Prototype of two-way system utilizing HiVi RT2C and 6 shielded 12 ohm 4 inch drivers (PE 299-460, series-parallel for 8 ohm nominal load).  Crossover is 3rd order at 2000 Hz for high pass and 2300 Hz for low pass.  Despite cardboard box (30% fiberglass fill) and strange midwoofer orientation and mistuned port (should be less than 1/2 the current length) the speaker sounds incredible. The near field sound is obviously subject to considerable interference patterns, but from about 10 feet out the sound is spacious, brisk, and powerful (about 96 dB per watt at 1 meter).  No L-pad is needed.  These drivers match up very well.  The final box will be wood of course, twice the current volume, properly tuned, and with the midwoofers arranged strictly vertically, probably 4 below and 2 above tweeter.  Naturally, the baffle will be narrow, about 8 inches.  To achieve necessary volume; I'm thinking a floorstander will do.  Final cost will be approximately $250 per pair (the drivers were or are on sale).
HiVi RT2C and midwoofer array project