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
viewtopic.php?f=2&t=21544
and this
viewtopic.php?f=2&t=21545
more to come... and thank you!!
Groundlift Research & Development NEW STUDIO (consolidated)
Originally posted at johnlsayers.com, topic 21546.
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!
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?
As many evenly dispersed as possible, yes. Hence Abbey Road being awesome sounding. It's huge. Bigger = lower Schroeder Frequency.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.
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.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?
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.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"?
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.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?
I understand them, yes. My new place will have one. My friends have them. They're great.Also: regarding HVAC systems, have you all had any experience with "Heat Reclaim Ventilator" or "Energy Recovery Ventilator" systems?
If possible, you should design your HVAC so that you are getting 25-30% fresh air into your system.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.
"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 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. GregLastly: 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?
I love this forum!!
Thank you!! I’ll read this through. Again. And again.
"Modes" not "nodes", but yes, basically. Just to confuse you more: Modes can have nodes, but nodes can't have modes! :shock: :shot: 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.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.
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! :shock: 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.2 - Once the room has been measured, adding bass traps will help bring down the "worst offenders" as far as low end bumps,
For axial modes, yes.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?
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.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?
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.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"?
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.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
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.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)
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!thus the standing waves would be of a decreasing frequency, as one moves further back in the control room?
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.(in short, control rooms are designed with splayed wall primarily - or at least partially - for this purpose?)
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 -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?
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.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?
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!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,
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., 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.
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.... So... double the average diameter?
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 -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?
Note that in the past "Darth Fader" was a user name that 'j.j.' sometimes used.
'jj' is James D. Johnston.
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!!
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.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?).
Correct. More gap = lower resonant frequency.I presume having a wider airgap would help with the isolaton?
No. If there is, it's negligible.Is there an advantage to having the two leaves NOT be parallel? (even if they're not touching, obviously).
Insulation wrapped in fabric works well. You don't want to seal the space though.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...
No. Just wood on the floor.for a concrete floor and a concrete ceiling, would you put Mass Loaded Vinyl, Neoprene or similar btw the 2x4's (plates?)
Correct.and the floor, and would you have an 1/8"-1/4" gap btw the drywall and the floor, that gets filled with caulk?
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. GregOr 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?
Excellent, Greg.
Thanks!
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 -You can put some glue down before you anchor the walls to the floor.
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 ..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 -You can put some glue down before you anchor the walls to the floor.
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... cheersAs 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.... :)
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.How about that Mass Loaded Vinyl? Would that be a waste of money?
There are methods for "floating" walls, and they can be useful under some circumstances, but generally they are not needed.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?
"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.Or maybe there's really no vibration (transfer) to worry about, with a proper concrete floor.. so ..
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! :)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.
You are doing fine so far! :thu: - Stuart -Also.. is there a protocol, or preferred way to quote, reply, reference, etc?
Again, Stuart, great stuff!! when i dream of my new system (what, you don't dream of AC systems?) it has a way to switch over, 100%, to outside air if needed. So... like i said earlier, i feel like I'm constantly running the AC (perhaps at 75) when the outside temp is 65 (or even 55). Seems like a system would be very efficient, financially and "green-ly", if there was a way to have it simply use the fan(s) to pull the stale/warm air out and replace it with clean/cool air from the outside. And then, if the outside is not cold enough (which would be often) i would kick in the AC and do a "50/50" type situation. I've found some very inexpensive inline ducts that have a motorized louvers, and (in my mind, at least) this would be easy to set up in two places, to allow for this sort of a design. Example: right now, as i type this, the AC is set for 75, and in 3-4 hrs it will be close to 60 outside.. and then i should be able to switch over to 100% fresh air to cool the room... that's my goal. more to come!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.
WOW!!!!!! Nicely done!!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! :)
Stuart - this is great.. I did the math and it looks like I'm pretty well in the clear. The only area that's close is the height vs width. The place i'm looking at now has 11.5' high ceilings, and the plan calls for a 24' wide control room. This is all still at the "fact-finding" stages.. so the available space can change, BUT the theory remains the same, and that's why I'm here. SO: If i have a control room that's 11.5' high, making the width less than 24, that could prove problematic? (11.5 x 2 = 23.. straight multiple). And, 24 even would be cutting it close? Better to start at 25 or so, yes? (or 21) - in other words i want to be Plus/Minus 5% of 23, right? Then, of course, we're faced with the reality of: ok, sure, it looks (and sounds) right - but it's too narrow for anyone to want to book the room, so... moot point, eh? (i'm speaking in broad terms, of course..) Another Question: A few studios back, i had a machine room. This was a HUGE plus. Especially since that control room was VERY quiet, so even having a laptop in there (with a fan going) was disruptive. It really made me see and value the benefits of having a LOW noise floor in the control room! I found that i started to mix at lower volumes, and genreally adapt a more zen aproach. I miss that. So I'm looking to incorporate that into this design, at some point as well. The obvious choice would be in the front, somewhere, since there is that false wall and all that space (along side the bass traps, potentially). Do you have any pics of that detail from that studio you designed (and linked to) for Rod? I believe there was something similar there? (hidden door?) Maybe adequate to just have something like "half a closet" built into the front wall, with a door to the control room... I also presume there is some theory there, in regards to air flow, cooling, etc? In the old days, i had a separate window unit for that room, with its own thermostat. Seemed to do the trick, even if not the most elegant solution.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! :)
Weelll...... There's a problem with that approach. HVAC systems don't just deal with temperature and fresh air: another very big part of HVAC is controlling humidity. Your studio should have a fairly constant relative humidity of around 40%. Your instruments (especially ones that use wood or other natural fibers in their construction) will swell and shrink as the humidity in your room changes, and both the tone and tuning will therefore change... Probably not what you want when you are trying to repeat takes from yesterday, when it was sunny and dry out, but today it's raining and foggy! Some gear and some mics also like to have constant humidity... Fortunately, HVAC systems take care of that. There's two types of heat that air conditioners get rid of: latent heat, and sensible heat. "Sensible heat" is the type of heat that you are talking about when say the air is hot or cold. Latent heat is the type of heat you are talking about when you say the air is "muggy" or "clammy" or "dry". When the warm, moist air in your room moves through the coils of the HVAC unit, the first thing that happens is that excess moisture in the air condenses on those cold coils. The simple act of that water changing phase from gas to liquid, means that heat was released. That heat is carried away by the coolant in the system. So the system removes a lot of heat from the air... but the temperature of the air did not change yet! The only heat that was removed at this point, was "latent" heat: the heat that was stored in the gaseous state of the water in the air, but then released as the water changed phase to liquid. So heat was removed, but the temperature didn't change. Then, now that the air that has been relieved of its excess water load, as it continues to move over the rest of the coils in the HVAC unit, it can cool down: That's the "sensible heat" part of the equation. OK, so what does all that mean? Firstly, if you forget to take BOTH of those heat loads into account when you dimension your HVAC capacity, you could end up with a system that is only able to remove the humidity (latent heat), but doesn't have enough "power" to also remove the sensible heat. So the air comes out drier, but still warm. And if you then pump in warm air from the outdoors, the room will end up getting hotter, not colder, even though the HVAC system is running at full capacity, maximum speed, and 100% duty cycle. It will wear out real fast like that, since it is overloaded, and even so still can't handle the job. "So!" you say to yourself "I'll just get one that is bigger than I need! Has extra capacity, beyond what my room needs!". That's just as bad. If the unit has too much capacity, it will dry out the air too much, cool it too fast, then go into standby with just the fan running but no compressor... and stay like that for a long time, until the air gets moist and warm again. In other words, the duty cycle will be very short (just a small percentage of the time actually doing it's thing, then the rest of the time just moving air). Which means that the temperature and humidity in the room will swing wildly from extreme to extreme, all the time! A sudden blast of icy, dry air that yanks the temperature and humidity way down, then a slow build up again to high humidity and high temperature... rinse ... repeat.... The point being? Don't try to do stuff that won't work! Yes, it's nice to think you are saving power, and saving money... but in reality you are not. Instead, follow the guidelines to correct size your HVAC system: It needs to have the capacity to deal with the highest latent heat and sensible heat load that your studio will ever conceivably have, on the hottest, dampest day in summer with a dozen musicians jamming breathlessly, working hard and sweating hard and breathing hard (which greatly increases both the temperature and humidity in the room....), plsu all the gear turned on and running at max levels, plus beer and pizza (more heat, more humidity)... and the HVAC system needs to be able to deal with that, without overloading or running beyond about 90% duty cycle... but it also needs to be able to deal with the situation where it is just you in there, sitting quietly, listening, with minimum gear and lights on, on a cool dry day in winter, late at night. The system has to be designed to deal with both extremes: enough capacity to handle that highest load and still keep everyone cool with the humidity under control, while also not freezing your butt off at the other extreme. So, the VENTILATION part of the HVAC system needs to be adjustable (preferably automatically, controlled by sensors and a system controller) such that it always dumps the right mount of stale air and also provides the corresponding amount of make-up fresh air from the outside world, as needed for each situation. You could do it yourself, manually, sure, but you'd soon get bored rushing around checking the temperature, humidity and CO2 levels in each room, then adjsuting the dampers, fan speeds, and air flow rates... then adjsuting it again when the pizza arrives, or when Joe fires up his new 10,000 watt bass amp, or three musicians suddenly take a break in the green room, or a couple of WAGs arrive unexpectedly and want to sit in on the session in the control room... I think you get the picture! That's not something that you want to be trying to handle manually. Just install a system controller, sensors in each room (and outdoors), and let the controller do its job. So, that's my rant for the day on why your plan might sound good on the surface, but isn't practical, and wouldn't work anyway... Sorry! :)when i dream of my new system (what, you don't dream of AC systems?) it has a way to switch over, 100%, to outside air if needed. So... like i said earlier, i feel like I'm constantly running the AC (perhaps at 75) when the outside temp is 65 (or even 55). Seems like a system would be very efficient, financially and "green-ly", if there was a way to have it simply use the fan(s) to pull the stale/warm air out and replace it with clean/cool air from the outside. And then, if the outside is not cold enough (which would be often) i would kick in the AC and do a "50/50" type situation.
Probably not! See above... As a point of reference, when I design a studio from scratch, I often end up spending as much time on the HVAC system as I do on the entire rest of the studio! Lot's of things to take into account, and juggle... It's big. Way bigger than most people realize.I've found some very inexpensive inline ducts that have a motorized louvers, and (in my mind, at least) this would be easy to set up in two places, to allow for this sort of a design.
If you had a proper system, designed and programmed correctly, you would leave the temperature set at 70 ALWAYS; and allow the system to do it's thing: It will decide when it can use more outside air... but it will consider the humidity of that outside air, and decide if it would waste more power in removing that humidity than it can save by not needing to cool the air as well... If you bring in humid air (you live in LA! It's ALWAYS humid!) then that needs to be dehumidified (latent heat removed), which means the compressor has to run to do that, even if the air doesn't need cooling! It still has to to the work of cooling the coolant, pumping it through the pipes to the indoor unit, so the cool humid air can flow over it to have its excess humidity removed, but then NOT be cooled additionally... all of that takes electrical power to accomplish: it would probably have been more efficient go just circulate the warm-but-already-dry air that is in the room, and cool it a bit WITHOUT needing to first remove the latent heat, because it is already at the right humidity.... If the humidity is high, it takes a lot of power to remove that latent heat, but the slight extra sensible heat from cooling recirculated room air isn't such a big deal, probably.... Just follow the usual guidelines. With a good HRV (or ERV) and a good AHU / Heat Pump combination, with sensors and controller, it will be very efficient, and you won't have to worry about it. It will be a "set and forget" system. If you use one of the ultra-efficient "inverter" HVAC systems, then it's going to be very, very efficient. I guarantee that you would be totally unable to make it more efficient by trying to manually adjust the make-up air ratio... and very likely you would make it far less efficient, as the system would have to fight against your decisions all the time, to fix what you messed up.... :)Example: right now, as i type this, the AC is set for 75, and in 3-4 hrs it will be close to 60 outside.. and then i should be able to switch over to 100% fresh air to cool the room... that's my goal.
Yup! :) Edited to add... :more to come!
Then your system is likely either not designed correctly (inadequate capacity for dealing with high latent heat), or IS designed correctly and is doing its job perfectly: removing latent heat but NOT cooling air that doesn't need cooling. If the compressor is running at a high duty cycle (eg, more than 70% "on"), then likely it is a design issue: wrong system for that job. If it is running around 30% to 60% duty cycle, it's probably doing just what it is supposed to do. - Stuart -feel like I'm constantly running the AC (perhaps at 75) when the outside temp is 65 (or even 55).
Thanks Stuart. As always, clear and on point! It's all coming together now.. albeit slowly (but that's why I'm here!). I've read a LOT about HRV, and I like what I'm finding. It's a clever idea, and makes total sense. Not entirely free ($$) but i like it. It's a big job, and I'm intrigued and fascinated with all I'm learning here. I had a thought that every single room maybe wouldn't have to be cooled.. or vented.. but the more i think about it, that's probably not a good idea (read: the fainting singer) = especially if the doors to the ISO booths (for example) are not sliding glass doors, but double doors on pumps (i.e. always closed). So.. ideas come and go, almost as quickly as I can come up with them. Which is kinda part of the brainstorming (and the fun) Would you feel comfortable sharing any sketches of your designs? As far as HVAC? Rod's super-studio, for example? I'd really want to have two (smaller) systems: one for the control room and one for the recording spaces (I do a LOT of mixing and mastering, so cooling an add'l 1000sf of recording space would be wasteful) Would i then (since i do so much mixing, and so much work mostly alone) only want to add the HRV unit to the control room only? And save money? Or just figure that in the scheme of things, an added $1k (?) for an add'l unit is worth it, and the clean, fresh air for those big band-tracking dates (every room occupied) will make people so happy that i should just go for it. I know.. a lot of "what if's" and speculation.. sorry.If you had a proper system, designed and programmed correctly, you would leave the temperature set at 70 ALWAYS; and allow the system to do it's thing: It will decide when it can use more outside air... but it will consider the humidity of that outside air, and decide if it would waste more power in removing that humidity than it can save by not needing to cool the air as well... If you bring in humid air (you live in LA! It's ALWAYS humid!) then that needs to be dehumidified (latent heat removed), which means the compressor has to run to do that, even if the air doesn't need cooling! It still has to to the work of cooling the coolant, pumping it through the pipes to the indoor unit, so the cool humid air can flow over it to have its excess humidity removed, but then NOT be cooled additionally... all of that takes electrical power to accomplish: it would probably have been more efficient go just circulate the warm-but-already-dry air that is in the room, and cool it a bit WITHOUT needing to first remove the latent heat, because it is already at the right humidity.... If the humidity is high, it takes a lot of power to remove that latent heat, but the slight extra sensible heat from cooling recirculated room air isn't such a big deal, probably.... Just follow the usual guidelines. With a good HRV (or ERV) and a good AHU / Heat Pump combination, with sensors and controller, it will be very efficient, and you won't have to worry about it. It will be a "set and forget" system. If you use one of the ultra-efficient "inverter" HVAC systems, then it's going to be very, very efficient. I guarantee that you would be totally unable to make it more efficient by trying to manually adjust the make-up air ratio... and very likely you would make it far less efficient, as the system would have to fight against your decisions all the time, to fix what you messed up.... :)
A lot of reading, the last couple of days.. and Stuart is right, a LOT to learn!
One thing that is (still) a mystery to me is the actual placement and _connection_ of the (presumably home made) duct silencers.
If, in my design, i have a large rigid duct feeding the control room (for example) I'd want to have the silencer somehow IN the wall, going into the room, no?
And if so.. which leaf is it actually connected to, and which one isolated from - and then, how?
Same would go for the other rooms
I can't seem to see it in my mind. . . the box somehow must 'live' between the leaves, essentially?
Or is it best - if i have the space - to hang it from the ceiling (in a hallway?) outside of the room(s) and then 'penetrate' carefully through the outer leaf, via flexduct perhaps, and then terminating tied to the inner leaf / register?
Does this make sense?
Also: i imagine the same would hold true for a control room that has a large rigid duct across the ceiling, as a supply? I assume the duct-silencer(s) would always have to be AT/IN the point entry, through the wall (the 2leaves) yes?
Lastly: (getting ahead of myself again) - bonus question: what is the "de rigueur" way to get cables and things through our fantastically constructed and sealed 2 leaf walls? i always see the 'ol 4" PVC pipes in studios here in LA - with foam stuffed in either end after the cables are run through), which now i realize are TOTALLY killing the isolation btw the two leaves (!).
Perhaps a PVC pipe on either end with a rubber or cloth coupling between the two? (where the air gap would be in the walls)
Hope you all had a fab weekend!
Ideally, both your inner and outer leaf silencers should live between the walls. Some people will fully decouple the boxes from the walls and have them sitting on their own stands so they are only touching the concrete. You could probably go super hardcore and mount them on sorbothane or 703, but personally, I feel that is a bit overboard. For the times we are unable to fit them between our walls and have them only touching the concrete, we have to mount them to the walls.
For the penetration through the sheathing, you must leave a small gap (maybe a few mm or so) around the sleeve. The sleeve is typically just an extension of the box itself, being made of the same material and thickness to maintain the surface density of the silencer. So, usually a square or rectangular sleeve made out of MDF. You're right in saying that the silencers are typically right at the point of penetration. Often, people will just throw a register cover over the penetration and be done with it (if they are able to have the silencers at the rights spots in their rooms).
If you need to run duct work inside your room like you said, you can use normal duct with liner to get it wherever you need it. Obviously you will want to frame it in and stuff insulation around it.
You connect the inner and outer leaf silencers with flex duct or a flexible duct connector like Durodyne. You do NOT use it for the penetration as it does not have the surface density needed to not trash your isolation.
Regarding cable runs, it personally freaks me out. As far as I'm aware, the standard practice is to have at least 2 bends in the pipe, have a flexible connector in the middle (unless you're running the conduit through concrete), and yes, stuff the ends. From there, you can also run the pipe into a box/panel where you can seal it up. The crappy thing is that conduit is light and doesn't have much surface density, and therefore, it sucks for maintaining isolation. Luckily, with fresh ground up builds, it's easy (considering) to run conduit under ground. For retro-fit builds, you can do it if you bust up the concrete. Maybe one of the pros can chime in here with some more knowledge bombs to help out!
Greg
It all depends on how much isolation you need, which is another reason for starting out your entire project by defining that: settling on a number: the number of decibels of isolation that your situation merits. If you only need low to moderate isolation, then you can probably get by with a single silencer on each duct, where a solid, massive "sleeve" on that silencer will pass through both leaves of the wall, without touching either of them. But for the typical case where you need moderate to high isolation, you need one silencer box on EACH leaf, for EACH duct. In other words where each duct has to pass through a wall, there is one silencer box on the outer leaf, and one on the inner leaf. Usually they are linked by a short section of flexible duct. If that's the case, and you are not shooting for very high / extremely high isolation, then each silencer box could touch the leaf it is associated with, but if you do need that very high / extreme isolation, then you would decouple each box from the leaf, by making the hole a little larger than the "sleeve" of the silencer box that goes through it, then using highly flexible caulk to seal that gap between them. That's also where you'd want to use Sorbothane to decouple the box from the structure that is holding it in place, to eliminate any possibility of sound flanking through the box and into the structure. I did that a couple of years ago, for a customer who has a drum teaching studio in his residential house: With two drum kits in there, playing together and synchronized as he teaches drums to his students, there was a need for very high isolation. In that case, the silencers were actually fitted in between the ceiling joists, with close tolerances around them, so it was very important to maximize isolation.I'd want to have the silencer somehow IN the wall, going into the room, no? And if so.. which leaf is it actually connected to, and which one isolated from - and then, how?
It can if you want, and if you have enough space for that. Another option is to have the boxes inside the rooms and outside the outer leaf. Generally, I try to put the silencer boxes in the ceiling space, wherever possible, since you normally do want to have the registers in the ceiling in any case, so it makes sense.I can't seem to see it in my mind. . . the box somehow must 'live' between the leaves, essentially?
The actual penetration through the leaf CANNOT be flex duct. That would be sort of like water-proofing your roof very carefully, but then cutting a large hole in it and covering it with a piece of cloth... :) Think of it this way; the silencer box is an extension of the leaf itself. It has to have similar mass to the leaf, and also create an "envelope" that mass outwards from the exact point where the "hole in the leaf" starts, all the way to the point where the duct connects to it.and then 'penetrate' carefully through the outer leaf, via flexduct perhaps,
Yup! Very true. For a studio that is supposed to get you high isolation, that would be a pretty bad plan...to get cables and things through our fantastically constructed and sealed 2 leaf walls? i always see the 'ol 4" PVC pipes in studios here in LA - with foam stuffed in either end after the cables are run through), which now i realize are TOTALLY killing the isolation btw the two leaves (!).
You mean like this? : Yup! That's how to do it. Here's the concept: - Stuart -Perhaps a PVC pipe on either end with a rubber or cloth coupling between the two? (where the air gap would be in the walls)
Greg, Stuart. Thank you for this.
This all makes a lot more sense to me now!
I read something a while back - from one of you - where we were talking about supply and return silencers (the need for both) and i remember being confused by the number(s) you came up with.
It's all clear now - i.e. 4 per room (yikes)
PROVIDED that's the isolation I'm going for - but yes, looking at each silencer as a part of each leaf brings it all into focus now. (btw.. i used to make these silencers - huge ones - as a teenager, when i was working in the metal shop.. and i used to HATE that stuff.. the liner.. stingy and itchy.. I'm sure there are more 'humane' options available today.. this was ages ago! = so full circle here.. amazing!)
Thank you.
NEXT: the question of "how much isolation do i need?"
This is actually a good question (which is why Stuart asks this at the beginning of every post he replies to 8) ) - being the pro he is!
And oddly, even if I've been making records for over 25 years now, and worked in all the best studios over the world (a lot of them, anyway) I've never really considered an actual dB number for isolation. Usually it's more of a "hmm.. there's a bit of leakage from the drums into THIS iso booth but not so much into this one", or similar.. As opposed to "hmm.. that sounds like roughly 50dB of isolation.. not bad :D "
All i know is that I want it to be really great (ha!).
I have a (ahem) Radio Shack SPL meter (I've ordered the one recomended in the REW thread, the white one, btw) and it does have A and C weightings on it. Perhaps a good place to start would be to actually see where my current studio stands, as far as isolation, and try to get a dB number here. Another mystery to solve, and another brick in the foundation here. Maybe that will help determine what I'm actually trying to do :-)
Any tips on how to make that measurement? Besides the 'obvious' (i know... shot myself in the foot again) which would be "play some music loudly, measure SPL in room, go to other room, close door, measure SPL" ??
Ok, onward and upward!!
Thanks again.
PS = yes.. the 4" PVC straight through both leaves.. you'd be amazed to see how many times I've seen that. In "real studios" - i like the idea of angles and rubber couplings!
:thu: That is, indeed,the way to do it! :) If you could get an actual band together to play in the room, live, with their normal instruments and gear, and tell them to go crazy, that would be the best. If not, you can get close with a good full-range speaker system playing music that covers the spectrum well. In both cases, set the meter to "C" and "slow", measure inside the room at least 3 feet away from the speaker / band, then measure in many places outside the room: in other rooms, outside the building, upstairs, down stairs, near, far. Make several tests with different music genres. Then send everyone home, and measure again in the same places with all the gear turned off, late at night, when it's really silent... Also check your local "noise regulations", to find out what your legal limits are: It's one thing to set a level that you think is nicely quiet, and doesn't annoy the neighbors... but the law might have a different view on how loud you are permitted to be on your own property.... IT would be sad if you invested all that money in building a superb studio, then you get the cops knocking on your door every day while you are tracking, and writing nasty things on bits of official paper that cost you a lot more money! :) It pays to do your homework.... - Stuart -Any tips on how to make that measurement? Besides the 'obvious' (i know... shot myself in the foot again) which would be "play some music loudly, measure SPL in room, go to other room, close door, measure SPL" ??