I'm still in the design phase of my newest creation and I have realized that I will have plenty of room to make this one ported. This is for a 12" W7. First off am I going wrong with JL's recomended enclosure? If not, the port they recomend is 14" x 1.75" x 32.5" inside dimensions (with the extension). If I cut it width-wise from 14" to 7" and made two ports with everything else unchanged, would that be the same thing as the earlier?
Also since this isn't gonna be square box, and won't have 32.5" for the port length, how much can I snake the port around before running into issues. In case that isn't clear, how many turns can I put in the port? I might need just 2 turns.
Thanks
::Edit::
This is a fiberglass box just in case you were wondering.
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Nik
Jeeputer Progress
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Check it out.Look again at that slot length. The total length is 24" (notice that if 24" were the length of the first port lenth before the turn it wouldn't fit into the 15.5 external depth given for the box...)
That might change your way of thinking about your needs for length and turns of the port, but your first question about changing a port to two ports still needs to be addressed. 14" X 1.75" represents an area of opening that is meant to be large enough to prevent port noise. If you divide that into two half-size openings.....hmm
Theoretically it should be okay, because each port (same length) would be dealing with half the air volume. A drawback to doing that is the increase in port structure that you will have to add to the overall enclosure volume because the total sum of port walls will increase. I wouldn't make any changes like this unless I looked at port noise using a modelling program or other port noise calculators. Here is a calculator that you can use to experiment with in seeing what changes are needed if you add a port.
As a substitute remedy, if the height dimension of 14" doesn't fit into your plans, you can reduce it and compensate with a wider slot dimension so that the port opening area remains the same square inches. The length would remain the same and you would still have only one port.
And as far as "going wrong with the JL recommendation"....of all manufacturers I would guess this one to be on the money. They even state that this recommended enclosure was tested in a real-life buildup and wasn't totally reliant on computer simulation.
https://www.jlaudio.com/subwoofers/pdfs/12W7_MAN.pdf
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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
stevdart- "Look again at that slot length. The total length is 24" (notice that if 24" were the length of the first port lenth before the turn it wouldn't fit into the 15.5 external depth given for the box...)"
Woops, glad you pointed that out before I jumped into this thing. I need to pay a little more attention. If I can get the ports right on the computer, I will build an all MDF box first to make sure it won't just be way off before I spend all that time on the FG. If I can't get it right, I'll have to find a way to make the one port work.
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Nik
Jeeputer Progress
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Check it out.