Magnitude and phase response
Characteristics:  

Complex Transfer function  
Total phase (unwrapping, without constant time delay)  
Minimalphase, excessphase response  
Polarity  
Nyquist plot 
The transfer behaviour of a linear system between input and output can be described by a complex transfer function H(jω) in the frequency domain. The transfer function is independent of the spectral properties of the stimulus as long as the system behaves linearly and as long as the input and output signals are measured at sufficient SNR. The real and imaginary part of the transfer function H(jω) can be displayed as a Nyquist plot. Alternatively, the complex transfer function can be represented as magnitude and phase response. Simultaneous acquisition of input and output signal is recommended for measuring phase responses. A linear system can be described as a combination of three subsystems (minimalphase subsystem, an allpass and a subsystem having a constant time delay). The minimalphase response can be calculated from the amplitude response by using the Hilbert transform.
KLIPPEL R&D SYSTEM (development)
Module  Comment 

TRF is dedicated for the measurement of the complex transfer function by using a sinusoidal sweep (chirp) as stimulus and performing a twochannel data acquisition. In the small signal domain the transfer function (amplitude and phase response) is independent on the properties of the stimulus (spectral properties). A variety of tools for postprocessing is provided (impulse response, windowing, smoothing, timefrequency transformation, …).  
LPM uses a multitone complex as stimulus which is perfect for measuring the electrical impedance, the mechanical transfer function Hx(f)=X(f)/U(f) between displacement and voltage and the sound pressure response Hp(f) in the small signal domain.  
DIS performs a steadystate measurement of phase and magnitude of the fundamental component referred to the internal stimulus. This module is perfect to investigate the dependency on the measurement amplitude.  
SCN measures the mechanical transfer function between loudspeaker terminals and the laser displacement sensor using a sweep with amplitude profile (amplitude increases by 10db/octave to ensure high SNR at high frequencies).

KLIPPEL QC SYSTEM (endofline testing)
Module  Comment 

SPL Measurement Task (in QC Standard)  SPL measures the amplitude and phase response of the electrical or acoustical input signal using a sinusoidal sweep as stimulus. The sweep may vary versus frequency according to an amplitude profile or a user defined sweep speed to ensure sufficient SNR of the input signals and optimal resolution of the transfer function at particular frequencies. 
Impedance Task (in QC Standard)  Impedance Task measures the electrical impedance and phase using a sinusoidal sweep or a multitone complex as stimulus. 
Motor Suspension Check (MSC)  MSC dispenses with an additional small signal measurement but measures the nonlinear parameters at the rest position x=0 while operating the transducer in the large signal domain using an ultrashort multitone stimulus. It measures the electrical impedance and phase using multitone complex as stimulus. 
MultiStep Task (MST)  MultiStep Task performs a steadystate measurement using a singletone or twotone stimulus where the voltage and frequencies can be varied in each step. 
MultiTone Task (MTD)  MultiTone Task measures the amplitude response using a multitone complex as stimulus. 
Templates of KLIPPEL products
Name of the Template  Application 

TRF Scanning Cone Vibration  Manual scanning of cone vibration using a laser sensor with high cutoff frequency (>15 kHz) 
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 
TRF cumulative decay  Cumulative spectral decay 
DIS SPL, Harm protected  Harmonic distortion measurement with protection 
DIS X Fundamental, DC  Fundamental and DC component of displacement 
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 
IEC 20.6 Mean SPL  Mean sound pressure level in a stated frequency band according IEC 602685 chapter 20.6 
IEC 21.2 Frequency Range  Effective frequency range according IEC 602685 chapter 21.2 
IEC 22.4 Mean Efficiency  Mean efficiency in a frequency band according IEC 602685 chapter 22.4 
Standards:
 IEC Standard IEC 602685 Sound System Equipment, Part 5: Loudspeakers
 AES21984 AES Recommended practice Specification of Loudspeaker Components Used in Professional Audio and Sound Reinforcement
Papers and Preprints:
A. Farina, “Simultaneous Measurement of Impulse Response and Distortion with a SweptSine Technique,” presented at the 108^{th} Convention of the Audio Eng. Soc., J. of Audio Eng. Soc. (Abstracts), Volume 48, p. 350 (2000 Apr.), Preprint 5093.
G. B. Stan, J. J. Embrechts and D. Archambeau, “Comparison of different impulse response measurement techniques,” J. of Audio Eng. Soc. 50 (2002), pp. 249–262.
E. Mommertz and S. Müller, “Measuring impulse responses with digitally preemphasized pseudorandom noise derived from maximumlength sequences,” Applied Acoustics 44 (1995), pp. 195–214.
S. Müller, P. Massarani, “TransferFunction Measurement with Sweeps,” J. of Audio Eng. Soc. 2001, June, Volume 49, No. 6, pp. 443471.
D. D. Rife and J. Vanderkooy, “Transferfunction measurement with maximumlength sequences,” J. of Audio Eng. Soc. 37 (1989), pp. 419–443.