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Why does port length increase when two ports replace one?

14442 Views 14 Replies 8 Participants Last post by  talunceford
As per title,

Just wondering why two ports are required to be longer than a single port?

For instance if I tune a cab with a single 10" port, but the port velocity is too high and I add another port, these ports are then required to be 22.5" long each?
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I wouldn't ever sacrifice tuning frequency for a shorter port, unless onyl absolutely necessary. Another hugely important note is that the cross-sectional area of the port will allow enough airflow for the sub(s) of the given design. I think air velocity should not exceed 30 m/s. Anybody correct me if I'm wrong here...
You are correct there. I typically try and use 15-16 sq in of port area per cubic ft of air space. It keeps the air velocity down to a min.
Yeah, I used 3 3" ports on my 18hz tuned enclosure. It worked out perfectly. BUT my enclosure started out as a 7 cu. ft. enclosure. By the time you take into account for port, sub and various other displacements, it worked out to where the usable volume was 5 cu. ft.

I use bass box pro 6 to model my projects. Not sure if that makes a difference or not, but it might.
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