I'll check with Eminence on Monday, but I don't see how it would be possible to expect flux to be the same when voice coil energy is constructive as it is when destructive without a magnetic compensation circuit, i.e. flux stabilization ring. So I don't think flux is as symmetrical in the earlier models as it is in the Magnum series.I am hoping they incorporate a stabilization ring in the motors of the rest of their line. Their other models are great parts, but I don't think the harmonic distortion level is down as low as designs having motors that use flux stabilization. The earlier models sound very good, but they don't sound like they have the low distortion afforded by the improved motor design.