Port size calculation

[89t295k]

Hello, can someone tell me how to calculate port size. I downloaded the software but, it can't answer questions like-

how much do I add for 1 lb of dampning material, does port size include the .75 inch box wall, and how much do I subtract for the driver itself/port?

Anyway, I have a simple 5.806 ft box built for a single 15 inch Dayton Titanic with one pound of dampning installed and 4" pvc for single port.

Thanks

[Chris Roemer]

> Hello, can someone tell me how to calculate
> port size. I downloaded the software but, it
> can't answer questions like-

> how much do I add for 1 lb of dampning
> material, does port size include the .75
> inch box wall, and how much do I subtract
> for the driver itself/port?

In general, you stuff a sealed box with fiberglass or poly (even a sub, since the stuffing can effectively add about 20% to the box's internal volume). Vented boxes usually don't get stuffed (and stuffing a vented box will not make it appear larger to the driver), they get lined with convoluted (egg carton) foam. Many people don't bother to line a true sub at all, since if it's limited to a max of 80 Hz or so, the lining isn't really of much benifit.

If you need a port that's 10" long, that's its total length. If your front baffle is 3/4", then your 10" port will stick IN to your box 9-1/4". On small boxes (like 1 cu. ft. or smaller) that get tuned low, the port can take up a considerable amount of space inside the box. For a 5 cu. ft. box, I wouldn't bother worrying about the space taken up by the driver or vent.

> Anyway, I have a simple 5.806 ft box built
> for a single 15 inch Dayton Titanic with one
> pound of dampning installed and 4" pvc
> for single port.

I can't recommend a single 4" port for a 15" sub. You'll be prone to "chuffing". I'd use TWO 4" ports, each 22" long. ONE 4" port, 10" long, will tune the box properly, but estimates are that the speed of the air in the vent at high output levels will be near 160 mph!

> Thanks

[89t295k]

Thank You so much.

Does the dampning material negitively effect the ports ability to function?