Each mode applies a fixed EQ curve before the saturation stage, altering which frequencies drive the distortion. 5. Harmonic Distortion Profile Using a 1 kHz sine wave test tone at -18 dBFS input, the following harmonic behavior was observed (via SPAN analyzer):
| Mode | Dominant Harmonics | Character | |------------|-----------------------------------|-----------------------------------| | Neutral | 2nd (even), 3rd (odd) balanced | Warm, mild tube-like | | Keep Low | 2nd > 3rd, slight 4th | Round, fat, tape-ish | | Keep High | Strong 3rd, 5th, 7th (odd-heavy) | Aggressive, biting, transistor-like|
Characterizing Harmonic Distortion in the Softube Saturation Knob: A Freeware Solution for Analog-Style Coloration