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3rd February 2009, 04:41 PM  #1 
diyAudio Member
Join Date: Oct 2004
Location: Raleigh/Atlanta

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 crosssectional 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 
3rd February 2009, 04:47 PM  #2 
diyAudio Member
Join Date: Mar 2005
Location: UK

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.

3rd February 2009, 04:51 PM  #3 
diyAudio Member
Join Date: Oct 2004
Location: Raleigh/Atlanta

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 
3rd February 2009, 05:39 PM  #4 
diyAudio Member

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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3rd February 2009, 05:51 PM  #5 
frugalphile(tm)
diyAudio Moderator

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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3rd February 2009, 06:04 PM  #6 
diyAudio Member
Join Date: Oct 2004
Location: Raleigh/Atlanta

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 
3rd February 2009, 06:07 PM  #7  
diyAudio Member
Join Date: Aug 2002
Location: victoria BC

Quote:
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3rd February 2009, 06:22 PM  #8 
diyAudio Member
Join Date: Oct 2004
Location: Raleigh/Atlanta

chris,
Can you point me in the right direction to find the primes. I don't see them on p10hifi. Josh 
3rd February 2009, 06:30 PM  #9  
diyAudio Member
Join Date: Aug 2002
Location: victoria BC

Quote:
http://homepage.mac.com/tlinespeaker...1v01amap.pdf 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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3rd February 2009, 08:06 PM  #10 
diyAudio Member
Join Date: Oct 2004
Location: Raleigh/Atlanta

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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