Audiophilepure

One of Class A’s great virtues is that its harmonic distortion spectrum is primarily second and third harmonic, with virtually no odd-order upper harmonics, such as sevenths and ninths. We hear those upper-harmonic distortion components as harshness. Second-harmonic distortion, however, is relatively benign since it occurs in nature, and is a significant component of instrumental overtones. In fact, some studio-processing devices intentionally add a bit of second-harmonic to make an instrument sound warmer and “fatter.” By contrast, seventh and nineth harmonics are rarely heard in nature, and add a hard, steely character to the sound. Not coincidentally, these upper-order harmonics are produced when metal is struck—not a pleasant sound, or one you want overlaying harmonic textures. A distortion spectrum that’s primarily second and third harmonic, without the upper-order harmonics, confers the warmth and liquidity that are hallmarks of Class A designs.

Comments are closed.