  The nature of resonances and excited states near decay thresholds is encoded
in scattering amplitudes, which can be extracted from single-particle and
multiparticle correlators in finite volumes. Lattice calculations have only
recently reached the precision required for a reliable study of such
correlators. The distillation method represents a significant improvement
insofar as it simplifies quark contractions and allows one to easily extend the
operator basis used to construct interpolators. We present preliminary results
on charmonium bound states and resonances on the Nf=2+1 CLS ensembles. The long
term goal of our investigation is to understand the properties of the X
resonances that do not fit into conventional models of quark-antiquark mesons.
We tune various parameters of the distillation method and the charm quark mass.
As a first result, we present the masses of the ground and excited states in
the 0++ and 1-- channels.
