Large Signal Identification (LSI)

• Identification of large signal model in real time
• Electrical and mechanical state variables (displacement, temperature, …)
• For woofers in free air, sealed and vented enclosures
• For micro‐speakers, headphones, mini‐loudspeakers, tweeters, shakers
• Measures signal distortion on‐line
• Full thermal and mechanical driver protection
• Finds dominant sources of distortion
• Locates weak points in design and assembly

The module LSI3 identifies the elements of the lumped parameter model of woofers, micro‐speakers, headphones, tweeters, shakers, mini‐loudspeakers and other electro‐dynamical transducers. Transducers can be measured either mounted in an enclosure or in free air. The transducer is operated under normal working conditions and excited with a broadband noise signal. Starting in the small signal domain the amplitude is gradually increased up to limits admissible for the particular transducer. 

The maximal amplitude is determined automatically using the identified transducer parameters and general protection parameters describing the thermal and mechanical load. The identification of the model parameters is performed in real time using an adaptive system. It is based on the estimation of the back EMF from the voltage U(t) and current signal I(t) measured at the electrical terminals. The identified model locates the sources of the nonlinear distortion and their contribution to the radiated sound. The dynamic generation of a DC‐part in the displacement, amplitude compression and other nonlinear effects can be investigated in detail.

Large Signal Identification for Distortion Analyzer 2 - LSI (for DA2)