Magnepan 1.6 active 24db slop better than stock?

The woofer and tweeter crossover slopes are different (as you mention) but the break frequencies are also different. If you use a L/R crossover the break frequencies will be the same. Who knows how the speakers will sound.

The electrical crossover is 1600 (maybe 1500).

The accoustical crossover is where the woofer and tweeter SPLs are equal. If you have a spectrum analyser, connect the tweeter with inverted polarity and look for a deep notch in the frequency response.

The inverted polarity of the tweeter is correct for the stock tweeter crossover (12 dB). For a L/R 24 dB crossover normal polarity is correct. (Otherwise you get that deep notch).

Magfan... Yeah. I got ir backwards. It is the woofer that is 12 dB slope, and the tweeter 6 dB.

As to the crossover frequency, 1600 is what you get from calculations using the values of components in the crossover. The accoustic crossover includes mechanical characteristics of the drivers. No doubt that the accoustic frequency is what matters when listening to the stock speaker, but for designing a new crossover the electrical crossover is important.

By the way, I am a bit leary of driving any tweeter directly from a power amp. Power amps are apt to output nasty thumps.

Magfan... I redid my crossovers using an aircore inductor with lower DCR (don't remember the value). However, if it slightly boosts the woofer output this means that there is less need for a tweeter pading resistor. Overall results are good. The speaker measures flat, but by the time that room equalization is done flat response is not needed.

Mag... I used Hovland. For best bang for the buck, and ease of work, I would recommend leave the Solens alone and put the $$ into a good inductor.