the ideal room ratio

Hello! I'm trying to design a good mixing room. I've found these "ideal" room rations on the Ethan Winer site: Height X Width X Lenght 1. 1 X 1,14 X 1,39 2. 1 X 1,28 X 1,54 3. 1 X 1,60 X 2,33 The ceilings in the room are about 4m high, the lenght of the room is variable (i'll have to tear down some walls...) and the biggest problem is the Width. It is only 3,44m wide. Now, the other piece of information I got from the Ethan's site is, that minimum volume of the room is about 70,79m3. If i put in the ratios the width, it's always way too small. Height X Width X Lenght = Volume 1. 3,01 X 3,44 X 4,19 = 43,38 2. 2,69 X 3,44 X 4,14 = 38,30 3. 2,15 X 3,44 X 5,01 = 37,05 The thing i would like to know is would these ratios work, if i would swich Height ind Width... or is What is how long important? The way i see it (and i know i'm probably dead wrong...) that only the ratio is important, not what is how long... It's all about how long waves are, not where they are... (no, I don't surf...;) ) This would save me: Height X Width X Lenght X Volume 1. 3,92 X 3,44 X 4,78 = 64,48 The volume is much closer to the required 70,79m3... Am I thinking right? Would this ratio work good? And another question: Would you rather have the perfect ratio, or volume bigger than 70,79m3? I could make the room longer, if i would brake the ratio... If I brake it, would it do any good, if one lenght would be precisely 2X longer? If i would have the lenght 2x longer (max is 7m)than in the "perfect" ratio, the calculation would be: Height X Width X Lenght X Volume 1. 2,52 X 2,87 X 7,00 = 50,68 Borut

Borut, In a room that small I'd focus on making it as big as possible rather than worry about the ratio. Just avoid a cube. :) --Ethan

I'd really like to make it as flat as possible... I could do demo masterings there (the room is dad's)... So the main concern for me is, that everything is optimised and as flat as possible. Perfect ratios would be a good starting point, I think, if all the big boys use them... And I must admit, i was shocked to see how cube-like the ratios are! 1 : 1.14 : 1.39! How big should a mastering/audiophile system room be? My dad is thinking about moving to a new house, if we couldn't build a great room in this apartment. How could I design a good room? Would starting with "perfect ratios" help? Thank you! Borut Edit: I should probably design the room good for the speakers... The speakers will be MBL Monitor Speakers 311 E (http://www.mbl-germany.de/english/start.html) They are not very big... surprisingly powerful, but still I don't think the room should be as big as if we had B&W nautilus or something... Am i thinking right?

Borut, can you post the maximum available dimensions in all three axis ? There may be as good a combination of dimensions as the "golden ratios" that's hiding in there somewhere - ONe thing to remember is that these so-called "ideal" ratios are all pretty old; they ALL predate the use of PC's to figure things out, and as such they don't represent ALL the posibilities, only SOME of them. The BBC has successfully used ideal ratios for voice booths by "standing the room on it's end" - meaning, you're right that the ratios are the important part, not which is height, width, etc. Also, in your planning do you need to worry about isolation to other rooms or the outside? If so, that will take some of your space depending on how MUCH isolation you need... Steve

Things have changed a little. My dad decided that he's going to move to a house... So my hands now are completely free... The only thing that is not a variable is wich speakers and TV he's gonna use. Maybe the choice of speakers isn't the best one for large rooms. Also i will have to calculate, that the sweet spot is not in the same half of the room as the speakers, because the room will be used for TV too (wouldn't wat to sit 2m from the TV) Are there any newer "ideal ratios"? Should i take the ratio of some fameous mastering studio? Thank you so much! (I'll make shure i'll post lots of pic when the constructions starts!) Borut

I'd wait til you have a space, to see what's possible. Then I can help you if you need to build one wall to improve the modal distribution before treatment... Steve

I knew i can count on you guys to help me out! Thank you so much! Knightfly... The thing is, that we'll modify a room in the new house, to be as good as possible for audio. So I'll have to decide on the room size, razios... What would be the the best room to start with? And thank you again for your help! Borut

Ok... here's some info about what i'd like to do, I hope you could help me with some pointers in the right direction... The room will have 3 main functions: Home theater (movies), audiophile listening enviroment and mastering studio. The mastering part is the least important, but i'd love to have a room good enough for it! Because of the home theater part, the sweet spot should be in the other half of the room as the speakers (not close to speakers, more in the back). I think it would be quite unnatural to sit right infront of the TV. This is really tricky because of the early reflections... as far as I understand it, they're all directed to the back of the room, so they're not present in the sweet spot... How should i shape the room, so that I wouldn't get early reflections? I though i could sit somewhere 2/3 from the front wall. I wouldn't like to soffit the speakers, because... well... they look nice ;) But soffiting is not critical, few of the mastering studios have those Bowers and Wilkins soffit mounted ;) Anyway, does anybody have any advice? Where should I start? I can't eved decide on the room ratios and dimensions, that's the first thing to do i think... And what shape (those nasty early reflections... ;) Thank you so much! Borut

Most mastering rooms are NOT shaped; they are chosen for correct ratios, made large enough so that a lot of the modal problems are too low frequency to matter, and treated at early reflection points and bass trapped to sound as neutral as possible. The comments I've heard from mastering engineers (I'm NOT one) are that they want a "perfect living room" - in other words, something that's theoretically possible in a NORMAL house. (yeah, right...) Here are a few things to read on placement - http://www.audioholics.com/techtips/set ... Audio.html http://www.audiophilia.com/hardware/visears.htm http://www.moultonlabs.com/slides/smallrooms/index.htm http://www.johnlsayers.com/phpBB2/viewtopic.php?p=18059 http://forum.ecoustics.com/bbs/messages ... 31062.html http://www.cardas.com/content.php?area= ... Room+Setup HTH... Steve

Thank you for the reply! I'll read through the links you gave me, and come back with any questions, wich i'm shure I will have! Borut

Incredible links knightfly! Thank you! I used the "perfect" ratio (1 : 1,28 : 1,54), so my dimensions to this point are: (10ft : 12,8ft : 15,4ft). I have a few questions... If mastering studios don't have angeled walls, they're all in the "damned if you do, damned if you don't" situation, where you have to be in nulls of First and Third harmonics and peaks of Second and Fourth harmonics to have a good stereo image. I most definately want to angle the walls to get rid of this problem! How do i calculate the sweet spots in a room with angled walls? Should i even start to worry about standing waves at this point? Or should i be focusing on something else, while setting the fundations to my room? I also have a question about calculating sweet spots... How wide should i make the "strap" from the peaks? Hm... I just randomly draw a line very close to the peak. If i would draw it higher, the "strap" would be narrower, if i would draw it lower, it would be wider... I hope someone will be able to understand this question (i'm not a native speaker... sorry)

I have been following this thread with interest. There are a couple of items that seem to misunderstood. These include: All rooms have modes, regardless of the shape. The goal of room ratios is to equalize the effect of modes. Not eliminate their effect or make a flat room. Most room ratios are based on several assumptions, including: All surfaces are completely reflective The room is perfectly symmetrical. There are no obstructions (like furniture, or humans) Sweet spot calcualtions are theoretical considerations of effects which result in data is practically useless. Trry ot hold your head in location for any extended time :D Good luck! Andre

Thank you for your reply AVare and for great wishes! about your post... That's exactly what i've been thinking (I just thought i could get rid of standing waves, if no walls were parallel... I have a lot to learn!)! As far as I understand room ratios, the objective is to have harmonics of the room as different as possible (since the worst possible shape is a cube...). Am I right? But still, calculating what the room would be like, if all the walls were concrete. Then when i'll have the angles right, and i'll know the standing waves of the room (is this the same as the rooms modes?)... I'll know where and what frequencys i'll have to effect... Right? I have no intentions to have a special reflective suit for the room, so that i'll be able to calculate it and a special head holder with bolts securing my skull in place... :lol: Just a good room. So... how could i calculate those room modes with angled walls? Am I thinking in the right direction here, or should i start somewhere else?

Your Welcome Soulfood. I am not certain of your knowledge of english, as what you write is excellent, but may the result of much work to make it good. What I have noticed is a good grasp of mathematics, and applying it. It may be too technical, but if it is not BBC RD1993-08 is considered one of the best papers on room ratios. Andre

Wow! Incredible link AVare! Thank you so much! I'll read it and, as usual, come back with quesions... :?

I jope you enjoy it. It is one of the most advanced papers on the subject available today. Note that any of the reverence papers of the RD 19XX are available from the BBC website for free. Good studios are 90% design and 10% construction. Keep the questions coming so that you understand it well. Have fun! Andre

Thank you everyone for the help so far! I've been REALLY busy... had no time to study acoustics... (school+work+music - no free time) I will post some more questions soon! And sorry to everyone who helped me so far, and maybe thought this thread is dead... I assure it is far from dead, so none of your whisdom sharing here is pointless :oops: Borut

Hi all! I'm back! :) There are a few new questions i have... when calculation the room ratios, should i think of the empty room, or "the inner room"? If I will build a room-in-a-room, i should probably calculate, so that the inner room will have the right ratios, shouldn't I? What about wall resonators? Should the ratios be correct from the ROOM WALLS or the wood slats.. (i can't form a better question... :roll: I hope you know what i mean...) If i would put some sort of resonators in the room, wouldn't they effect high freqs differently than low freqs? It seems, that low freqs would go right through and boutnce from the wall, and high freqs would bounce off the resonator... I'm a little confused... Thank you so much for your help! Borut

Welcome back! I hope you enjoyed the report, and any others you may have read referenced it. The questions you have are great. They show abvious knowledge of the referenced report, not an easy thing to get if you new to acoustics. Answering them here will also help many othere people who have, or will have the same questions.

when calculation the room ratios, should i think of the empty room, or "the inner room"?

Think of the walls (remebering that ceilings and floors are just walls on their side :D ) that are reflective at the frequencies involved. If you have a thin panel in front of a concrete wall, then use the concrete wall. If your interior walls are stiff and heavy then use them. In all situations I have been involved with, the inner walls have been built strong enough to be the walls used in mode calculations.

If I will build a room-in-a-room, i should probably calculate, so that the inner room will have the right ratios, shouldn't I?

Correct.

What about wall resonators? Should the ratios be correct from the ROOM WALLS or the wood slats.. (i can't form a better question... I hope you know what i mean...)

You are using (hopefully) the tuned absorbers (resonators as you wrote) to compensate for what the room is doing without the absobers, so use the room walls for the calculations. What makes this easy if you build the absorbers into the walls, so that the dimensions are the same!

If i would put some sort of resonators in the room, wouldn't they effect high freqs differently than low freqs? It seems, that low freqs would go right through and boutnce from the wall, and high freqs would bounce off the resonator...

I had to put these two questions together as they are asking the same thing in two slightly different ways. Yes, what frequencies the tuned absorbers do not absorb they will reflect. I am very impressed with your new knowledge. Keep the questions coming until you are completey comfortable with the acoustic knowledge that you have for designing your studio! Andre

Thank you so much for your kind words AVare!!!! And thank you again for the BBC link... so much knowladge there! They really give me hope! I'm still fighting the acoustic Goliath here, but people like you make it sooo much easier!!!

Hello again! I have a few questions this time... 1.)About tuned absorbers... What happens to isolation, when I replace a portion of the inner wall with the Helmholtz resonator (I think that's the same as tuned absorber, isn't it?) The resonator reflects the freqs above of it's range, absorbs the freqs i want it to, but don't the low freqs go right trough? 2.) A/ About bass traps... They're usually in a corner, so that changes the shape of the room. I read somewhere, that i should use the average width of the room to calculate room modes, where there are non-paralell walls, so i should probably have to absorb some of that freqs too... B/ Maybe a stupid question but... Are those different room modes just betwen the two basstraps, or do they "resonate" troughout the room? If they're just between the basstraps, there really is no point in fixing them, i will never sit right next to a wall... 3.) A big issue I'll probably have to deal with are also early reflections... I know i'd definately have to deal with them, if i was planning a normal control room... But the sitting position will be relatively far away from the speakers (definately not the "correct" triangle). That is beacuse the room will be also used as a home theater, and it would feel unnatural to sit right infront of the TV, and have a lot of room behind your back... So now I don't know, if I should even try to diffuse the early reflections, or will I be far enough from the speakers, so they will not bother me... Thank you! Borut

1 - you're correct, although I've not seen actual AMOUNTS of isolation that's lost due to the multi-leaf effect; it would only weaken the wall BEHIND the trap so it's not like your entire wall would be worse. 2 - You may be over-thinking this; keep in mind that the term "bass trap" is really abused on these types of sites, it can mean anything from a bale of insulation tossed in a corner, to several inches of rigid insulation, to a tuned panel resonator, to a sheet of homosote across a corner with insulation behind it, etc..... Corner traps made from absorbent material are arguably the simplest and best way to treat MOST rooms; these tend to be called "bass" traps, but are really BROADBAND traps that also happen to work on bass - just not as low a frequency as a tuned panel trap can. But these do so much for smoothing out ALL room modes, that they are the defacto standard "first thing" most rooms should have done. Specific, TUNED, panel traps should only be used in extreme circumstances IMO; and only after broadband treatments haven't finished the job. Placement of these is more critical and if used WRONG, they can DAMAGE the room sound instead of fixing it. 2(B) - doesn't apply to broadband corner traps, but would to TUNED panel traps placed FLAT against the wall. See the previous paragraph. Early reflections - if ANY sound path (other than the DIRECT one) can reach your ears less than about 20 milliseconds later than the direct sound (about 23 feet DIFFERENCE in length from direct sound) and is NOT at least 10 dB LOWER in level, then it needs to be absorbed or re-directed (to lengthen its path and weaken its level) - the human brain, when presented with two identical sound events LESS than about 20 milliseconds, INTEGRATES the two into one sound - this causes reinforcements/cancellations at different frequencies, providing a "comb filter" effect. It's like having a 100-band graphic equalizer on your sound, and alternately peaking and dipping every other slider. Worse, if you move your head less than an inch this will CHANGE. So yes, you need to consider early reflections. Something like 2" (minimum) rockwool/rigid fiberglass can be used at these points, and nearly ANY decorative cloth covering (chosen by someone who CARES what they look like :wink: ) will help... Steve

Hello again! I think i now have a reasonable good idea of room ratios! Thank you so much guys! Really! I'll start with a new thread for the design. I feel like I can't plan anything (even the ratios of the room the studio and home theater room will be in!) until i know, what shape it should be and basic layout of the rooms (and how thick walls will be...) Thank you again for all the help! Borut

HI again! I just realised that i forgot a huge part of room ratio questions... :? Almost all the material i read about room ratios were made for rooms with 90 degree angles. In planing a studio, I will use angled walls. Do they have to be symetrical to calculate room modes? How to calculate room modes in a room without paralell walls? just take the average of every wall? Thank you!

[quote="SoulFood"]HI again! In planing a studio, I will use angled walls. Do they have to be symetrical to calculate room modes? How to calculate room modes in a room without paralell walls? just take the average of every wall? quote] USe the average of every wall. It will be close enough for room mode calculations. Andre