LCR meter show strange impedance values

[adason]

It depends on the inductance, that affects measured resistance
I already wrote that
If you use multimeter in ohm (dc resistance), you will get ~5-6 ohm for 8 ohm woofer

 

[JMFahey]

Around 70% of nominal value.

Nothing complicated.

What salas said in post #16

 

[weltersys]

Three feet of teflon coated 16AWG silver plated stranded copper wire are soldered to the driver tabs so the meter leads are three feet away from the driver tabs. Could that cause the crazy reading?

That length of wire should add almost no series resistance.
It sounds like you are just measuring the difference between DCR, which should be below the nominal impedance, and the impedance at 1kHz.
There is nothing "crazy" about impedance differing with frequency.
Here is an example of an "8ohm" woofer:

Re (DCR) is 5.8, rising to around 130 ohms at Fs, dropping to around 6 at 150Hz, and rising to 20 ohms at 1kHz, 60@10kHz, 80@20kHz.
Also note Le (voice coil inductance) is 3.38mH at 1kHz- Le also changes with frequency..

 

[henrylrjr]

I know that impedance varies with frequecy. I was just tryiong to clarify that my woofer was disconnected so varying frequecy was not an issue.

 

[weltersys]

OK, you have measured different impedance at different frequencies, what is or is not an issue?

This thread addresses the Le semi-inductance changes with frequency:
https://www.diyaudio.com/community/...e-model-incorporating-semi-inductance.329096/

 

[Robh3606]

It wouldn't be the easiest thing to spot a shorted turn in a resistance measurement.

Why are you assuming there is a shorted turn ??

 

[JMFahey]

I know that impedance varies with frequecy. I was just tryiong to clarify that my woofer was disconnected so varying frequecy was not an issue.

Sorry but this statement makes no sense.
Of course we measure speakers disconnected from anything else.
And like weltersys said:

OK, you have measured different impedance at different frequencies, what is or is not an issue?

 

[AllenB]

@ Robh, I'm not assuming nor expecting there to be a shorted turn.

 

[limono]

That tester is pretty much useless measuring DCR resistance of the voice coil of the speaker or DCR resistance of pretty much any coil. Some of the cheap multimeters have the same issue. Measure using regular multimeter and the reading should be within 5-6 ohms for nominal 8 ohm impedance.

 

[markbakk]

To sweep or not to sweep, that is the question. 😊

 

[NIXIE62]

Measuring the impedance of any driver requires a PC, some external parts and REW free software. I personally use LIMP and ARTA software for all measurements. Only the ribbon tweeter should not be measured this way, but add a 22-33uF bipolar capacitor, say polyester. I don't know about electrostatic speakers, I haven't tried. With the help of these measurements, it is possible to determine the actual TS parameters (bass and midrange drivers), which is useful in the construction of the box. Impedance measurement is also needed to design the crossover.

https://www.roomeqwizard.com/help/help_en-GB/html/impedancemeasurement.html

https://www.roomeqwizard.com/help/help_en-GB/html/thielesmall.html

 

[Mainframe]

I'm surprised that this is so complicated based on the numerous sites showing how easy it is. So just to clarify, if I buy a driver with a label marked 8ohm, take it out of the box, set the mutlimeter to ohm and connect the meter leads to the driver input tabs what should the results be?

The result will likely be a little less that the "rated" impedance of the woofer. You need to find the spec sheet for the driver and see if your results match the "Rdc" or "Re"

for example the Dayton RS225-8 is an 8 ohm woofer, but doing the test as you describe will get you a result of 6.5 ohms, as per 'Re' on the datasheet.