|KLIPPEL R&D System|
Variation of dc resistance Re versus time
|LSI3, PWT, LAA|
Increase of voice coil temperature ΔTv
|LSI3, PWT, DIS, LAA, MTON|
Heating and cooling curves
The voice coil temperature can be monitored without using an additional sensor by measuring the dc resistance and considering the material properties of the voice coil. The dc resistance corresponds with the electrical impedance at very low frequencies. An additional pilot tone (1 – 4 Hz) has to be added to the stimulus (test signal or audio signal) to ensure a reliable measurement of the dc resistance which is not affected by the motional impedance and inductance of the coil. The short thermal time constants in small transducers (microspeaker, tweeter) require a fast method and dedicated signal processing to measure the dc resistance as fast as possible.
Increase of voice coil temperature Tv and input power PRE dissipated in resistance RE versus measurement time during power testing using different kinds of music signals as stimulus.
LSI3 measures the resistance of the cold transducer at very low frequencies at the beginning of the measurement. This value is used as a reference for calculating the increase of the voice coil temperature during the following identification process.
PWT adds a pilot tone of 1 - 4 Hz of low amplitude to the excitation signal generated by the internal generator or to the external audio signal. Thus, the temperature can also be measured during an off-cycle when no regular stimulus is supplied to speaker. The power test provides an ultra-fast sampling of the voice coil temperature (100 ms) to measure the temperature variation at high temporal resolution.
DIS provides a special measurement (pilot tone at 375 / 750 / 2250 Hz) which estimates the voice coil temperature at sufficient accuracy to protect the transducer under test.
|Live Audio Analyzer (LAA)|
LAA measures the DC resistance of a transducer by adding a pilot tone of low amplitude to the excitation signal. The pilot tone is added to the signal provided by the computer, thus temperature measurement during off-cycles is supported. For external signals, the user may specify a single tracking frequency, or uses a whole tracking band with sufficient excitation.
|Multi-Tone Measurement (MTON)|
MTON measures the DC resistance of the DUT to monitor the increase of voice coil temperature by adding a low-frequency pilot tone to the multi-tone stimulus.
Name of the Template
Thermal Parameters (woofer)
Analysis of heat transfer in woofers based on identified thermal woofer parameters
Thermal Parameters AN 18
Thermal Parameters measured by using PWT module according Application Note 18
Thermal Parameters AN 19
Thermal Parameters measured by using PWT module according Application Note 19
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
DIS Compression Out(in)
Output amplitude versus input amplitude at four frequencies
DIS Harmonics vs. Voltage
Harmonic distortion measurement versus amplitude
DIS SPL, Harm protected
Harmonic distortion measurement with protection
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 Therm. Analysis (1 tone)
Heat transfer based on thermal parameters imported from LSI using a single-tone stimulus
SIM Therm. Analysis (2 tone)
Heat transfer based on thermal parameters imported from LSI using a two-tone stimulus
PWT 8 Woofers Param. ID Noise
Parameter identification of woofers using internal test signal (no cycling, no stepping)
PWT EIA accelerated life test
Accelerated life testing according EIA 426 B A. 4 using any external signal to monitor temperature, power and resistance
PWT IEC Long term Voltage
Power test to determine long-term maximal voltage according IEC 60268-5 paragraph 17.3 without parameter measurement for one device monitoring voltage, resistance, temperature and power
PWT IEC Short term Voltage
Power test to determine short term maximal voltage according IEC 60268-5 paragraph 17.2 without parameter measurement applied to 1 DUT monitoring temperature, power and resistance
PWT Powtest (fast Temp.)
Power test for fast monitoring of temperature, power and resistance without parameter measurement using external continuous signal (noise) supplied to IN1
PWT Powtest EXT. GENER.
Power test for monitoring temperature, power and resistance using external continuous signal (noise) supplied to IN1
PWT Powtest LIMITS
Power test to find maximal input voltage, power and temperature limits without parameter measurement applied to 1 DUT
PWT Powtest MUSIC
Power test without parameter measurement monitoring temperature, power, voltage and resistance using any external signal
PWT Powtest SWEEP
Power test for measuring the thermal time constant of the voice coil using sweep signal with low crest factor
PWT Powtest TIME Const.
Power test for measuring time constant of voice coil using internal test signal with cycling (ON/OFF phase)
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)
Audio Engineering Society
AES2 Recommended practice Specification of Loudspeaker Components Used in Professional Audio and Sound Reinforcement
Consumer Electronics Association
CEA-426-B Loudspeakers, Optimum Amplifier Power
European Telecommunications Standards Institute
EIA 426B Loudspeaker Power Rating Test CD provided by ALMA International
International Electrotechnical Commission
IEC 60268-5 Sound System Equipment, Part 5: Loudspeakers
Y. Shen, “Accelerated Power Test Analysis Based on Loudspeaker Life Distribution,” presented at the 124th Convention of Audio Eng. Soc., May 2008, Preprint 7345.
W. Klippel, “Nonlinear Modeling of the Heat Transfer in Loudspeakers,” J. of Audio Eng. Soc. 52, Volume 1, 2004 January.
C. Zuccatti, “Thermal Parameters and Power Ratings of Loudspeakers,” J. of Audio Eng. Soc., Volume 38, No. 1, 2, 1990 January/February.
K. M. Pedersen, “Thermal Overload Protection of High Frequency Loudspeakers,” Report of Final Year Dissertation at Salford University.
Henricksen, “Heat Transfer Mechanisms in Loudspeakers: Analysis, Measurement and Design,” J. of Audio Eng. Soc., Volume 35, No. 10, 1987 October.