Prof, and other 02 guys - here's a little report from fun in the trenches. I picked up a single SCS4 this week, and have some PowerPoints and 02s in the hotrod garage. I set up a 4-way comparison with those models plus a CS2.2 for reference. I both listened and measured. What I learned is that not only was the 02 a very good little speaker, but that it holds its own very well against the others. Since I have 4 02s, I'm upgrading a pair for giggles and grins and learning.
The SCS4 is the 4th generation of the coincident driver, but is actually the 5th generation of the 6.5" 2-way. The crossovers are the same topology - 2nd order / positive polarity with the (high-pass / low-pass) crosspoints separated to eliminate the classic 3dB hump rather than inverting polarity as B&W, Wilson, et al do. The frequency and phase response measurements are very good, as good as the SCS4. The motivation for the coincident driver was because anybody could place a bookshelf speaker in any position or orientation. But on the proper axis the 02 is as coherent as the SCS. BTW, that topology is also employed in the passive coincident drivers in the 2.4, etc.