I'm looking to build a sealed enclosure for a 5.5" fullrange with the approximative golden ratio inner dimensions of 11" x 17" x 29".
29" will obviously be the height. Is there a consensus as to which other dimension, depth or width, sould be the second largest?
WinISD gives me width as 17". OTOH, I have often seen depth as the second largest. I can see how baffle step might be affected by this choice. Anything else to think about? Thanks!
29" will obviously be the height. Is there a consensus as to which other dimension, depth or width, sould be the second largest?
WinISD gives me width as 17". OTOH, I have often seen depth as the second largest. I can see how baffle step might be affected by this choice. Anything else to think about? Thanks!
The Golden Ratio tends to be a 1.6 to 1 ratio so that standing waves given off by the driver are diminished as much as possible. With this in mind, the 17" dimension is the width and the 11" is the depth.
Here is a web site calculator that may help you out: http://www.carstereo.com/help/Articles.cfm?id=5
Here is a web site calculator that may help you out: http://www.carstereo.com/help/Articles.cfm?id=5
Once you have the GR, which side you put the driver on is determined by aesthetic, baffle loss/diffraction, room placement, and whether you are putting a number of drivers on it...
aesthetics is wholly up to you. A classic GR would have you putting the driver on the wide side.
baffle loss/diffraction: the wider baffle (nominal 250 Hz, assuming 19mm walls) will give a lower baffle step, and push the baffle step ripple to lower frequencies and push BS down closer to where you can use wall proximity to cancel BS, the narrow baffle (365 Hz) will have a shorter time till edge diffraction and the box will tend to dissappear more easily. For minimum edge diffraction you'd want to put the driver on the nominal bottom of the box.
BTW: those internal dimensions aren't really that close to golden ratio at 1.7:1:1.65. For a box your desired volume 11x17x29 = 5423 in^3 = 88867 cm^3. Take the cube root = 44.625, you need a box of 72.2 cm x 44.6 cm 27.6 cm (28.42" x 17.57" x 10.86"). i would round off to the nearest 1/8" if working in imperial units.
dave
aesthetics is wholly up to you. A classic GR would have you putting the driver on the wide side.
baffle loss/diffraction: the wider baffle (nominal 250 Hz, assuming 19mm walls) will give a lower baffle step, and push the baffle step ripple to lower frequencies and push BS down closer to where you can use wall proximity to cancel BS, the narrow baffle (365 Hz) will have a shorter time till edge diffraction and the box will tend to dissappear more easily. For minimum edge diffraction you'd want to put the driver on the nominal bottom of the box.
BTW: those internal dimensions aren't really that close to golden ratio at 1.7:1:1.65. For a box your desired volume 11x17x29 = 5423 in^3 = 88867 cm^3. Take the cube root = 44.625, you need a box of 72.2 cm x 44.6 cm 27.6 cm (28.42" x 17.57" x 10.86"). i would round off to the nearest 1/8" if working in imperial units.
dave
greenmark59 said:
Oh, is that how it works?
phi=1.61803398874989484820458683436564......
interestingly:
phi^2 = phi +1
1/phi = phi - 1
..and here's some more....
http://www.mcs.surrey.ac.uk/Personal/R.Knott/Fibonacci/fibFormulae.html
Actually, it does not matter what face you put the drivers on. In fact, these ratios don't do much except give overly type "a" people something to fret about. As long as you avoid (and in most cases even if you don't avoid) duplicate dimensions or dimensions that share a common factor, damping material will take care of the rest.
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