Measuring Speaker Impedance Curve

[Littlewyan]

I want to measure the impedance curve of my speaker cabinet so I can do comparisons with and without certain attenuators. I have a Picoscope which has a spectrum analyzer and a signal generator built in. I did a bit of reading and as I understand it I need to put a resistor in series with the speaker, connect the signal generator before the resistor and then connect the spectrum analyzer probes between the resistor and speaker AND just before the resistor? Is this right? Is it possible with the equipment I have?

[teemuk]

http://sound.westhost.com/tsp.htm