Overview
Signal and System Analysis
Waveform and Spectrum
- Time domain analysis
Statistical analysis
Spectral analysis
Signal to noise ratio SNR
Magnitude and Phase Response
- Magnitude and phase response
Complex transfer function
Total phase (unwrapping, without constant time delay)
Minimal-phase, excess-phase response
Polarity
Nyquist plot
Impulse Response
- Time windowed impulse response
Step response
Energy time curve
Group delay response
Excess time delay response
Constant time delay detection
Time-frequency Analysis
- Wigner-distribution
Cumulative decay spectrum
Sonagraph
Wavelet transform
Sound Radiation and Propagation
Far Field Sound Pressure On-axis
- SPL sensitivity at 1W and 1m on-axis
Mean level in frequency band
Effective frequency range
Directional Radiation Characteristics
- Off-axis far field SPL response
Directional response pattern
Polar and balloon plots
Coverage and radiation angle
Directivity index
Sound power response
Near Field Measurement
- Extrapolated far-field SPL response
Low frequency measurements without anechoic condition
Splicing near-field/ far-field measurement
Merging multiple sound sources
Distortion measurements at high SNR
Area of Radiation
- Effective radiation area Sd
Radiation Analysis
- Far field SPL-response generated in a half space
Directivity index, sound power response
Polar and balloon plot
In-phase component (constructive contribution to SPL)
Anti-phase component (destructive contribution to SPL)
Quadrature component (no contribution to SPL)
Mechanical Vibration
Voice Coil Displacement
- Transfer-function Hx(f)=X(f)/U(f) between voltage and displacement
Linear parameters (Thiele-Small)
Nonlinear parameters
Peak, rms and dc displacement
Rub & Buzz analysis
Scanning Mechanical Vibration
- Complex transfer function Hx(r, f) at point r on the radiator’s surface
Magnitude and phase plot
Animated vibration pattern
Distributed mechanical parameters
Vibration Analysis
- Accumulated acceleration level AAL
Modal analysis (natural frequencies, modal loss factor, mode shape)
Radial and circumferential modes
Rocking modes
Scanning Geometry
- Geometry of the surface in cylindrical coordinates
Export in dxf, stl and other format
Material Parameters of Loudspeaker Parts
- Young’s E modulus
Modal loss factor
Transducer Parameters
Small Signal Lumped Parameters
- Resonance frequency fs
Mechanical quality factor Qms
Electrical quality factor Qes
DC resistance Re
Force factor Bl(x=0)
Mechanical resistance Rms(v=0)
Stiffness Kms(x=0) and compliance Cms(x=0)
Additional Thiele-Small parameters (e.g. Vas)
Visco-elastic parameter (creep factor λ)
Lossy inductance parameters (Wright, Leach, LR2 model)
Transducer Nonlinearities (Curve Shape)
- Force factor Bl(x) versus displacement x
Mechanical compliance Cms(x) versus displacement x
Mechanical stiffness Kms(x) versus displacement x
Incremental stiffness Kinc(x) versus displacement x
Inductance L(x,i) versus displacement x and current i
Mechanical resistance Rms(v) versus velocity v
Force-deflection curve F(x)
Single-valued Nonlinear Parameters
- Voice coil offset Xoffset
Suspension asymmetry Ak
Maximal peak displacement Xmax
Force factor limited peak displacement Xbi
Suspension limited peak displacement Xc
Inductance limited peak displacement XL
Stiffness Kms(x=0) at the voice rest position
Force factor Bl(x=0) at the voice coil rest position
Effective stiffness related to effective resonance frequency
Symmetry point xsym in force factor curve
Electrical Impedance
- Amplitude and phase response
Nominal electrical impedance Zn
Impedance measured by using a large signal model
Parameters of the Enclosure
- Port resonance fb
Quality factor Qlb of vented enclosure
Nonlinear Distortion
Harmonic Distortion
- Total harmonic distortion (THD, THD+N)
Nth-order component versus frequency and amplitude
Hi-2 distortion (weighted low order harmonics)
Equivalent input distortion
Intermodulation Distortion
- Nth-order difference-tone and summed-tone intermodulation
Total intermodulation distortion (absolute and relative)
Amplitude modulation distortion
Multi-tone Distortion
- Relative multi-tone distortion
Distortion-noise-ratio
Separated Loudspeaker Distortion
- Total distortion in a reproduced audio signal
Distortion generated by force factor Bl(x)
Distortion generated by stiffness Kmx(x)
Distortion generated by inductance Le(x)
Distortion generated by inductance Le(i)
Compression of Fundamental Components
- Output amplitude versus input amplitude
Thermal power compression
Nonlinear amplitude compression
DC Displacement – Dynamic Offset the Voice Coil
- DC displacement versus frequency
DC displacement versus amplitude
Asymmetrical probability function pdf
Peak-bottom value
Rub & Buzz and Impulsive Distortion
- Peak value of higher-order harmonics
Rms value of higher-order harmonics
Crest-factor of higher-order harmonics
Crest-factor versus voice coil displacement
Peak value of deterministic component
Peak value of random component
Isolated defect distortion
Noise immunity
Air Leakage Noise
- Absolute envelope of modulated noise MOD
Relative envelope of modulated noise RMOD
Peak value of random distortion RAND
Peak value of deterministic distortion DET
Crest factor of deterministic distortion CREST
Inter-channel delay time
Incident angle
Mechanical loss factor Qms
Port resonance frequency fp
Quality factor representing box leakage
Auralization
- Distortion generated by force factor Bl(x)
Distortion generated by stiffness Kmx(x)
Distortion generated by inductance Le(x)
Distortion generated by inductance Le(i)
Voice coil displacement
Voice coil temperature
Voltage, current and input power
Maximum SPL
- Tone burst measurement according to ANSI CEA-2010
Power Handling and Heat Dissipation
Accelerated Life and Power Testing
- Input power versus time
Displacement versus time
Voice coil temperature
Durability, endurance, reliability
Parameter variation over time (aging)
Voice Coil Temperature
- Variation of dc resistance Re versus time
Increase of voice coil temperature δTv
Heating and cooling curves
Thermal Parameter Measurements
- Thermal resistances of voice coil and magnet
Thermal capacities of voice coil and magnet
Air convection cooling coefficient
Eddy current heating factor
Thermal Analysis and Heat Transfer
- Increase of voice coil temperature δTv
Increase of magnet temperature δTm
Bypass factor
Power Pcoil transferred to coil
Power Pcon transferred by convection cooling
Power Peg transferred by eddy currents
Voltage and Current
- Rated noise voltage
Short term maximum voltage
Long term maximum voltage
Peak and rms value, crest factor
Probability density function
Electrical Input Power
- Real input power Preal
Power PRe dissipated on Re
Pn nominal impedance Zn
Short term maximum input power
Long term maximum power