These are my doubts. And still I have not decided what enclosure I'm going to build.
And, just for the records, this is the first time for me with a Horn system.... (well I've built a Lowther folded horn once)

Thank you all in advance.
Best regards,
Enrico.

P.S. In case the seven PI (15") should be a suitable design, is there any place on the web I could get the plans?

The trouble is that all the plans are drawn for current production devices, specifically, those made by Eminence and JBL. As such, the cabinet would not be optimal for your woofer. I would recommend that you enter the woofer's parameters into PiAlign and let it calculate cabinet dimensions for you. If memory serves, the Theater Series seven π and Professional Series seven π-18 speakers are closest to what you'll want in size, and the crossover used in the Professional Series seven π-18 model is the one you'll want.

I'd be happy to send the plans for either of these speakers to use as a starting point, but I think it would be best to do a little studying first. Download the PiAlign program and read the "readme.txt" file contained in the distribution archive. It is only a couple of pages long, so it won't take long to read and will familiarize you with how to run the program and what parameters are required. You'll use familiar T/S specs, with one exception, Qd = 1/Qts. Other parameters Vas = Vad and Vas = Vad, but all this is described in the "readme.txt" file, so I simply encourage you to read it and run the program. If you have any trouble, feel free to ask.

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