[cma29]

Originally Posted by drchaos

This is consistent with something I saw about the 3.7i change (I can't find the source, sorry), that it involved changing the tensioning in the bass/mid panel during manufacturing.

The tensioning is pretty important and a big Magnepan trade secret---the tension isn't even uniform around the sides, presumably tighter at top and looser near the bottom. Remember the Apogee trapezoid? Why a trapezoid? For the same reason--- a non-uniform geometry makes less resonance degeneracy (multiple geometrical resonances piling up on the same frequency) and so a broader, lower Q, resonance behavior.

The tensioning (and the resonance dots) are part of the 'black arts'.

Perhaps the bass on 3.7 non-i was a bit overdamped vs the ideal and the 3.7i change fixes this. It corresponds to the description of something that was adapted into the manufacturing process at low cost, unlike the major model upgrades.

The description of the phase-coherent crossover I think refers to changes from 3.7 over 3.6.

drchaos - welcome and please keep posting!