A cassotto is a sound chamber built into the treble side of some higher-end accordions, housing one or more reed blocks (typically the low and/or middle reed sets) mounted at a right angle to the other reeds instead of firing straight out.
How it changes the sound
Because sound from the cassotto-mounted reeds has to travel a longer, bent path before leaving the instrument, the chamber acts as a passive acoustic filter - attenuating higher frequencies and reinforcing lower ones. The practical result is a noticeably warmer, more mellow, less sharp tone from those reed sets, often described as "rounder" with fewer harsh overtones compared to the same reeds mounted without a chamber.
What it means for buying
- Cassotto construction adds complexity and cost, so accordions with it sit toward the higher end of the market - it's a reasonable proxy (though not a guarantee) for a more serious, better-built instrument.
- Whether the mellower cassotto tone suits a given playing style is genuinely a matter of taste and genre, not an objective upgrade in every context.
Listening for the difference directly - ideally comparing a cassotto and non-cassotto instrument side by side - is the most reliable way to judge whether it matters for your own playing.
