Pretty much every sampler and virtual instrument these days comes with some sort of factory installed sounds. To me this is a matter of convenience really. A way to demonstrate the capabilities of the sampler or instrument.

One of the many features that makes Reason such a powerful tool is the ability to import your own samples and loops including vocals. Reason has three highly flexible and sonically incredible synthesizers which all generate sound through the use of oscillators, filters and the modulation of these devices.

All the presets you see are simply generated through the manipulation of the parameters. Often a good starting point for designing your own sound is by manipulating the factory presets which you can then overwrite by saving and renaming it in your own custom location. There are two samplers in Reason. One is the NN19 and the other is the NNXT. Both of these can import custom audio samples of most all audio file types. The NNXT can even import Rex Slices ( i.e individual slices from a Rex file ) from your Recycled files.

So if you have your own custom drum sets, piano sounds or even special effects you can trigger all of these and modulate them through the use of these samplers. The Dr Rex loop player is the third device which imports audio into Reason. Dr Rex is where you will import most of your custom loops which all can be easily created in Recycle which is a relatively inexpensive program available from the Props. One of the unique parts of Rex Files in Reason is that you can trigger the individual rex samples with your keyboard, apply filters and re sequence the loop which can create effects that would be difficult of virtually impossible to do in Pro Tools.

Happy sound designing and music making.