Accordion reed ranks and switches

Visually, they each have a fixed dot in a three-level icon as displayed in the photo on the right and tables below.

[1] Accordions with three 8′ ranks have the third tuned the same distance below the center, doubling the effect of the beats when all three play.

Register switches select combinations of reed ranks to produce contrasting timbres.

High-end accordions often have a feature called a cassotto (Italian for "box"), also referred to as a "tone chamber", in the treble (right-hand) reed section.

The sound of cassotto bassoon (low) reeds is particularly favored by jazz accordionists.

The cassotto design requires a sophisticated treble mechanism where each key must open and close air passages not only for reeds mounted at the traditional angle, but also for air passages at a relative 90° angle (for the cassotto reeds).

To do this properly, each rod and pad must be positioned precisely in relation to its perpendicular counterpart.

Right-hand manual register switches. This accordion has three different voices.
Accordion reed ranks with closeup of reeds
Set of two-way rocker switches (labeled LOW, HIGH, MIDDLE, MIDDLE) controlling individual reed ranks for the treble keyboard of an Excelsior accordion.
Two-way rocker switches controlling individual reed ranks