If you wanted to use a driver like a 4590 or 4592 in a pi system it would then become a three way system. This would be a variation of Wayne's Audiophile design that is a 3 way system using a 10" for the midrange.

You wouldn't necessarily be wasting the bandwidth of the 4590 or 4592, because this driver is capable of taking the place of the 10" cone driver.

BMS recommends a lowest crossover point for these drivers to be 400hz. I have made test and measurements with FFT Spectrum Analyzer and The driver does have very good response to 400 rolling out down to 300. If horn you use will load down to 250 or 300 I would say crossing these drivers at 400 is no problem at all. The BMS recommended crossing point for the mid to hi is 6300hz and there should be no deviation from this. 6.3-6.5khz is the best spot.

Aside from all this I have some personal opinions that are purely subjective and just what I like. Generally speaking I like crossing into a 2" format driver around 750hz and a 1" driver at 1600hz. This is largely depending on the woofer. If you look at woofers like a JBL 2226 or kilomax they run up to 1600 with out problems. crossing them over at 600-800 is a great spot. For me this puts less strain on the compression driver where it's working the hardest. Pushing the compression drivers down to the cut off point is is fine and they are design to do so with steep enough crossover slopes. I find they sound nicer when not pushed quite so low.

The 4592 IS by far more sonically superior to the 4590. The 4590 sounds fine but 4592 is very very sweet sounding. For that matter I also find that all 3 neodymium models outperform the ceramic magnet counterparts.

My favorite driver is the little 4540. This has to be crossed at 1600hz or higher. The recommendation is a little higher but there has been no problem with home stereo use. the 4552 will cross lower is you need but I feel the the small one sounds better.

That's all the info and opinions I can offer about the BMS parts. Take it for what it's worth. Free information and I sell them.

Bill