I need some help with crossovers!

I am working on building a quadraphonic speaker system involving 4 10" Pioneer poly cone woofers and 4 Motorola horn tweeters. I'd like a crossover right in the middle of the two ranges (26Hz-2.5Khz and 1.8KHz-30KHz, so 2.15KHz would probably be ideal). But as soon as I got the calculator out, I hit problems. The major problem is that the tweeters are rated at "high impedance at low frequencies" and the woofer is 6 ohm. I have no idea what sort of crossover network I need to use!

If you are talking about the Motorolla Piezo Model KSN1025s you will end up with the kind of sound that you are describing. These tweeters are pretty good, as compared with the rest of the Motorolla Piezo clones and certainly better than all of the other cheaper far-east brands.

Use the normal kind of crossover for the woofers, second or fourth order or whatever else you prefer. Use a metallised plastic film capacitor of 4.7uF 250V or higher for the tweeter. If you find that the SPL of the tweeter is more then that of the woofer, you may use suitable low value, high wattage resistors to equalise the sound. Since these tweeters present a high impedance to low frequencies, higher order crossovers are not required; you may change the value of the capacitor within limits.

Crossing over the woofer also at 6db per octave is a good choice. Following my suggestions may not be theoretically precise but you will be more than surprised with the results. I have used such configurations in the past with great success.

In fact, I use an active crossover network crossed over at about 2KHz for the highs, (and 400 Hz for Low/Mid) for outdoor performances, and the results obtained with the above mentioned tweeter model have been more than just satisfying. Check out the passive filter first since it is not expensive before widening your choices.