Try changing the Tempo in RB and save as a native SEQ file format.

RB should ask about stretching/shrinking the audio, try not shrinking it or pitch shifting or anything .. just change the tempo.

Better yet use the Audio Chord Window (ACW) to manually set the tempo you want.

I made a couple minute video on how to do this many years ago.
The example I used did exactly as you need; cut tempo in half and adjust to suit.

Then you have what is called a 'Tempo Map' that everything can follow.

http://www.masteringmatters.com/stuff/ACW_Tempo_Map_creation.avi

Looking at it, it appears the video was done around 2010, so 2012 should have the same functionality.


Make your sound your own!
.. I do not work here, but the benefits are still awesome