Question about port length tube vs slot

[AdelaaR]

I'm in the process of making statements as fronts and they will be accompanied by Jed's Line-Up F4's as surrounds.
My statements will have front ports with black tubes and I would like to match the F4's to them in look by outfitting them with similar tube ports instead of the original slot ports.
If I use a port that is 50mm (2 inches) ... which is quite close to the area of the original ports ... can I just assume the length should remain the same? Or are there more complex things to add to the equation?
If I let go of the slot port ... does that mean I should make the cabinets slightly smaller too to compensate?
Thanks for any suggestions.

[AdelaaR]

Never mind ... I did some research and I think I figured it out =)

[kraniet]

whats important in a port is the area of the opening and the length of the port.
Since most simulationprograms only include circular ports it can be bit confusing when tryiong to do a slot port instead.
but it isnt hard at all. Just calculate the area of the circular port and make sure the slot is the same area. With the same area the length will be the same.
What might be a bit trickier is getting the relation between height and width right. There is a technical paper from JBL on ports that is quite good.

But the general idea is that the port should be as thin as possible without restricting the flow. The port will handle larger airflows without turbulence the thinner it is in relation to its width. Also you could make it thinner in the middle and larger at the ends for even better capacity. The ratio here is around 1,5 times higher at the ends than in the middle.

Also you could read this thread from the swedish forum faktiskt.se. Although you might need to use a translation tool for it. It will explane most of what one will need to know regarding ports in general.

http://www.faktiskt.se/modules.php?name=Forums&file=viewtopic&t=3140&postdays=0&postorder=asc&list=full

edit: should add that very wide ports can get problem with standing waves but then youd have to have a pretty wide port.

As for what a proper height might be I dont have any clear answer. The slots Ive made have had a height of around 1-1,5 cm for a 5 inch and 7 inch driver. Seems to work very well. But its well worth some experimentation I guess.