Zenith "Extended Stereo"

[old_tv_nut]

The schematic will tell the tale, but I believe the extended stereo is mainly a boost in the difference components (left minus right and right minus left) of the left and right speaker drives. So, for example, something mostly in L tends to be made entirely in L, and something entirely in L actually produces some out-of-phase output in R. Not sure about the drop in the mid-range - could it be a drop in common-mode (centered) content rather than a mid frequency drop?