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Discussion Starter #1
I am lacking in wisdom about ports and would like to know more. With a 20"H x 20"W x30"D and a 12 or 15 inch driver.........?

Is it possible or even reasonable to do two slot ports, one above and one below the driver, having total depth 36" for each, and with a 15" driver the height of each would around .75 inches and the width (??? up to the 20" enclosure???)

Just trying to learn and figure it all out.
 

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I personally use the Box-Port Design software. It is freeware (just google it) and will help you decide how large the enclosure should be, and port lengths. If you have an enclosure already it will plot response curves for varying sized ports. It's pretty awesome. You'll need the specs for the speaker though. The only thing is it assumes a round port. So you can use the lengths as is, but will need to convert circular area to rectangular area for a rectangular port.

Kyle
 

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Yeah I you want. Post the following speaker parameters:

# of drivers
Vas
Fs
Pe
Re
Qes
Qts
# of ports
internal volume of the box

... and I'll run it through Box port design and give you measure measurement on the length of the .75" slot and the length required (if other than 36")

Kyle
 

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Oh one more thing. Are you planning on flaring the port (highly recommended) and if so how much? What radius flare? 3/4", 1" etc.

Thanks,

Kyle
 

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Discussion Starter #6
Ports, whether round or slot, is all about keeping the port air speed within acceptable limits. State what sub in what volume and what tuning frequency so the specifics of that combination can be figured out.
With that said, is it okay to make adjustments to the port during modeling? I have learned that doing so always changes tuning frequency. I assume that as long as the response is acceptable to ones self then it would be okay.Just trying to learn and figure it all out.
 

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I have seen construction pics of a slot port here at this site and the internal corners were rounded. Is it necessary to round the inside corners to prevent any 90 degree angle?
 

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I have seen construction pics of a slot port here at this site and the internal corners were rounded. Is it necessary to round the inside corners to prevent any 90 degree angle?
It is not necessary, but is a good step to take as rounded edges will minimize air turbulence at medium/high output.
 

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Thank you! I will definately use some rounding then. I am soooo close being able to start my own sub project, it is exciting!
 

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I have seen construction pics of a slot port here at this site and the internal corners were rounded. Is it necessary to round the inside corners to prevent any 90 degree angle?
Are you saying that the port internal opening had a rounded flare to it? OR that the cross section of the port was a rectangle with rounded corners?

The first question is yes for air turbulence for sure. The second question is more interesting. Would it matter? This sound like the same question as is is a round or square port better? (Or some shade of gray in between)

Kyle
 

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Discussion Starter #12
The second question is more interesting. Would it matter?
OR that the cross section of the port was a rectangle with rounded corners?
Good point. I would also wonder the same thing. Although I truly hope it would not matter. On the other hand maybe this is another reason why some speakers are more money, because of more detail.
 
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