|KLIPPEL R&D System||KLIPPEL QC System|
DC displacement versus frequency
DC displacement versus amplitude
Asymmetrical probability function pdf
|Peak-bottom value||DIS, TRF, LSI, PWT, SPM, LAA||MSC, DCX|
Asymmetries in the motor and suspension nonlinearities generate a dc component in the voice coil displacement which can be detected by a laser sensor. The sign of the dc component has a high diagnostic value because it is directly related with the shape of the nonlinearity. For example, an asymmetrical stiffness characteristic generates a dc component which always shifts the coil to the softer side of the suspension. An asymmetrical force factor characteristic may cause a significant dc component for excitation frequencies above resonance in the same order of magnitude as the fundamental. DC displacement generated by a poor suspension system may spoil the performance of an expensive motor structure because a dynamic voice coil offset produces audible intermodulation distortion.
The figure to the left illustrates the typical frequency of the dc displacement caused by an asymmetrical shape of nonlinear stiffness Kms(x), nonlinear force factor Bl(x) and nonlinear inductance L(x).
TRF reveals the dc component in the waveform of the displacement and in the Rub & Buzz analysis (instantaneous distortion 3D plot).
LSI3 predicts the dc displacement generated by a pink noise stimulus by using the nonlinear large signal model and the identified loudspeaker parameters. The predicted value can be compared to the value measured independently by using a laser sensor.
PWT provides similar features like the LSI but may be used to monitor the dc component of multiple devices under test using ordinary audio signals.
DIS module measures the steady-state response of the dc component versus frequency at different excitation levels.
|Live Audio Analyzer (LAA)||LAA measures the dynamic dc displacement versus time. Generated pink noise, or any given music signal may be used. In addition, by using linear modelling, irregular Rub & Buzz effects can be auralized.|
MSC calculates the dc component using the large signal model and the identified nonlinear parameters in ultra short time (< 1s).It dispenses with a laser sensor.
|Dynamic Excursion Check and Control (DXC)||The DCX Add-On to the SPL task analyzes the envelope of excursion and the dynamic offset of the voice coil using an excursion sensor. Limits can be applied and compression and non-linear (instable coil position) effects can be detected. A sine chirp stimulus is used. A KA3 hardware with DC coupled inputs is recommended.|
Name of the Template
DIS Motor stability
Checking motor stability at frequency 1.5 fs (where Xdc is maximal) according Application Note AN 14
DIS X Fundamental, DC
Fundamental and DC component of displacement
SIM X Fundamental, DC
Maximal displacement, dc displacement, compression using large signal parameters imported from LSI; Results are comparable with DIS X Fundamental, DC.
SIM Motor Stability
Checking motor stability according Application Note AN 14; Simulated results are comparable with DIS Motor stability.
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)
Diagnost. RUB & BUZZ Sp2
Batch of Rub & Buzz tests with increased voltage (applied to low power devices)
Diagnost. SUBWOOFER (Sp1)
Comprehensive testing of subwoofers with a resonance 10 Hz < fs < 70 Hz using standard current sensor 1
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
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
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
TRF Crest Harmonics (x,f)
Crest factor harmonic distortion versus displacement to find Rub & Buzz and other loudspeaker defects
TRF Peak harmonics, time domain
Peak value of higher-order harmonics in time domain for Rub & Buzz analysis
TRF rubb+buzz w/o Golden Unit
Rub & Buzz detection without "Golden Unit" according Application Note AN 22
TRF rubb+buzz with Golden Unit
Rub & Buzz detection with "Golden Unit" according Application Note AN 23
DIS Compliance Asymmetry AN 15
Checking for asymmetries caused by compliance according Application Note AN 15
SIM closed box analysis
Maximal displacement, dc displacement, compression, SPL, distortion using large signal parameters imported from LSI BOX
SIM Compression Out(In)
Output amplitude versus input amplitude at four frequencies using large signal parameters imported from LSI; Simulated results are comparable with DIS Compression Out(In).
SIM vented box analysis
Maximal displacement, dc displacement, compression, SPL, harmonic distortion using large signal parameters imported from LSI BOX
AN 1 Optimal Voice Coil Rest Position
AN 2 Separating Spider and Surround
AN 3 Adjusting the Mechanical Suspension
AN 13 Dynamic Generation of DC Displacement
AN 14 Motor Stability
AN 15 Checking for Compliance Asymmetry
AN 21 Reduce Distortion by Shifting Voice Coil
AN 24 Measuring Telecommunication Drivers
AN 26 Nonlinear Stiffness of Suspension Parts
W. Klippel, Tutorial “Loudspeaker Nonlinearities - Causes, Parameters, Symptoms,” J. of Audio Eng. Soc. 54, No. 10, pp. 907-939 (2006 Oct.).
W. Klippel, “Assessment of Voice-Coil Peak Displacement Xmax,” J. of Audio Eng. Soc. 51, Heft 5, pp. 307 - 323 (2003 May).
W. Klippel, “Nonlinear Large-Signal Behavior of Electrodynamic Loudspeakers at Low Frequencies,” J. of Audio Eng. Soc., Volume 40, pp. 483-496 (1992).
W. Klippel, “Prediction of Speaker Performance at High Amplitudes,” presented at 111th Convention of the Audio Eng. Soc., 2001 September 21–24, New York, NY, USA.