The poly-coherent composite higher order spectra (pCCHOS) were used earlier for faults diagnosis in the rotating machine. Earlier research studies have also suggested the unified multi-speeds approach for identical machines but with different operating speeds. However the studies were only tested at several machine speeds but below the first critical speed. In the present study, the same unified method using the poly-coherent composite bispectrum (pCCB) is further tested when the experimental rig runs below and above the machine’s first critical speed. The results and observations are presented here.