really dumb question about ports

[havoc06]

i know this is a dumb question, but oh well........i wasnt aware that a slot port and a square port were different...can anyone explain this to me and are the A/D of both

[LoneRanger]

Originally posted by havoc06
i know this is a dumb question, but oh well........i wasnt aware that a slot port and a square port were different...can anyone explain this to me and are the A/D of both

They're different? That's news to me!

A port is a port is a port. It doesn't matter if it's round, square, rectangular.....whatever. It serves a basic purpose which is to let air move freely out of the enclosure.

A lot of people use round ports because you don't have to construct them. You simply go down to the store and get some PVC of a suitable length diameter and cut a hole in the box for it. Square/Rectangle ports are commonly used in SPL applications because they have more surface area. I personally use slot ports on all but two of my box designs, and the only reason I don't use them on those two is because they require small ports and the round ones are more cosmetically appealing than a tiny little slot port.....and on my RE SE box (The SPL-inator), the round port somehow reduces port noise (don't ask me why. I'm still trying to figure this out myself).

[havoc06]

well i didnt think there was a difference..but on one of the threads posted here, there was this port freq calculator...and it asked it it was a slot port or square or round...when i was just playing with some numbers, i typed in what i wanted the port length to be to tune to 35htz with 50sq opening...with a "square" port, it was 17 inches long, which is what i expected, but when i clicked slot, it shortened it to 12.....it even had a little link on there to explain the difference but it was broken..just a little confused thats all

[Mercureie]

end correction. don't fully understand it but it deals with the friction of the air in the slot port that makes it seam to extend out of the actual port, making the effective port length longer then the boards used to make it. someone help me out on the specifics.

[delvryboy]

end correction. don't fully understand it but it deals with the friction of the air in the slot port that makes it seam to extend out of the actual port, making the effective port length longer then the boards used to make it. someone help me out on the specifics.

end correction= effective length(the length the air will see) of a port...only used when 1 'wall' of the enclosure as a port wall...this is calculated by subtracting 1/2 the port width from your overall port length...(example- your box plans call for a port that is 3"Wx8"Hx20"L...you are using one wall of the enclosure for your outer port wall....in this case the actual length you make the port is 18.5"L)...slot ports allow for large amopunts of port area as mentioned above...port size and shapes are endless since you are not stuck within the boundries of premade pipes....one thing that i like about round ports are the fact that their displacement is much less than a slot port...sometimes a must when trying to squeeze a large enclosure in a small spot

[havoc06]

ok, you totally just confused the hell out of me...so when using walls of the box as walls of the port...you mess with the actual calculation? Becuase i usualy put ports in the upper corner of a box so i only have to make two other walls...maybe this is why all my boxes are sounding like ***...

[jbl_marshall21]

ok, you totally just confused the hell out of me...so when using walls of the box as walls of the port...you mess with the actual calculation? Becuase i usualy put ports in the upper corner of a box so i only have to make two other walls...maybe this is why all my boxes are sounding like ***...

maybe