Is it possible to measure Impedance with an ohm meter. For example can you measure the Impedance of a 4 ohm car speaker with an ohm meter? When I tell people they cannot measure Impedance with an ohm meter, you need an impedance meter and the impedance must be measured with the speaker in operation, with a signal generator supplying a fixed frequency, this always leads to disagreements with the person who demands an ohm meter to measure what he calls Impedance, when I tell him an ohm meter can only measure the resistance of the coil there is always disagreement. I tell them Impedance is AC resistance and what they measure with an ohm meter is DC resistance. Disagreement here again. Will somebody take me up on this and clarify the situation. Thanks in advance Denny B
A quick search on google tells me that typical voice coils have an inductance in the 100 uH range. Your impedance is sqrt(Zdc^2+Zac^2) with Zdc what you measure with the ohmmeter (resistance) and Zac the contribution of the inductance of the coil. Assuming a working frequency of f~500 HZ, then the impedance of the inductor is 2*L*\pi*f=1 ohm (assuming an inductance L of 320 uH) so the AC contribution is not negligible compared to the DC resistance in the calculation of the total impedance. Jean-Michel
