I have a 1938 Candido Iorio 4 reed treble with 2 in tone chamber. I have found no other American or Italian made accordions that
offered a tone chamber (Cassotto) this early. The craftsmanship is unique and the sound quality is very full BUT, the accordion
itself is quite large & heavy compared to a modern 4 reed tone chamber. A few accordionist friends have played it and jokingly
have named it "Godzilla" because of it's large size & weight . I won't refurbish it for resale but on my next trip to see my friend
Paul Ramunni I'll place it in his Museum ---
And as far as who invented the double tone chamber -- Zevy you were on the right track -- the original Iorio firm started business
in 1907 on 44 Baxter St in New York, NY . By 1923 the Iorio Co. had already established one of the finest reputations among the
manufacturers in New York. By that time Candido had already INVENTED THE DOUBLE TONE CHAMBER , along with a long list of
refinements that included invisible bass & treble shifts, aluminum shift plate mechanisms, and celluloid cases.