The Blackbirds (Eb, D and C; black top, nickel tube) are the purest/sweetest voiced. They take the lightest breath. Some like the fact you can play a longer passage without taking a breath.
The Bluebirds (Eb, D; blue top, nickel tube, “Bluebird” label) are at the pure/sweet end of the continuum, but a little more complex than the Blackbirds. They retain some of the distinctive Generation character, but they’re sweeter than Generations.
The tweaked Generations are voiced to match as closely as possible, the vintage, pre-1980’s Generations, which were a bit sweeter than the Generations being made now, but still a bit more complex/reedy than the Blackbirds and Bluebirds.
The Mellow Dog (green top, brass tube) is a wide body whistle. It has a bigger sound, and takes more of a “push” of air, especially at the top end. (This refers to the key of D Mellow Dog. A C Mellow Dog is a standard body C whistle, exactly the same as a key of C Blackbird except for the brass tube and green color of the top.)
The alto A, low G, Enat and Bnat tweaked Generations are keys Generation does not make, but I have created them.
Best wishes,
Jerry
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