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-   -   golden ratio. I dont get it (http://www.diyaudio.com/forums/multi-way/224937-golden-ratio-dont.html)

 murphythecat8 4th December 2012 02:58 AM

golden ratio. I dont get it

hi
my dimension for my bass (30 to 300hz) enclosure requirement is that the box is no more then 38cm wide and 82 heigt.

I want to have around 110 liter.

I dont know I to make the golden ratio, can anyone help

thanks

 planet10 4th December 2012 03:10 AM

38 x 61.5 x 99.5 is golden ratio. If 18 mm ply, gross volume would be 191 litres,

115 litre = 115,000 cm^3. Take the cube root = 48.6

48.6 x 1.618 = 78.7
48.6 / 1.618 = 30

So interior dimensions of 30 x 48.6 x 78.7 cm

dave

 speaker dave 4th December 2012 10:27 AM

I don't get it either.

The golden ratio was originally for visually pleasing proportions. Put proper absorption in the cabinet (fiberglass) and don't worry about the dimension ratios.

David

 DeonC 4th December 2012 10:33 AM

Quote:
 Originally Posted by planet10 (http://www.diyaudio.com/forums/multi-way/224937-golden-ratio-dont-post3269455.html#post3269455) 38 x 61.5 x 99.5 is golden ratio. If 18 mm ply, gross volume would be 191 litres, If we start with 110 litre add 5 litre for bracing and back of driver then: 115 litre = 115,000 cm^3. Take the cube root = 48.6 48.6 x 1.618 = 78.7 48.6 / 1.618 = 30 So interior dimensions of 30 x 48.6 x 78.7 cm dave
Thanks, Dave. I did not start this thread, but find the info very useful. That method is so simple I wish I had thought about it. :D

Deon

 Mark.Clappers 4th December 2012 10:35 AM

The golden ratio spreads the internal standing waves in the frequency domain (ie they don't overlap, both the base and the harmonics). This is useful for mid-range but not so much for bass as the wavelengths involved are usually much larger then the enclosure size.

 balerit 4th December 2012 10:51 AM

Quote:
 Originally Posted by speaker dave (http://www.diyaudio.com/forums/multi-way/224937-golden-ratio-dont-post3269809.html#post3269809) I don't get it either. The golden ratio was originally for visually pleasing proportions. Put proper absorption in the cabinet (fiberglass) and don't worry about the dimension ratios. David
I agree, it's for looks only, just another myth. I use Square root of 2 to propertion my bass reflex boxes. Also remember when you calculate a boxes volume it is the ideal volume and therefor everything that goes inside the box takes away from this ideal volume and you have to compensate for this by making the box larger, my free software does this for you.

Sample - The Book Worm

 puppet 4th December 2012 02:10 PM

Quote:
 Originally Posted by speaker dave (http://www.diyaudio.com/forums/multi-way/224937-golden-ratio-dont-post3269809.html#post3269809) I don't get it either. The golden ratio was originally for visually pleasing proportions. Put proper absorption in the cabinet (fiberglass) and don't worry about the dimension ratios. David
I've wondered about this, too. If you're just modeling a flat baffle for diffraction purposes (say for an OB), seems like the "golden ratio" doesn't produce an optimal response in sim. Might be fine to start there though.

 speakerdoctor 4th December 2012 02:21 PM

When it comes to room acoustics, use of the GR to position speakers can be helpful.

 awkwardbydesign 4th December 2012 02:56 PM

Quote:
 Originally Posted by speaker dave (http://www.diyaudio.com/forums/multi-way/224937-golden-ratio-dont-post3269809.html#post3269809) I don't get it either. The golden ratio was originally for visually pleasing proportions. Put proper absorption in the cabinet (fiberglass) and don't worry about the dimension ratios. David
Wasn't it for concert halls? Unlike Victorian structures, such as the Albert Hall.

 mondogenerator 4th December 2012 05:23 PM

I always thought it was observed in ancient egyptian design, adopted by the greeks, and used visually to proportion windows, paintings etc. Ive never tested if it really works in acoustics. My favourite adaptation of GL is to halve the longest length, calculating for twice the volume. Its a nice way to get a more cube-like shape. Of course standing waves would be more bunched up, but i never heard a problem. GL is better than guesswork, or breaking the 'rules' i.e. W equally a third H for example.

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