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Discussion Starter #1
I would like to build a new box for my subs. The current box is a standard rectangular and has one chamber for each sub (2 subs). Each chamber is tuned to about 30hz.

The new box will be a single chamber and one port. I would like the box to have a sloped back to match the angle of the rear seats (middle row) of my Tahoe when they are reclined. This is where I am running into an 'issue' with the design. If I do one slot port at one side of the box, the top of the port will have to bend about three inches before the bottom of the port. Should the end of the port (inside the box) be cut at an angle so as to maintain proper port length at the top and bottom or some other method?
 

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Listener of Music
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Measure down the center of the port through turns to maintain length, always maintain width/height, and keep at least the width of the port distance away from the wall for the port end inside the box. If you are to close to the wall it will act like an extension of the port and ruin your projected tuning.

The port end/plain, in most circumstances, is 90° in relation to the port wall. I like to taper my ends but I add a quarter inch of length to compensate.
 

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Discussion Starter #3
Because of the size of the current box, there are two 180 degree bends in the port to get the proper port length and the end of the port is almost twice the width of the port, so there was no chance of it extending the port. The new design will only have a single 90 degree bend at the back and run to almost the halfway point of the enclosure. It also runs the full height of the face. I had briefly thought about just turning the port completely where the top has to bend, but this would leave a shallow cavity between the port and the back wall. While that cavity would technically count toward the internal volume of the box, I have a strange feeling the speaker would almost treat it as a closed up area as air wouldn't move too much there. But that's just a layman's perspective.

If I cut the end of the port at an angle, then the top, bottom and center of the port would all measure the full 34". I am just concerned that having a port end like that would cause problems, especially near the bottom where there would be a narrow space for the air to move...

But as I type this out, I think it just sunk in what you were saying. By measuring the length of the port at the center and making a straight cut, the top of the port would be shorter and the bottom would be longer, but the overall volume of the port would remain the same.
 

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Listener of Music
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I wasn't saying that but your right if the angle stayed the same.

You can't just change port size from end to end without messing up tuning and port speed.
 

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Discussion Starter #5
Well, I am rethinking the port now as I realized a basic geometry fact. The back wall will be taller than than the original port dimensions. Instead of 5x14 it would be 5x 15.something. Trying to correct that difference would take some convoluted woodworking. I'll find a new spot for the port.
 
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