Cassotto
A cassotto is a 'sound chamber' within some more expensive accordions that contains one or more reed blocks of the treble side of the instrument. The sound of a cassotto register is warmer, less sharp than that of a register with unenclosed reeds. Technology The cassotto enclosure works as a passive frequency filter, attenuating higher frequencies and reinforcing lower ones (resonance). Instruments with cassotto have a sound quality distinctly different from instruments without. Usually only some reed blocks are placed in the cassotto enclosure, typically for low reed sets 16' and/or 8'. The remaining treble reed blocks are mounted straight. The firm Öllerer built a diatonic instrument with cassotto without register switches and two 8' (M) reed sets. Making a cassotto for diatonic instruments is quite more difficult due to the different reed plate arrangement. For chromatic accordions, a cassotto does not perform equally in every tone. On piano keyboards, the reed plates for black keys are usually located closer to the filling than those for most white keys. On chromatic button keyboards, two reed sets are typically distributed across 3 or 2 reed blocks (the latter solution often requiring particularly slim reed plates). The cassotto effect tends to be