> The Twin Passband Tuning on various Icom transceivers, including the
> IC-781, IC-756Pro and IC-756Pro2, allows the operator to shift the
> upper and lower flanks of the IF passband independently of one another
> - or to shift the passband without varying its bandwidth.
I am very familiar with the Icom's version of Twin Passband Tuning.
The radio I sold to purchase the Orion was a 781 I've owned since
1989. I had IRCI/INRAD 2.1 Khz crystal filters in the IF's which
vastly improved passband tuning sharpness and performance over
the stock filters.
Although I no longer own the 781 (shipped it out a couple months
ago) and can't do a side-by-side, my overall impression is that the
BW/PBT and Hi/Low cut controls on the Orion accomplish the
objective very well and produce a significantly superior result. The
ability of this radio to reject adjacent channel interference in a wide
range of conditions is remarkable.