Take a casual look at the Mk.II edition of MBL's Reference 101E Radialstrahler loudspeaker, and you won't immediately see what's new compared with the original version, which I reviewed in October 2004. But the Mk.II has a shorter, sleeker bass cabinet, designed to, among other things, slightly lower the stack of omnidirectional drivers it supports. While the many other major revisions to this familiar and fascinating loudspeaker can't be seen, it's fair to say that, from the ground up, the Reference 101E Mk.II is a new loudspeaker in design, if not in concept.

There is always a conflict between the needs of reviewers and the realities of the marketplace. Once a reviewer has invested his time and energy in a review, he would like that product to remain in production for all time, which would allow it to be used as a reliable recommendation forever. But whatever the product and whatever the category, sales of a product almost always follow the same triangular curve: a sharp rise at the product's introduction, a maximum reached sometime thereafter, and then a steady decline to a sustained but low plateau. Marketing-minded manufacturers therefore introduce a new model every three or four years, in hopes of turning that single triangle into a continuous sawtooth wave.