golden ratio. I dont get it - Page 2 - diyAudio
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Old 4th December 2012, 06:06 PM   #11
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Another skeptic, here.

As Mark said, the theory is, the standing wave harmonics will be evenly distributed, but this merely means they will retain the maximum possible energy. I think a more sophisticated cabinet design would cause the standing waves to cancel each other.

I think there's nothing special about 1.6180339..... I think any irrational number will do.

I also think if you were to try to design a box where the standing waves reinforced each other, you would find it quite difficult, and due to braces and battens, etc., you would not end up with 1' x 2' x 4'.
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Old 4th December 2012, 07:21 PM   #12
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Quote:
Originally Posted by balerit View Post
I use Square root of 2 to propertion my bass reflex boxes.
Just don't use it twice or you end up with the long dimension twice the smallest one.

I don't hold fast to the golden ratio, but do use irrational numbers to determine aspect ratios of rectangular boes.

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Old 4th December 2012, 07:34 PM   #13
Juhazi is offline Juhazi  Finland
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Here is a neat calculator. Just give a desired mid-value and you'll get the smaller and bigger numbers
Golden Ratio Calculator
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Old 4th December 2012, 07:46 PM   #14
Nanook is offline Nanook  Canada
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Default GR is so much more...

...than just visually appealing. It's defined as

GR:=[1 +/- (5)^-3]/2

Our bodies are formed using this ratio, as well as most everything in nature. Strictly speaking, it is the one "perfect ratio". The Fibanicci series becomes this at the limit as x--->0 (IIRC).

P10's statement regarding the use of irrational numbers as ratios is for all practical purposes suitable.
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Old 4th December 2012, 08:20 PM   #15
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Quote:
Originally Posted by awkwardbydesign View Post
Wasn't it for concert halls? Unlike Victorian structures, such as the Albert Hall.
Royal Albert Hall is a large ellipse, so I don't know how you would apply it. A lot of Architects seem to lean on the Golden ratio but I don't know that there is any magic to it. I certainly don't know of anything in Architectural Acoustics that relates to it.

Again, with enclosures, it only makes sense to worry about the distribution of resonances if you plan to do nothing about them. Since internal stuffing can do a good job of damping I wouldn't worry about exact dimension ratios.

David S.
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Old 4th December 2012, 08:26 PM   #16
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Originally Posted by speaker dave View Post
Again, with enclosures, it only makes sense to worry about the distribution of resonances if you plan to do nothing about them. Since internal stuffing can do a good job of damping I wouldn't worry about exact dimension ratios.
In any BR where one is only putting damping on the walls, you will never have sufficient damping to kill a standing wave so it does not hurt to cover all the bases.

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Old 4th December 2012, 08:36 PM   #17
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It doesn't hurt in a "belt and suspenders" sort of way (braces for the Brits). Still, the only time I've seen standing waves that defied treatment was with very tall towers, i.e. with extreme aspect ratios. With cabinets close to the usual 2 cubes high ratios I find good absorptive material (FG and Rock Wool) do a pretty good job, even as linings.

David S.
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Old 4th December 2012, 10:18 PM   #18
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Quote:
Originally Posted by planet10 View Post
In any BR where one is only putting damping on the walls, you will never have sufficient damping to kill a standing wave so it does not hurt to cover all the bases.

dave
Theres no advantage in using irrational numbers. You can use normal numbers like 3,5 and 7.
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Old 4th December 2012, 11:24 PM   #19
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Given my carpentry skills, the numbers are going to be irrational no matter what I do.
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Old 4th December 2012, 11:28 PM   #20
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Quote:
Originally Posted by speaker dave View Post
It doesn't hurt in a "belt and suspenders" sort of way (braces for the Brits). Still, the only time I've seen standing waves that defied treatment was with very tall towers, i.e. with extreme aspect ratios. With cabinets close to the usual 2 cubes high ratios I find good absorptive material (FG and Rock Wool) do a pretty good job, even as linings.
In the sense that your belt doesn't have enuff holes in it to tighten them up. I have always used the rule of thimb that to completely kill a standing wave you need to pass it thru at least a 1/4 wl of damping.

And if you have a tower with an extreme aspect ratio you need to treat it as an ML-TL not a BR, and you usually want to take advantage of the 1/4 wave resonance to get more/lower bass extension.

dave
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