Measuring impedance with multimeter


I am measuring a new full range speaker impedance that is advertised as 12 ohms and I am getting  a consistent reading of 4.2. 

I checked the multimeter on another bookshelf speaker advertised as 6 ohms nominal and I get exactly that.

I am using a multimeter at the speaker leads not connected to amp.

Why is this reading so low?
recluse

Showing 1 response by atmasphere

So is there no instrument that can be acquired without breaking the bank for nonEE to broadly measure impedance, or in this hobby where snake oils are rampant does everyone blindly except vendor claims?
You need a sine wave generator and probably a 100 ohm potentiometer in addition to your meter.


The sine wave generator drives the speaker, which is wired in series with the potentiometer; the latter only uses the center lead and one other lead.

Set the meter to AC volts.


You adjust the pot so that your meter reads the same voltage across the speaker terminals as the across the pot. Then remove the pot from the circuit and measure the DC resistance- that is the impedance of the speaker at that frequency.


So you need to do this a bunch of times but with a bit of graph paper you can draw up the impedance curve.