Thiele/Small Parameters
In loudspeaker design the Thiele/Small Parameters are a set of electromechanical parameters that determine the low-frequency performance of loudspeaker drivers.
The parameters are named after two Australian loudspeaker engineers: Richard H. Small and A. Neville Thiele.
The parameters are divided into three categories: electromechanical parameters (or fundamental parameters), small-signal parameters and large-signal parameters.
Electromechanical Parameters
These parameters are the physical properties of the loudspeaker driver, measured at small signal levels. They are often very difficult to measure in a finished loudspeaker driver, and as such the small signal parameters are often more practical when using an “off the shelf” loudspeaker driver.
| Parameter | Name | Description |
|---|---|---|
Sd | Surface area | The effective projected area of the diaphragm. Very difficult to measure accurately because roughly half of the surround moves with the cone. |
Bl | Force factor | The product of magnetic flux density B produced by the magnet and the length of the voice coil l, in Tesla-metres (T·m). It is the mechanical force developed by the current flowing through the voice coil. |
Small Signal Parameters
These parameters are measured at small signal levels.
