Impedance Measurement – Dual Channel Method Using Transfer Function
This sequence demonstrates an alternative to the traditional SoundCheck single channel impedance measurement method. A pink noise stimulus (10Hz – 10kHz) is played through the speaker while the signal across the amplifier terminals is recorded by Direct In 1 and the signal across the sense resistor is recorded by Direct In 2. A transfer function analysis step is then applied to the recorded time waveforms to calculate the impedance curve. The curve is then post-processed to calculate resonance frequency, maximum impedance and Q of the resonance peak. A set of arbitrary limits steps are also provided to generate pass/fail results. The final display shows the impedance curve and a results window.