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Waveform and spectrum

Characteristics:

KLIPPEL R&D System KLIPPEL QC System
Time domain analysis LSI, LPM, TRF, DIS, PWT, AUR, SCN, DA QC Standard
Statistical analysis LSI, LPM, TRF, DIS, PWT, AUR, SCN QC Standard
Spectral analysis LPM, TRF, DIS QC Standard
Signal to noise ratio SNR LPM, TRF, DIS, SCN

Many modules of the KLIPPEL R&D SYSTEM measure important characteristics of the signal measured by using a sensor or predicted by using a loudspeaker model. Those characteristics can be monitored over time and stored in a history using a stand-alone hardware or a PC. The rms value is important for calculating power and efficiency but also for assessing the heat dissipation. The peak value is very important for monitoring the voltage at the loudspeaker terminals and for defining the amplifier requirements. The measurement of the negative and positive peak value of the voice coil displacement and its difference is important for explaining nonlinear rectification mechanisms generated by asymmetrical nonlinearities. The crest factor and the probability density function are very useful to describe the audio signals and complex test signals (noise, multi-tone signal). The signal to noise ratio SNR is also a simple and important measure describing the noise immunity of the signal. A spectral analysis applied to the primary measurement signals reveals humming components and other disturbances and the SNR at critical frequencies (for example at very low frequencies).

Short-term SPL spectrum with one-third octave resolution measured by using the TRF module.
Short-term SPL spectrum with one-third octave resolution measured by using the TRF module.

KLIPPEL R&D SYSTEM (development)

Module

Comment

Transfer Function Module (TRF)

TRF always shows waveform, spectrum and other single-valued characteristics of the measured signals. A spectral analyzer mode repeats the measurement and calculates the magnitude in octave and third-octave band. Noise floor monitoring reveals the SNR.

Linear Parameter Measurement (LPM)

LPM reveals all relevant properties of the signals (voltage, current, displacement and sound pressure) used for Linear Parameter Measurement and multi-tone distortion measurements. It separates noise from distortion to find the optimal voltage required for doing reliable measurements in the small signal domain.    

Large Signal Identification (LSI)

LSI monitors the signal properties of voltage and current signals and the internal states (displacement, velocity, distortion in sound pressure output) during the large signal measurement using the internal noise stimulus.

Power Test (PWT)

PWT measures the signal properties of the arbitrary stimulus (test signal from internal generator or external audio signal) and the state variables of the transducer (e.g. displacement). 

Distortion Analyzer Hardware (DA)

The DA used as a stand-alone unit provides displacement meter functionality to measure peak and bottom values and other signal characteristics of the laser signal. 

3D Distortion Module (DIS)

DIS module monitors the signal properties of the two-tone stimulus and of the measured signals.

Scanning Vibrometer (SCN)

SCN displays the spectrum and waveform of the measured displacement during the scanning process.

Auralization (AUR)

AUR analyzes the signal properties of the audio input signal at the loudspeaker terminals, the internal states (displacement, velocity) and the acoustical output signal.

Simulation (SIM)

SIM module predicts the state variables and acoustical output signal of loudspeaker systems based on a large signal model and parameters. Spectral and time domain analysis is applied to the different signals.

KLIPPEL QC SYSTEM (end-of-line testing)

Module

Comment

QC Standard

All modules and tasks of the QC SYSTEM provide a summary on the signal properties, including rms, peak and headroom in the ADC and DAC.

For most measures spectra in definable resolution are provided.

QC Standard / Tools

A special tool called “Signal Test” provides analysis and export of waveform and spectra of any user selectable input. It is included in all QC System versions.

The figure above shows the peak and bottom displacement measured by the laser sensor and predicted by large signal modeling within the LSI module.
The figure above shows the peak and bottom displacement measured by the laser sensor and predicted by large signal modeling within the LSI module.
The figure above shows the probability density function (pdf) of the measured voice coil displacement using audio-like noise signal. Comparing the pdf histogram (brown vertical lines) with the mirrored pdf curve (black line) reveals the asymmetry in the displacement waveform.
The figure above shows the probability density function (pdf) of the measured voice coil displacement using audio-like noise signal. Comparing the pdf histogram (brown vertical lines) with the mirrored pdf curve (black line) reveals the asymmetry in the d

Templates of KLIPPEL products

Name of the Template

Application

TRF 3rd oct. spectr. analyzer

Continuous loop measurement giving the spectrum of the signal acquired via IN1 integrated over 1/3 octave

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

IEC 20.6 Mean SPL

Mean sound pressure level in a stated frequency band according IEC 60268-5 chapter 20.6

IEC 21.2 Frequency Range

Effective frequency range according to IEC 60268-5 chapter 21.2

IEC 22.4 Mean Efficiency

Mean efficiency in a frequency band according to IEC 60268-5 chapter 22.4

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

LPM multitone distortion SP1

Multi-tone distortion at high amplitudes (see Application Note AN 16) using standard current sensor 1

LPM Microspeaker T/S (SP2)

Linear parameters of microspeakers using sensitive current sensor 2

LPM Subwoofer T/S (Sp1)

Linear parameters of subwoofers using standard current sensor 1

LPM Subwoofer T/S (Sp2)

Linear parameters of subwoofers using sensitive current sensor 2

LPM Tweeter T/S (SP2)

Linear parameters of tweeters using sensitive current sensor 2

LPM Woofer T/S (Sp1)

Linear parameters of woofers using standard current sensor 1

LPM Woofer T/S (Sp2)

Linear parameters of woofers using sensitive current sensor 2

LPM Woofer T/S added mass

Linear parameters of woofers using added mass method

TRF cumulative decay

Cumulative spectral decay

TRF Elect. Impedance (Sp 1)

Electrical impedance using the standard current sensor 1

TRF Elect. Impedance (Sp 2)

Electrical impedance using the sensitive current sensor 2

TRF Harmonics current (Sp1)

Harmonics of the current signal using standard sensor 1

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

TRF sensitivity (Mic 2)

Calibration of the microphone at IN2 using a pistonphone

TRF SPL + harmonics

Standard measurement for fundamental component (SPL) and harmonic distortion

TRF SPL + waterfall

Sound pressure level and cumulative decay spectrum

TRF true acoustical phase

Total phase without time delay

DIS 3D Harmonics AN 9

Harmonic distortions versus frequency and voltage according to Application Note AN 9

DIS 3D Intermodulation AN8

Intermodulation distortions versus frequency and voltage according Application Note AN 8

DIS Compression Out(in)

Output amplitude versus input amplitude at four frequencies

DIS Harmonics vs. Voltage

Harmonic distortion measurement versus amplitude

DIS HI-2

Weighted harmonic distortion (blat distortion) used for Application Note AN 7

DIS IM Dist. (bass sweep)

Intermodulation distortion in current and sound pressure using a variable bass tone fs/4 < f1 < 4fs and a fixed voice tone f2 >> fs

DIS IM Dist. (voice sweep)

Intermodulation distortion in current and sound pressure by using a fixed bass tone f2 < fs and a variable voice tone f1>> fs

DIS Motor stability

Checking motor stability at frequency 1.5 fs (where Xdc is maximal) according Application Note AN 14

DIS SPL, Harm protected

Harmonic distortion measurement with protection

DIS X Fundamental, DC

Fundamental and DC component of displacement

DIS Separation AM Distortion

Amplitude modulation distortion according Application Note AN 10

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 Equiv. Input Harmonics

Equivalent input harmonic distortion using large signal parameters imported from LSI; Simulated results are comparable with TRF Equiv. Input Harm. (SPL).

SIM IM Dist. (bass sweep)

Intermodulation distortion in current and sound pressure by using a variable bass tone fs/4 < f1 < 4fs and a fixed voice tone f2 >> fs; Simulated results are comparable with DIS IM Dist. (bass sweep).

SIM IM Dist. (voice sweep)

Intermodulation distortion in current and sound pressure by using a fixed bass tone f2 < fs and a variable voice tone f1>> fs; Simulated results are comparable with DIS IM Dist. (voice sweep).

SIM Motor Stability

Checking motor stability according Application Note AN 14; Simulated results are comparable with DIS Motor stability.

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

SIM vented box analysis

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

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 Separation AM Distortion

Amplitude modulation distortion according Application Note AN 10; Simulated results are comparable with DIS Separation AM Distortion.

MAT Add curve (dB)

Adding the sound pressure of two curves given in 'dB'; The weighting is applied to the sound pressure.

MAT FreqTranslate

Transformation of the frequency axis

MAT Sub curve (dB)

Subtracts "CurveB" weighted with "weightB" from "CurveA" weighted with "weightA" using curves in various formats (real, complex, dB + phase)

CAL Add curves

Adds "CurveA" weighted with "weightA" to "CurveB" weighted with "weightB"

CAL Add curves (power)

Adding the power of two curves given in 'dB' considering weighting factors applied to the power of the input curves; Phase information is accepted but neglected in the calculation.

CAL Add curvs (dB)

Adding the sound pressure of two curves given in 'dB' considering weighting of the sound pressure

CAL Sub curves

Subtracts "CurveB" weighted with "weightB" from complex "CurveA" weighted with "weightA" using curves in various formats (real, complex, dB + phase)

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)

AUR auralization

Real-time auralization of the large signal performance

Standards:

  • IEC Standard IEC 60268-5 Sound System Equipment, Part 5: Loudspeakers
  • AES2-1984 AES Recommended practice Specification of Loudspeaker Components Used in Professional Audio and Sound Reinforcement
  • CEA-2034, Standard Method of Measurement for In -Home Loudspeakers
  • CEA-2019, Testing and Measurement Methods for Audio Amplifiers

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