posted
I'm about to make my fourth attempt at building a box for my 10L7. What I'd like to know is if a longer port is beneficial.
Here's the two potential box designs, both are 3 cubic feet tuned to 38 hz:
Box 1, Short port:
Box 2, Long port:
So is there any benefit to me making a larger port that wraps almost the whole way around the box, or should I stick with the short one beside the sub?
P.S: sorry if this is the wrong forum, I'm tired.
Posts: 577 | From: wienerpeg canada | Registered: Sep 2002
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posted
A longer port (with larger cross-section area) will give you a reduced port velocity, which is a very good thing. Port velocity is important because when it gets too fast, you get port whistling (distortion), and compression of SPL, both of which are bad. The larger port is a good idea if you have the room. You will get louder, cleaner bass.
Posts: 21 | From: Maine | Registered: Apr 2003
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quote:Originally posted by dkmst23: putting in a large port is a compromise first
volume loss of box by the port Vs. the gain of port area. The larger the port the more volume you will loss from the box.
unless you compensate for the extra space being taken up by a larger port
quote: second
the loss of power handling Vs. gains of spl. The bigger the port the less power the sub will handle the less spl.
no so........if the port is tuned to the same frequency the sub will still handle the same amount of power.....the sub isn't going to move any more with a larger port, than with a smaller port, nor is the port's passband going to be narrowed or widened.....it just doesn't work that way, because the acoustical mass of the port remains constant if tuning is constant......so if you fold a port inside a box, just gotta round out the edges as much as you can to reduce turbulence at the corners, and compensate for the extra volume taken up by the larger port
posted
I presume that the cabinet diagrams you posted are NOT going to be the actual design ? The reason I ask is because your port LOCATION , in relation to the speaker and cabinet in the diagram are not an ideal design. The ideal location for a port is " half the diameter of the woofer away from the cone edge on the same plane (side) of the woofer, and away from cabinet walls "
The port should be tuned to one octave above or below the tuning of the woofer. this will augment the overall output. As for port noise and internal cabinet turbulance, to eliminate or reduce it, you can , as suggested, round off any angles or sharp edges in the cabinet and port. There are flanged ports available from "AeroPort" that address this very issue.
-------------------- E.C. Wuz here Posts: 1057 | From: Vancouver, British Columbia, Canada 'eh | Registered: May 1999
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