overview what is thiele-small? speaker design basics view applet download applet more info what is thiele-small? Thiele-Small is the name given to a number of transducer (loudspeaker) performance characteristics, first developed by Neville Thiele and Richard Small. These characteristics or parameters are used to analyse the behaviour of a given transducer in any of a number of different loudspeaker cabinet designs. Most manufacturers publish the Thiele-Small parameters for transducers that they sell. Below is a brief description of the Thiele-Small parameters used by the ISHTEK speaker design applet. Fs the free air resonant frequency of the transducer. Qes the electrical Q of the transducer. Qms the mechanical Q of the transducer. Vas the compliance volume of the transducer. Sd the area of the transducer diaphraghm. Xmax the maximum displacement limit for the transducer before ten percent (10%) distortion is reached. Re the DC electrical resistance of the voice coil. No the reference efficiency of the transducer. Pe the continuous thermal power rating for the transducer. Some manufacturers also quote Vd, which is the maximum volume displaced by the diaphragm. Note that Vd equals Sd multiplied by Xmax. (Vd = Sd * Xmax).