We present a preliminary study of using the information theoretic concept of cross entropy to measure musical contrast in a symbolic context, with a focus on melody. We measure cross entropy using the Information Dynamics Of Music (IDyOM) framework. Whilst our long term aim is to understand the use of contrast in sonata form, in this paper we take a more general perspective and look at a broad spread of Western art music of the common practice era. Our results suggest that cross entropy has a useful role as an objective measure of contrast, but that a fuller picture will require more work.