Dimensions to make the enclosure look tall and slim.

[markp]

Originally posted by rakeshln
Its the same, 0.62:1:1.62 or 1:1.62:2.62 or 1/x:1:x or x^0:x^1:x^2.

Or x^(n-1):x^(n):x^(n+1), where n is an integer and then applying the Fibonacci rule you get x=1.62.

But, how does this get into dimensions? There has to be some reasoning.

I believe it is because .62 x 1.62 = 1 or .8 x 1.25 = 1 or any ratio like that where the product of the two non-one variables is one.

[rakeshln]

Still my head.

I dont know how right i am

10log(x)=-1 .... x=0.794

10log(y)=0, .... y=1.

10log(z)=+1, ....z=1.258


10^(-1/10) : 10^(0/10) : 10^(+1/10)

x:y:z=0.8:1:1.26 (approx).

x, y and z look like power ratios to calculate SPL.

Looks good mathematics but nowhere near whats happening physically.

[markp]

Originally posted by rakeshln
Still my head.

I dont know how right i am

10log(x)=-1 .... x=0.794

10log(y)=0, .... y=1.

10log(z)=+1, ....z=1.258


10^(-1/10) : 10^(0/10) : 10^(+1/10)

x:y:z=0.8:1:1.26 (approx).

x, y and z look like power ratios to calculate SPL.

Looks good mathematics but nowhere near whats happening physically.

This would not explain why .62:1:1.62 is valid.

[rakeshln]

Hi markp,
I have no idea. just a wild calculation.
And yes i am the follower of those ratios but everything should have proper reasoning dont u think so??
everything=LS.

[GM]

>When considering the Golden ratio also consider the lowest frequency being reproduced. If the wavelength of the lowest frequency is 4 times or more that of the longest dimension standing waves are pretty much a non-issue; in this case that would limit you to an F3 of about 110 Hz, which could be problematic.

====

???? If a golden or acoustic ratio is used, then it doesn't matter how large or small it is WRT BW since any eigenmodes in all three dimensions will sum into a diffuse pressure field as far as what the driver(s) 'feel'.

====

>The answer: Put a subdivider inside the box to shorten it internally. If you can't do that for volume reasons then put in a 'shelf' or two that doesn't extend fully across the box interior but does serve to shorten the inside pathway dimension. The additional bracing gained won't hurt either.

====

Hmm, if you use shelf braces large/dense enough to stop eigenmodes from forming then it will become a multiple chambered reflex with a null at each tuning frequency, like a Karlson, which may or may not be a bad tradeoff depending on the speaker's desired BW and at what frequencies each chamber are tuned to.

====

I've seen it used in some HT/music rooms I've read about, but AFAIK haven't actually auditioned one. Since it falls within the acceptable ratios defined by the Bolt, Beranek, and Newman graph, I'm confident it works well enough. Really, whether an HT or music room or speaker cab, a truncated golden or acoustic ratio pyramid is the best compromise and why it's a recording studio's, music hall's, and theater's basic layout.

I've only had the opportunity to do one room this way and IMNSHO all these folks who design/build high $$ HTs using rectangular boxes are really 'missing the boat'.

====

>"....uses the "almost similar" to power calculation ratio of 1 : 1.43 (= 10:7)."

====

You lost me, which 'power calculation ratio'? Anyway, yes, it falls within the acceptable ratios. One of the more popular room ratios is ASHRAE's 1:1.45:2.10 so will also work well in a wide BW speaker cab.

====

>Any material on net which supplies proper reasoning?

====

Do a Google search, there's lot's of info on golden and acceptable room/building ratios from ancient times to present.

====

>x, y and z look like power ratios to calculate SPL.

====

Not surprising since it's not practical to try and attenuate eigenmodes, instead using ratios that gets a 3D wave action to create a diffuse pressure field with no strong peaks/nulls.

GM

[rakeshln]

Thanks GM!!