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

For me, the magnet is too small to control the mass of the woofer cone well. As far as dc resistance, also too low. I've never seen any woofers rated at 8 or 16 ohms read 2.3 ohms dc. I'd be very leery. Unusually low resistance could be indicative of a partially shorted/damaged VC from excess driving. Are you saying your 8 ohm woofers read 3.5 ohms dc?

fiesta, thanks for your reply, we agree, magnet for 18" seems too small, part of the job is to control it after moving it!

 and something is wrong with the impedance readings.

I never measured my 15W's. I know Electro-Voice made mine, 16 ohm version, (based on being in an all 16 ohm 3 way system made in 1958) and, from their service bulletin which shows they also made an 8 ohm version.

the last link was to show what my 15W LOOKS like, see the monster magnet I'm referring to. That seller's meter shows his 15W as 3.5 ohms, also makes no sense to me.

I have a spare 15W downstairs, seller said 16 ohm version, I am realizing I should check it. I also have a spare cone/coil kit, I suppose I should measure it if specs are not in the box, I never opened it.

Yes, I see what you mean about the magnet size. One thing that shocked me was the last link of the 15W’s, the WK & BWK’s models say 3.2 ohms dc for a 16 ohm impedance. Maybe a misprint or I just learned something new. Not seen any 16 ohm speakers to read below 5.6 ohms or so dc in my 40+ years...?

      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).

     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).

That would be resistance not impedance. Efficiency was a major factor back then because amplifiers were not that powerful. If you are stuck on flea watt amps these old drivers are great it they are in decent shape which is unlikely. Most of them will require remanufacture at some level. 
I can understand collecting old cars they are art but not old audio equipment. Modern material science has improved drivers particularly suspensions. There are many modern High efficiency woofers available up to 32"! https://ds18.com/products/tm-sn32-32-troublemake-subwoofer?currency=USD&variant=13961390850109&a...

rodman99999

thanks for the clarifications. 

Now I see the spec sheets have a separate DC resistance line, thus the 15W link I posted must be a 15WK.

The 18" drivers I found, the foam ones in the Model EV-Six are NOT 18W or 18WK

18W and 18WK are bigger versions of my 15W (or 15WK), with monster magnets as you would expect

https://www.manualslib.com/manual/43604/Electro-Voice-18w.html

the Model EV-Six has 1/2" thick foam cones, the smaller magnets.

I don't know what their impedance was, or, if the DC resistance of 2.4 ohms is 'good/normal' or problematic.

??? Anyone know the specs of the 18" 1/2" thick cone driver???

here is a 18Wk (see the small k stamped into the label) from a Patrician

https://www.ebay.com/p/28028667707?iid=254883146782

     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/

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

                                Happy listening and enjoy the journey!

rodman

I seek active discouragement, knowledge always a push/pull, experience from others here 'smartly sought'.

from the temptation of a pair of Model EV-Six's only 1hr, 20 minutes away.

https://www.ebay.com/itm/154513478054

I was thinking of building new enclosures for them that would replace my existing 'all electro-voice' speakers shown here (drivers from a 1958 Fisher President II that was my uncle's)

https://systems.audiogon.com/systems/9511

give the current ones to my Son; sell the old; or use for a while, then sell the 'new' ones.

I'm drawn to both the bigger 18" woofer (I have 15W now), but also the very rare resistor based network they use for 5 optional response curves. (Royal 400, 3 way, uses L-Pads)

Also, the Model EV-Six is 8 ohm (I understand nominal). That would let me move to a tube amp with external bias meters (my existing speakers are 16 ohm nominal, the version one Cayin A88T has 16 ohm taps, internal bias adjusters).

Or should I say, WAS drawn. I cannot find any info about re-coning those 18WS woofers, so that's that. This 18WS now seems a lightweight comparatively.

I recently installed new 16 ohm L-Pads, hard to match L to R, took me a few weeks, but the match to my room is probably better than one of the E-V Six's fixed response curves anyway. 

No, no way, but .... 

      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!  

rodman

good thinking, my son’s suv is gassed up!

I wrote EV, let's see what they say. I also asked what currently available 18" woofer could be substituted for the 18WS.
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Have a laugh: I just instantly schemed this: mix 18" WS with my existing 15W, like adding a pair of 18" subs

new wide rolling box, like a square or round pedestal. fit’s width of the 18WS facing/firing down (avoid eventual surround sag/voice coil rub). big hole in the top

sit my existing speakers on top, 15W; mid horn with it’s L-Pad; T-350 with it’s new L-Pad.

cut matching big hole in the bottom of existing speakers, so air spaces are joined to around 11cf

low feed from existing crossover: split very low out to 8 ohm L-Pad to 18WS, add 16 ohm L-Pad for 15W, now 4 L-Pads each side (hear lewm screaming?) and the joy of getting L/R to match.

Oh yeah, I have my existing rear port I could mess with too.

Saves a lot of carpentry. All Vintage, just a Late Idea Electro-Voice never came up with.
...........................................

It needs a name, anyone?
.........................................

Put a new modern 18" in the Model EV-Six boxes, sell them with no real concern about the nearly non-existent 18WS.

did I recently say "too clever" somewhere?

did I forget to say I am not looking for more bass, it's just .....

       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.

rodman

I am only finding foam repair kits, you are referring to voice coil, cone, surround correct?

source?

I’ve got a spare 15W ready to go, and a 15W needing a new cone right now that I will eventually repair. I have a 15W coil/cone/pleated fabric surround kit ready for it, but trying this sounds interesting.

Of course I've got spare horns ready, and they can be more readily found in the future by my great grandchildren I hope!!!

rodman, all

I just noticed, that pair of EV-Sixes near me: it's a pair of identical Mono Boxes, they are not mirror images like Stereo Pairs are.

https://www.ebay.com/itm/154513478054

clearly it's hard for me to keep my eyes off them.

rodman,

how close to Plainfield New Jersey 07062 are you?

E-V says no parts or help with 18WS available

I have four pairs of electrovoice speakers and none of them measure that way. The dc resistance is way higher than that in all cases so i would be leery of a fake 18 inch woofer for sure especially if the magnet is small, ev did not use small magnet assemblies in any of their woofers.

speakermaster

they are original E-V 18WS Woofers, used in both the E-V Model Six and the Royal 400 models.

have a good look inside

https://www.ebay.com/itm/154513478054

loose

https://www.ebay.com/itm/254646609730?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc...

I have not come across all specs of the 18WS, but these are genuine IMO.

Royal 400 Specs: 8 ohm impedance, 4lb-10 oz ceramic magnet, which is why it appears so small, compared to my 15W's physically larger Alnico type magnet at 5-1/4 lb.

DC resistance of my 16 ohm 15W is 11.6 ohms; the 16 ohm 15Wk (klipsch baffle version) DC resistance is 3.2 ohms, 

https://products.electrovoice.com/binary/15W,%2015BW,%2015WK,%2015BWK%20EDS.pdf

then, when buying replacement 15W, I will need a DC reading to verify it is not the K version. Seems they simply stamped the label with a lower case k, and who knows who has replaced a voice coil???

I'm gonna measure my spares someday.

       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.

              "...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.

rodman,

I hope you got a kick out of my Bass Base Idea, I did.

        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!

I've kept my 63 yr old E-V speakers going myself for 48 years, and have spare drivers for my great grandchildren, that's why these E-Vs intrigue me.

If I wasn't so crowded here by the 4,000 lps I just inherited, had the space to store them until I got to it, I probably would have those Model EV-Sixes stacked here already! 

I generally want forward facing, no ports, but this quickie idea, I considered the18WS facing down.

1. key to the design staying shorter
2. one 18WS eBay seller said surround sagged, in one position the coil rubs
3. my 15Ws started their life facing down in Fisher President II, up on 8" bronze legs. Never a coil rub, strong bass. That way 1958 to 1973 when I inherited them.
4. new identical but separate enclosures 75-1985, still facing down.
5. current enclosures, moved vertically 1985-now. Strong bass, discovered bass can be directional, yeah. 
6. 1980 had refurbed, coils and cones, by pro, a voice coil rubbed, he re-did them. 
7. I refurbed coils and cones myself twice over 40 years, vertically, never a rub.
8. I inspect them every other year, never a sign of weakness or sag from surround
9. one cone dried out, near hot air heating vent (since replaced with new damper vent)

I could design nice enclosures, I'm an Interior Designer, specialized in Corporate Office Space, designed and had built a lot of custom furniture and millwork over 46 years, and have current experience with a very good local custom woodworking firm.