i need the formula for converting round ports to slot ports and also the formula for calculating port size per frequency.....i need these asap as i lost mjy notebook with all my formulas and relay diagrams.......please help asap....
I kept a file of an answer I wrote to a post awhile back and will just reprint it here, re: converting round to slotted:
pi r^2 to find the area of a circle
pi is 3.14
r is radius, or half the diameter of a circle
^2 is squared, or the number times itself
pi r^2 is 3.14 X the result of radius squared
pi r^2 gives you the square inches of a circle
You want to change the shape of the opening but keep it the same square inches. The length of the port is not a factor and you will leave it exactly the length it already is.
Find the square inches of your circle using pi r^2 (ex. a 6 inch diameter circle yields 28.26 square inches)
Decide on the longest side you want your square or slotted port opening to be
Divide the total square inches of the circle by that long side, in inches (ex. 28.26 / 11.5 = 2.46)
The result is the measurement of the shorter side of the port opening
In the example, the 6" round port equals a slotted port 11.5 X 2.46 inches. Round measurements to the nearest Imperial or metric value. 2.46 would be 2 7/16 to 2 1/2.
You should keep the ratio of length to width of the slotted opening at no greater than 8:1.
For calculating ports, here is the formula per The Subwoofer DIY page:
https://www.diysubwoofers.org/misc/portcal.htm
And here are a couple of online calculators:
https://www.carstereo.com/help2/Articles.cfm?id=31
https://www.mhsoft.nl/spk_calc.asp#top
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