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-   -   Golden ratio - Example? (http://www.diyaudio.com/forums/multi-way/32409-golden-ratio-example.html)

icebear 17th April 2004 09:30 AM

Golden ratio - Example?
 
Hi

I'm aboute to put my Beyma AG8/N into an open baffle which measures: 110cm * 60cm.
I'v tried to understand the golden ratio for placing the center of the driver in the baffle. Please correct me if I am wrong:

From side: 60 / 1.618 = 37cm

From bottom 110 / 1.618 = 68cm

From top 110-68 = 42cm

Am I way off ?

Bjorn

sreten 17th April 2004 12:21 PM

From what I can tell not at all.

However in the art of compromise something sometimes has to give.

When placing a tweeter you'd only use the baffle width ignoring the hieght.

And use ratios of ~ 0.6 : 1 : 1.6 for distance to top a sides.

However in the open baffle the short distance would compromise rolloff frequency some what.

In a 2 way open baffle the higher unit would be placed like the tweeter.

The bass unit would be placed (asumming the baffle is floorstanding) as
though the baffle is double the hieght due to floor symmetry.

For a single full range unit ideally you treat it as a cross between
the two.

I'll just point out that 42 cm is too similar to 37cm to be ideal.

:) sreten.

markp 17th April 2004 04:39 PM

You may also use the ratio of .8 : 1 : 1.25

sreten 17th April 2004 05:18 PM

Quote:

Originally posted by markp
You may also use the ratio of .8 : 1 : 1.25
sounds like a good idea.

:) sreten.

icebear 17th April 2004 09:15 PM

Ok, calculate it
 
Ok, but i don't see the measures and the calculation. Can you give me an example for the baffle i mentioned?

bjørn

sreten 17th April 2004 09:40 PM

no problem :

using 0.8 : 1 : 1.25 and baffle width = 60cm

1)
centre distance from side 1 = 27cm
centre distance from side 2 = 33cm
centre distance from top = 42cm

or :
2)
centre distance from side 1 = 23.5cm
centre distance from side 2 = 36.5cm
centre distance from top = 29cm

or :
3)
centre distance from side 1 = 27cm
centre distance from side 2 = 33cm
centre distance from top = 21cm

I'd say its between 2 & 3 decide on ear hieght.

The first is good for bass with an angled baffle.

Note that 1&3 are the same except
one dimension is doubled.

(cube root of 2 = 1.26, its inverse = 0.79)

:) sreten.


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