Originally posted by 1100xxben
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Hi Ben, I made several iterations of bass-box models and port length adjustments before zeroing in (check out post number 70 in this thread). I had measured with DATS until the Fb matched BassBox. The port length is modeled as 12.75" long x 4" wide x 0.75" high. The internal width of the whole cabinet is 8 inches, so I made a slot port tunnel from MDF and glued it to the bottom of the cabinet before opening up the baffle's slot entrance with my router and flush trim bits. The baffle thickness itself is 1.25", so the actual port length inside the cabinet is ~11.375". On the front baffle, the slot port has a flush face without roundover. This is likely to transfer to the final design even though I did my CAD work assuming I would add a 3/8" roundover to that edge for a bit of flaring. Inside the cabinet, the slot port terminates with a 1/4" roundover applied to the internal edges of the slot to be a little bit of a flared end. I doubt this little of a flare really translates to the modeling programs well, so I guess you could consider this a single flush end with free other end?
You make an interesting point that I hadn't considered regarding the port effective length. The recent test sweeps I had been doing were on the carpeted floor with the cabinet laid on it's side. I'll take another sweep here in a bit with the cabinet back up on the testing stand. That should remove any possibility of external influence.
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