I don't sing so I don't use the vocal harmonizer on my Pa800. However here is what Keyboard Magazine said in their recent review of the Pa800:

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Selecting the “Mic” tab on the Pa800’s touch screen brings up options for types of harmonies, mic EQ and overall effect level, mute icons for your own voice and your three virtual backup singers, plus a talk-over button. The Pa1X Pro Elite adds a fourth harmony voice and pitch-correction. The underlying technology is from TC-Helicon, and since they’re an industry leader in hardware vocal harmony boxes, our expectations were quite high. We weren’t disappointed — the sound quality is a perceptible notch above other arrangers’ best efforts in this area.

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Kind regards,
Tommy