DIY Subkick Questions

[Natman]

I'm planning to make a sub kick for recording purposes. A ton of people seem to be making them with solid results. Even the worst examples I've seen online are an improvement over the usual dynamic mic alone, but I have a few little questions before I start. I have read up quite a bit but don't feel these have been covered...

1) I have a few speakers I could use, but I'm on the fence as to which will work best. Conventional speaker wisdom tells me that the effect of the sub kick will probably center around the speaker's resonant frequency. If that's the case, an actual subwoofer designed for bass should work better than a guitar speaker for example. Yet I don't see anyone using a dedicated bass speaker. Why is that? Is Xmax (excursion) helpful for getting lower tones?

2) I am concerned about phantom power. I have condenser mics running into my interface which puts the 48V on all channels at once. It doesn't affect normal dynamic mics, but what effect would this have on the DIY sub kick made from a speaker?

3) The speakers I have on hand are:

a) a 10" out of a cheap Electar guitar amp,
b) a 10" concave (convex? -the opposite curve of most speaker cones)speaker out of a Fender Rumble 350, cheapish construction but presumably made for bass? could be full range, the magnet is big
c) a 12" actual subwoofer with foam surround, poly cone (also concave/convex?) that goes real low.

Which would you chose and why?
(I realize everyone is talking about 6-8" speakers because that's what Yamaha used but there is not much logic in that argument.)

4) Why does the cable need to be XLR if most interfaces can accommodate 1/4" plug?

Thanks!

[GoyaDrumr!]

I made one using an old guitar amp with a 10 inch speaker, I reversed the wires soldered to mic input and it worked well. I don't know anyone that has made one using a bass speaker. I used both my drum mic and the diy subkick for recording & the engineer said he could have added effects to get that tone. Live, however is probably where it will come in handy. There is also a way to use a regular guitar amp and a DI box and use it as an subkick. Good luck! tons of info on the youtube.