Electrovoice 18" Woofer: smallish Magnet; only 2.3 ohms?

     If your drivers did come out of an EV Six system: they should be a nominal 8 Ohm, far as what your amp's output will see, regardless of how they measure with DC.

     Everything changes, depending on the way the woofer is loaded and it's design parameters.

      ie: https://audiojudgement.com/speaker-impedance-curve-explained/#:~:text=Speaker%20impedance%20is%20not.... 

the prior 12/15/18 W's and WK's used huge alnico magnets

the 18" 1/2" thick foam driver uses a ceramic magnet, here are decent photos of a Model EV-Six with that foam woofer

http://www.fisherdoctor.com/ev.html

Vintage Electro-Voice Info, click on any individual image

http://www.hifilit.com/hifilit/Electro-Voice/Electro-Voice.htm

says the K versions were 3.2 ohms, "for Klipsch K Type Baffles"

OK, it's a 18WS, used in both the

Model EV-Six (4 way, 8 ohm system) 5 position resistor based optional frequency curves

https://products.electrovoice.com/binary/E-V%20Six%20EDS.pdf

and

Royal 400 (3 way, 2 AT-37 L-Pads, 8 ohm system)

https://products.electrovoice.com/binary/Royal%20400%20Manual.pdf

"a Special Woofer, 18WS, 4lb 10oz Ceramic Magnet"

I like learning this stuff, thanks for the help. That pair of Model EV-Six's is only 1 hour from my house which is why this stays in my unconscious.

       What do want to know?  

       In your first post and again 07-18-2021 10:10am: you asked about a nominal speaker spec (8 Ohm) vs a DC spec.

       Again: if your 18" woofers came out of either EV Six or 400 systems: an amplifier's outputs will see a nominal impedance of 8 Ohms, playing music into them.

       Why are you concerned about EV's magnet structures and materials, specifically?

                    Are you going to horn load your 18" driver?

     That's the only case in which you should concern yourself, as regards any K Series, EV driver.    They were designed only for horn-loaded output and a very limited, rear enclosure volume, which controls/restricts their cone motion/excursion.

           ie: Note how narrow the aperture is, in the woofer mounting baffle of the following corner horn.

                                                       
                         http://wp.volvotreter.de/projects/khorn/