Transmission line for 8' subwoofer.

After about 36 hours of playing with hornresp a calculator and some rough sketches I settled on my plan. This is for a Dayton Audio rss210hf 8". I had trouble getting the fold right and not having the driver located in a bend. Somewhere I saw a picture of the Bose sub, where the tube wraps around the closed end, and I copied it. It is very much a snail shell. About 4 hours of sawing, glueing and nailing it altogether I had one super heavy box. I'm working on the second coat of paint right now. I'm likely too impatient to wait for the driver to arrive and use something I have laying around in the meantime. Sorry for the rotation in the photos.
 

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S1 was determined from the driver depth plus a bit and the drivers cut out plus a bit. Here are some screen shots from Hornresp.
 

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Here are some screen shots from Hornresp.

You have set the path length to zero. Strictly speaking, it should be the distance from the centre of the driver to the centre of the port, as shown by the red line in the attachment. If you make the change I think you will find that the amplitudes of the ripples at the higher frequencies are reduced.
 

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