20ft by 13ft live Room - Would the Modes be Evenly spaced?

[Daz12344]

hey guys

this is a studio Construction question but more towards the acoustics of it (apologies if in the wrong place feel free to move it)

A friend and i have been looking for an ideal place to look in order to setup a general recording studio but alas to no avail, so weve opted to downsize and start a mixing/Mastering house/Suite made from office(s).

now pre-made offices can have smaller rooms to industrial warehouse etc but we both have agree on a 20ftx13ftx8/9ft Live room. the reasons for choosing this is so that the walls/celing/floor cannot be divisible by a common number but would this give an even spread of modes?

been researching a lot about different room sizes and it appears that biger/wider rooms have better spreads of room modes, but i have noticed alot of professional recoding studios have room dimensions that can be divisible by a common number.

if the room size is fine and divisible numbers aren't an issue then the ratio that will be applied when building the room would be 1:1.16:1.28 giving the room a grand total of 20ftx 20.8ftx11.52ft which would make the room too square and produce flutter echo but it would be big enough for an even spread of modes based on the research i have found. i assume that using a bigger ratio will give me a less square room?

can anyone help confirm or give some advice please as i feel abit confused atm and feeling as ive got something wrong somewhere. all help is appreciated

[Soundman2020]

Hi "Daz12344", and welcome!

now pre-made offices can have smaller rooms to industrial warehouse etc but we both have agree on a 20ftx13ftx8/9ft Live room. the reasons for choosing this is so that the walls/celing/floor cannot be divisible by a common number but would this give an even spread of modes?

Well, it's not as simple as just having numbers that aren't divisible by each other or by a common factor. What matters is that you choose a good room ratio. Your ratio comes in at #22 on a commonly used list of known good ones (Bob Golds), so there are certainly some better ones out there!

been researching a lot about different room sizes and it appears that biger/wider rooms have better spreads of room modes, but i have noticed alot of professional recoding studios have room dimensions that can be divisible by a common number.

Are you talking about control rooms or live rooms? Once again, it's not a matter of whether the dimensions can be divided by common factors, but rather whether they are multiples of each other. The actual ratio matters, not common denominators.

Also, when you say you have seen pro studios like this, are you considering the actual dimensions of the inner-leaf surface of the room, without any treatment? The real walls might be hidden a long way back behind what you see, which is often just the surface of the treatment.

Could you maybe link to a couple of rooms that you have seen with such ratios?

giving the room a grand total of 20ftx 20.8ftx11.52ft

Whoa! How did we get from 13 feet wide to nearly 21 feet wide, and 9 feet tall to 11 and a half feet tall? Just how big is the space that you have available? Start from the total size, and work down from there until you get close to a decent ratio. For example, at 20 x 15 x 10.8 you are really close to Louden's best ratio, which is much better than the one you started with

which would make the room too square and produce flutter

Flutter echo is not a result of the room being too square: it is a result of having parallel surfaces. maybe you are confusing flutter echo with standing waves and room modes? Room mods are standing waves resulting from the dimensions of the room, and yes, square rooms do mean that the standing waves in different directions will occur at the same frequency, which is a bad thing (and why you need a good ratio: to ensure that the modes are spread around evenly, not bunched up), but they are not related to flutter echo. That is something else entirely.

i assume that using a bigger ratio will give me a less square room?

Not really, no. depending on what you mean by "big ratio". For example, a ratio of 1 : 6 : 6 is really "big", but still square. A ratio of 1 : 3 : 3 is much "smaller", but also still square.

Maybe it would be good if you could provide some photos of the space you have, and the total overall inner dimensions, plus a description of what it is that yo want to do in there. That would help to understand your situation better, and maybe offer some suggestions.

- Stuart -

[Daz12344]

hey stuart, thanx for the reply. i was kinda worried i wouldnt get a reply back by having such a vague and picless question lol

well ive haven't actually got anywhere or any pictures to upload and share only due to the fact that after about almost 10/11 months of searching we've haven't found anything that is with our budget (ie, rent, build up costs, business rates etc) but we have been to speak to some ppl to today about extra financing so hopefully within a months maybe 2 we might have some extra finnacial backing in order to actually start building. in an addition the area that we are looking in only have spaces, that we can find and have viewed are roughly 20,000sqft warehouses, which i suppose is ideal for a big recording studio with lots of different rooms such as practice, recording both live and control rooms 1, 2, etc but again its down to financing :/

anyway on with the important stuff lol.........

ratio - i do agree there are better ratios out there but 1:1.6:1.28 was just a random ratio i had managed to find and use for an example tbqh but the site i manage to "pinch" it from said that it was a good ratio for small rooms and due to finding ideal places i chose it becuase we were having a thought about looking into office blocks as they have smaller rooms but when the ratio was applied it came out to to be the 20x20x11 dimension.

Common number - the thing about the common number thing is that ive been around viewing alot of forum post and threads and i seem to have either missed something somewhere as i remember 1 saying that as long as the walls ceiling etc couldn't be divisible by a common number such as 2 and inst square, more oblong and quite a wide open space, then the modes will be evenly spaced out and it made sense within the contest of the first persons question but from what ive been taught and college and university is only a basic level of acoustics hence i was a bit confused on this. i have done more research into this but not as much i would like as a friend of mine is borrowing my acoustic book atm i used for university :p

Room sizes - just general room sizes of recording studios from an initial search from Google, but what you've said about the modes being multiples of each other being a problem makes sense as this will cause the "frequencies sort of overlap and cause a ringing" as far as Ive been taught/told. i would assume that it would be the room sizes after treatment, such as building a room within a room etc i had been looking at as most sites i looked at were live room/control room being ??x??x?? sqft a bit of a noobish mistake but when your confused and not sure about something your prone to makes these mistakes

Flutter echo - thanx for clearing that up i have always assumed that a square room will produce flutter echo, but thinking about it i know that flutter echo is reduced with proper absorber and diffusion panels but that is dependent on the room and any parallel walls as you explained i guess?

as i said, ive got a basic understanding and knowledge of Acoustics but have never really gone as far as studio design, hopefully my friend is coming back from uni soon so ill try and get my book back of him and have a read lol.

Atm everything is all theoretical as id rather try and have some idea of what achieve...really is best way to explain it. a sort of adaptable floor plan i suppose instead of sitting around doing nothing and waiting for the right location and size to pop up from somewhere and then do the calculations based on the room sizes that we want which is more ideal but under the circumstances its all we can do for the time being.

[Soundman2020]

I hope you find something suitable, or more financing! It's hard to have a dream and no way to implement it...

Anyway, just a couple of quick comments:

On room ratios, it seems like you haven't been looking in the right places! You might find this thread very interesting:

http://forum.studiotips.com/viewtopic.php?t=684

It's by Eric Desart, a very well respected acoustician and studio designer. It is one of the best basic introductions to room ratios that I have seen.

i remember 1 saying that as long as the walls ceiling etc couldn't be divisible by a common number such as 2 and inst square, more oblong and quite a wide open space, then the modes will be evenly spaced

I wish it were that simple!, but in reality it is more complex. If you take a look at some of the X-Y plots on the Studiotips thread, you'll see that it would be possible to meet the criteria you quote quite easily, and still have a poor ratio. If you are just talking about axial modes, that might be the case, but axials are just one of three types.

being multiples of each other being a problem makes sense as this will cause the "frequencies sort of overlap and cause a ringing" as far as Ive been taught/told.

It's not that equal dimensions CAUSES the ringing, but rather that it multiples the "ringing" that is already there. I wouldn't even really call it "ringing": "modal behavior" would probably be more appropriate. The issue is simply that if you have a mode at 82 Hz on one axis, and a mode at 82 Hz on a tangential, and another mode at 82 Hz on an oblique path, then any time you play a an "E" in the second octave, you will excite some or all of those modes, and it will sound much louder than it should, and continue sounding after you stop playing the note before gradually dying away, whereas if you play an "F" in the same octave, it will just sound normal. I guess you could call that "ringing".

i would assume that it would be the room sizes after treatment, such as building a room within a room

Building a room-in-a-room is not treatment! That is isolation. They are two different things. If you build a room-in-a-room (which is a good idea), then it is the hard, rigid, massive surfaces of the inner room, before treatment is applied, that govern the room modes. Treatment has little effect on change the frequency of the modes, since the wavelengths are so long, so it is the inner-leaf walls that matter for that. Yes, there might still be some other stuff going on from the outer-leaf walls, but that will be at a much lower level, and probably not much of an issue. So it is the surfaces of the inner-leaf, or inner-room that matter. It's the walls, floor and ceiling that you see around you as you stand inside the final finished room, before any equipment, furniture, treatment or anything else goes in: just the bare wall surfaces. That is what the low frequency sound waves also "see", even after the treatment is in place. Those are the acoustic boundaries of the room.

Anyway, I hope you find something soon, and can start on your design!


- Stuart -

[Daz12344]

hey Stuart sorry about not replying soon and apologies to the mods for posting on a dead post....

but anyway... I have managed to find a small space for about £375 a month only problem is that it is 468sqft not exactly ideal but around my area i would be looking at £2000 a month in rent for some of the other buildings

i have done a layout plan of the best possible room dimmensions based on the size of the room and was wondering you could take a look and possibly help with a raito for the rooms (CR and LR only tho not the entrance lol)

i was thinking something like 1.00:1.5:2.1 might be best for the live room perhaps? but im not exactly sure how you would calculate a room ratio from room dimensions.....

[Soundman2020]

No problem! No apology necessary!

i have done a layout plan of the best possible room dimmensions based on the size of the room and was wondering you could take a look and possibly help with a raito for the rooms (CR and LR

The ratio for the CR is 1 : 1.36 : 1.8, which is reasonably good, and close to Louden's best ratio. It's strange to have the room higher than it is wide, and the narrowness might create some problems for you with laying out your room geometry, but the ratio is OK.

For the LR, you have a problem. The length (18') is exactly twice the height (9'), so you have double- resonances lining up with each other. Not a good situation. I would try to vary both the width and the height somehow. The ratio is 1 : 1.47 : 2. Apart from that rather important issue, the rest seems fine.

but im not exactly sure how you would calculate a room ratio from room dimensions.....

Simple! Just plug the numbers into any of the on-line room mode calculators (ones that show all three types of mode, that is: not the ones that only show axial modes, without measuring tangential and oblique).


- Stuart -

[Daz12344]

Ah right i see lol

one that we did notice the other day when we had the electrician in checking out some overhead lighting in the suspended ceiling is that the total height is just under (7 1/2"ft) would this cause more problems or less. (-10/15cm for the Floating floor)

my theory is that it would create more problems on the Oblique Modes than the Axial modes due to the modes being too close :/

but as a starting point its the best possible solution which the room sizes due to the Room itself being 468Sqft in total ggrrr......

i didn't know that mode calculators could give you your ratios lol learn something new everyday

[Soundman2020]

is that the total height is just under (7 1/2"ft)

But your model shows it as 9'! Where did the other 18" go???

would this cause more problems or less

More problems. Way more. Low ceilings sound bad, and the lower they are, the worse they sound. 9' was fine, 8' is reasonable, but 7.5' is getting very marginal.

-10/15cm for the Floating floor

Why do you need a floating floor? I thought you said that this was in a warehouse, which normally have concrete slab on grade floors? Or maybe I misunderstood? If it is concrete slab on grade, then what is the reason for also wanting to float your floor?

my theory is that it would create more problems on the Oblique Modes than the Axial modes due to the modes being too close

Perhaps, perhaps not. It would be necessary to plug the numbers in and see how much each set of modes changes, but it really doesn't matter too much if it is the axials, tangentials, or obliques that move most: what matters is the final distribution of the modes, as well as the spread, and the lowest frequency with modal support.

i didn't know that mode calculators could give you your ratios lol learn something new everyday

They are related, very closely. Two faces of the same coin, actually. Modes are due purely to the dimensions of the room, nothing else, so the room ratio has a direct effect on the modal distribution. That's why there are "good" ratios and "bad" ratios: solely because of the modal distribution. With good ratios, the modes are distributed evenly across the low end of the spectrum, without being "clumped together" around some frequencies, and without leaving large gaps between modes. That's what room ratios are all about: modal distribution.

And some calculators give you a lot more information as well, such as room volume, surface area, required treatment area, Bonello graphs, and many other things. They are useful tools, to a certain extent, but there's no need to get hung up on finding a "perfect" ratio. Just get close to a good one, and you'll be fine.

- Stuart -

[Daz12344]

hi Stuart

yes im afraid you have jumped the gun a bit and assume that it was in a warehouse, which was the original plan but unfortunately (again i am repeating myself) a 468SQFT office type room is what we've managed to find which is financially affordable.

If we would be able to afford a warehouse then there wouldn't need to install a floating floor as everything would be ground floor anyway; if there was room then the Studio would be upstairs and rehearsal facilities downstairs to keep things a bit separate. the floating floor would be required due to the request from the landlord of excessive noise due to a previous incident several years ago.

regarding the plans and the height issue, we only had a brief look at the property the first time after speaking to the site manager due to a time related issue on his part and didn't go over the place with a fine tooth comb, in which we briefly discussed various business details and also a view of the room.

The point was made that the ceiling would be an issue if it was too low at the time, but when we went to go and view the property properly we realized that it is 7.5ft (roughly) also including that the ceiling is actually the concrete layer for the offices above us, and the suspended ceiling of the room has no isolation in between :/ so the reason for 9ft ceiling height is what we would like but this isn't the case for this property.

just wondering which calculator did you use to get the ratio because i used jhbrandts Excel spreadsheet and got completely different results. for the live room especially i got 1:1.6:2.4 which is close to one of the optimum ratios to my knowledge.... i could be wrong ofcourse lol

[Soundman2020]

yes im afraid you have jumped the gun a bit and assume that it was in a warehouse, which was the original plan but unfortunately (again i am repeating myself) a 468SQFT office type room is what we've managed to find which is financially affordable.

Well, I'm just going on what you said in your thread: That you were looking in an area that only had industrial warehouses, then you mentioned 9 foot ceilings. Your re-start of the thread did not say that the new place you found was not in a warehouse, nor that it had lower ceilings. I'm not a mind reader: If you don't provide correct information, I cannot know that. I can only go on what you said.

the floating floor would be required due to the request from the landlord of excessive noise due to a previous incident several years ago.

OK, but floating a floor is a big undertaking, is expensive, and will take up a lot of space. I'm still not clear if you have 9 foot ceilings or 7 foot 6" ceilings, since you keep on providing conflicting information on that. I was guessing that you have 9' to start with and are calculating that it will end up as 7'6" after you float the floor and build the actual MSM isolation walls / ceiling on top of that, which is a reasonable assumption. But if you are starting out with a 7'6" ceiling and ALSO want to float your floor, AND isolate the walls/ceiling, well, I just don't see how you re going to do that and still end up with a usable ceiling height. Ceilings approaching 6 feet are a major problem, acoustically, not to mention uncomfortable.

so the reason for 9ft ceiling height is what we would like but this isn't the case for this property.

See, that's why we ask (in the forum rules) people to post accurate information on their threads: to avoid wasting time and effort with information that simple is not correct. In your post of March 5 you provide a Sketchup model that shows 9 foot ceilings. Now you are saying that the Sketchup model shows what you would LIKE to have, but not what you ACTUALLY have. That's misleading, and helps no-one.

So, just to confirm what you said: "we realized that it is 7.5ft (roughly) also including that the ceiling is actually the concrete layer for the offices above us". That clearly says that the ceiling is concrete, and the height is 7'6". I honestly don't see that as being an acoustically usable space if you plan to float the floor and also isolate the ceiling and walls to high levels. You are going to lose about 8" for the ceiling, at least that much for the floated floor, and around 6" on each wall. The final interior dimensions of the control room will be roughly : H 6'2", W 5'7", L 11'1". There just won't be enough space to get the speakers in the positions they need to be, nor even to stand up properly, since that ceiling height does not even include the acoustic treatment! 4" of 703 would bring the ceiling down to 5'10"...

just wondering which calculator did you use to get the ratio because i ... got completely different results

That's probably because you used the REAL dimensions, not the ones you put in your Sketchup model! I use Bob Golds' calculator, since that provides the most comprehensive amount of information I have found in any calculator, clearly presented.

In any case, now that we have the final dimensions of the control room, the ratio will be 1 : 1.08 : 1.94, which is listed as number 24 on the list of ratios, and the associated comment is; "A worst case scenario". That ratio also fails 2 out of the 3 critical tests that the BBC uses for checking if a room can be used as a control room, and the Bonello graph looks like a mountain range, not the smooth geometric curve that is needed for a control room. The floor area is about one quarter of the minimum area specified by organizations such as the ITU, EBU, AES, etc., and the room volume is about one fifth of those same recommendations. The lowest mode that that room supports is at 51 Hz, and indeed there are just 3 modes below 100 Hz! I honestly cannot see any use for that room, except perhaps as a vocal booth or guitar cab isolation booth, and even then it is on the small side, after considering the amount of treatment that would be required.

or the live room especially i got 1:1.6:2.4

The ratio of the live room does not really matter, since a live room is not supposed to be perfectly neutral, like the control room must be. The purpose of a live room is to have it's won "character" and "vibe" and "feeling", which are subjective words that just describe a non-neutral acoustic environment. Part of that "vibe" can, indeed, be due to the modal distribution.

In any case, the final dimensions of the control room (after floating the floor and building the isolation walls) will be roughly : H 6'2", W 12'3", L 17'. That gives you a ratio of 1 : 1.98 : 2.74, which is not too bad, but still not very good. And with that extremely low ceiling height, it will be impossible to record things likes drums, strings or choirs. How can you get the drum overhead mics into a usable position when the ceiling is only 6'2" above the floor?

Sorry to be so negative, but I just don't see that as being a usable space, acoustically. Even if you did not float your floor, just from the wall and ceiling isolation, those rooms are simply not going to have enough height to be usable.


- Stuart -

[Daz12344]

ok... i dont really the tone of you previous post and wish to point out a few things that you have ACTUALLY jumped ahead of yourself with.....

1) Where have i actually specified that i have manage to find a warehouse within the first few posts?

now pre-made offices can have smaller rooms to industrial warehouse etc

that we can find and have viewed are roughly 20,000sqft warehouses, which i suppose is ideal for a big recording studio with lots of different rooms such as practice, recording both live and control rooms 1, 2, etc but again its down to financing :/

these are the only 2 PHYSICAL post i can actually see where i have specifiably mentioned anything about a warehouse. where in the below Quote says i have found a warehouse.... and more to the point, why would a WAREHOUSE of a TOTAL of 468SQFT not SQm even exist?!

I have managed to find a small space for about £375 a month only problem is that it is 468sqft

.

A SMALL SPACE!!!

2) The plans are 9ft high because when i did the plans i assumed that is was 9ft and as previously mentioned

regarding the plans and the height issue, we only had a brief look at the property the first time after speaking to the site manager due to a time related issue on his part and didn't go over the place with a fine tooth comb

The point was made that the ceiling would be an issue if it was too low at the time, but when we went to go and view the property properly we realized that it is 7.5ft (roughly)

I have not posted these plans to waste you time and i have not given you false information either....

one that we did notice the other day when we had the electrician in checking out some overhead lighting in the suspended ceiling is that the total height is just under (7 1/2"ft)

It says "Total Height" what the hell do you think it means....... TOTAL or OVERALL AMOUNT

Did i say that it was an accurate acoustical space, no, i said that this is a space that we have found, and i had drawn up some plans for said space.....

within the space of most probably 2, 3 days of posting the sketchup plans and actually looking the property in FULL things have obviously changed and you have not taken everything on board to exactly what i replied to which you have asked. but to clear up the confusion...

the TOTAL height is 7/12ft; NOT 9ft...
the Space/Room found is 468SQFT NOT a Warehouse...

And yes after talking to my friend over the place yes we shall not be using this particular ROOM and shall be looking else where for a more suitable propety and lastly not least since this has cause you so much trouble because you jumped the gun and you may close this thread.

i am grateful for the information in which you provide to help me with. you shall not hear from me again i shall look else where for my acoustical needs....

[Soundman2020]

why would a WAREHOUSE of a TOTAL of 468SQFT not SQm even exist?!

Ummmm.... Don't look now, but many studio builders actually do rent or buy a small part of a much larger building...

i have not given you false information either....

So posting a SketchUp model that shows 9' ceilings when in reality they are only 7' 6" is not "giving false information"

the TOTAL height is 7/12ft; NOT 9ft...

Which leads back to the same question: If the height is 7.5 feet, they why show it as 9 feet in the SketchUp model? You might want to refer back to the FORUM RULES about this. Regardless of whether or not you like the tone of those rules, they are the rules, and you did agree to them when you signed up. If you don't stick to them, then you can fully expect to be called out on them.

within the space of most probably 2, 3 days of posting the sketchup plans ... things have obviously changed

Then perhaps it would be a good idea to mention that somewhere? Instead of flipping your lid, maybe just a quick comment like "Things have changed and we only have 7'6" now" would have helped others to understand? If you don't tell us, how are we supposed to know?

you have ACTUALLY jumped ahead of yourself with

Naah, sorry. I don't do "jumping ahead of myself". All I do is to respond as factually as I can, based on the information people provide. If the information is wrong, misleading, or not up to date, well, then it isn't my fault, is it? Have you ever heard the phrase "Garbage in, Garbage out"? In any logical process, if you provide garbage information, you will get garbage results. Simple logic.

since this has cause you so much trouble

No trouble at all, actually! I enjoyed helping you, for free. But thanks for caring. I even enjoyed the rather surprising spew of blistering sarcastic drivel you threw back at me, in gratitude for the free advice I gave you. The only thing to do with people who react like that is to laugh them off. So I did enjoy that part too, and it really was no trouble!


Anyway, if you can't explain yourself clearly in your posts, and also don't want to follow the forum rules, and also get a bee in your bonnet over some imagined "tone" that you didn't like, then I guess that says a lot more about you than it does about me! If you can't handle being given top quality free advice just because you didn't like being called out on breaking the forum rules, well that's problem, not mine. No skin off my nose!

you may close this thread.

OK, no problem. Thread closed, as requested.



Bye!


- Stuart -

PS: I never can fathom the tiny handful of people like this who waltz through the forum each year with a chip on their shoulder, then rush off in a sulky huff, because they didn't like the way they were given FREE advice! Go figure...