Here we continue the description of the previously found passive amplification effect in thin pyroelectric films placed on a massive heat-conducting substrate. We show that in the definite modulation frequency range the amplification effect occurs i.e., a current generated by a thin pyroelectric film placed on substrate exceeds that in freely suspended film. The frequency dependence a pyroelectric current is illustrated by set of examples including achiral ferroelectric liquid crystals, ferroelectric polymers and polycrystalline compounds.