Vintage could be anything from an Edison roll through to cassette, depending on who you talk to and ask.
Vintage generically just means 'Old', something from the past - like me!
In as far as I have seen in regards to audio and music, something is referred to as vintage when it becomes rare or uncommon. I may be wrong, but I would take a stab at the 'vintage sound' terminology being anything analogue-based in audio recording terms, like tape. It can refer to many things, depending on the context it is used in.
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♫ C. Emu ♫
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