There was further interesting information in the Stereophile review about the new clamps:
Originally Posted by Stereophile
A new clamping system for drivers results in an even better behaved cabinet. Meridian claims that the only resonance you can detect is at 5Hz. This is below the threshold of human hearing, and also well below the level of those pesky port resonances that excite many a room's bass nodes.
This attests to the thoroughness of Meridian's revision of the standard models to produce the new SEs. This has clearly been the result of very detailed and careful examination of the performance of the standard models. But the information quoted above suggests that it is even more of a shame that the new clamp rings are not available as a part of the upgrade packages.

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