box port locations

here's a tricky one.

once you calculate the port length, does the entire length have to be inside the box. could you for example have half the length inside and half outside extended from the box surface.

No. The entire length does not have to be in the box. It's a unique look, for sure, but you can have the entire port outside of the box, as long it is to whatever spec is needed.

Having the opening the right size is important. If it's too small, you will have problems with air flow, thus creating resistance in the passage of air which leads to wind noise and improper performance of the port.

Again, the vent should always be on the same plane as the woofer (face of the box) whenver possilbe. If not possible, then your second choice is the side. A realistic application in which it's not possible is a box for a single cab truck for one speaker. The box is too narrow to have the vent on the face so there you would have to put it on the side or even firing up towards the roof (I've done both and to the side sounds and looks better--plus up to the roof becomes tempting for children if the person you are building it for has kids: they like to put things in the port!).

Another tricky box that may not be feasible for having the vent on the face of the box is the traditional slant face box that you see in many hatchbacks. I think the design of the box should emphasize that if you just sit and think about what the box looks like and just how the port would be. It's very doable but awkward to build.

Someone pointed you right too about rounding off the edges (even though I had made that point earlier--thanks for re-itterating it though!). That is an important factor!

Also note that a port does not have to be straight. In other words, if you build enough of these, you will come to a situation that needs the vent to be L shaped. This is perfectly okay to do, just rememeber to measure correctly. I would recommend doing as I always do and draw a side view of the box to scale and actually draw the vent in the box. This takes some time to do but it is well worth the effort b/c it makes sure you have your bearing before you tackle the job. When doing an L shaped vent, keep in mind that air has to flow through that and you want to keep the edges as rounded as possible. You may find yourself manufactor some smaller equilateral-shaped triangle pieces (pull out your high school geometry book if you dont know what shape that is hehehe) to put in the inside corner of the "L" to allow a smoother flow of air. Bondo works good too. With ports, this is possible as well and not as time consuming either. PVC 90degree elbows and such can be used to make the port.

Okay I think this covers everything about the basics of building vented/ported boxes (unless someone posts something else).