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Old 3rd February 2009, 04:41 PM   #1
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Default Golden Ratio Height

I'm interested in hearing why we don't use the golden ratio to determine the height of the cabinet. I've been building all of my cabinets with golden ratio cross-sectional areas but never a golden ratio height. Why is this?

I bought some FR6.5C for cheap and am going to be building some small cabinets for them on stands (look similar to the recommended FE167 design, except sealed). Since I'm building the stands for them the actual hight of the cabinet doesn't really matter much.

Thanks,

Josh
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Old 3rd February 2009, 04:47 PM   #2
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There are undoubtedly several reasons; however, if you want a couple, 1) it's not appropriate for all cabinet types, and 2), it might mean in some cases a larger footprint than is desired. And so on.
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Old 3rd February 2009, 04:51 PM   #3
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This is a sealed enclosure. I figure that since sound radiates in all directions from the back of the driver that the golden ratio would be helpful in terms of the hight of the cabinet.

On the other hand, if the Z is based on the golden ratio for a cabinet with a desired cabinet height, that would be more important than the actual hight be based on the golden ratio.

Josh
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Old 3rd February 2009, 05:39 PM   #4
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You don't need to use the Golden Ratio. Any irrational number can be used to build a box with incommensurate dimensions (i.e. don't share a common divider which might help set up standing waves). So you can use SQRT(2), SQRT(3) etc.

In reality, if you get the chance to make the inside surfaces of the box irregular (.e.g. glue some 'knobly bits' of wood) about, then sound waves don't really see the box as having a simple size and you can be a bit more relaxed the requirements of exact ratio's quite a bit.

My advice - let the box size be dictated by other factor such as Driver cut out size, aesthetic appearance, balance (i.e. not 'tippy'), port length (for BR).
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Old 3rd February 2009, 05:51 PM   #5
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I suspect that one of the major reasons for not making a box a rectangular golden prism is that the resulting shape is "inconvienient" in some respect. or some other more important constraint precludes it.

For instance in the FonkenPrime, one of the constraints was a minimum width baffle. That fixed one of the dimensions. One of the others was determined using the golden ratio. The last one falls out because of the required volume.

The Classic Golden Ratio Fonken shows what happens when the Goldn Ratio (internal) becomes the highest priority.

dave
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Old 3rd February 2009, 06:04 PM   #6
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Bigun,
I'm actually planning on doing that as well.

Dave,
As you may remember from helping me with the BiTonkens I have been using the golden ratio to find the cross sectional area for years, but I've never used to find the height.

Well I think I'll try it out for this project. I'm not going to mind the odd shape, even though it may look a little... fat.


Josh
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Old 3rd February 2009, 06:07 PM   #7
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Quote:
Originally posted by planet10
I suspect that one of the major reasons for not making a box a rectangular golden prism is that the resulting shape is "inconvienient" in some respect. or some other more important constraint precludes it.

For instance in the FonkenPrime, one of the constraints was a minimum width baffle. That fixed one of the dimensions. One of the others was determined using the golden ratio. The last one falls out because of the required volume.

The Classic Golden Ratio Fonken shows what happens when the Goldn Ratio (internal) becomes the highest priority.

dave
What I think he means by the last sentence is that the sonics of the GR were a bit underwhelming compared to the Prime - most notably in the in the imaging and smoothness of roll off at the bottom end (midbass on down) . We can speculate for the reasons, but the Prime enclosure seems to disappear more.
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Old 3rd February 2009, 06:22 PM   #8
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chris,

Can you point me in the right direction to find the primes. I don't see them on p10hifi.

Josh
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Old 3rd February 2009, 06:30 PM   #9
chrisb is online now chrisb  Canada
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Quote:
Originally posted by edjosh23
chris,

Can you point me in the right direction to find the primes. I don't see them on p10hifi.

Josh

http://homepage.mac.com/tlinespeaker...-1v01a-map.pdf

Click the image to open in full size.


Note the bottom right enclosure is with CSS FR125 (pre EnABL) - only minor differences in port slot dimensions required. Very different presentation.
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Old 3rd February 2009, 08:06 PM   #10
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I didn't know those were called FonkenPrime.

Do you guys not attribute that to the ports?

The GRs have the wider baffle and drivers off centered. I would think that with the golden ratio cross sectional area and what i just stated would help the GRs to be the better contender.

Josh
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