how far from the bottom of the box should my ports be?

[Unregistered]

ok.,.i got two rockford he10s.

running in a dual ported enclosure with a 280 watt mtx blue thunder amp.

ive been doing a little reading in car audio monthly..and in january 2002 had an article on different boxes ...says

"ported boxes suffer from one major drawback, the response of the speaker below the tuning frequency.may also cause serious damages to your speakers."

a) i contacted rockford and they recomend the ports being 13.25 inches in a 15 (bass of box)inche box. however my box has the ports shooting out of the top and in the manual they have it shooting out of the side. the currents length of the ports is ten inches ...leavin about 1.25 inches from the bottom of the port to the bottom of the box....is that enough to get a low bass sound without damaging the speaker...

b) if not should i cut them to a certain length.,....

c) what is a tuning frequency.??

thnx. tj

[IASCA pro 301-6]

one common misconception people have is that they are porting a speaker. You are tuning a volume of air to react a certain way. The port size that is recommended HAS TO BE EXACT for the volume of air it is recommended...any changes will change the tuning frequency...that is bad!

If you have too...leave the additinal port sticking out of the box...it will look funny, but it still works. Port should have 2" of clearance at back...any less and you might hear some turbulence. If this is a trunk mount...you might not hear the turbulence, and that would be fine...

but you will definately hear the tuning frequency change...

Try the recommended port length...leave it stick out a little if necessary and see if that helps...write back and let us know...

[stones]

Clearance should be at least the diameter of the port itself, or so Im told.