Ideal room dimensions for great system sound?

I have just completed a room based on the Fibonacci Series which is related to the Golden Ratio. In this series, each number is the sum of the previous two numbers starting with 0, 1, 2, 3, 5, 8, 13, 21, 34 etc. The ratio of each number to the previous one approaches the Golden Ratio as the series approaches infinity. For example, 13/8 = 1.625, and 34/21 = 1.6190476190 etc.

In theory, a room built using these ratios would spread the first order modes such that they were not directly additive at any point. The room modes are what they are depending on the distances between walls, and you can not change that, however, you can spread them out. This would minimize the constructive and destructive interferences and make the room response as smooth as possible.

I chose the dimensions of 8H, 13W and 21L which required building a new rear wall. You can also compute the room size for different sizes by using the ratio. For example, if you had a 10 foot ceiling, the width would be 10*1.618 = 16.18 and the length would be 16.18*1.618 = 26.17924.

Currently, I am in the process of measuring the room using both a RS Meter and a computer based system which generates a sweep and computes the frequency response and waterfall chart. Preliminary measures confirm the fact that the response is within +/- 3 db and there are three peaks corresponding to the primary modes generated by the floor/ceiling, front/back walls, and side walls.

So far I am very pleased with the outcome, as I put many hours into the construction of the room and would have been very disappointed if this turned out to be sub optimal. There are many approaches to room design, and I can recommend this one based on my experience.

I also did some additional things to the room, including a floating ceiling (ISOMAX sound clips, RC channel and Green Glue) for isolation, dual sound lock doors, and a hemholtz resonator built behind the back wall. As soon as I get some time, I will post my system with pictures and more detail.

The Golden Section is just one among many, mostly ancient, geometrical methods/systems for structuring pleasing VISUAL proportions in the physical world. Any association with room acoustics, sound, or vibrational progressions is pure rubbish, and something the Greeks never contemplated -- expecially since they hadn't learned much about volume calculations at that time; something upon which acoustics fundamentally depends.

And then there's the Fibonacci numbers and those people who have turned themselves into pretzels trying to link them to Golden Ratio progressions. It all reminds me of the story about the guy who was obsessed with measuring every circle he saw -- trying to see if Pi would ever come out an even THREE!! It's simply PAINFUL watching people grasping to make these meaningless connections when any acoustician will tell you that absolute dimensions of a space relative to volume, and not their ratio, are what affect acoustic properties.

This is a good primer on the subject: http://www.friesian.com/golden.htm All this ridiculous hype would die a quick death, if folks just do a little research. It's as easy as g-o-o-g-l-e !!

And SHAME on you, George Cardas!!

Make certain none of your room dimensions are evenly divisible into any other. Non-parallel surfaces are even better. 'The Master Handbook of Acoustics' by F. Alton Everest is an excellent info resource. Mr N is correct about the use of the "Golden Ratio", and there are a wide variety of correlations that can be found in our bodies and in nature(our ear's cochlea, the Nautilus shell, the DNA molecule). I suppose a spiral shaped room........ Then again- the application of the ratios to your room would avoid any evenly divisible dimensions, so I wouldn't really hurt to apply the principles(though there wouldn't be any gold involved other than what was spent on the project). (http://aibek.nomadlife.org/2005/09/golden-ratio-or-da-vinci-code-reloaded.html) Have fun and Happy listening

Actually, the Fibonacci Series was named after an Italian mathematician named Leonardo of Pisa (c. 1170 - c. 1250) also known as "Fibonacci". He used it as an example in one of his writings.

Leonardo of Pisa

The earliest trace of this is not to the Greeks, but to the anciet writings of an Indian named "Pingala" in the 4th century BC.

Pingala

The importance of this series on room design is, as Rodman points out, the avoidance of evenly divisible dimensions leading to overlapping room modes, as well as producing a pleasing room shape. I looked at a number of studies of room ratios, including one done by vast numbers of computer simulations of many potential combinations. The Fibonacci ratios fall nicely into the region of "best ratios". So while they are not the only ratios that can work, if you are starting out with the freedom to choose your ratios, I see no reason not to consider them.

Has anyone built a golden ratio room? And if so, where would the ideal speaker placement be?(according to the greeks!!!)