Cab designing, Xmax + port velocity wrt harmonics

[agedhorse]

Or simply avoid the conditions that make this a problem in the first place. Why focus so hard on a "solution" when it can easily be made a "non-problem"?

 

[DukeLeJeune]

Or simply avoid the conditions that make this a problem in the first place. Why focus so hard on a "solution" when it can easily be made a "non-problem"?

Sometimes the combination of box dimensions and driver displacement capability and theoretically required port diminsions calls for finding a solution.

If there are a lot of demands made of the port system, then flared ports can provide an extra margin before the onset of chuffing. For example, I like to do fairly compact cabs with adjustable tuning via multiple pluggable ports. But this means the cab will probably at some point be used with most of its ports plugged, resulting in higher airspeed through the remaining port(s). So that is the condition I have to design for, rather than the easy-peasy "all ports open" case, and if the margins are tight, then ime flared ports are definitely helpful.

Also, I tend to deliberately place ports right smack behind my woofer cones, with the intent of allowing midrange energy off the back of the cone to exit the ports. In my experience, that midrange energy sounds better through a flared port than through one with sharp edges. I believe it has to do with minimizing diffraction.

 

[beans-on-toast]

One way to do a "poor man's inner flare" is to cut the inner end of the port on a 45-degree angle, which makes the inner opening an ellipse of increased cross-sectional area. This increased cross-sectional area facilitates intake fluid flow. Credit to Earl Geddes for the idea. Measure the port length down the centerline, rather than along the long side.

A poor man may not have a 3D printer, but it can be used to create some nifty port end attachments or even entire ports. Printers are coming way down in price.

 

[bodgiebass]

Thanks to all, lots of great info.
Extra thanks to Agedhorse for the comprehensive clarification on the matter, and Fdeck for providing a perfect graphical answer to the two very questions I had! Invalid Link Removed is very useful.