I have considered flipping the room 90° but that posed two problems. 1. to keep the room rectangular with nice dimensions
"Nice Dimensions" in what sense? "Nice" as in comfortable for fitting in people and gear? Or "nice" as in "fitting a good modal response room ratio"? If it's the former, that that0s understandable, but it doesn't look that way to me: a room 4m wide by 6 long doesn't seem uncomfortable. If it's the latter, then don't worry about it TOO much: room ratios are useful for predicting disaster, but if you have to choose between making a room smaller to hit a "good" ratio, or leaving it a bit larger with a not-too-bad ratio, then go with larger. Always. As long as your dimensions are not exact multiples, or within 5% of being exact multiples, then you should be OK. It seems to be that this should be attainable in your case.
it would reduce the live room
Why? I don't see that. If you simply take the outline of your first option, turn it into a rectangle (instead of having those angled walls), and rotate the interior so that it is facing the live room, then that would leave you with both rooms about the same size as they are now...
The entrance would have to be on the front wall of the control room. Not sure if the second one is a problem or not but just always see designs with the door on the side walls of the CR.
BRAUS-CR-to-ISO-SML-ENH.JPG
Maybe that answers your question?
That's from a studio I designed for a customer in Australia a few years back. That's actually the door from the CR to the isolation booth, but it could just as well be the door from the CR to the live room in your case...
I was inspired by many control rooms designed on this site and many seem to have angled CR walls.
Right! But there's a specific reason for that, and it has to be done with a full understanding of "why" and "how" and "what".
There's basically on four valid reasons why you would want to angle your control room walls:
1) You have no choice, because there's something structural in the building that prevents you from keeping them straight (eg, support columns, exterior walls, HVAC ducting, pipes, etc.)
2) You want to solve a flutter echo problem that you are predicting will occur. In this case, you would have to angle the walls by a total of more than 12° to deal with that, but in reality flutter echo can be dealt with much more simply with ordinary acoustic panels on the walls, which you would need in any case. So this isn't really a valid reason.
3) Because your basic control room design concept requires it. Some concepts, such as RFZ, NER, MR, CID and others require angled surfaces at the front of the room, as they are an integral part of the acoustic design, reflecting sound away from the mix position. This is a VERY valid reason, and personally I highly recommend the RFZ style approach. Pretty much all of the control rooms I design these days are RFZ, as it produces the best room acoustics, even in very small rooms (and large ones too, of course!). But if you want your room to be RFZ, then that takes a lot of extra design effort, and in reality the room itself is usually rectangular anyway: it's just the speaker soffits and "wings" that are angled, not the actual walls. You might have seen me mention this room on other threads:
http://www.johnlsayers.com/phpBB2/viewt ... =2&t=20471 That room is rectangular at the front (not the back, but that's another story....
.) Even though it LOOKS like the front has angled walls, it doesn't: Here's the front of the room under construction:
RDMOUS-BUILD-02nd-construction-all-soffits--2012-12-08-photo 1-ENH-SML.JPG
You can clearly see the rectangular front of the room itself, and also the shape that it will eventually have, after the soffits are finished.
Here's another case, currently in the final stages:
http://www.johnlsayers.com/phpBB2/viewt ... =2&t=21368 That one is even "worse": it's based on a square! Technically, its a "corner control room", oriented on the diagonal across the square, and it's more of an equilateral trapezoid than a true square, but you can see that the room shape is basically square. The front corner is "chopped off", then once again the speaker soffits create the angled surfaces that forms the reflection free zone (RFZ) around the listening position.
If you want to do an RFZ style room, I would highly recommend that. But keep your walls and basic room shape rectangular, then create the RFZ shape with that shell using angled "panels" at strategic locations, and angled correctly.
4) The fourth reason that you might validly decide to angle your walls, is "because it looks cool"! Some people just want a "cool" looking room, and decide to angle their walls for that reason alone. If you follow the "function follows form" school of architecture (I don't...), then you could do that, and then adjust the design and treatment as necessary to accommodate the angled walls.
In general, splaying or angling your walls will waste space, and in general you want as much space (air volume) inside your room as possible. That's why I prefer to build rectangular rooms and then shape them internally. Occasionally I have NOT gone that route, and I ended up angling the actual front section of the side walls, for various reasons. It can work, certainly, but from experience I can tell you that it's a lot more complex to do that.
Many years after John wrote that manual, he updated his design concept, then posted this, right here on the forum: " it's not necessary to angle sliding glass doors. I used to think it was but I don't angle them now." Most of the designs on that page of the Rec Man show the angles due to the sliding glass doors being angled.
That said, John is a very experienced designer! He sometimes does things that "break the rules", and he succeeds! Because he has the experience and knowledge to be able to do that.
Luckily my space is not so small so hopefully it will be more forgiving of my lack of experience when it comes to studio building.
No problem! Don't let lack of experience hold you back. After all, every single studio designer started out with a total "lack of experience" on his first design...
The most important thing when you start out is to overcome that lack of experience by researching and learning, and playing around and reading and asking, until you get the basics in place in your head, and can adapt them to your own place.
I have read that good ratios can help treatment and reduce modal problems.
Weelllll....yes and no! Modal response is important, yes, but it's not the most important aspect of studio design. Not by any means. It's just one of many aspects. As long as your room ratio is not terrible (a cube, for example), then you are likely going to be OK. And even then, even if it is a square or a cube, it can still be made to work. Take another look at that room I mentioned: I deliberately designed that based on a square, since there's no other option for a corner control room: it HAS to be square! If not, then it won't be symmetrical, and symmetry is more important than ratios. So I designed it as a square, then modified the square to improve the modal response, then treated the problems. So even though it is square (and not far off from being a cube, either!), with careful design you can get around that. It's far more important to maximize the room volume, get good symmetry, get decent layout and geometry, set up the speakers and mix position in optimal arrangements, and design good treatment.
Yes, it is better to avoid rooms that have bad ratios, absolutely. When you can. But a room with a bad ratio is not necessarily a death sentence, as long as you treat it properly.
Here's something I wrote on another thread a while back, and I'll repeat it here for you, as it describes the issues with modal response:
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Room ratios is a whole major subject in studio design. It works like this: The walls of your studio create natural resonances in the air space between them, inside the room. This is totally different from the MSM resonance of the walls themselves: this is all about what happens INSIDE the ROOM, not what happens inside the walls. Two totally different things.
So you have resonant waves inside the room. We call those "standing waves" or "room modes". Those "modes" (resonances) occur at very specific frequencies that are directly related to the distances between the walls. They are called "standing waves" because they appear to be stationary inside the room: they are not REALLY stationary, since the energy is still moving through the room. But the pressure peaks and nulls always fall at the exact same points in the room each time the wave energy passes, so the "wave" seems to be fixed, static, and unmoving inside the room. If you play a pure tone that happens to be at the exact frequency of one of the "modes", then you can physically walk around inside the room and experience the "standing" nature of the wave: you will hear that tone grossly exaggerated at some points in the room, greatly amplified, while at other points it will sound normal, and at yet other points it will practically disappear: you won't be able to hear it at all, or you hear it but greatly attenuated, very soft.
The peaks and nulls fall at different places in the room for different frequencies. So the spot in the room where one mode was deafening might turn out to be the null for a different node.
Conversely, if you have a mode (standing wave) that forms at a specific frequency, then playing at a slightly different frequency might show no mode at all: for example, if a tone of exactly 73 Hz creates a standing wave that is clearly identifiable as you walk around the room, with major nulls and peaks, then a tone of 76 Hz might show no modes at all: it sounds the same at all points in the room. Because there are no natural resonances, no "room modes" associated with that frequency.
That's the problem. A BIG problem.
Of course, you
don't want that to happen in a control room, because it implies that you would hear different things at different places in the room, for any give song! At some places in the room, some bass notes would be overwhelming, while at other places the same notes would be muted. As you can imagine, if you happen to have your mix position (your ears) located at such a point in the room, you'd never be able to mix anything well, as you would not be hearing what the music REALLY sounds like: you would be hearing the way the room "colors" that sound instead. As you subconsciously compensate for the room modes while you are mixing, you could end up with a song that sounds great in that room at the mix position: the best ever! But it would sound terrible when you played it at any other location, such as in your car, on your iPhone, in your house, on the radio, at a club, in a church, etc. Your mix would not "translate".
And you also don't want major modal issues in a tracking room, for similar reasons: As an instrument plays up and down the scale, some notes will sound louder than others, and will "ring" longer. The instrument won't sound even and balanced.
OK, so now I have painted the scary-ugly "modes are terrible monsters that eat your mixes" picture. Now lets look at that a bit more in depth, to get the real picture, and understand why they look bad, but aren't so bad in reality.
So let's go back to thinking about those room modes (also called "eigenmodes" sometimes): remember I said that they occur are very specific frequencies, and they are very narrow? This implies that if you played an E on your bass guitar, it might trigger a massive modal resonance, but then you play either a D or an F and there is no mode, so they sound normal. Clearly, that's a bad situation. But what if there was a room mode at every single frequency? What if there was one mode for E, a different mode for D and yet another one for F? In that case, there would be no problem, since all notes would still sound the same! Each note would trigger its own mode, and things would be happy again. If there were modes for every single frequency on the spectrum, and they all sounded the same, then you could mix in there with no problems!
And that's exactly what happens at higher frequencies. Just not at low frequencies. Because of "wavelength"...
It works like this: remember I said that modes are related to the distance between walls? It's a very simple relationship. Remember I said the waves are "standing" because the peaks and nulls occur at the same spot in the room? In simple terms, for every frequency where a wave fits in exactly between two walls, then there will be a standing wave. And also for exactly
twice that frequency, since two wavelengths of that note will now fit. And the same for
three times that frequency, since three full waves will now fit in between the same walls. Etc. All the way up the scale.
So if you have a room mode at 98 Hz in your room, then you will also have modes at 196 Hz (double), 294 (triple), 392 (x4), 490(x5), 588(x6), 686(x7) etc., all the way up. If the very next mode in your room happened to be at 131 Hz, then there would also be modes at 262 Hz(x2), 393(x3), 524(x4), 655(x5), etc.
That's terrible, right? There must be
thousands of modes at higher frequencies!!! That must be awful!
Actually, no. That's a GOOD thing. You
WANT lots of modes, for the reasons I gave above: If you have many modes for each note on the scale, then the room sounds the same for ALL notes, which is what you want. It's good, not bad.
But now let's use a bit of math and common sense here, to see what the real problem is.
If your room has a mode at 98Hz, and the next mode is at 131 Hz, that's a difference of 32%! 98 Hz is a "G2". So you have a mode for "G2". but your very next mode is a "C3" at 131Hz. That's five notes higher on the scale: your modes completely skip over G2#, A2, A2#, and B2. No modes for them! So those four notes in the middle sound perfectly normal in your room, but the G2 and C3 are loud and long.
However, move up a couple of octaves: ...
There's a harmonic of your 98Hz mode at 588 Hz, and there's a harmonic of your 131 Hz mode at 524 Hz. 524 Hz is C5 on the musical scale, and 588 Hz is a D5. They are only two notes apart! Not five, as before.
Go up a bit more, and we have one mode at 655 and another at 686. 655 is an E5, and 686 is an F5. they are adjacent notes. Nothing in between! We have what we want: a mode for every note.
The further up you go, the closer the spacing is. In fact, as you move up the scale even higher, you find several modes for each note. Wonderful!
So at high frequencies, there is no problem: plenty of modes to go around and keep the music sounding good.
The problem is at low frequencies, where the modes are few and far between.
The reason there are few modes at low frequencies is very simple: wavelengths are very long compared to the size of the room. At 20 Hz (the lower limit of the audible spectrum, and also E0 on the organ keyboard), the wavelength is over 56 feet (17m)! So your room would have to be 56 feet long (17 meters long) in order to have a mode for 20 Hz.
Actually, I've been simplifying a bit: it turns out that what matters is not the
full wave, but the
half wave: the full wave has to exactly fit into the "there and back" distance between the walls, so the distance between the walls needs to be half of that: the half-wavelength. So to get a mode for 20 Hz, your room needs to be 56 / 2 = 28 feet long (8.5M) . Obviously, most home studios do not have modes at 20 Hz, because there's no way you can fit a 28 foot (eight meter) control room into most houses!
So clearly, the longest available distance defines your lowest mode. If we take a hypothetical dimensions as an example (typical of home studio sizes), and say the length of the control room is 13 feet (4m), the width is 10 feet (3m), and the height is 8 feet. (2.5M) So the lowest mode you could possibly have in that room, would be at about 43 Hz (fits into 13 feet or 4M perfectly). That's an "F1" on your bass guitar.
The next highest mode that you room could support is the one related to the next dimension of the room: In this case, that would be width, at 10 feet / 3M. That works out to 56.5 Hz. That's an "A1#" on your bass guitar. Five entire notes up the scale.
And your third major mode would be the one related to the height of the room, which is 8 feet /2.5M, and that works out to 71 Hz, or C2# on the bass guitar. Another four entire notes up the scale.
There are NO other fundamental modes in that room. So as you play every note going up the scale on your bass guitar (or keyboard), you get huge massive ringing at F, A# and C#, while all the other notes sound normal. As you play up the scale, it goes "tink.tink.tink.BOOOOM.tink.tink.tink.tink.BOOOOOM.tink.tink.tink.BOOOOOM.tink.tink...."
Not a happy picture.
There are harmonic modes of all those notes higher up the scale, sure. But in the low end, your modes are very few, and very far between.
So, what some people say is "If modes are bad, then we have to get rid of them". Wrong! What you need is MORE modes, not less. Ideally, you need a couple of modes at every single possible note on the scale, such that all notes sound the same in your room. In other words, the reverberant field would be smooth and even. Modes would be very close together, and evenly spread.
So trying to "get rid of modes" is a bad idea. And even if it were a good idea, it would still be impossible! Because modes are related to walls, the only way to get rid of modes is with a bulldozer! Knock down the walls...
That's a drastic solution, but obviously the only way to get a control room that has no modes at all, is to have no walls! Go mix in the middle of a big empty field, sitting on top of a 56 foot (17 M) ladder, and you'll have no modes to worry about....
Since that isn't feasible, we have to learn to live with modes.
Or rather, we have to learn to live with the LACK of modes in the low end. As I said, the problem is not that we have too many modes, but rather that we don't have enough of them in the low frequencies.
Obviously, for any give room there is a point on the spectrum where there are "enough" modes. Above that point, there are several modes per note, but below it there are not.
There's a mathematical method for determining where that point is: a scientist called Schroeder figured it out, years ago, so it is now known as the Schroeder frequency for the room. Above the Schroeder frequency for a room, modes are not a problem, because there are are lots of them spaced very close together. Below the Schroeder frequency, there's a problem: the modes are spaced far apart, and unevenly. (The Schroeder frequency is a bit more complex than just that, since it also considers treatment, but this gives you an idea...)
So what can we do about that?
All we can do is to choose a "room ratio" that has the modes spaced out sort of evenly, and NOT choose a ratio where the modes are bunched up together. For example, if your room is 10 feet long and 10 feet wide and 10 feet high (3m x 3m x 3m), then
all of the modes will occur at the exact same frequency: 56.5 Hz. So the resonance when you play an A1 on the bass, or cello, or hit an A1 on the keyboard, will by tripled! It will be three times louder. The nulls will be three times deeper. That's a bad situation, so don't ever choose room dimensions that are the same as each other.
You get the same problem for dimensions that are multiples of each other: a room 10 feet high (3m) by 20 feet wide (6m) by 30 feet long (9m) is also terrible. All of the second harmonics of 10 feet will line up with the 20 foot modes, and all of the third harmonics will line up with the 30 foot modes, so you get the same "multiplied" effect. Bad.
In other words, you want a room where the dimensions are mathematically different from each other, with no simple relationship to each other.
That brings up the obvious question: What ratio is best?
Answer: there isn't one!
Over the years, many scientists have tested many ratios, both mathematically and also in the real world, and come up with some that are really good. The ratios they found are named after them: Sepmeyer, Louden, Boner, Volkmann, etc. Then along came a guy called Bolt, who drew a graph showing all possible ratios, and he highlighted the good ones found by all the other guys, and predicted by mathematical equations, plus a few of his own: If you plot your own room ratio on that graph, and it falls inside the "Bolt area", then likely it is a good one, and if it falls outside the "Bolt area", then likely it is a bad one. Sort of.
So, there are no perfect ratios, only good ratios and bad ratios.
It is impossible to have a "perfect" ratio in a small room, simply because that would require enough modes to have one mode for every note on the musical scale, but that's the entire problem with small rooms! There just are not enough modes in the low end. So you can choose a ratio that spreads them a bit more this way or a bit more that way, but all you are doing is re-arranging deck chairs on the Titanic, in pleasant-looking patterns. The problem is not the location of the deck chairs; the problem is that your boat is sunk!: Likewise for your studio: the problem is not the locations of the modes: the problem is that your room is sunk. No matter what you do with the dimensions, you
cannot put a mode at every note, unless you make the room bigger. It is physically impossible.
But that does not mean that your room will be bad. That's the common perception, and it is dead wrong.
All of this leads to the question you didn't ask yet, but were probably heading for: What can I do about it?
Here's the thing: Modes are only a problem if they "ring". The wave is only a problem if the energy builds up and up and up, with each passing cycle, until it is screaming, and then the "built up" energy carries on singing away, even after the original note stops. That's the problem. If you stop playing the A1 on your guitar, and the room keeps on playing an A1 for a couple of seconds, because it "stored" the resonant energy and is now releasing it, then that's a BIG problem! The room is playing tunes that never were in the original music!
If a mode doesn't ring like that, then it is no longer a major issue. (It is still an issue for other reasons, just not a major one....)
So how do you stop a mode? You can't stop it from being there. But you
CAN stop it from "ringing". You can "damp" the resonance sufficiently that the mode dies away fast, and does not ring. You remove the resonant energy and convert it into heat: no more problem! In other words, it's not good if you own a large angry dog that barks all the time and bights your visitors, but it's fine to own a large angry dog with a muzzle on his mouth, so he cannot bark and cannot bight!
You do that with "bass trapping". A bass trap is like the dog muzzle. It doesn't get rid of the problem, but it does keep it under control. You use strategically placed acoustic treatment devices inside the room that absorb the ringing of the mode, then it cannot ring. There are several ways to do that, with different strategies, but the good news is that in most rooms it is possible to get significant damping on the modes, so that they don't ring badly, and don't cause problems. Note that bass trapping does not absorb the
mode: it just absorbs the
ringing. Some people don't understand this, and think that the bass trapping makes the modes go away: it doesn't. All it does is to damp them. The modes are still there, and still affect the room acoustics in other ways, but with good damping, at least they don't "ring" any more.
And that is the secret to making a control room good in the low end! Choose a good ratio to keep the modes spread around evenly, then damp the hell out of the low end, so modes cannot ring. It's that simple.
The smaller the room, the more treatment you need. And since those waves are huge (many feet long), you need huge bass trapping (many feet long/wide/high/deep). It takes up lots of space, and the best place for it is in the corners of the room, because that's where all modes terminate. If you want to find a mode in your room, go look for it in the corner: it will be there. All modes have a pressure node in two or more corners, so by treating the corners, you are guaranteed of hitting all the modes.
As I said, there is no single "best" ratio, but there are good ones. You can use a "Room Mode Calculator" to help you figure out which "good ones" are within reach of the possible area you have available, then choose the closest good one, and go with that. And stay away from the bad ones.
Arguably, Sepmeyer's first ratio is the "best", since it can have the smoothest distribution of modes... but only if the room is already within a certain size range. Other ratios might be more suitable if your room has a different set of possible dimensions. So there is no "best".
But that's not the entire story: So far, all the modes I have mentioned are only related to two walls across the room, opposite from each other. I mentioned modes that form along the length axis of the room (between the front and back wall), others that form along the width axis (between left and right walls), and others that form on the height axis (between floor and ceiling): Those are the easiest ones to understand, because they "make sense" in your head when you think about them. Those are called "axial modes", because they form along the major axes of the room: length axis, width axis, height axis.
However, there are also other modes that can form between
four surfaces, instead of just two. For example, there are modes that can bounce around between all four walls, or between the front and back walls as well as the ceiling and floor: those are called "tangential modes". And there are other modes that can form between all
six surfaces at once: they involve all four walls plus the ceiling and the floor. Those are called "oblique modes".
The complete set of modes in your room consists of the axial modes, plus the tangential modes, plus the oblique modes.
That's what a good room mode calculator (a.k.a. "room ratio calculator") will show you. There are bad calculators that only show you the axial modes, which is pretty pointless, and the good ones show you all three types.
Use one of these Room Ratio calculators to figure out the best dimensions for your room:
http://www.bobgolds.com/Mode/RoomModes.htm
http://amroc.andymel.eu/
Both of those are very good, and will help you to decide how best to build your room. They give you tons of information that is really useful to help figure out the best dimensions.
However, modes aren't that important, despite all the hype they get: Modes are one aspect of room design, but there are many more. It's wise to choose a ratio that is close to one of the good ones, or inside the Bolt area, but you do NOT need to go nuts about it! There's no need to nudge things around by millimeters or smalls fractions of an inch, hoping to get a "better" ratio. Just stay away from the bad ones, get close to a good one, and you are done. End of story.
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so there you have it! "Everything you ever wanted to know about modes, but were afraid to ask"!
Do you know why so many designs over here have angled walls? Does it depend on the design/dimensions some how or if there are many rooms?
For the reasons I mentioned above. Like me, John is also a fan of RFZ design ("Reflection Free Zone"), which is why many of his rooms do have angled walls (or what appear to be angled walls...). NER, CID and other concepts also use angled walls, for similar purposes. You can do it if you want, as long as you understand WHAT you are doing and WHY you are doing and HOW to do it correctly.
- Stuart -
