Coloration is an alteration in the natural timbre or frequency response of a sound.

Think of "coloration" as adding a subtle "filter" to the audio, making it sound different from the original. It is any deviation from a perfectly "flat" or "transparent" reproduction.

Coloration can be:

• Undesired: Such as the resonance of a poor recording room or the uneven frequency response of a low-quality microphone. In these cases, the coloration "dirties" the sound.

• Desired: Many vintage analog audio equipment (preamps, compressors, EQs) are revered precisely for the sonic coloration they add. Their subtle harmonic distortion, smooth compression, and unique equalization curves can add "warmth," "weight," and "character" to the sound, making it more pleasant and musical. It's like adding a special spice to a dish.