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

        I'm certain you could shake things up, with a design like that!

        My reservations would be: the weight of the moving parts, dropping the voice coil out of center with the gap and having to fight gravity, during half of their musical excursions.

        Those old suspensions are (undoubtedly) quite limber, by now.

        However: far be it for me, to ever dissuade another from their experimentation.

                                            Ya never know!

              "...who knows who has replaced a voice coil???"

      Back in the day: we reconers were buying our parts from Waldom Electronics*.     All of their voice coils were wound with round, copper wire and they carried parts to recone virtually anything commonly manufactured.

       If their catalog/parts list didn't have an exact reference, via the speaker's ID numbers: they could be sized and estimated, to fit and function.
         
       In either case: very seldom exactly to original specs or T/S parameters.


       At the VC and cone junction: EV always used epoxy, which can't be dissolved, chemically.    That would require a reconer to replace everything, to change the VC, which should be easy to spot.    If you're familiar with the original EV components, that is.

           Old as the systems/components you mention are: anything's possible!

        *That's: IF a customer wanted to go the cheap route and not buy an OEM reconing kit, from the likes of JBL, Cetec GAUSS, Altec, etc, which COULD get pricey.

       No one is going to have OEM/EV Sentry III reconing kits, except EV  or an authorized EV warranty center..

        Anyone else would be proffering aftermarket, junk parts.    I'd never consider that an option!

        I'm in the neighborhood of 685 Miles, from Plainfield, NJ.

       btw: I still have a pair each of ST350As (w/new OEM diaphragms), 1824M drivers, 8HD horns, X8 and X36s (all 8 Ohm stuff), left over from the shoppe.

       Always did my own x-overs, but: those from EV: I just couldn't throw away, in good conscience

       I've been hoping to have another room*, large enough to merit the 15" Three Ways, that I used to build, to do Hard Rock justice.            *Doesn't appear likely!

       Speaking of which: if you really want to step up your game, with 8 Ohm 15s: get a pair of OEM, EV Sentry III woofer kits.     Everything will fit your existing 15W frame and magnet structure (NOT the 15SW), but: you'll have a much longer VC throw (more linear excursion), foam surround and less distortion.

      When I had my shoppe in Central Florida; EV was one of the companies for which I did authorized warranty repair.

       It never mattered how old the drivers might be; they always had parts to repair them.

       I suppose things probably have changed, over the past 40 years, but: it wouldn't hurt to call their Support line, and inquire.  

          https://electrovoice.com/support/repair-and-exchange/

       Then too: chances are excellent the original parts in those systems, close to your home, are still fine.  

                                      Couldn't hurt to listen to them, right?  

        You mention the 18WS seeming a, "lightweight".     I never did find anything EV designed, failing to deliver everything intended.

       If you like the flexibility that L-pads offer; there's no magic to installing them (in/out/ground, as you know) and the 8 Ohm, ceramic versions are easy to find.    Piece of cake, if you wanted to convert the Sixes from their five-position, step control.

          ie:  https://www.parts-express.com/L-Pad-100W-Mono-3-8-Shaft-8-Ohm-260-262

        Sounds as though you were looking for a way out of the temptation to play further, with your system(s).    

                                                      Sorry about that!  

       Then again, if your goal is simply seeking info and learning; too much data still isn't enough!

                                Happy listening and enjoy the journey!

       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/

     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.... 

     btw: That last link shows a driver with just one of the many magnet ENCLOSURES that EV used, over the years.

     That's not the actual magnet structure (front plate, magnet and pole/rear plate).

      Electro-voice made their 15" and 18", W Series woofers in two versions.     The WK types were specifically designed for use in corner-horn (K-type) enclosures, with a restricted enclosure volume and a horn-loaded output.

       Though they were both rated as 16 Ohm nominal: the K types spec at 3.2, as opposed to the W's 11.6, with DC.

        The W types were designed for infinite baffle enclosures.

        There were also 15BW and 15BWK versions, that had a smaller voice-coil (2") and lighter magnet structure, than the W and WKs (2.5" VC).