measuring TS parameters of metal former coil speakers

[PATTOOo]

i am using REW for measuring TS parameters for couple of months now.

i was repairing one of my friends Marshall Kilburn Woofer. After that i tried to measure T/S parameters of it.
sorry for the bad image of 2 measurements of same woofer.

whenever i measure TS parameters of metal former coil i get Zmin of 50 Ohms+ ..
is this normal ?
Qts 2.9 Woofer for ported enclosure by Marshall is it possible?
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[John Mulcahy]

You may have the input channels the wrong way around, that gives an impedance which is offset by the sense resistor value. Try changing the input channel selection.

 

[PATTOOo]

i measured this few days back. and used same setup for this also.
i will try re-calibrating my test leads.

 

[PATTOOo]

You may have the input channels the wrong way around, that gives an impedance which is offset by the sense resistor value. Try changing the input channel selection.

Thank you for the help. problem is solved.
while open leads calibrating it was going near clipping (3-4db) so i decreased level of input. and it solved the problem.

i got decent numbers now.
can you please suggest me setup for SPL measurement using U-mik ?
i should mount speaker on wooden ply like open baffle ?

 

[jschwender]

Without a baffel you don't get reasonable results. As the ideal baffle is indefinite size, this can only be approximated. So in reality your baffle will have limited size and will have an edge. At the edge there will be edge diffraction, you will see that in the frequency response. Therefore an irregular edge form, round edges with large radius or damping material helps to reduce that. If you do near field measurements, the mike distance to the speaker should be smaller than the distance to the edges.