OPL3 offers 18 FM 2-op chans in its standard mode, but that can be configured:
* One setting converts 3 of the FM channels into a 5-channel percussion set (Bass Drum, Snare Drum, Tom-Tom, Top-Cymbal, Hi-Hat)
* Another setting pairs 12 of the FM channels into 6 FM 4-op channels
* Both settings can be used at the same time