Well, my Mate Jim designed it using a software program for bass cab design using the speaker's Thiele-Small parameters, though I drove it a bit by asking for dimensions in an 8:10:12 ratio to best avoid internal standing waves that were very close to each other. The two ports were off-the-shelf plastic ports.
The speaker itself has a good bass frequency response. You can see that the response from 90Hz down to about 30Hz is pretty flat, if 10dB down from it's 1kHz value, though about 8dB from the average value of the mids, so the bass boost from the port gives quite a loud bass-end.
A lot of other 10" speakers, especially the Eminence ones, fall right off from about 100Hz.
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