Editing Thiele/Small parameters (section)

==Small signal parameters==

These values can be determined by measuring the [[Electrical characteristics of a dynamic loudspeaker|input impedance]] of the driver, near the resonance frequency, at small input levels for which the mechanical behavior of the driver is effectively linear (i.e., proportional to its input). These values are more easily measured than the fundamental ones above. The small signal parameters are:

*<math>f_{\rm s}</math> – Resonance frequency of driver
:<math>f_{\rm s} = \frac{1}{2 \pi\cdot\sqrt{C_{\rm ms}\cdot M_{\rm ms}}}</math>
*<math>Q_{\rm es}</math> – Driver [[Q factor|<math>Q</math>]] at <math>f_{\rm s}</math> considering electrical resistance <math>R_{\rm e}</math> only
:<math>Q_{\rm es} = \frac{2 \pi\cdot f_{\rm s}\cdot M_{\rm ms} \cdot R_{\rm e}}{(Bl)^2} = \frac{R_{\rm e}}{(Bl)^2} \sqrt{\frac{M_{\rm ms}}{C_{\rm ms}}}</math>
*<math>Q_{\rm ms}</math> – Driver <math>Q</math> at <math>f_{\rm s}</math> considering driver nonelectrical losses only
:<math>Q_{\rm ms} = \frac{2 \pi\cdot f_{\rm s}\cdot M_{\rm ms}}{R_{\rm ms}} = \frac{1}{R_{\rm ms}} \sqrt{\frac{M_{\rm ms}}{C_{\rm ms}}}</math>
*<math>Q_{\rm ts}</math> – Total driver <math>Q</math> at <math>f_{\rm s}</math> resulting from all driver resistances
:<math>Q_{\rm ts} = \frac{Q_{\rm ms} \cdot Q_{\rm es}}{Q_{\rm ms} + Q_{\rm es}}</math>
*<math>V_{\rm as}</math> – Volume of air having the same acoustic compliance as driver suspension
:<math>V_{\rm as} = \rho \cdot c^2 \cdot S_{\rm d}^2 \cdot C_{\rm ms}</math>
:where <math>\rho</math> is the [[density of air]] (1.184&nbsp;kg/m<sup>3</sup> at 25&nbsp;°C), and <math>c</math> is the [[speed of sound]] (346.1&nbsp;m/s at 25&nbsp;°C). Using [[SI units]], the result will be in cubic metres. To convert <math>V_{\rm as}</math> to [[litre]]s, multiply by 1000.
*<math>R_{\rm ms}</math>– Mechanical resistance of driver suspension
:<math>R_{\rm ms} = \frac{\rho \cdot c^2 \cdot S_{\rm d}^2}{2 \pi \cdot f_{\rm s} \cdot Q_{\rm ms} \cdot V_{\rm as}}</math>
*<math>C_{\rm ms}</math> – Mechanical compliance of driver suspension
:<math>C_{\rm ms} = \frac{V_{\rm as}}{\rho \cdot c^2 \cdot S_{\rm d}^2}</math>