Audio Engineering

696 Chapter 23

This represents a simple series resonant circuit shown in Figure 23.15. While one can
predict resonant frequency from lumped mechanical constants, the analysis must be
carried several stages further to arrive at the correct transfer characteristic from electrical
input to sound output in practical loudspeaker design.

Figure 23.16 takes the analogue a stage further:

● Lmd , Cmd , and Rmd are the mechanical components of diaphragm, voice coil, and

suspension.

● Lma , Rma : mechanical impedance components of air load.

● Z me : mechanical impedance due to electrical system.

● Z ma : mechanical impedance due to air load on rear of cone.

● Z mx : normally zero, but see motional impedance.

Rc Lc Lmd Rmd

Rma

Lma

Cmd

Eg Fc

Bl : 1 Zmx

uc

Figure 23.16 : Analogue referred to mechanical side.

Lm

Rm

F Cm

Figure 23.15 : Analogue of lumped mechanical constants.