Hi
I'm building some PA speakers and i wanted to make the refleks ports triangular so i can place the on the front around the speaker unit.
But i can't find any calculator or formulas to calculate the size of the ports (that provide the same answer...)
Can you guys help me?
Thanks a bunch! 😀
I'm building some PA speakers and i wanted to make the refleks ports triangular so i can place the on the front around the speaker unit.
But i can't find any calculator or formulas to calculate the size of the ports (that provide the same answer...)
Can you guys help me?
Thanks a bunch! 😀
As a first approximation I would probably calculate based on a square/rectangular port of the same area, as a triangle would have turbulence closer to a square than a round port, as they both have sharp corners.
A triangle has half the area of a square port of the same width and height, so I would just enter the width of the triangle base as the rectangle width and half the height of the triangle as the rectangle height.
Bear in mind that calculation of ports is only a rough approximation anyway - even if you use a smooth round tube or a rectangle it will never be exactly what is calculated because there are other variables at play that are only estimated in the calculation, such as proximity of the internal end of the port to other cabinet walls, the size of the baffle the port is located on and how close it is to the edge of the baffle etc. (Most programs assume the port is flush mounted in an infinite baffle)
Always allow room for an extra 30% length beyond that calculated and expect to trim the length down based on measurement...
A triangle has half the area of a square port of the same width and height, so I would just enter the width of the triangle base as the rectangle width and half the height of the triangle as the rectangle height.
Bear in mind that calculation of ports is only a rough approximation anyway - even if you use a smooth round tube or a rectangle it will never be exactly what is calculated because there are other variables at play that are only estimated in the calculation, such as proximity of the internal end of the port to other cabinet walls, the size of the baffle the port is located on and how close it is to the edge of the baffle etc. (Most programs assume the port is flush mounted in an infinite baffle)
Always allow room for an extra 30% length beyond that calculated and expect to trim the length down based on measurement...
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Just a wild guess here but the true value of a triangular port would probably be closer to the diameter of the circular tube that would fit inside the triangle
Hi,
Most sims include the necessary end corrections and rectangular ports.
So simply halving the shortest dimension should work, i.e triangle area
is half base time height, make the base the longest dimension and
plug in a port base x half height into a simulator, should be near.
rgds, sreten.
Most sims include the necessary end corrections and rectangular ports.
So simply halving the shortest dimension should work, i.e triangle area
is half base time height, make the base the longest dimension and
plug in a port base x half height into a simulator, should be near.
rgds, sreten.
I too would guess closer to the round. You'll have to prototype and measure, then report back. I can see the attraction of putting ports in the corners.
Hi,
It depends on the end corrections built into simulators.
You can guarantee the end corrections are wrong for slot ports
formed with a cabinet edge or triangular ports across corners.
rgds, sreten.
It depends on the end corrections built into simulators.
You can guarantee the end corrections are wrong for slot ports
formed with a cabinet edge or triangular ports across corners.
rgds, sreten.
OK point taken, although most of the designs I have seen are of equilateral triangles, as these fit the corners of most boxes more easily
Hi,
They are not equilateral (60 degrees each vertex), they are half squares.
Equilateral does have the least difference between its area and a circle
that fits inside, but the same for half a square is clearly much worse.
rgds, sreten.
for a given cross sectional area, a triangular port will have much more frictional loses than an equivalently sized round, or even square port. Are you dead set on triangular? I hope this is not for a subwoofer type cabinet.
It's for a 2 way cap tuned to around 50hz
Maybe i could move the tweeter horn a little to the side and make room for a slot port or a couple of round ports.
Is the triangular port a really bad idea? Seen it a couple of times before.
Maybe i could move the tweeter horn a little to the side and make room for a slot port or a couple of round ports.
Is the triangular port a really bad idea? Seen it a couple of times before.
I'll leave that up to you to decide, all I'm saying is I would not use one for a subwoofer enclosure.
Many commercial reflex cabinets use triangular ports. They have the advantage of a small front baffle area.
Art Welter has a plan for 2 x lab 12 drivers in a reflex cab with triangular ports.
FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems
Due to the amount of variables involved in any reflex cab, the best way to confirm the port tuning is to build and test the cabinet.
Art Welter has a plan for 2 x lab 12 drivers in a reflex cab with triangular ports.
FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems
Due to the amount of variables involved in any reflex cab, the best way to confirm the port tuning is to build and test the cabinet.
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