Will a bigger port area increase SPL???


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i have a brahma in a 4 cu ft enclosure tuned to 47hz (spl enclosure). the port i have for it is a 6in pvc port. i ran the box specs in WinISD and it said that w/ my JBL 1200.1 on the brahma, my air speed at the port was like 180ft/sec.

i have heard that if your air speed is low you can get better SPL. is this true?

If so i am going to rebuild the box so that the port is 12" x 6" and tune the box to 47hz. will this bigger port opening help???
i am thinking about

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 4988
Registered: Dec-03
you could go to a slot vented design instead of a round 6" ID port.
I don't think it'll really help your SPL, and the box may not sound as "present" at very low volumes, but what it will do, is reduce any port noise, since more air is allowed to flow and flow more easily.
Using too small of a port will cause port whistle which is really nasty sounding.

generally, these are minimum port diameters for sub sizes:
10" or smaller sub, 3" ports
12" sub, 4" ports
15" or larger sub, 6" ports
that's what I tend to use anyway
if the sub is an 18", I'll use two or three 6" ports, or just go slot vented.
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