Golden, or acoustic, ratios do not eliminate, or even attenuate, standing waves. What they do is keep them from summing to a higher magnitude, spreading them apart enough that they average out into a ~uniform, diffuse particle density field.
Once you begin increasing the aspect ratio it all falls apart in the longest dimension and shifts towards a 1/4WL (vented) or 1/2WL (sealed) resonator. Standard box programs don't show the effect this has on the driver/vent location and vent length. AFAIK, only MJK's excellent Mathcad worksheets do this so I highly recommend getting familiar with them if you plan to design/build high aspect ratio cabs.
WRT the other two dimensions that make up the cross sectional area (CSA) of the pipe (SO and SL values in the worksheets), I prefer to use a golden or acoustic ratio just in case it makes a subtle sonic difference since I use construction materials/bracing that yields relatively light, yet extremely rigid cabs, though MJK is of the opinion that the requisite stuffing damps the system enough for this to be a moot point, while some other pipe designers mass load the cabs so much it is a moot point.
GM
Once you begin increasing the aspect ratio it all falls apart in the longest dimension and shifts towards a 1/4WL (vented) or 1/2WL (sealed) resonator. Standard box programs don't show the effect this has on the driver/vent location and vent length. AFAIK, only MJK's excellent Mathcad worksheets do this so I highly recommend getting familiar with them if you plan to design/build high aspect ratio cabs.
WRT the other two dimensions that make up the cross sectional area (CSA) of the pipe (SO and SL values in the worksheets), I prefer to use a golden or acoustic ratio just in case it makes a subtle sonic difference since I use construction materials/bracing that yields relatively light, yet extremely rigid cabs, though MJK is of the opinion that the requisite stuffing damps the system enough for this to be a moot point, while some other pipe designers mass load the cabs so much it is a moot point.
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. 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.
Re: Its teasing me.
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 said: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^: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.
Still 
my head.
I dont know how right i am
10log(x)=-1 .... x=0.794
10log=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.
my head.I dont know how right i am
10log(x)=-1 .... x=0.794
10log
=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 said:Still
I dont know how right i am
10log(x)=-1 .... x=0.794
10log
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.
>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
====
???? 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
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