Port sourcing?

[jjcarr]

What's the preferred source for port tubes? Since various plans call for an exact length and diameter tube, what solutions have you used? I'm thinking about building a ported design, but not sure where to get a tube of the correct dimensions. (4" x 2 1/16")

 

[xrk971]

I use whatever I can get that is handy. Get close to dia and adjust length as needed by simulation or testing. Parts Express has good assortment and schedule 40 PVC works well too. Rectangular vents that you make work too. Paper roll tubes, mailing tubes for posters, etc

 

[chrisb]

and if you can rip a reasonably accurate 45dg, you can always make triangular port(s) in the corner with a single piece of wood - just do the math to convert area of circle to right angle triangle

 

[Squeak]

Failing the angle cut, just use plenty of clue. ;-P

 

[jjcarr]

I like the idea of the angle cut, I might try that. Would make for an interesting look.

 

[planet10]

and if you can rip a reasonably accurate 45dg, you can always make triangular port(s) in the corner with a single piece of wood - just do the math to convert area of circle to right angle triangle

This document gives the calc needed to change one port diameter to another:

http://frugal-phile.com/boxlib/Changing-Port-Size.pdf

The home depot (or your favorite building supply) plumbing section has PVC ports. Just cut to length.

Wemost often build a slot vent into the box

dave

 

[planet10]

and if you can rip a reasonably accurate 45dg, you can always make triangular port(s) in the corner

dave

 

[jjcarr]

Good info, I think I'm going to try that angle cut port, as it's a pretty simple conversion and I like the look.

 

[sreten]

Hi,

The maths of a corner port are not the same as a bottom slot
and neither are the same as a typical free port on the baffle.

The end corrections applied differ for all three cases,
mainly on the internal end of the port, less the front.

In fact with ports is very difficult to be precise, unless
you measure. Good things like entry and exit flaring
make calculations even more imprecise. If you can't
measure find someone who has and use that info.

e.g. Zaph|Audio - ZA-SR71 for info on a 2" double
flared port in 0.5cuft. You can then extrapolate
for other box volumes for similar length ports.

rgds, sreten.

 

[fastbike1]

PVC tube comes in standard 4" dia and various lengths in the major home improvement stores in the US. Parts Express, Meniscus Audio, and Madisound also have ports of various diameters