The Dr. Rex Loop Player plays drum loops and a few music loops as well. This is a good option if you don't feel comfortable with Redrum or just don't know how you want the percussion to go. It plays premade drum loops that come from a number of different pop genres.

Dr. Rex looks like this:

Aside from loading the loops through our usual process by clicking on the open folder, then choosing the "Reason Factory Sound Back" folder, then choosing the "Dr. Rex Drum Loops" folder and then you face the choice of what genre you are trying to create (Abstract HipHop, Chemical Beats, Drum N Bass, etc.) and you can preview the loops by clicking the autoplay button in the patch browser window. You can then manipulate the filter, envelopes, and LFO settings to make the sample sound more like you desire.

Next we will talk about the Redrum Drum Computer.