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Single-valued nonlinear parameters

Characteristics:

KLIPPEL R&D SystemKLIPPEL QC System

Voice coil offset Xoffset

LSI, PWTMSC

Suspension asymmetry Ak

LSI, PWTMSC

Maximal peak displacement Xmax

LSI, PWTMSC

Force factor limited peak displacement XBl

LSI, PWTMSC

Suspension limited peak displacement Xc

LSI, PWTMSC

Inductance limited peak displacement XL

LSI, PWT

Stiffness Kms(x=0) at the voice rest position

LSI, PWTMSC

Force factor Bl(x=0) at the voice coil rest position

LSI, PWTMSC

Effective stiffness related to effective resonance frequency

SPM

Symmetry point xsym in force factor curve

LSI, PWT

In IEC standard 62458 single-valued parameters are derived from the nonlinear characteristics to simplify the interpretation and the data handling. For example, maximal peak displacement Xmax is limited by 10 % harmonic or intermodulation distortion generated by two-tone signal. For the motor and suspension nonlinearities Bl(x), Cms(x) and L(x) a corresponding displacement limit XBl, XC, XL can be derived from the shape of the nonlinear characteristic. The voice coil offset Xoffset is a single value derived from the symmetry point in the Bl(x) curve, expressed in mm. The suspension asymmetry describes the difference between the stiffness at positive and negative peak displacement referred to the mean value. All those values can be used for limit setting during end-of-line testing and for automatic control of the production process.

The symmetry point Xsym measured at the steep slopes of the Bl(x) characteristic (for xac > XBl) is a useful single-valued parameter describing the voice coil offset Xoffset≈Xsym.

KLIPPEL R&D SYSTEM (development)

Module

Comment

Large Signal Identification (LSI Woofer, LSI Tweeter, LSI Box)

LSI primary measures the nonlinear characteristics and derives the single-valued parameters from the nonlinear curve shape. A noise signal is used as stimulus, and the bandwidth is adjusted automatically to ensure persistent excitation of the transducer. The permissible working range is automatically determined by using a protection system. An optional laser sensor may be used to check the orientation of the voice coil movement (coil in or out) and to calibrate the mechanical parameters. There are three versions of LSI dedicated to woofers, tweeters and loudspeaker systems (transducer mounted in enclosure).

Power Test (PWT)

PWT also provides full identification of the woofer’s lumped parameters using an arbitrary stimulus (music). In contrast to LSI, the voltage and the working range are determined by the user.    

Suspension Part Measurement (SPM)

SPM measures the nonlinear stiffness and compliance of spiders, suspensions, drones and passive radiators. The stiffness asymmetry and the maximal peak displacement Xc limited by a decrease of the compliance down to 75% can be derived from the measured curves.

KLIPPEL QC SYSTEM (end-of-line testing)

Module

Comment

Motor Suspension Check (MSC)

MSC determines the single-valued nonlinear parameters by using an ultra-short multi-tone stimulus (0.2 …2 s) and measuring voltage and current at the terminals giving relative parameters only. Importing the value Bl(x=0) or the moving mass Mms allows to express the mechanical parameters absolutely using SI units (m, N, kg).

Example:

The Motor and Suspension Check (MSC) within the QC SYSTEM provides the voice coil offset within 1 s and less. The sensitivity can be demonstrated by measuring the offset of the voice coil generated by the gravity. The measured values agree with the values predicted by loudspeaker parameters.
The Motor and Suspension Check (MSC) within the QC SYSTEM provides the voice coil offset within 1 s and less. The sensitivity can be demonstrated by measuring the offset of the voice coil generated by the gravity. The measured values agree with the values
The minimum of the single-valued parameter XC, XBl, XL and XD limited by the compliance, force factor and inductance and Doppler nonlinearities, respectively, give the maximal peak displacement Xmax generating 10% harmonic or intermodulation distortion according AES2.
The minimum of the single-valued parameter XC, XBl, XL and XD limited by the compliance, force factor and inductance and Doppler nonlinearities, respectively, give the maximal peak displacement Xmax generating 10% harmonic or intermodulation distortion ac

Templates of KLIPPEL products

Name of the Template

Application

LSI Tweeter Nonlin. Para Sp2

Tweeters with fs > 400 Hz at sensitive current sensor 2

LSI Headphone Nonlin. P. Sp2

Nonlinear parameters of headphones with fs < 300 Hz at sensitive current sensor 2

LSI Woofer Nonl. P. Sp1

Nonlinear parameters of woofers with fs < 300 Hz at standard current sensor 1

LSI Woofer Nonl.+Therm. Sp1

Nonlinear and thermal parameters of woofers with fs < 300 Hz at standard current sensor Sp1

LSI Woofer+Box Nonl. P Sp1

Nonlinear parameters of woofers operated in free air, sealed or vented enclosure with a resonance frequency fs < 300 Hz at standard current sensor Sp1

LSI Microspeaker Nonl. P. Sp2

Nonlinear parameters of microspeakers with fs > 300 Hz at sensitive current sensor 2

Diagnost. MIDRANGE Sp1

Comprehensive testing of midrange drivers with a resonance 30 Hz < fs < 200 Hz using standard current sensor 1

Diagnost. RUB&BUZZ Sp1

Batch of Rub & Buzz tests with increased voltage (applied to high power devices)

Diagnostics MICROSPEAKER Sp2

Comprehensive testing of microspeakers with a resonance 100 Hz < fs < 2 kHz using sensitive current sensor 2

Diagnostics TWEETER (Sp2)

Comprehensive testing of tweeters with a resonance 100 Hz < fs < 2 kHz using sensitive current sensor 2

Diagnostics VENTED BOX SP1

Comprehensive testing of vented box systems using standard current sensor 1

Diagnostics WOOFER (Sp1)

Comprehensive testing of subwoofers with a resonance 30 Hz < fs < 200 Hz using standard current sensor 1

Diagnostics WOOFER Sp1,2

Comprehensive testing of subwoofers with a resonance 30 Hz < fs < 200 Hz using current sensor 1 and 2

Force - Deflection Curve

Using the results from LSI, the force -deflection curve is calculated.

Separate suspension

Separated stiffness of surround and spider according to Application Note AN 2

SPM Suspension Part

Nonlinear stiffness of spiders and smaller cones based on ONE-SIGNAL Method

SIM closed box analysis

Maximal displacement, dc displacement, compression, SPL, distortion using large signal parameters imported from LSI BOX

SIM vented box analysis

Maximal displacement, dc displacement, compression, SPL, harmonic distortion using large signal parameters imported from LSI BOX

PWT 8 Woofers Param. ID Noise

Parameter identification of woofers using internal test signal (no cycling, no stepping)

PWT Woofer Param. ID MUSIC

Parameter Identification of Woofers

using external test signal (no ON/OFF cycling, no stepping)

PWT Woofer param. ID NOISE

Parameter Identification of Woofers

using internal test signal (no ON/OFF cycling, no stepping)

Standards:

  • IEC Standard IEC62458 Sound System Equipment – Electroacoustic Transducers - Measurement of Large Signal Parameters
  • IEC Standard IEC62459 Sound System Equipment – Electroacoustic Transducers – Measurement of Suspension Parts
  • AES2-1984 AES Recommended practice Specification of Loudspeaker Components Used in Professional Audio and Sound Reinforcement
  • IEC Standard IEC 60268-5 Sound System Equipment, Part 5: Loudspeakers


Papers and Preprints:

W. Klippel, et al. “Fast Measurement of Motor and Suspension Nonlinearities in Loudspeaker Manufacturing,” presented at the 127th Convention of the Audio Eng. Soc., 2009 October 9-12, New York, NY, USA.

W. Klippel, “Dynamic Measurement of Loudspeaker Suspension Parts,” J. of Audio Eng. Soc. 55, No. 6, pp. 443-459 (2007 June).

D. Clark, “Precision Measurement of Loudspeaker Parameters,“ J. of Audio Eng. Soc., Volume 45, pp. 129 – 140, (1997 March).

W. Klippel, “Measurement of Large-Signal Parameters of Electro-dynamic Transducer,” presented at the 107th Convention of the Audio Eng. Soc., New York, September 24-27, 1999, Preprint 5008.

M. Dodd, et al., “Voice Coil Impedance as a Function of Frequency and Displacement,” presented at the 117th Convention of the Audio Eng. Soc., 2004 October 28–31, San Francisco, CA, USA.

R. H. Small, “Assessment of Nonlinearity in Loudspeakers Motors,” in IREECON Int. Convention Digest (1979 Aug.), pp. 78-80.

A. J. M. Kaizer, “Modeling of the Nonlinear Response of an Electrodynamic Loudspeaker by a Volterra Series Expansion,” J. of Audio Eng. Soc., Volume 35, pp. 421-433 (1987 June).

W. Klippel, “Dynamical Measurement of Non-Linear Parameters of Electro-dynamical Loudspeakers and their Interpretation”, J. of Audio Eng. Soc. 30 (12), pp. 944 - 955, (1990).

M. Knudsen, et al., “Determination of Loudspeaker Driver parameters Using a System Identification Technique,” J. of Audio Eng. Soc., Volume 37, No. 9.

W. Klippel, “Nonlinear Modeling of the Heat Transfer in Loudspeakers,” J. of Audio Eng. Soc. 52, Volume 1, 2004 January.