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Large Signal Identification (LSI)

Features and Benefits

  • 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) 


Specification for LSI Tweeter and Woofer (Distortion Analyzer 2)


Test Hardware





LSI3 Woofer
The LSI3 Woofer measures woofers and other electro-dynamical transducers with a resonance frequency between 15 Hz and 400 Hz operated in free-air or coupled with an additional mechanical or acoustical resonator (vented enclosure, horn, panel) giving a total mechanical-acoustical system of 2nd or 4th-order. There are three working modes: Free air, sealed enclosure and vented enclosure.

LSI3  Micro-speaker
This module is dedicated to micro-speakers, tweeters, and horn compression drivers and which may be modeled by a 2nd-order mechanical system with a resonance frequency between 100 Hz and 1.5 kHz.

Related Information


Consumer Electronics Association

International Electrotechnical Commission 
IEC 60268-5, IEC 60268-7, IEC 60268-22, IEC 62458, IEC 62459, IEC WD 63034

European Standards
BS EN 54-24

Audio Engineering Society 

Institute of Electrical and Electronics Engineers
IEEE 269, IEEE 1206, IEEE 1329, IEEE 1652


Germany: 10 2007 005 070; USA: US8,078,433B2; China: ZL200810092055.4; Japan: 5364271; India: 162/DEL/2008; Germany: 10 2012 020 271 7; USA: 10,110,995; China: 201380054458.9;Korea:10-2015-7012390;Taiwan: 102137485;India: 844/MUMNP/2015