It is really not that ahrd to sing a ohh and an ahh on a separate track. Clone it and change the pitch a 3rd and or a 5th. take a track and sing a harmony over the lead and run that thru the TC plugin as one voice and do several separate tracks and slowly blend them in.

I use my TC voice works and program out the lead voice and record one harmony at a time.

Where RTs wouls come in handy is that after a while your own voice starts to sound the same and having another voice helps sound more diverse.

So many options and ideas!!!

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