vent air speed.

[garfa]

hi all,
just wanting to know if there is a lower limit to the speed of the air coming from a port?
i know to keep it under about 30 m/s but when does the woofer tend to bottom out from no back pressure?


thnx

[Luke0011]

Below the frequency of the tuned port specification the woofer is guided only by its mechanical abilities. Below this frequency the sub can bottom out. Cheers Garth long time no see!!!!

[garfa]

hey man, where have you been? holidays for a few months?

didn't quiet understand you, could you expand a bit?

[wh33lzz]

The tuning frequency of a ported subbox is as low as you want the sub to play at 0Db you want roll off (-3 or 6Db or more if possible, using a subsonc filter can help here) under this as the sub will mechanically bottom out due to lack of acoustical suspension (air pressure behind the subs cone) under the port tuning frequency.

Bottom line is you will hear port chuffing stop, and your woofer may die if over excurted below this point.

[garfa]

ok, so pretty much i can make the port/s as big as i want.
wont it eventually be just like having the woofer in a free air set up?
so i could chuck in a few 4 inch ports with my 12 inch woofer and not be too worried as long as i have my filters set up correctly as always.