Seamless change/play came out in the 80s when digital and sampling started to make inroads and it is surprising that in 2018 (30 years later) there are still instruments that don’t have it. (NOTE: Pure analogue instruments by their very nature do not have seamless play, but there is no reason why digital sampling instruments should not have it)
The first time I came across it for my own use was in 1985 when I built my Wersi Alpha organ, (The DX range were the first digital organs from Wersi) and it was great as you could change from a string sound (Which always have a fairly long release) to a new voice and the string release would carry on until it came to its natural end, plus it was great for an ending as you could hold a solo note (For example) select another voice and play the rest of the chord with your other fingers with the new voice while the solo voice carried on.
Bill
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English Riviera:
Live entertainment, Real Ale, Great Scenery, Great Beaches, why would anyone want to live anywhere else (I�m definitely staying put).