fix modulator calc for fixed key and vel
fix modulator calc for fixed key and vel

nezticle/fluidsynth,nezticle/fluidsynth,FluidSynth/fluidsynth,FluidSynth/fluidsynth,FluidSynth/fluidsynth,nezticle/fluidsynth,FluidSynth/fluidsynth,nezticle/fluidsynth