The Impact’s FM Drum channel uses frequency modulation to create percussion sounds with extra complexity. This uses two oscillators, the carrier – the main sound you hear – and the modulator, an audio rate signal which modulates the frequency of the carrier when the FM Amt rotary is turned up. Without FM engaged, the FM Drum sounds much like a high tom, handy for simple top-end percussion hits. Dialing in modulation makes things much more interesting though; allowing for discordant hits, clangorous tones and dark FM bass throbs. The FM Drum has a decay rotary too, which lets it range from short percussive knocks to longer synth hits. Sadly, however, you can’t sequence or automate the pitch. The lack of CC control or automation overall is less bothersome, but the FM Drum really misses it. The drum sounds best when you start tweaking the pitch of the two oscillators as a sequence plays, and it’d be good to do this automatically. An expression/CV input for either carrier or modulator pitch would’ve been great. Alternatively, pitch sequencing would let us use the FM Drum as a basic synth; it’s a shame that’s not an option.