Groundlift Research & Development NEW STUDIO (consolidated)

[Darth Fader]

Hello again

As per Greg and Stuart, here is the new consolidated thread for my studio build.
I'll post here from now on, continuing on from this

http://www.johnlsayers.com/phpBB2/viewt ... =2&t=21544

and this
http://www.johnlsayers.com/phpBB2/viewt ... =2&t=21545

more to come... and thank you!!

[Darth Fader]

Ok, so making some progress with SketchUp.

Couple of questions re: acoustics, size, shape, etc...

1 - From what i gather, every room will have several nodes, areas of low end build-up, and the goal when picking a size would be to make it so those nodes are as evenly dispersed across the (low) frequency spectrum. And the same or double, per each 1/3rd octave going up? (Bonello?) - I.e. as few holes as possible.

2 - Once the room has been measured, adding bass traps will help bring down the "worst offenders" as far as low end bumps, and this is where it gets foggy for me... For example: Front-Back distance would create one (or more) strong nodes, and thus, a bass trap along the back of the room could help alleviate this? Next: Left-Right distance (btw walls) would present another set of nodes.. so now: Where do those bass traps go? Along the side walls? Also in the corners?

3 - Once the largest nodes have been adressed, is it typical to design bass traps that are more specifically tuned, frequency-wise, for "that last really bad node at 145hz, that just won't go away"?

4 - If one is to assume (i know... don't assume ) that a standing wave is created btw. two surfaces (like L/R walls of a control room) would it be correct to assume that if the side walls are splayed out, from front to back (narrower at front of ctrl room), this would have a positive effect - i.e. the theory being a standing wave of freq. X is only created at that one particular point along the side wall (as opposed to all along it, from front to back) and thus the standing waves would be of a decreasing frequency, as one moves further back in the control room? (in short, control rooms are designed with splayed wall primarily - or at least partially - for this purpose?)

And as before, short version: Does a bass trap located in the front two corners of a control room do justice to L/R and F/B low end build-up? Or is that just a starting point?

Thank you, and have a great week!

[Darth Fader]

Also: regarding HVAC systems, have you all had any experience with "Heat Reclaim Ventilator" or "Energy Recovery Ventilator" systems?

I find it very difficult to find an AC person that is not stuck in the "old style" way of doing HVAC, where 80% of the inside air is recycled, and 20% (roughly) comes from the outside, and there is no real control (or option) to add more outside air. Obviously this is key when it's 105 F outside, but not always.

This has always been an issue for me, when the temperature outside is 50 degrees F and i have to keep the AC running at 74 because i have no way of drawing in (and using) the cooler air from the outside.

Any thoughts on this?

Lastly: is there a rule of thumb, for ductwork in the studio setting? I'm going to assume the key here is to keep airspeeds as low as possible, and again here, dealing with "normal guys" they will aproximate duct diameters based on home setups, I presume, not our particular needs for the studio. So... double the average diameter? Or?? For me, a lot of the noise seems to come from the air actually moving through the registers, so the larger (slower) the better, no?

[Gregwor]

1 - From what i gather, every room will have several nodes, areas of low end build-up, and the goal when picking a size would be to make it so those nodes are as evenly dispersed across the (low) frequency spectrum. And the same or double, per each 1/3rd octave going up? (Bonello?) - I.e. as few holes as possible.

As many evenly dispersed as possible, yes. Hence Abbey Road being awesome sounding. It's huge. Bigger = lower Schroeder Frequency.

2 - Once the room has been measured, adding bass traps will help bring down the "worst offenders" as far as low end bumps, and this is where it gets foggy for me... For example: Front-Back distance would create one (or more) strong nodes, and thus, a bass trap along the back of the room could help alleviate this? Next: Left-Right distance (btw walls) would present another set of nodes.. so now: Where do those bass traps go? Along the side walls? Also in the corners?

Bass traps don't "bring down the worst offenders". They will always exist in that room. Again, referencing my response above, we want more. This is because we can't turn them down. And the only way to add them is to make the room bigger. What we can do with treatment is convert their energy to heat and ultimately dampen them. Corner, tri-corners specifically are where the most bass buildup exists. So that's why corners are the best places to place low frequency absorption. The idea is to treat your room so that the frequencies decay evenly.

3 - Once the largest nodes have been adressed, is it typical to design bass traps that are more specifically tuned, frequency-wise, for "that last really bad node at 145hz, that just won't go away"?

Again, you aren't really addressing nodes per say. Treatment can help with several issues. A room's modal response is only part of the battle. Phasing, SBIR, power imbalance, decay, etc are all things that need to be addressed. Luckily, a thick rear wall helps with a lot of the issues in a control room. The design from the get go (ray tracing, making sure you're sitting at a good distance from the front and rear walls, making sure your speakers are at a good height, making sure your speakers are at a good distance from the side walls, etc, etc) can help alleviate issues before they even start.

Does a bass trap located in the front two corners of a control room do justice to L/R and F/B low end build-up? Or is that just a starting point?

The front two corners (vertically) are 2 of 12 corners that should be addressed if possible! Every little step helps. Bass traps in the corners, first reflection point and rear wall absorption are your biggest bang for your buck treatments. From there, the improvements get smaller and smaller, but everyone helps. The treatment stops when you run out of room or budget/time.

Also: regarding HVAC systems, have you all had any experience with "Heat Reclaim Ventilator" or "Energy Recovery Ventilator" systems?

I understand them, yes. My new place will have one. My friends have them. They're great.

I find it very difficult to find an AC person that is not stuck in the "old style" way of doing HVAC, where 80% of the inside air is recycled, and 20% (roughly) comes from the outside, and there is no real control (or option) to add more outside air. Obviously this is key when it's 105 F outside, but not always.

If possible, you should design your HVAC so that you are getting 25-30% fresh air into your system.

Lastly: is there a rule of thumb, for ductwork in the studio setting? I'm going to assume the key here is to keep airspeeds as low as possible, and again here, dealing with "normal guys" they will aproximate duct diameters based on home setups, I presume, not our particular needs for the studio. So... double the average diameter? Or?? For me, a lot of the noise seems to come from the air actually moving through the registers, so the larger (slower) the better, no?

"Normal" HVAC guys are fine to give you your CFM numbers. But even you can do those calc's using rudimentary figures. Stuart is the boss when it comes to latent heat loads and things like that. In my own studio, I don't have a big console or tons of outboard gear to worry about generating heat.

CFM = (# of air changes per hour X volume in cubic feet) / 60 minutes
You need at LEAST 6 air changes per hour. 8 or 10 is better if you have the space for that larger duct work and silencer boxes... and a unit that can handle that amount of air

The cross sectional area (I call this CSA) in square feet = CFM / <300 feet/min
Note: Square inches = Square feet X 144

Cross sectional area of a circle = pie R squared
Cross sectional area of a rectangle = width X height

Here are some standard duct sizes for CFM... or you can use a ductulator

Duct Sizing.png

So, to answer your question more directly, yes, you need to keep your air velocity below 300 feet per minute otherwise it will be too loud. You can figure out how big of ducts you need to hook into your silencers by having your room cubic feet and knowing how many air changes you want. From there, make the inside of your silencers twice the cross sectional area as your supply duct. Maintain that size going into your second silencer. If you can't put a register cover directly on your silencer sleeve, you will have to run duct work inside your room. That duct work must maintain that big cross sectional area providing you with that 300 feet per minute or slower air velocity. Also, check the specs on your register covers as some are louder than others. The manufacturers have charts that show their NC values.

Greg

[Darth Fader]

I love this forum!!

Thank you!! I’ll read this through. Again. And again.

[Soundman2020]

1 - From what i gather, every room will have several nodes, areas of low end build-up, and the goal when picking a size would be to make it so those nodes are as evenly dispersed across the (low) frequency spectrum. And the same or double, per each 1/3rd octave going up? (Bonello?) - I.e. as few holes as possible.

"Modes" not "nodes", but yes, basically. Just to confuse you more: Modes can have nodes, but nodes can't have modes!

Modes are also sometimes called "standing waves". A "mode" in this sense refers to one specific manner in which a wave can bounce around the room then get back to the spot where it started, going the same way as it did the last time, and in phase with itself. Picture a kid on a swing: each time he passes his dad, dad gives him a little extra push: that's what the speaker does to a room mode: it gives it a little extra "push" each time the wave goes by, and that push is in phase with the wave, and going in the same direction. So the wave intensity builds up and up. If Dad gave Kid a push at the wrong moment, or going in the wrong direction (eg, pushed him sideways, or backward, not forward), the kid would not swing higher and higher: he's soon stop. It's only when Dad gives Kid a shove in the right direction (forward) at the right time ("in phase" with the way Kid is already swinging), that Kid goes higher. Same with room modes: When you have one, it goes "higher and higher" each time it passes "Go" and collects $ 200. They are called "standing waves", because they have the strange characteristic that they seem to "stand still" in the room. They don't actually stand still, of course; the wave is still dashing around the room at the speed of sound. But the pressure peaks and nulls always form at the exact same locations in the room. Imagine if you are watching the Dad / Kid / Swing scenes, but you keep your eyes closed most of the time, and only open them for a fraction of a second at the exact point where Kid rushes past Dad. What you see is Kid not moving at all! Every time you blink your eyes open, he's in the exact same spot, and you never see him in any other spot, so you could assume that he is not moving. Hence, he would be a "standing wave".... (yeah, I know: weak analogy... but it might help...)

Modes occur at very specific frequencies: when the wavelength matches the path length that the wave took around the room to get back where it started. So for axial modes, that means the wavelength matches the distance between two walls on opposite sises of the room. That means that you can adjust the FREQUENCY where a mode will form by adjsuting the distance between walls! And by adjusting all three distances together, you can get your modes to happen at various frequencies and in various patterns.

2 - Once the room has been measured, adding bass traps will help bring down the "worst offenders" as far as low end bumps,

Weeellll.... yes and no. Sort of. The thing is, the absorption of a bass trap does NOT change the mode! It does not "go away". It is still there. It's a consequence of having walls around your room, so the only way to make a mode "go away" is to bring in a bulldozer and knock down the wall! What a bass trap does is not to get rid of the mode, but rather to damp the resonance. Think of the kid on a swing: if you put a big puddle of water under the swing, and the kid has to drag his feet though the water each time he goes past Dad, then he ain't gonna swing so high no more! The drag of the water removes MORE energy than Dad can put in on each cycle, so the Kid soon stops swinging. The deeper the water (the more of the kid's legs are in it), the quicker he stops swinging. But the swing and the kid and Dad are all still there. By adding water, you didn't make them go away: you just damped their motion.

Same with a bass trap: it doesn't make the mode go away, it just reduces the "ringing". You can sort of think that the mode has "inertia", like the kid on the swing. The more energy Dad adds on each pass the higher the Kid goes, ... then when Dad STOPS pushing (and goes home, for example), the kid still carries on swinging because of his own inertia. Modes "ring" for the same reason: after the speaker stops making that note, the mode still carries on bouncing around the room for quite some time, due to its "inertia". There is energy "stored" in that mode, and it carries on for a while. But when you put a bass trap in there, that's the same as putting the puddle under the Kid. The bass trap "damps" that inertia, and stops the ringing.

Front-Back distance would create one (or more) strong nodes, and thus, a bass trap along the back of the room could help alleviate this?

For axial modes, yes.

Left-Right distance (btw walls) would present another set of nodes.. so now: Where do those bass traps go? Along the side walls? Also in the corners?

Answer: Yes! Back to modes and nodes. All modes have peak pressure nodes in the room corners, so that's a really good place to put bass trapping. Think of this: If you put thick absorption in the middle of one wall, that will reduce the ringing of axial modes associated with that wall, but it won't do anything for modes associated with the other walls. However, if you put the same absorption in the corner where two walls meet, it now has the same effect as before, but for modes associated with BOTH walls. And if you put it in the "tri-corner" where two walls meet the ceiling (or two walls meet the floor), then you can hit modes associated with all three of those room axes. That's why tri-corners are the best place for bass traps: because you hit all possible modes at once. That's why you frequently see references to "all modes terminate in corners": all modes have a pressure peak (and velocity null) in the room corners.

3 - Once the largest nodes have been adressed, is it typical to design bass traps that are more specifically tuned, frequency-wise, for "that last really bad node at 145hz, that just won't go away"?

It might be necessary, yes, but usually isn't a problem. Especially with a frequency as high as you give in your example. The ones that "just wont go away" are usually the lowest ones: first order axials. It's hard to hit those with just porous absorbers, as the wavelengths are just so long, so you might need specifically tuned traps for those. But the best plan is to first go with abundant broad-band porous-absorption type traps, then deal with the stubborn left-overs (if there are any).

If you are interested in seeing how this all works out in practice, here's a thread where we are tuning the control room for one of my customers, and he really wanted to share this process on the forum: www.johnlsayers.com/phpBB2/viewtopic.php?f=2&t=21368 You can see how it all comes together.

4 - If one is to assume (i know... don't assume ) that a standing wave is created btw. two surfaces (like L/R walls of a control room) would it be correct to assume that if the side walls are splayed out, from front to back (narrower at front of ctrl room), this would have a positive effect

Not really, no. Take into account that you are dealing with waves that are dozens of feet long: splaying a wall by a few inches is not going to have a huge effect on that. If you could splay a wall by ten feet, that might have a worthwhile effect.... but it would eat up a huge amount of space!

Besides, it's a common misconception that you should try to "get rid" of modes... Myth. That's actually a really BAD thing to do: The problem with small rooms is not that you have too many modes in the low end: the problem is that you don't have enough!!! So getting rid of them (even if it were possible) would be a bad thing.

i.e. the theory being a standing wave of freq. X is only created at that one particular point along the side wall (as opposed to all along it, from front to back)

Bad assumption! Once again, the wave is huge: tens of feet long. It affects the entire wall (not just a single point on it). In fact, it affects the entire space in between the two walls as well! a mode "fills" the room.

thus the standing waves would be of a decreasing frequency, as one moves further back in the control room?

Do the math. Let's say your walls are ten feet apart, and thus your mode is at 56.5 Hz. The wavelength is 20 feet! (twice the lowest mode, since the mode occurs at the frequency of the "there-and-back" distance). Let's say you splayed the wall so that one end is a foot different from the other. So one end is now 9'6" away from it's partner, and the other end is 10'6" away. So the frequencies are now 53.8Hz and 59.5 Hz at the ends, and still 56.5 Hz in the middle... not a lot of difference!

(in short, control rooms are designed with splayed wall primarily - or at least partially - for this purpose?)

Not really, no. control rooms have splayed walls in order to implement one of the design concepts that requires splayed walls, such as RFZ, NER, CID or other similar. The walls are splayed to reflect mids and highs away from the mix position, not to slightly adjust the modal frequencies.

Does a bass trap located in the front two corners of a control room do justice to L/R and F/B low end build-up? Or is that just a starting point?

Assuming they are large enough, then yes: if you put bass traps in the front vertical corners of a room, that will have an effect on both the lengthwise axial, and also the width-wise axial, but it will have no effect on height-wise axial. It will also have a good effect on the length-width tangential modes, and a lesser effect on the length-height and width-height tangentials. And it will have a small effect on the oblique modes.

As Greg pointed out: don't get too tied up on room modes and modal response. Yes, you can (and should) choose dimensions that help to spread the modes around evenly, but that's only one of many aspects that you need to take into account. Studio design involves juggling dozens of aspects at all once, and trying to come up with an optimal solution. It's all about trade-off: frequently in studio design, you'll need to sacrifice some aspect in order to improve another aspect. For example, if you have to choose between making a room smaller in order to get slightly better modal response, then don't! It's more important to maximize the air volume in a small room, even if that means a modal response that isn't fantastic. As long as the modal response is not terrible, then it's usually better to forget about it, and just go for more room volume. Usually, but not always....

- Stuart -

[Soundman2020]

I find it very difficult to find an AC person that is not stuck in the "old style" way of doing HVAC, where 80% of the inside air is recycled, and 20% (roughly) comes from the outside, and there is no real control (or option) to add more outside air. Obviously this is key when it's 105 F outside, but not always.

This has always been an issue for me, when the temperature outside is 50 degrees F and i have to keep the AC running at 74 because i have no way of drawing in (and using) the cooler air from the outside.

Any thoughts on this?

An ERV or HRV (they are not the same!) can recover a large percentage of the energy that would otherwise go overboard. Very recommendable. But there's also the issue you mentioned, of dumping too much air overboard when you didn't need to. The REAL reason you dump the stale air is CO2. You want to get rid of the CO2 that people are exhaling. Most people think that if you seal your head in a plastic bag (or an air-tight studio), that you'll die from lack of oxygen. Actually, you won't: long before the oxygen level drops low enough to kill you, the CO2 level will have risen to many times the level that will kill you. You can die in air that has plenty of oxygen in it, but way too much CO2. So you dump the stale air overboard, mainly to get rid of excess CO2. But commonly, you dump more than you need to! If only there was a way to detect the CO2 level in the room air, and only open the "dump" valve if the level is too high . . .

Yup, you guessed it; there are sensors you can buy for your HVAC system, and controllers to go with them, and motorized damper valves... put it all together, and you have a system that regulates the flow of stale air (and make-up fresh air) based on the CO2 level. so when it is just you in the studio, the damper valve is nearly closed, and only a small percentage of the re-circulation air gets dumped, but when there's a whole band in there, sweating an huffing and puffing, the system detects the much higher CO2 levels, and opens that valve wide, so it dumps far more bad stuff (and sucks in far more good stuff). Yes, that adds extra expense and complexity to the HVAC system, but the cost will be offset by the reduced need to cool that incoming make-up air.

Combine that with a good HRV (or ERV if you live in a climate region where that makes more sense, and uf you have ore money.... ) and you can have a very efficient system that doesn't waste much energy in the air that it dumps.

Lastly: is there a rule of thumb, for ductwork in the studio setting? I'm going to assume the key here is to keep airspeeds as low as possible,

Yes. As Greg mentioned, you should aim to have the air velocity at the registers no higher than about 300 FPM. Lower wherever possible. If the velocity goes much higher than that then the air movement itself is creating noise that will annoy you in the very quiet control room, and get into your mics in the tracking rooms / iso booths.

Don't confuse air velocity with air flow volume: not the same. For a studio you need to move large volumes of air at low speeds, which is different from what most houses/shops/office do; they move lower volumes at higher speeds. Especially in offices, where the HVAC system is deliberately designed to CREATE noise... it is supposed to create low-level white noise (or brown noise) that helps to mask the sounds of conversations close by, as well as masking all the other typical office sounds. But for a studio, you do NOT want any HVAC noise. You want NC-15 ideally (or lower), and certainly no more than NC-20. You can't get that with noisy HVAC that is moving air too fast.

The speed in the ducting can be higher than 300 FPM, of course, but it must have been slowed down below that by the time it comes out the register. And the "slowing down" process should not produce turbulent air flow, because turbulence is noisy!

, and again here, dealing with "normal guys" they will aproximate duct diameters based on home setups, I presume, not our particular needs for the studio.

Right! That's why you do NOT want those "normal" guys to design your system! Don't let them anyplace NEAR your design! Hire them to BUILD the design, but not to MAKE the design. Do that part yourself, and just give them the specs of what needs to be built.

. So... double the average diameter?

Nope! Start with your room volume (how many cubic feet or air are inside each room?) Multiply that by 6, at least, since you need to have at least 6 room changes per hour. That's how much air you have to move. So if (for example) your control room has a volume of 2,000 cubic feet, then you would need to design the HVAC system to move 12,000 cubic feet per hour. You already know that the air cannot move faster than 300 FPM at the register, so do the math to figure out the minimum duct diameter at the register, and work backwards from there. Silencer boxes are a BIG part of studio HVAC design...

For me, a lot of the noise seems to come from the air actually moving through the registers, so the larger (slower) the better, no?

That's why you want less than 300 FPM at the registers, with non-turbulent flow! So you need low-noise registers that have a very large open area percentage. Hint: the actual open area of a register that measures 10" by 10" is NOT 100 square inches! More like 60 or 70 in2... The vanes and frame take up space... and create turbulence in normal registers. Specially designed low noise registers streamline the air flow, and crate less turbulence.

Lots of things to consider!

- Stuart -

[Speedskater]

Note that in the past "Darth Fader" was a user name that 'j.j.' sometimes used.
'jj' is James D. Johnston.

[Darth Fader]

OK - again, really really great stuff here! Thank you guys!!

What I've learned so far (and then some questions, to follow up)

1 - Yes.. MODES, not nodes.. should have remembered that from my school days (we did in fact read most of that F. Alton Everest book - but that was many moons ago!)

2 - Wavelengths are much larger (longer) than I really gave myself to realize. So the "splayed wall concept" and why it has no effect makes total sense now - AND i understand that it still will help with the RFZ design, so good.

3 - You have a lot of data and experience at your fingertips (here) to design your own HVAC system, and then have the "regular AC guys" build it. AND you trust me (in theory) to do the same for my studio. Again = good news.

4 - I've really come to look at studio construction and the 2-Leaf system differently, or more clearly, i should say. Really makes sense now: look at it as an outer shell (outer leaf) and several inner shells (control room, tracking room, iso's etc) = again.. awesome.

Question: On the attached photo (from one of John Sayer's designs, i belive) there are several different shapes and sizes, when it comes to the air gaps between the leaves (some are parallel, some are not, some are very narrow - an inch perhaps, and some are up to a foot?). I presume having a wider airgap would help with the isolaton? Is there an advantage to having the two leaves NOT be parallel? (even if they're not touching, obviously). And.. from a practical standpoint: what do you use to seal the gaps (around doors, for example = in RED on the attached photo) so the cat doesn't get lost btw the walls when walking from the Control Room to the Vocal Booth? I'm assuming some sort or neoprene? or fabric? One would want to avoid anything that actually connects the two leaves, so...

Also, at the risk of getting ahead of myself: for a concrete floor and a concrete ceiling, would you put Mass Loaded Vinyl, Neoprene or similar btw the 2x4's (plates?) and the floor, and would you have an 1/8"-1/4" gap btw the drywall and the floor, that gets filled with caulk? Im guessing drywall sitting on the floor is not good? Or is the vibration from a solid concrete floor minimal enough to not cause a problem, and i can then just nail the 2x4's straight into the floor / ceilings?

Ok, good for now!!

[Gregwor]

On the attached photo (from one of John Sayer's designs, i belive) there are several different shapes and sizes, when it comes to the air gaps between the leaves (some are parallel, some are not, some are very narrow - an inch perhaps, and some are up to a foot?).

John has stated somewhere that he used to believe that having glass angled from one another would help is isolation, but he doesn't believe that anymore. Maybe you've dug up one of his older designs.

I presume having a wider airgap would help with the isolaton?

Correct. More gap = lower resonant frequency.

Is there an advantage to having the two leaves NOT be parallel? (even if they're not touching, obviously).

No. If there is, it's negligible.

what do you use to seal the gaps (around doors, for example = in RED on the attached photo) so the cat doesn't get lost btw the walls when walking from the Control Room to the Vocal Booth? I'm assuming some sort or neoprene? or fabric? One would want to avoid anything that actually connects the two leaves, so...

Insulation wrapped in fabric works well. You don't want to seal the space though.

for a concrete floor and a concrete ceiling, would you put Mass Loaded Vinyl, Neoprene or similar btw the 2x4's (plates?)

No. Just wood on the floor.

and the floor, and would you have an 1/8"-1/4" gap btw the drywall and the floor, that gets filled with caulk?

Correct.

Or is the vibration from a solid concrete floor minimal enough to not cause a problem, and i can then just nail the 2x4's straight into the floor / ceilings?

Things contract and expand. You never want your drywall sitting directly on the floor. You can put some glue down before you anchor the walls to the floor.

Greg

[Darth Fader]

Excellent, Greg.

Thanks!

[Soundman2020]

You can put some glue down before you anchor the walls to the floor.

Caulk. Not glue, but caulk. Glue hardens, but good quality flexible bathroom / kitchen caulk does not: it remains soft and rubbery, even when fully cured. And it sticks like crazy to most typical construction materials. So it gives you an excellent seal, and can also move, bend and flex along with the structure (thermal expansion, settling, vibration, seismic, etc.) without cracking.


- Stuart -

[Darth Fader]

You can put some glue down before you anchor the walls to the floor.

Caulk. Not glue, but caulk. Glue hardens, but good quality flexible bathroom / kitchen caulk does not: it remains soft and rubbery, even when fully cured. And it sticks like crazy to most typical construction materials. So it gives you an excellent seal, and can also move, bend and flex along with the structure (thermal expansion, settling, vibration, seismic, etc.) without cracking.


- Stuart -

Got it.
How about that Mass Loaded Vinyl? Would that be a waste of money? Seems like it'd be a simple enough thing to get a few feet of that and cut into strips to put btw the plates and the floors / ceilings?

Or maybe there's really no vibration (transfer) to worry about, with a proper concrete floor.. so ..

[Darth Fader]

As Greg pointed out: don't get too tied up on room modes and modal response. Yes, you can (and should) choose dimensions that help to spread the modes around evenly, but that's only one of many aspects that you need to take into account. Studio design involves juggling dozens of aspects at all once, and trying to come up with an optimal solution. It's all about trade-off: frequently in studio design, you'll need to sacrifice some aspect in order to improve another aspect. For example, if you have to choose between making a room smaller in order to get slightly better modal response, then don't! It's more important to maximize the air volume in a small room, even if that means a modal response that isn't fantastic. As long as the modal response is not terrible, then it's usually better to forget about it, and just go for more room volume. Usually, but not always....

This is invaluable, Stuart!
I really do like (and need) a large control room, and the whole Bonello thing, along with the Golden Ratios really gave me a headache.
I can see what the really bad shapes / designs are, that's sort of a given.. but not having to "worry" if i want to have a longer control room than the "ratios say is good" ... is good.

Also.. is there a protocol, or preferred way to quote, reply, reference, etc?
I guess what i'm saying, is that i want to make sure you all know that i am reading (and re-reading) all your replies.. and i am responding, collectively, as it were...

cheers

[Soundman2020]

How about that Mass Loaded Vinyl? Would that be a waste of money?

MLV does some have uses in acoustics, but that isn't one of them! The useful things about MLV: flexible, limp, massive. The not-so-useful aspect: Expensive, fragile. So it's good for things like isolating strange-shaped curved things, such as pipes, ducts, and suchlike. It's also useful for limp-mass devices, such as membrane traps. And for adding lots of mass in a thin profile, where you need high density without adding much thickness (I often use it in speaker soffit front baffles, for example). But it's not much use under wall sole plates. The good properties that it has would not be useful there. What you need under a wall, is excellent seals, and caulk will get you that. The normal recommendation is to run three beads of caulk under the sole plate before you put it in place: one down the middle, and the other two about an inch either side of that.. That gives you three seals; in case one is breached, you still have two. Then you run another bead under the bottom edge of each layer of sheathing. TO do that, you place the sheathing on shims, then nail it in place, then pull the shims and caulk the gap.

Seems like it'd be a simple enough thing to get a few feet of that and cut into strips to put btw the plates and the floors / ceilings?

There are methods for "floating" walls, and they can be useful under some circumstances, but generally they are not needed.

Or maybe there's really no vibration (transfer) to worry about, with a proper concrete floor.. so ..

"Slab on grade" is about the best possible floor you could hope for. It is rigid, hugely massive, solid, and rests directly on the ground. So you have the entire planet acting as the damper on your slab... Hard to beat that!

Unless you need extremely high isolation (and have an extremely high budget to go with that...) then there's no need to decouple the walls from a slab-on-grade floor.

I really do like (and need) a large control room, and the whole Bonello thing, along with the Golden Ratios really gave me a headache.
I can see what the really bad shapes / designs are, that's sort of a given.. but not having to "worry" if i want to have a longer control room than the "ratios say is good" ... is good.

There's three basic rules here: No dimensions that are direct multiples of each other, or within 5% of being a direct multiple. Plus these two:

l < 3h & w < 3h
(translation: "Length less than three times the height, and width less than 3 times the height")

1.1w / h < l / h < ((4.5w / h) - 4)
(Translation: "Multiply the width by 1.1 and divide by the height. That result must be LESS THAN the length divided by the height, and BOTH OF THOSE must be less than the width multiplied by 4.5 divided by the height, less four.")

As long as your dimensions meet those, you should be good. Some other things to take into account: Recommended floor area for a control room is minimum of 200 square feet, maximum of 600 square feet. If you really want to get into all the technical specs, then google download the document "ITU BS.1116-3". Thta lays out the exact specs for a critical listening room. Skip the first few chapters, as they are not applicable: chapters 7 and 8 are what you need. If your room meets all those specs (like this one does: www.johnlsayers.com/phpBB2/viewtopic.php?f=2&t=20471 ), then you have an absolute top-quality, world-class room. OF course, it's not easy to get there!

Also.. is there a protocol, or preferred way to quote, reply, reference, etc?

You are doing fine so far!


- Stuart -