On October 29, 2019 at 08:28, highfigh said...
You can measure the voltage drop across a resistor at a fixed frequency, but it's not possible to easily measure actual impedance. You can measure the DC resistance and get a ballpark idea of the total, though- an 8 Ohm speaker will measure roughly 6 Ohms when a multi-meter is used.
Parts Express had a piece called WT-3 (now upgraded to the DATS v3) and it will gather the Thiel-Small parameters, including an impedance plot.
It may not be important to your needs but speakers will measure a variety of different impedances at different frequencies, hence the comment about the impedance plot. And often that same driver will measure differently in open air vs in a loaded cabinet. So the term "nominal" is a ball park figure to suggest where the appx impedance range of said driver is.
For parallel-series calcs, and its effect and load on an amplifier, sometimes the D.C. resistance is usually good enough, unless you're on the threshold of an amplifier's tolerance, then maybe it's not good enough
