I had a thought and wondered if the O/P was referring to an adjustable "Velocity Curve"?

Attached Files (Click to download or enlarge) (Only available when you are logged in)
2017-08-12_04-46-39.jpg (129.18 KB, 18 downloads)

BIAB & RB2025 Win.(Audiophile), Sonar Platinum, Cakewalk by Bandlab, Izotope Prod.Bundle, Roland RD-1000, Synthogy Ivory, Kontakt, Focusrite 18i20, KetronSD2, NS40M Monitors, Pioneer Active Monitors, AKG K271 Studio H'phones