoupled wall (floor, ceiling) is many-fold. Yes, one thing it does is to damp resonances, and there are multiple types of resonance potentially going on in there. The MSM resonance is only one of those, and no, it will not "soak it up" completely. That would be impossible. At best, really good insulation might be able to knock off 20 dB from the resonance (0.9 coefficient). The theoretical limit is about 0.95, which aprox. 27 dB, so you can never have more than 27 dB reduction in resonance, even if you had perfect absorption. But of course there are no "perfect" absorbers anyway that attain the theoretical limit, and 60 kg/m3 insulation is far short of perfect...

The other things that insulation does, is to slow down the speed of sound, which is why the cavity should be completely filled, for maximum effect (despite some misguided statements from so-called "experts" who should know better): The lower c in the cavity also makes the cavity "seem" deeper by a factor of up to 1.4 (roughly), so the sound waves "think" they are traveling though a distance that is 1.4 times greater than what it really is. And the insulation also changes the way that air deals with heat, from adiabatic cooling to isothermal cooling, which obviously makes it more efficient at removing the energy from the compression phase of the sound waves, instead of just returning most of it in the rarefaction.

So you have all of those going on at once: If he thinks that all the insulation does is to "soak up MSM resonance", he is sorely mistaken. Which is why it is so important to choose the CORRECT insulation for the job....

BTW, he has since confessed that the fibre wood (canite) part of the sandwich doesn't get used any more as he's never been convinced it is worth the expense or the 13mm space.

Well that's interesting! So his "perfect and proved in a thousand studios" sandwich, isn't so perfect after all! :roll:

How surprising...

Which leads to the obvious next question: what OTHER parts of his method don't work, are are not effective? What other materials might he eliminate, add, or modify in the future, as his mood changes? How would he ever know which parts work and which don't, if he never had his sandwich tested, nor any variations of it? "Not being convinced" about something doesn't seem like a good way of designing a multi-thousand dollar isolation project... Is there a money-back guarantee if you don't actually get the 85 dB isolation he is promising you?

He's not a fan of the "inside out" module, not just because of extra materials and expense, but more so because he feels 450mm centres (not 600) is a critical part of his stiffness-centric approach...

Whooaaa!!! Hang on a sec! So he wants his walls to be MORE stiff, not LESS stiff, in order to get his isolation to work? Ummm.... he seems to be a little confused. What I was talking about yesterday, in relation to stiffness, is to use LESS stiff products for those ranges I mentioned. That is what maximizes isolation! Reducing stiffness raises the frequency of the coincidence dip, and raises the dip itself. The best isolation comes from high mass and low stiffness. This is why materials like lead and MLV provide high isolation; they are "limp mass": high mass, low stiffness: they have no coincidence dip at all!

Simple demonstration for yourself: pick up any acosutic guitar you happen to have around, and pluck a string: any string. Now increase the stiffness of that string, by rotating the tuning peg to make it tighter: the tone goes up (duh!). Now do the opposite: REDUCE the stiffness by rotating the peg he other way... and keep on going as you loosen, pluck, loosen, pluck... the less "stiff" the string, the lower AND QUIETER the note... sooner or later you'll get to the point where the string is "limp": not stiff at all... and no longer makes any sound.

QED.

If you want better isolation from a wall, you INCREASE the stud spacing from 400mm OC to 600mm oc (16" to 24"). That LOWERS the resonant frequency, and improves isolation. Check out IR-761, if your guitar didn't already convince you. There are several examples of otherwise identical walls performing better at 600 OC than 400 OC. Those are real world real walls actually tested in real acoustic labs: no fairy tails and "not too convinced it does anything useful"...

Hooo boy....

The other bombshell relates to the deflection of the mounts supporting the floating floors. He said I could always add more mass to the floor after the fact, even as much as double, without upsetting the working deflection range of the Embleton "blue" rubber mounts.

Got a link for those guys? For the specs, I mean. What is the loading that he is proposing, what deflection does that produce, and what is the resonant frequency of such a system?

On the other hand, doubling your floor mass might move your studio form the 7th floor down to the 6th, unexpectedly...

You are already close to the load limit...

You might want to ask him if he recognizes the implications of these two equations:

T=2*pi*sqrt[m/k]
k=F/d

I'm guessing he won't have a clue what they are, and could consider them meaningless even if he did recognize them... Hint; they are related to springs and resonant frequencies...

If the spec worsens by doing this it would apparently be so slight as to be virtually insignificant.

That would be going the wrong way! Yet another misunderstanding. Increasing the mass of a floated floor will INCREASE the deflection on the springs, which LOWERS the resonant frequency, thus IMPROVING isolation. With two caveats: the springs are not overloaded, such that the deflection is outside the working range (in simple terms; the springs are not squashed flat), and 2) adding the extra mass does not cause structural failure! Once again, you hit your load limit on the slab under your studio.

In simple terms: If you didn't have a load limit for your floor, it would be dead easy to solve your problem: Float each room completely, and give it a high enough mas, with enough spring deflection, that resonance is way down in the single digits, and isolation is way up high. The problem is not that you need a magical combination of esoteric materials that somehow forms an esoteric sandwich that defy the physical laws of the universe: the problem is a lot simpler: your floor can't take the load needed to get the isolation you want. And there are no magical materials! Unicorn hair and pixie dust seems to be in short supply these days...

John Sayers also used to make certain claims that defied the accepted practices, insisting that experience trumps any theory that is commonly touted. You obviously left his site a while back,

Yup. About six months back, to be precise. And I'm not going to speak badly about him, if that's what you were expecting. I also think you misunderstood what he was saying. The point he was making with those claims was that, if you have enough experience, you don't need to do the math since you already know what will happen. Some people might think that in his case he never even did the math at all, ever... which isn't true in most cases; he even posts the calculators that he uses, some of which he developed himself, along with the equations. (He even wrote a book about acoustics, filled with all the usual equations). So he perfectly understands the math, and used it at one point... except later he no longer needed to do it, since he had done it so often that he knew what it would say. The same is true of most experienced studio designers: they can look at a product or a design, and give you a rough "guesstimate" of the performance without needing to do the math, and they won't be far wrong. And that's fine for typical situations! But when it gets to unusual things, beyond the norm, you still need math and theory. Once things are outside the realms of "common" and "normal" and "typical", then it's time to break out the equations and the calculator. You can't rely on experience for areas where you have none! On the other hand, your guy doesn't seem to accept math or equations or theory or science at all! :shock:

Even worse, he wont use math to check his own guesses.... He rejects your attempts to check his designs, and gets upset every time you try.... Red flag! Big one!

but would you say you and he diverged in opinion about various practices?

In essentials, no. He knows his stuff, as far as his experience goes, and I learned a lot from him that I later found to be correct when checked with math and science.

Would you dare to say that you had misgivings regarding some of John's methods (some which also refute common accepted "science")?

Seldom. And I don't agree that his studios are designed using principles that "refute science". I'd agree that he doesn't like theory too much, and does some strange things occasionally, but none that "refute science".

Has he ever been "wrong" about anything?

I imagine he probably has! So have I! So has everyone. We are all human, and sometimes make mistakes. Honest folks admit it, correct it, and carry on. Only a dishonest person would claim that he never makes mistakes, that all his efforts were perfect, flawless, with no failures, not even after building a thousand times....

any disappointed clients you know of? I understand if you'd rather not say,

I'd rather not say...

And to be very honest, I don't know of any studio designer who has a 100% perfect track record, with every single client being totally satisfied. I'm aware of some having higher success rates than others, but that's all I'll say. I'll also say that, personally, I would not trust anybody who said they had one thousand clients and every singe one of them was 100% perfectly satisfied, with no "disappointments".

but it is interesting how some of the old school guys seem to thumb their noses at the Gervais / Newell books that seems to be accepted as the industry's "Bibles"...

I don't have any beef against Rods' book (except maybe that he could go into more detail in places), but I'll happily jump on the bandwagon and thumb my nose at some of Newell's stuff! So will many other acousticians, both "old school" and "new school" (to coin a term....)... there just so much in "Recording Studio Design", for example, that makes no sense and flies in the face of science. Did it work? Sure! He got results. But was it all necessary? Nope. In many cases, the results he got by combining multiple layers of unusual material in exotic, undocumented ways, could have been obtained (or even exceeded) with more conventional materials in a far simpler (and proven) arrangement. A lot of his explanations are speculation, not science. "Layer 5 absorbed the low mids, and layer 7 cancelled the resonance, and layer 14 did something else, and all together we got 50 dB of isolation with only 23 layers..." Ok, I exaggerate, but that's the style of his book. You just have to take his word for it, most of the time... yet real theory and practice show that the multiple layers were not necessary, and the same results (or better) can (and frequently are) be obtained in far simpler ways. Don't get me started on Newell and his strange stuff... we had a discussion about that on the forum a while back... the general consensus was that we all agreed: Everest and Gervais and Toole and Cox and D'Antonio and Long and many others, all know their stuff, and use science, research, testing, theory, and careful documentation, with proven, repeatable, consistent, coherent, logical results. But Newell doesn't do that, for most of his book. The parts where he does have equations and theory and explanations are fine, for sure, and correct... but the parts where he describes how he actually built places, do not really use much of the theoretical stuff he spouts... it's just sort of "winging it": Not to mention that he only includes his successes in the book! As far as I recall, he doesn't discuses his failures...

So, no, I would not consider Newell's book to rise to the level of "Acoustic Bible Gospel Truth": maybe "cult ramblings" would be a kind way of putting it. Everest's MHoA is probably the one that most acousticians would call the "Acoustic Bible". Maybe Marshall Long's "Architectural Acoustics" too. And a coupe of other, less well known ones.

Anyway, getting back to the "old school" guys: my beef with them is that they know their "old school" stuff rather well, but acoustics is a young science, and is not static: it advances all the time, and just staying up to date is a challenge! There are new things coming out all the time, some of which can be incorporate into studio design, and some of which improve on the "old school" methods. There are now better ways of doing things, which had not been discovered 20 or 30 or 40 years ago when the "old school" guys were in their hay-day periods: They built rooms back then that worked, and sort of got "locked in" to that method... then didn't want to change and adapt as the science moved ahead, breaking new territory. And they still design studios the same way today! The studios still work, of course: just like they always did. So if you want a 70's or 80's style studio, then great! Use an old design from an old-school designer! Nothing wrong with that. But there are better methods today, better understanding of how acoustics works, how humans perceive sound, how that can be used to improve studio designs, better materials, better tools. So if you want an up-to-date studio design that performs better than the old school designs, then you have that option today.

For example: LEDE again. It was al the rage in the 70's and 80's, until the shortcomings were identified, and along came NER, RFZ, CID, and few others, which improve on, and extend the original LEDE concept. No modern designer would do a traditional LEDE room today! Yet a very few people still want true LEDE rooms, and one or two "old school" designers still do them, even though they suck, when compared to modern designs. There are far better design concepts today. You probably know that I'm a fan of RFZ myself, and pretty much all my designs are based on the RFZ concept... but I don't do standard RFZ rooms! I use the basic concept, but I do some things differently, because the science of acoustics has also moved on from when RFZ first came around. There are ways to improve on, and extend, traditional RFZ design, and that's what I do in my rooms. You can see the results in the rooms I have designed.

And maybe if another design concept comes along, with new research to show THAT it works better, and WHY it works better, then you'll see me leaving RFZ behind, and moving on to the new one. Because I don't plan to get bogged down in the past, like some of those "old schoolers" have done, who carry on building studios "the way I've always done it". Their studios might still work OK... as long as what you want is a design from 20 or 30 years ago, limited by what was known back then, and the materials that were available back then. But me? I prefer to stay up to date, and to things as well as they can be done today, based on current acoustic science and knowledge, not obsolete stuff from the last century. I want to give my clients the best that they can afford, the best available. Not a Model T ford, but rather a Bugatti or Lamborghini.. or perhaps a Tesla....

And here endeth my rant for today!

- Stuart -

#11

Well, if you ever put a book together, I'm sure it will surpass most of the existing ones out there. It certainly won't be lacking any details! 8-)

. Another excellent and much appreciated post. (I sent you a PM btw...)

Care to expand on all your perceived negatives re the North facing CR?

#12

... also, I have some questions about his idea of having a "double decker" floating floor (one on top of the other). He claims that loud drums will be attenuated sufficiently through 2 floating systems, each around 60mm insul filled gap with 19mmm and 25mm particle board on rubber mounts. That's 2 similar cavities creating the same resonance twice!. I rang some ex clients (very big industry ames) and they have claimed these floors work well. Apparently the 60kg/m2 insulation absorbs all the cavity resonance. Still, I don't understand why you wouldn't make each floor different, or just have a 100mm gap with the 4 layers of particle board on top. Did you check out my PM? Any thoughts?

#13

killerjoe wrote:Source of the post Well, if you ever put a book together, I'm sure it will surpass most of the existing ones out there. It certainly won't be lacking any details! . Another excellent and much appreciated post. (I sent you a PM btw...)

I've been considering writing a book for a while now.... maybe I will get around to it one day!

Care to expand on all your perceived negatives re the North facing CR?

Here's just a couple:

- Not deep enough. Not enough distance between the engineer's head and the rear wall. A known and well understood problem these days in psycho-acoustics.

- For the same reason as above: you can't get the client couch far enough away from, the rear wall, so your clients will not be hearing the same acoustic as the mix engineer... and will then complain about the lack of bass and focus when they listen to to the mix in their car, homes, ear-buds, etc. "But that's not what I heard when we listened in your CR! It sounds different! Where did the bass go?"...

- For the same reason as above: you won't be able to get enough treatment on the rear wall. In any studio, the rear wall is the most critical, and needs stacks of treatment. Deep, thick, broad, high, wide treatment. You won't be able to do that, due to limited depth.

- You won't be able to use numeric-sequence diffusion on the rear wall: too close to the engineer's head.

- Poor sight-lines to the LR: the poor engineer is going to end up with a permanent neck-ache, from twisting his head sideways all the time while tracking. (Ditto for the producer / director / musicians / WAGs sitting back there on the client couch...)

- Poor speaker geometry: they will have to be spread too far apart, but still too close to the mix position, at strange angles, and hard to soffit mount them successfully with that layout.

And a few others too, but for me, those would be deal-breakers. The entire purpose of a control room is accuracy, precision, providing an environment that sounds crystal clear, natural, transparent, where you can hear ONLY the sound from the speakers, totally unaffected by the room itself. You stand a much better chance of achieving that with the East-facing layout.

You might want to take a brief look at a thread just started a couple of days ago by a new member to the forum: viewtopic.php?t=690 He says it all, in a few words.

... also, I have some questions about his idea of having a "double decker" floating floor (one on top of the other).

My simple answer would be: don't do that! Firstly because that would be a three-leaf system (or even a FOUR-leaf system) in combination with your floor, so very poor isolation for some low frequencies..... secondly it won't do what you are hoping it will do, and thirdly because it will reduce your headroom: Raising your drums up so high means they will be closer to the ceiling. Your inner-leaf ceiling is already going to be low.... you don't want it lower still, due to the lousy sound that a low ceiling gives to drums, and also to the artifacts that ceiling reflections cause in the overhead mics...

He claims that loud drums will be attenuated sufficiently through 2 floating systems, each around 60mm insul filled gap with 19mmm and 25mm particle board on rubber mounts.

So, adding all that up, you would be losing about 220mm (nearly 9") in headroom, for now real benefit.... And adding a large additional load of heavy wood, on an already close-to-the-limit floor... Hmmmm...

Not to mention that the drum riser will do NOTHING AT ALL for air-borne sound! Sound in the room that reaches the part of the floor NOT covered by the drum riser, is still going to get through to the room below just as strongly as it did before, regardless of the drum riser. What the drum riser REALLY accomplishes, is to reduce the transmission of impact noise into the floor

But if you really want to build a drum riser properly, take a look at how Jennifer did it, and the results she got: viewtopic.php?f=6&t=9

That's 2 similar cavities creating the same resonance twice!

Yup. Very correct. Did he give you the results of the independent laboratory testing he did on that, to show how it works in practice?

and they have claimed these floors work well.

Compared to what?

If you have no point of reference to compares something against, then how would you know if it was better or worse? Did any of those "big clients" do any testing in the rooms WITHOUT the riser in it, and compare it to the results WITH the riser in it, like Jennifer did for example? Not to mention the highly subjective nature of the "big money" syndrome: If you spent many tends of thousands of dollars getting something built, or buying something, you do tend to evaluate it far more favorable than a more objective person, who has no vested interest! Do you really think that a big-name studio is going to say in public: "Actually, our place sounds like crap! We hate it. The isolation is terrible, the acoustic response is all wrong, and it sounds lousy.".

They would not be in business very long, if they said that. Would you go to a restaurant that advertised how lousy their food was, after the installed XYZ cookers, and ABC food processing equipment?

Apparently the 60kg/m2 insulation absorbs all the cavity resonance.

No it does not. Sorry. It just doesn't. Here's why:

We are taking about isolating drums here, where most of the energy is
below about 200 Hz. That's the point where 60mm of 60 kg/m3 mineral wool STOPS being effective. A kick drum typically has a fundamental resonance at 80 Hz, for example... See how well 80 Hz is absorbed by that stuff...

Still, I don't understand why you wouldn't make each floor different, or just have a 100mm gap with the 4 layers of particle board on top.

Exactly!

Did you check out my PM? Any thoughts?

I did yes.... And I'm still not buying it!

There's no OBJECTIVE measurements in there! Just a lot of SUBJECTIVE stuff, by people with very high dollar vested interests in convincing their clients that their studio has spectacular acoustics....

Now, getting back to YOUR place in the same context: How many of those folks built their studios the seventh floor of a commercial office building, where the elevator only goes to level six, and the floor slab has a low structural load-bearing capacity that isn't high enough to alow building a studio with high isolation? How many of them are in the same situation you are? Those are the only ones that matter. Those are the ones you should visit, in person, with your sound level meter in hand, to check how they REALLY perform. And most importantly of all, talk to their neighbors! The offices on the same floor, and the ones on the floor below. You can ignore every other client on the list, since their testimony is not meaningful to you, and just visit the ones who are in your same situation. How many on the list are like that? My guess is very, very low number....

- Stuart -

- Stuart -

Soundman2020 - Studio Design Forum