A demo: First 16 seconds no sound alteration then (North Church) added.
Registration:
Swell ONLY
----Swell Unison Off ---
Swell Octave - on
Lieblich Bourdon 16'
Rohr Flote 8'
Piccolo 2'
Just to compare. Also demonstrates St. Anne's "Unison Off" does allow the couplers for Swell Octave to produce sound alone.
Works with Suboctave and Swell-to-Pedal too.