Acoustics: Sound Fields, Transducers and Vibration, 2nd Edition

6.18. Nonlinearity [14]

There are a number of nonlinear mechanisms in electrodynamic loudspeakers which give rise to harmonic distortion. They tend to be dominant at different frequencies. In some cases, the nonlinearity is a function of input current and in others of displacement, or even both. An overview is given in Table 6.3.

Suspension compliance

The purpose of the suspension (see (9) in Fig. 6.1) is to provide a linear restoring force that moves the coil back to its rest position and to ensure that it is correctly centered. However, from Fig. 6.21a, we see that for large excursions, the suspension becomes stiffer as it stretches and so the compliance becomes nonlinear, typically in an asymmetrical manner, as shown in Fig. 6.21b. It ...