This breaks down Ableton's Spectral Resonator using Operator as a test signal, showing exactly what the device does to a sound before you ever touch it musically. A plain sine wave shows up as a single spike on the spectrum, since almost any sound, from a piano note to a voice, can be broken down into sine waves at different frequencies, amplitudes, and phases. Swap in white noise and the spectrum turns into a scribble of every frequency at once, with no tonal center at all.
Turning on Spectral Resonator reveals its core trick: it analyzes that incoming frequency content and regenerates it as a bank of sine waves called harmonics, instantly making white noise sound tonal. Dropping the harmonic count from 256 down to 5 makes each individual sine wave visible and countable on the spectrum, which is a fast way to understand what the device is actually building.
From there, Frequency sets where the harmonic series starts, Stretch controls the spacing between harmonics, and Shift moves the incoming spectrum up or down, acting almost like a filter or pitch shift on the input. These three controls together define the harmonic structure before any tone shaping happens.
Decay lets each harmonic ring out over time instead of cutting off immediately, and HF Damp and LF Damp let you fade high or low frequencies faster than the rest. The spectrogram makes this audible decay visible, showing the upper band fading to black quicker when HF Damp is applied, which is a useful way to confirm your damping settings are doing what you expect before moving on to real material like drums.