  The reference energy scale r_0 is evaluated for RG-improved Iwasaki and DBW2
gauge actions (N_f = 0), at values of the deconfinement coupling beta_c
corresponding to N_t = 3,4,6,8. The universality of r_0 T_c between Iwasa ki
and Wilson action is confirmed; the scaling behaviour and the influence of th e
violation of positivity in the extraction of effective masses are investigated.
