Shelving EQ after FM distortion restores high-end lost from the tube amp and overdrive

FM distortion (overdrive, tube amp) adds warmth and harmonics to the mid-range but attenuates or darkens the high end, making the sound increasingly muffled as drive increases. A shelving EQ inserted after the distortion chain compensates by boosting the high shelf — restoring the treble energy that distortion removed. This is a standard post-distortion EQ technique: apply the character-shaping effect (distortion) first, then use EQ to correct the frequency balance. In FM8’s internal effects chain, the shelving EQ’s high-shelf lift after the tube amp brings back the air and presence that makes the sound cut through in a dense mix. The sequence (distort → EQ) is important: EQ before distortion would merely feed different frequencies into the distortion, which would then mangle the EQ’d result.

Examples

In FM8 effects: turn on tube amp → high end gets darker; add shelving EQ → raise the high shelf back to compensate. Compare the sound with and without the shelf: with shelf sounds full-range; without sounds increasingly mid-heavy as drive increases.

Assessment

Describe the order of operations for distortion plus shelving EQ, and explain why shelving EQ should come after (not before) the distortion; then identify what perceptual change the high shelf corrects.