"Golden Mean"

[JBP]

Do the "Golden Rule" dimensions still work when setting-up an HT area within a larger room or are there some different calculations to consider? Thanks.

[Colin]

1.1 ROOM PLACEMENT WITH GOLDEN RATIOS

The distance from the center of the woofer face to the side walls is:

Room Width times .276 (RW x .276)

The distance from the center of the woofer face to the wall behind (the front wall) the speaker is:

Room Width times .447 (RW x .447)

This is all you need to know to place speakers in a symmetrical, rectangular room!

George Cardas, http://www.enjoythemusic.com/magazine/manufacture/0602/cardas.html

14 x .276 = 3.864 (three feet, 7 ½)

14 x .447 = 6.258 (six feet, 3)

http://www.enjoythemusic.com/magazine/manufacture/zingali.htm

[JBP]

Thanks for the explanation and link. It was full of good info but not what I was looking for, probably because of a poor description on my part.

I'm trying to figure out proper speaker placement for a HT within a portion of a larger room. I will basically only have two walls for the HT area, the wall behind the center and front speakers and one side-wall, with the remaining two walls a minimum 25' from the HT area. Simply put, the HT will be in one corner of a larger room.

So with only two walls touching the HT area do I still need to be concerned with speaker placement dimensions? Or are there other potential problems to consider since I will only have reflections bouncing off two walls instead of four? Thanks again.

[Colin]

you can use the same golden rules detailed above, but apply them at an angle, with stereo center, center channel and TV in the corner, mains on the walls at an angle and sweet spot at an angle, facing the corner ....

[J.4knee]

One comment on that speaker placement rule Klipschorns using that math they would never work properly, doubtful the square room dimensional formula would work.

[Colin]

yeah, silly me, i don't even knopw what speakers he has

please post your movie and music tastes, room dimensions and front-end equipment in your system profile, this will help forum members give you thoughtful, insightful answers before they tell you that Klipsch is the best!

Klipsch loudspeakers can usually be further apart and closer to the front and side walls than cone loudspeakers, the big ole horns are also best pointed directly at your ears or the back of your head

[artto]

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On 5/29/2004 11:14:46 AM JBP wrote:

Do the "Golden Rule" dimensions still work when setting-up an HT area within a larger room or are there some different calculations to consider? Thanks.

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I think Cardas & Colin are missing the point to some extent regarding the golden mean (sorry Colin). I believe the formula Colin supplied from Cardas has to do primarily with subwoofer placement. Room proportions will still influence the woofer (and subwoofer) portion of the system regardless of using that formula. Doing it that way may attempt to minimize the rooms influence on the speakers, but the only way to achieve the best performance is to do it right in the first place. And I will go so far as to say that it may be wise for George Cardas to stick to what he does best. Selling expensive speaker cables & interconnects. IMHO hes simply missing the boat as far as room acoustics goes and apparently only understands part of the 'equation'.

1. The golden mean (also known as the Fibonacci Sequence, among other things), for the most part, applies to simple rectangular (or square) rooms.

2. It applies to the entire room as the room boundaries determine the acoustic modes based on their dimensions, & proportion ratios of those dimensions relative to each other.

3. The modes primarily influence the lower frequencies.

4. As the room size increases, the modes become less & less influential.

5. At some point, where all room dimensions are far greater than the wavelength of the lowest frequency that is to be produced, the room modes have no influence at all.

6. The idea is NOT to minimize the number of modes. Actually, its just the opposite. You want as many, closely spaced modes as possible. The more modes, the lower the amplitude of those modes. This yields a smoother low-end response. Remember, when there is large peak at a particular frequency in one location of the room, there is going to be an equally large null, or cancellation of that same frequency in another location. By having the modes more evenly distributed you smooth out the peaks & dips in the low end frequency response. This is actually what happens at higher frequencies. The wavelengths are much shorter relative to any of the room dimensions. The modes become so closely spaced, & there are so many of them that the room doesnt have much influence on them anymore, at least not from the standpoint of producing standing waves that severely influence frequency response.

I might add that George Cardas does not even have the language or terminology down correctly. Its mode George. Not node. To some this may seem trivial. However, if we cant all speak the same language, eventually it just adds to the confusion.

[JBP]

artto,

I have read many of the past posts in the forum and you seem to be very knowledgeable and passionate about audio, I hope I could get your opinion on my room dimensions.

I'm planning on placing the HT area in the corner of a large room, 50' X 75'. I will have roughly 20' wide and 30' deep of available space. Do you foresee any problems? What will result in having two walls border the HT while the other two are 30'+ away? Thanks in advance.

Just a side note. My father has just begun teaching me to use fibonacci ratios to assist in options trading. The software takes the resulting info and overlays it on a chart to help determine future turning points. I'm not a mathematical person, but I wonder what else fibonacci ratios are used for?

[Colin]

The formula Cardas supplies is a classic, but it does NOT have to do with subwoofer placement. Room proportions influence bass and mid-range. Doing it this way minimizes the rooms influence on the speakers, but it is just as easy to say get them three- four feet away from the front and side walls. If your home movie and music reproduction system will have only one side wall, it is important to balance the system away from the side wall.

This exact measurement works great for conventional loudspeakers:

1. It does apply easiest to simple rectangular (or square) rooms

2. Room boundaries do determine acoustic nodes

3. The nodes do primarily influence the lower frequencies, causing bumps and suck-outs (dips)

4. As the room size increases, the nodes do become less & less influential

5. At some point, the room is so large that nodes have no influence

6. The idea is minimize the affect of the nodes.

A MODE is any fixed standard octave tone, as the major and minor scales of Western music.

A NODE is a point of virtually zero amplitude in a periodic system, or the point where a continuous curve crosses itself. In the case of wavelengths bounded by room boundaries, the continuous waves are crossing each other, causing a point of zero amplitude (a dip). In this case, I think the purveyor of expensive cables was right in calling them nodes.

[artto]

Ill also need the height dimension to accurately calculate the room modes. However, 50x75 is pretty large & even assuming a standard 8 ceiling, you should have very few problems. With this scenario almost all of the modes occur at the very lowest frequencies (below 37Hz), with a preponderance of them in the 22 Hz range & lower. There are 426 modes below 150Hz with an average spacing of only 0.2Hz and a resonant frequency bandwidth of 3.1Hz which is quite good! There are however several modal occurrences around 70Hz which could cause a large peak in the response at that frequency. The wavelength of 22Hz is about 50'. I'm sure you can see the correlation.

Its interesting that you mentioned your father is using Fibonacci Sequences for assisting in his options trading. I do what is called being an active investor or active trader, but by no means a day trader. I know lots of people are into using Fibs as they are called by traders for predicting a range of price movements in the stock market. One of my friends friends does this. I havent had the opportunity yet to inform him yet that its useless for stock or options trading. Ive back tested Fibs using real historical data and the results were absolutely ridiculous.

Fibs can work great on closed, static, systems. The stock market is obviously not static. Nor is it a closed system. Imagine if you will, the walls, ceiling & floors of your room constantly changing dimensions & positions, as well as the speakers continually moving around. Now were would the Golden Mean or Fibonacci Sequences leave you? What would it tell you about your room? Absolutely nothing!

The Fibonacci Sequence seems to occur in many natural systems. Snail shells, flower petals & pine cones, how fast rabbits can breed, etc. etc.

Contrary to popular belief, there was no one named Fibonacci who discovered these sequences. The guys name was actually Leonardo Bonacci of Pisa (Italy). In those days (1200A.D) one was often referred to by their first name & their city, in this case Pisa, or Pisano. He wrote five books on mathematical compositions. One of his writings was a book on mathematical puzzles, originally called Liber abbaci. Someone later renamed it Fibonacci. And as you may suspect by now, the word fib, being used in this context is of no coincidence. For instance, IN A CLOSED PERFECT SYSTEM, two rabbits would multiply to 144 in 12 months. But this scenario assumes a lot ideals, which in reality, doesnt exist. So basically Leonardo Bonacci wrote a book about mathematical puzzles or fibs, a fib being a trivial or childish lie.

I might also add, that for similar, but different reasons, George Cardas (Cardas Audio) has apparently decided to capitalize on the terminology and misapply it to his cable designs. I used to have some respect for Mr. Cardas. I no longer do. He may be a great marketing & business person, but as far as Im concerned, his technical expertise is somewhat suspect.

http://www.textism.com/bucket/fib.html

http://www.mcs.surrey.ac.uk/Personal/R.Knott/Fibonacci/fibnat.html

http://www.lib.virginia.edu/science/parshall/fibonacc.html

http://www-history.mcs.st-andrews.ac.uk/history/Mathematicians/Fibonacci.html

[artto]

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On 6/1/2004 1:48:48 PM Colin wrote:

The formula Cardas supplies is a classic, but it does NOT have to do with subwoofer placement. Room proportions influence bass and mid-range. Doing it this way minimizes the rooms influence on the speakers, but it is just as easy to say get them three- four feet away from the front and side walls. If your home movie and music reproduction system will have only one side wall, it is important to balance the system away from the side wall.

This exact measurement works great for conventional loudspeakers:

1. It does apply easiest to simple rectangular (or square) rooms

2. Room boundaries do determine acoustic nodes

3. The nodes do primarily influence the lower frequencies, causing bumps and suck-outs (dips)

4. As the room size increases, the nodes do become less & less influential

5. At some point, the room is so large that nodes have no influence

6. The idea is minimize the affect of the nodes.

A MODE is any fixed standard octave tone, as the major and minor scales of Western music.

A NODE is a point of virtually zero amplitude in a periodic system, or the point where a continuous curve crosses itself. In the case of wavelengths bounded by room boundaries, the continuous waves are crossing each other, causing a point of zero amplitude (a dip). In this case, I think the purveyor of expensive cables was right in calling them nodes.

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Colin, its really nice to see that you've finally jumped on the room acoustics bandwagon. However, you and Mr. Cardas are out of your league right now. I may not be Floyd Toole, or Arthur Noxon or the grandfather F. Alton Everest, but must honestly say, I'm way beyond the point where both you & George Cardas are at. Call this a flame if you want. But facts are facts. And if facts are going to be considered a flame, then so be it!

Here are the definitions of a "node" & a "mode" as it applies to the context of the subject at hand from Merriam-Webster.

NODE: "a point, line or surface of a vibrating body or system that is free or relatively free from vibratory motion. A point at which a wave has zero motion"

MODE: "the most frequent value of a set of data" "a value of a random variable for which a function of probabilities defined on it achieves a relative maximum" "any various stationary vibration patterns of which an elastic body or oscillatory system is capable"

Nice try with the "A MODE is any fixed standard octave tone, as the major and minor scales of Western music" thing. Yes, thats one of the definitions. It's just not the one that applies here. So forget about the "nodes" thing. It's the wrong word. And it's misapplied. In fact, I challange you or any one else to find anything on "nodes" in F. Alton Everest's book (widely acknowledged as a 'bible' of sorts)"Master Handbook of Acoustics". Try the same with any professional achitectural construction books that cover acoustics, noise isolation & sound transmission. Show me some technical 'white papers' from reputable sources. Browse the Klipsch Audio Papers & Dope From Hope newsletters on acoustics for anything about "nodes". I can save you some time. Don't even bother. Because you won't find anything about "nodes".

While the formula Cardas supplies is certainly "classic", as is usual, more often than not, it's wrongly applied. And in the matter of acoustics & speaker placement, it is most certainly is not "This is all you need to know to place speakers in a symmetrical, rectangular room!" It doesn't apply to all speakers! And furthermore, it has nothing to do with the question JBP asked!

[Colin]

No facts arent flames, I have no problem butting heads over facts, as long as you stay in your corner of the country!

From Heritage (of course) Dictionary, I thought he meant NODE, as in One of the fixed points of a sonorous string, when it vibrates by aliquot parts, and produces the harmonic tones; nodal line or point, but I guess Cardas meant MODE, as in any of numerous patterns of wave motion or vibration. I admit the Cardas article is a crude exploration compared to exact measurements performed by software, but it is simple start for newbies is that what you are using? How do you account large openings, half-walls and rooms that open into other rooms?

[JBP]

artto,

The ceiling height will be between 10'-12'.

Do you think the walls bordering the HT will need acoustic treatment?

I don't know enough about using Fibonacci Ratios to assist in prediciting market turning points to contradict your view but however my father has been using them he's been able to greatly increase his percentage of money making trades. I'll have to get back with you once I have a better idea of what he's doing. I know that he doesn't rely on them soley but combines them with other factors and he only uses them when trading E-Minis.

[artto]

Colin, the word node & mode are often mistakenly used interchangeably in acoustics. I have made the same mistake in the past. At some point I asked myself, Gee, I wonder if there is a difference? Sometimes the proof reader will change mode to node thinking that is what the original author meant. Or the word processor may have changed it. Or in some cases it could simply be a typographical error as the m & n keys are located next to each other. I understand what George Cardas is getting at. But he obviously doesnt really understand what hes talking about. And it certainly wasnt a typo because he consistently uses node.

For years I used to wonder why Cardas uses what looks like a sea shell or snail shell for his company logo. Eventually I realized it had something to do with the Fibonacci Sequence or Golden Section, Mean or whatever. However, either he knows not what he is doing, or he is using this to deliberately attract unsuspecting audiophiles who usually don't know any better, in believing he's "on to something", or that what he's doing has some mystical or technical application to his product design. Like I said, I used to have some respect for the guy. Now I know better.

For the most part I dont use any fancy software. I have an Excel spreadsheet I downloaded from Linkwitz.com. This website also has a room mode calculator: http://www.mcsquared.com/metricmodes.htm & http://arts.ucsc.edu/ems/music/tech_background/TE-02/modes/Modes.html There are others of course. Or you can go thru the calculations manually like we used to. AcoustiSoft http://www.etfacoustic.com/contactus.html has some software that takes into account somewhat more complex situations beyond that of a simple rectangular room, such as L shaped or vaulted ceilings. The more complex the room is, the more difficult it will be to predict mode influences. In fact, given enough complexity, there may be no mode influence at all! Which is exactly what we want (usually). I say usually, because sometimes, this might be used to ones advantage. For instance, in my room, both the length & the diagonal dimensions produce modes at 21Hz & 37Hz. The width produces a mode at 30Hz. The room also has a fundamental resonance at 19Hz. This is probably why I can get reasonably deep & flat low-end response using Klipschorns down to 20Hz (actually Ive measured it down less than 6dB at 16Hz at the listening position).

So to account for large openings, half-walls and rooms that open into other rooms, well, that kind of depends, again, on how large they are & where they are located. There is no magic bullet so to speak. Thats why in the end we use our ears. I find it helpful to think of these things not as hard & steadfast rules, but more as principals.

[artto]

JPB, as I mentioned, the larger the dimensions the less mode influence there is. If the ceiling of your 75 x 50 room is 10, the 70Hz problem I mentioned gets moved down to about 56Hz and is of lower amplitude. The number of modes increases to 517 with an average spacing of 0.1Hz. With a 12 ceiling it moves down to 47Hz & even lower amplitude. 598 modes. 0.1Hz is the mode spacing resolution of the software. Even as encountered in fine auditoriums, you'll still have to pay attention to diffusion, other wise you're sure to encounter prolonged reverberation time, & echos or 'flutter echo'.

As for the Fibonacci thing being used for stock & options trading, lots of people use it. I would never solely rely on it. Theres an old saying on Wall Street. As soon as you find the key, they change the locks.

I once ran across a website/publisher that featured an article on using Fibs for derivatives trading. However, once I discovered this same publisher also had written articles about using astrology & religion as trading tools I really had to question their credibility.

The point is anything works for a while at some point in time. Its my position that there are far more reliable indicators & real fundamental knowledge that are far more accurate & consistent than using Fibs.

[DrWho]

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On 6/1/2004 12:13:23 PM JBP wrote:

I'm planning on placing the HT area in the corner of a large room, 50' X 75'. I will have roughly 20' wide and 30' deep of available space. Do you foresee any problems? What will result in having two walls border the HT while the other two are 30'+ away? Thanks in advance.

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What is this huge room going to be used for? Would it be possible for you to build a 3rd wall to run down the other side of your HT (leaving the back open)? Perhaps you could try building a wall that is acoustically transparent above 100Hz or so.

The only reason I suggest this is because having a wall on only one side will result in a lopsided sound. There will be a lot of sound coming from the side with the wall and the side without the wall will sound very open and empty.

If at all possible, I would suggest putting the center of the HT into the corner and going out at an angle into the room rather than trying to stay square with everything. Doing this would make your system sound much more symmetrical; not to mention a properly setup system in a corner can sound much better than a rectangular room. (no early reflections, sub tucked into the corner will sound good, and no reflections off the back wall).

Anyways, if you must go with the setup you proposed, then I would suggest putting lots of broadband absorption on that side wall.

[IndyKlipschFan]

IN A CLOSED PERFECT SYSTEM, two rabbits would multiply to 144 in 12 months.

Hmm sounds like Amway, Quixtar whatever they call themselves now..Alticor?? this is the premise of lots of other MLM schemes. It is all about tapes, books, and seminars, and usually not the products where the BIG BIG money is made.

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Since your room is so unusual, why not fire it (direction wise) back at you, (the back wall) with a pull down screen?

And if you really enjoy HT at mid to high levels ... do NOT get in ceiling speakers...pointing down to you. With the room size you really have, you could also build a room within a room/ false walls as an idea also.

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As a side note...

I have been an Investment Advisor - Portfolio Manager buying stocks to invest in with my own money since joining my father in the Investment Business in 1989. I do this for my own family, and many clients. I agree with Artto... The stock market is just too big, and it moves all the time. Greed vs Fear makes the world go round for sure. Any computer, book, chart, seminar, guru or tape "system" that would guarantee results, would be used by everyone in our business I assure you, and thus make the model useless too. (e.g., Wal Mart will be up a dollar tomorrow for sure vs it might be down tomorrow for sure based on something "arbitrary" is silly). Wal Mart will either be up, down, or the same... is the only "Guarantee" anyone could promise you.

I used to, in the late 1990's, cringe when a few of my friends tried to be "Day Traders" thinking they were gonna get really rich and in EVERY case, not one of them made any money long term, and all have gone back to what they used to do or something else before hand.

The stock market, as my dad used to say, is an "Art and a Science" in picking companies/opportunities. It is easy to say looking back... that was a winner or a loser.. But very hard to "guarantee" a winner going forward. BTW, the other theory that you get a winner and diversify after you "hit it big" is also crazy, if it continues to look and grows like a winner HOLD ON TO IT! I doubt Bill Gates, The Walton family, Or any family that starts a small bank that grows to become something big, then selling out all of their holdings to "diversify," would ever have the power/wealth/opportunities they enjoy today. Course you know their accountant/ banker/ stockbroker/ friends told em they were crazy for holding onto their shares too.

[artto]

IndyKlipsch, absolutely correct. JBP, I've begun to take a look at that demo software you referred to me. It an application software based on TradeStation. TradeStation is an excellent trading platform. But the application software may actually not be needed. Like AutoCAD for instance, many companies rose to the occassion to provide customized application software 'overlays' for AutoCAD. For instance, LANDCADD for landscape architecture & site planning professionals or CivilSoft for civil engineers, niether of which could be used as standalone products without AutoCAD. This allow the 'value added resellers' to sell additional installation & techinical support services. This Fibonacci based analysis software for TradeStation appears to be similar. Everyone of these products that I have seen so far have the primary objective of selling you a monthly or annual subscription service for using their 'data stream' or data feed. Without it, the software is useless. One software I used for a while actually would change it's recommendation of buy or sell points, days or weeks later. Whats the point? Oh yeah, let just hop in my time machine & go back to May 15 & change the order. But since I try to keep an open mind, I'll give the Fib sofware a try. But like Indy said, if was some kind of magic bullet that consistently produced superior results over both the short & long term, everyone would be using it. There are just too many variables in the market place with many different kinds of investors & traders with all kinds of time frames & objectives. Beware of products that promise to be all things to all people. I prefer the KISS method (Keep It Simple Stupid)

[JBP]

The only reason I even brought up the trading software was because I thought it was interesting that Artto was using fibonacci to calculate acoustics and that it was also used in trading. . I never claimed that it was a sure thing and would produce huge returns, "BIG MONEY". My father just trades as a hobby. He's not trying to make "BIG MONEY", just have fun. He's trying to get me into day trading because he's convinced I have too much free time.

As a side note...

I wasn't trying to start an argument. I agree with everything you said IndyKlipschFan but I think we are talking about two different things. Trading E-Mini S&P 500 contracts, which my father does using the fibanacci software vs. buying company stock for the long-term are two completely different things. As I understand it, it is much easier to use statistical data when trading E-Minis and similiar markets. I'm not claiming that to be a fact, just the way I understand it, since I'm not an Investment Advisor - Portfolio Manager.

The room is going to be the main living area. Kitchen and and dining on one end, HT and pool table on the other, with a fireplace and lounge area in the middle. I'm not using ceiling speakers. I'm going to use Ref 7 with bookshelves for surrounds, which will be dropped from the ceiling.

I wanted to keep the room as open as possible so putting up a wall is something I'd like to avoid. Would moving the HT 5' away from the side-wall, more towards the center of the room improve acoustics or would I be better off just placing it in the corner? If I use the coner option, would that eliminate the need for wall treatments? Thanks for the advice!

[artto]

No argument here JBP. I just wanted to make the point of where the term Fibonacci came from, and how its often misapplied. Even in acoustics, it only has application in simple rooms that are relatively small compared to the lowest frequency wavelengths that are to be reproduced.

Since you seem to have enough space, I would try to get all the speakers away from the wall surfaces as much as possible. The closer you get, the more potential near term reflection problems you will have affecting mid/highs which in turn will affect imaging. The main thing corner placement will do is reinforce low frequencies. Since this is for HT application, youre probably going to have a subwoofer or two so you probably wont need the corner reinforcement.