Vortex Sound Research

This is not necessarily how to make a synth sound but you guys might be able to help.

Let's say I have a single note synth wav sample that I really like but only lasts a couple of seconds.

I wanna play this on a sampler so I can transpose it and also I would like to create a sustain effect so the sample plays for as long as I press my keyboard, rather than suddenly stopping.

I'm on Cubase + Kontakt if that's relevant.

Thanks!