Eminence Kappa Pro-15A - speaker driver repair [VERY LONG POST]

[momaka]

As posted a while back, I got two broken 15 inch speaker drivers from Craigslist: an ElectroVoice (EV) 815-3324 and this Eminence Kappa Pro-15A. While the EV speaker does work (albeit with voice coil rubbing noises), the Kappa Pro-15A was completely open-circuit when I got it. I thought this was probably due to operator error (either the original owner was playing it too loud or perhaps his/her amp was clipping a lot). But while surfing on eBay the other day, I found more listings for these Eminence 15 inch speakers. If I recall, one was exactly like this model (Kappa Pro-15A), while another was a Delta 15A, and also a Delta-Lite 2515. All of these were listed as not working, two of which with open voice coil. So I started thinking that perhaps this is not a random problem after all. Reason I say that is because I already repaired mine, and there are several things I suspect as a possible cause for this. So here goes a thread…
For those of you who are drinking something now, you might want to go and refill your drink here, because this could take a while to read.

As usual, I always start with the item in its “as is” condition.
Overall view:


Top view:
https://www.badcaps.net/forum/attach...1&d=1477969159
(notice how small the GU10 light bulb is compared to the speaker)

Bottom (sticker) view:


Terminals and magnet:
https://www.badcaps.net/forum/attach...1&d=1477969159

As you can see, it looks alright on the outside. But besides the completely open VC reading that I got, pushing down or pulling up the speaker cone made the VC produce a nasty scratching sound. I could even hear lots of metallic scraping noises, some resembling loose wire. Obviously noises like that are never good, so I started by removing the dust cap to see if there is anything in there that is visually wrong.

I took a carpet knife and started cutting right through the edges of the dust cap where it is glued to the cone. This is what was under the dust cap:

Yes, sirs and madams, that doesn't look good to me either!
I guess it really is time to disassemble the speaker completely.

Unlike most speaker repairs, where one simply starts tearing the old parts out and puts new ones in, I wanted to do the repair without buying replacement parts, if possible - more so as a challenge than anything else. Because of this, my goal was to not rip or destroy anything in the process. In particular, I tried to preserve anything that could later be re-used again (like the speaker cone, surrounds, spider, and voice coil former). I have rewound speaker voice coils before by hand (on small cheap 4 ½ inch speakers, that is), and it is a bit tricky, but definitely doable and fun, IMO.

So where does one start on a speaker like this?
– Normally, the cone surround; it needs to be separated from the basket/frame. Before starting that, however, I put the dust cap back on… but backwards (i.e. with the dome inverted like a cup), so that if any debris fell from the surround removal, it wouldn't get in the magnet gap. And that was indeed a good move in this case, because before I could pry the surround off, I first had to remove the paper gasket on top (which ended up being a bit messy). The removal of the paper gasket simply involved inserting a flat-head screwdriver between the speaker basket and the paper gasket, then prying away. It came off fairly easily.

Removing the surround, on the other hand, was probably one of the hardest parts about this speaker repair. The glue that Eminence used was that clear, sticky, snotty stuff similar to what bubble mail packages use, but much tougher. To remove it, I had to heat the basket and surround in portions (used my heat gun on the low setting for that) and then use a small sharp screwdriver to separate the surround from the basket/frame. NOTE: this is a very slooow process. After about an hour of prying and chipping, I got the surround off. Here is the not-so-pretty result, with the dust cap and gasket removed, and surround unglued:
https://www.badcaps.net/forum/attach...1&d=1477969159

Whew! That took a while to do (and explain too, lol). But the fight definitely wasn't over, because next came the spider removal from the speaker basket/frame. I was hoping that Eminence didn't use that snotty glue there again… but they did.

Thus, I struggled quite a bit to find a way to remove the spider easily and without damage. But to make a long thread a bit shorter, I will just jump straight to the method that I found works best, because I could otherwise type a book here on everything that I did and didn't try.

So, the method I found was rather simple after all, and without any special tools or supplies…. just needed a flat-head screwdriver, a sharp chisel, a hammer, and needle-nose pliers. To understand what I tried to do next, here is a picture:
https://www.badcaps.net/forum/attach...1&d=1477969456
Starting on the left, I first pried up (with the screw driver) on the white silicone that sits right on the edge of the spider, then used the needle-nose plies to pull it off, as seen on the right. Next, I took the chisel, placed it between the spider's edge and the speaker basket, then I gently whacked the chisel's handle with the hammer. Once the spider started to separate from the basket, I held the chisel in a downward angle (towards the basket/magnet area) and continued to hammer/chip away from the spider in a slightly right-ward direction. This helped keep the spider from ripping (though I still managed to put a few small rips on it here and there… but nothing critical.)

After lots of chipping, the speaker cone was finally ready to go. The final step in the disassembly process was to detach the flexible wires that go between the speaker terminals and speaker cone (they were held with screws, so I didn't need to unsolder anything here). Did that and out came the speaker cone.
AT LAST!!!


And here is a picture of the empty basket and magnet gap from up close:
https://www.badcaps.net/forum/attach...1&d=1477969159
https://www.badcaps.net/forum/attach...1&d=1477969159

Stay tuned as I have two more posts coming right after this one.

[momaka]

Re: Eminence Kappa Pro-15A - speaker driver repair [VERY LONG POST]

So let us see what the damage is in more detail, and decide if it is fixable:
https://www.badcaps.net/forum/attach...1&d=1477970112
https://www.badcaps.net/forum/attach...1&d=1477970112

Well, I think we can see why that voice coil went open-circuit. Looks like it was rubbing somewhere in the top plate (outer rim) of the gap, and that's probably what loosened it from the Kapton former. Then, it was just a matter of the wire getting stuck between the plates of the magnetic gap and the moving speaker voice coil hitting it and ripping it. In that first picture above, you can see that the wire broke just a little to the left of where the rubbing was going on. And you can also see the Kapton former is deformed a little where the broken wire is.

But why did the voice coil rub like that? Perhaps this was a factory defect? Or was the owner of this speaker pushing it too hard, so that the paper cone couldn't handle the power, deformed, and made the VC rub? I still couldn't understand.

Either way, look at that voice coil again! Aside from the ripped wire and scratched area, the rest of it just seems in excellent condition otherwise! So I though, why not try to fix the broken wire and see how that goes?

Before doing that, however, I checked the magnet gap for broken wire segments / turns from the voice coil - there were none. So I took the mangled wire of the voice coil and carefully straightened it out. Then, I checked for weak spots in the wire that could have been caused by any sharp bends; again, there were none. Thus, I took the loose wire that I just straightened and carefully rewound it by hand around the VC's Kapton former, just to see if the wire would be long enough to be soldered back together… and it looked like it was. In fact, the wire actually overlapped a bit at the ends (about 4-5 mm overlap.) I think the tension I put on the wire and the way I wound it around the Kapton former was probably a bit different than the factory, so that's most likely the reason why.

Generally, whenever winding a voice coil, a solid round former for the voice coil's former should always be used – especially when doing a complete rewind. Otherwise, the tension from winding the wire can crush and/or deform the voice coil former into a smaller or irregular shape, thus making it scrape inside the magnetic gap. (Been there, done that on a smaller speaker, so I know better now. ) On the VC of the Eminence speaker, there was no danger of that, since most of the VC was intact, and I only had to put three or four turns total.

Anyways, I was very gentle with this, so I am pretty sure that I did not deform the voice coil or Kapton former significantly (if at all). Then it just became a matter of stripping the coating off the broken ends on the voice coil and simply soldering them together. But before doing any soldering, however, I took the stripped wire ends and connected them together with an alligator clip, then checked the resistance of the voice coil with my multimeter. It read around 6 Ohms, which is pretty close to what the spec sheet (attached at the end of this post) has listed for the static resistance (5.23 Ohms for Re). Given my multimeter leads and the multimeter accuracy, 6.odd Ohms definitely seemed okay to me.

So the next step was to really put the voice coil back together. I started by carefully re-winding the turns of wire again, making sure they look as neat as possible. In the process of doing that, I decided to glue the wire to the VC, turn by turn, so that nothing would move around. Of course, I didn't have any special glue, so I had to think for a bit what to use. I've used wood glue before, but it was on a small 4 ½ inch speaker with a tiny 1 inch diameter voice coil (the magnetic forces from that are not too strong). But I didn't feel comfortable with wood glue for this big 3 inch diameter VC. Moreover, it had to be something that could stick somewhat to the Kapton tape former of the VC. My favorite hot (melt) glue was also a no-no, since the VC can heat up when pushed at high power levels, possibly enough to melt the glue (not to mention hot glue can degrade quickly over time and make a mess in the magnetic gap). So then I started thinking more and remembered that I had some old nail lacquer/polish that was discarded by my family a long time ago. Nail lacquer/polish dries quickly and I figured it is the closest thing to varnish used for potting transformers, so that seemed like it would have worked. It was a bit snotty due to being old, but a few drops of Acetone brought it back to life easily.

After using the nail polish to pot all of the wire turns at the end of the VC, I left it to dry overnight. The next day, I soldered the two wire ends of the ripped VC together. This is the result:


Yes, that nail lacquer job ended up looking quite ugly. But it held everything nicely and actually stuck to the Kapton former fairly okay (which is surprising, because nothing really sticks to Kapton well.) And here is the even uglier other side of the VC:
https://www.badcaps.net/forum/attach...1&d=1477970112

But who cares about how pretty that VC looks. After all, it is going inside that magnetic gap, so I could care less. The only thing that matters is that it doesn't rub and the speaker works at it should. Speaking of which, I checked the resistance of the VC again after the glue dried, and it read the same resistance as before – around 6 Ohms. Thus, I took the now-repaired VC/speaker cone assembly and put it back into the basket to check that the VC didn't rub anywhere in the gap. After some playing around (because without gluing the surround and spider back to the basket, it is difficult to have the VC stay in place for testing), I found that the voice coil did NOT rub anywhere. And then just for giggles, I decided to even do a quick live test by hooking the speaker to an audio source. Of course, with the cone loose in the basket, obviously I didn't hook it to my amp and crank it up. Actually, I just used the headphone output jack on my laptop as the audio source (used a 3.5 mm cable with stripped ends and hooked one channel to the speaker.) The speaker worked!
(Though, I should note, it wasn't very loud given the output source. )

That meant it was now time for the final step of this whole speaker repair: assembly.

[momaka]

Re: Eminence Kappa Pro-15A - speaker driver repair [VERY LONG POST]

As is often written in repair manuals, assembly process is the reverse of disassembly. In this instance, however, the assembly process turned out much easier than the disassembly. It just took multiple days to do, since I had to glue things in parts/sections and wait for the glue to dry before moving to the next part.

First part was fitting the cone/VC back into the basket and centering the VC in the magnetic gap so that it doesn't rub anywhere. Now, some YouTube videos might try to make you believe that you need to buy a special shim for your speaker to fit in the voice coil gap. That is nonsense, though! (Or at least, it's just not necessary.) Good old A4 or Letter printer paper will do the trick just fine. Here is the shim I made:
https://www.badcaps.net/forum/attach...1&d=1477970714

Basically, I cut four separate pieces of paper, with their length approximately equal to the circumference of the voice coil (3.1416 times the 3” diameter… but just a tiny bit shorter, actually, as we don't want any overlap.) This doesn't have to exact at all, though. As for the width of the paper: a few centimeters / about an inch wider than the voice coil former. This is so that the paper can be stuffed into the gap and later removed easily when everything is glued.

I ended up using only three of the four pieces of paper I cut for the shim. Basically, after inserting the second piece into the gap, it became really difficult to insert the third one. So a forth piece just wasn't necessary, as the three pieces were more than enough to space the voice coil evenly around the center pole piece. When I tried to wobble the cone sideways, the voice coil stayed firmly in place – an indication that the shim was good. Here is the paper shim from up close:


Next part was gluing the spider back to the speaker basket. Here again, I ran into a dilemma what to use for the glue. After some thinking and short experimentation, I came to the conclusion that regular bathroom silicone / caulk should work fine. And so I started gluing:
https://www.badcaps.net/forum/attach...1&d=1477970714
For those of you are wondering what that black cable is used for: it spreads the force from the clamps evenly on the spider. Basically, the cable is placed on top of the spider's outer edge, where the spider is being glued to the basket. That way, the glue (and spider) will be even everywhere. Here is a zoomed out picture that I think will help clear this up:
https://www.badcaps.net/forum/attach...1&d=1477970714
And yes, I had to do the spider gluing in sections, because I only had five clamps. Thus, I did half of the spider one day and the second half the next day. Once finished, this is how it looked:


With the spider done, the speaker cone surround was next item that needed gluing to the basket frame. Again, after a short debate, I decided to use silicone for this as well.

But if you remember that picture above with the surround and paper gasket unglued, you may have noticed that the surround edge didn't stretch very far onto the basket frame. Eminence was actually using the paper gasket to also help with holding the surround.

Thus for this particular speaker, I glued both the surround and the paper gasket at the same time. Because I had limited number of clamps and because there were four sections of the paper gasket, I did the gluing one section at a time, in a cross-pattern. Like this:


After this was all set and done, I removed the paper shim from the magnetic gap and checked if the voice coil was still aligned by moving the speaker cone up and down by hand. At first, it appeared that it was all OK. But then, when I pushed the speaker cone to near its Xmax travel distance, the voice coil rubbed on something again. I couldn't tell if the rubbing came from the outer side of the voice coil (i.e. where the wire turns are exposed, like the first time when the VC failed) or the inside (the Kapton former rubbing on the center pole). Either way, I was very surprised because I have shimmed speakers this way before, and I am sure the voice coil was centered properly. So I started thinking about the original failure again.

The first thing that crossed my mind is perhaps there is a factory defect (same one that caused the voice coil to break in the first place). Looking directly at the damaged voice coil again, we can see that the voice coil former is not perfectly round; there is a slight bump on the inner side of the VC former. In particular, there is an area where the wires for the VC are soldered to two metal terminals that then go out to the flexible wires. Almost directly on the opposite side of that is where the VC got cut and failed originally. Perhaps this deformation is what caused the VC to get misaligned at the factory when it was shimmed in the gap. (If I recall correctly from seeing a YouTube video of an Eminence factory tour, they appeared to be using a thick and fairly rigid shim for gapping the VC, which could have made the centering of the voice coil possibly even worse than my paper shim.) So I definitely think this “bump” could be the reason for the VC getting shimmed off-center (both by me and at the factory).

Or, perhaps the VC could have gotten off-center (or not going straight in the gap) because the speaker cone is made of really thin paper and easily deforms in any direction. Thus, if/when the speaker is pushed at very high powers, it may be possible that the cone looses shape and slightly alters the axis of the VC relative to that of the magnetic gap, thus making the VC rub near maximum excursion.

And yet another possibility is if Eminence didn't use enough glue/varnish (or the right type) to hold the voice coil turns to the Kapton former. In that case, the VC at the bottom of the former could have separated at high power levels, thus getting cut in the gap, and then the loose wire changed the path of the VC/former so that it rubbed.

I'm thinking the first two scenarios are more plausible, though who knows. But getting back to my “repaired” voice coil / speaker… I decided to solder the flexible wires back and then give the speaker a real test before gluing the dust cap back on. This time I used an actual amplifier/receiver: a Denon AVR-3200. With the speaker running *in free air* (no box), I could push maybe around 10-30 Watts at low frequencies (i.e. under 60 Hz) before stretching the cone to its Xmax positions. But once the speaker cone reached the upper Xmax excursion limit, the voice coil started to rub very abruptly accompanied by a nasty grinding noise. But if I turned the volume knob on the amplifier down just a notch, the rubbing disappeared again.

Of course, it is worth noting that I performed the above test with the speaker in free air. Once I flipped the speaker upside down so that the cone was facing the floor, the paper gasket created a sealed (or nearly so) enclosure with the speaker cone and the floor. As a result of that, I could push much more power through the speaker. I couldn't get the voice coil to rub at all. Thus, it is possible that with a proper speaker box, I can get a good amount of power out of the speaker before the voice coil starts to rub.

I decided that this repair is good enough for me, at least for now (since I do NOT plan on selling the speaker). So, I proceeded to gluing the dust cap to finish the job. In my case, I was dealing with a paper cone and paper dust cap, so just about any glue could be used here. For paper, I often use wood glue, but this time I used general “all-purpose” stuff, which also works well on paper surfaces.
https://www.badcaps.net/forum/attach...1&d=1477970714
And now we wait for the glue to dry again, as usual :
https://www.badcaps.net/forum/attach...1&d=1477970714

When it was all dried and done… this was the end result:
https://www.badcaps.net/forum/attach...1&d=1477970714


So now all I need is to make a speaker box. But I think that will be sometime later in the future (most likely when I accumulate enough scrap wood pieces ) and possibly in a different thread. Other than that, this is all for this speaker repair.
.
.
I hope I'm not getting annoying with these long threads. I just like to write my experiences in detail, because it often helps me remember how I did something and in case I need to refer back to that information again later in the future. But anyways, thanks for reading.

[goontron]

Re: Eminence Kappa Pro-15A - speaker driver repair [VERY LONG POST]

Good job! ive done this on my fair share of speakers. Toob radios. You can't really find the ones with field coils anymore. Well, not the correct ones anyway. If you ever need to patch a paper cone, coffee filters and paper glue. i recommend the unbleached filters, they blend better.

[diif]

Re: Eminence Kappa Pro-15A - speaker driver repair [VERY LONG POST]

Sweet repair momaka, thanks for taking the time to post it.

[Khron]

Re: Eminence Kappa Pro-15A - speaker driver repair [VERY LONG POST]

"Where there's a will, there's a way", eh?

[CapLeaker]

Re: Eminence Kappa Pro-15A - speaker driver repair [VERY LONG POST]

Nice job!

[momaka]

Re: Eminence Kappa Pro-15A - speaker driver repair [VERY LONG POST]

Thanks fellas!

If you ever need to patch a paper cone, coffee filters and paper glue. i recommend the unbleached filters, they blend better.

Nice, good to know!

Generally, I am not a fan of paper cone speakers (particularly woofers), as polymer composition is lighter and thus allows for a better response with same size magnet. That said, most of my speakers are with paper woofers/cones, so I guess it's irrelevant what I like.

Sweet repair momaka, thanks for taking the time to post it.

You're welcome!
Glad my long post didn't scare you away.

"Where there's a will, there's a way", eh?

Absolutely.
Next I will be looking at that ElectroVoice 15" speaker. But not sure when that will be. I'm thinking sometime this month, when I finish a few of my other projects, because there are too many things taken apart and "awaiting" parts/work.

Nice job!

Thanks!

By the way, I just tried the speaker again a few days ago. Man, with the cone flipped towards the floor and a hard low-pass filter, this thing works great as a sub-woofer (yes, I really meant *sub*woofer) and produces some seriously good low-end vibrations. When sitting/standing close to the speaker, it feels like a mini-earthquake is going on. And all of the loose various PC parts I have in my room start rattling around.
That said, with the speaker configured like that, I hardly get any bass above 20-25 Hz. But still a fun experiment, though. Oh, and no rubbing at all when the speaker is facing down, even when dumping a decent amount of power in it.

[Khron]

Re: Eminence Kappa Pro-15A - speaker driver repair [VERY LONG POST]

It might be interesting if it were possible to peek into the gap (with something akin to a laparoscope or some tiny-enough camera), to see if there might be some junk / imperfections at the backplate end of things...

[diif]

Re: Eminence Kappa Pro-15A - speaker driver repair [VERY LONG POST]

You're welcome!
Glad my long post didn't scare you away.

Quite the opposite, I've been a fan of big speakers and quality sound for a long time but i've never really taken the time to understand the anatomy of them.
Your thread has been great. I'd probably attempt a repair in the future because of it, although whenever glue is involved it tends to get mostly in the places I don't want it.

[kaboom]

Re: Eminence Kappa Pro-15A - speaker driver repair [VERY LONG POST]

Your audio "bug" is growing- soon you'll be building complete enclosures.

Nice job!



Sometimes silicone won't stick unless your surfaces are *perfectly* clean- in this case, solvent based adhesives may work better.

For your edge gasket/cone, this works well for something available "locally and quickly." Should be good for those spiders also.

http://www.homedepot.com/p/Amazing-G...0211/202533796

[momaka]

Re: Eminence Kappa Pro-15A - speaker driver repair [VERY LONG POST]

It might be interesting if it were possible to peek into the gap (with something akin to a laparoscope or some tiny-enough camera), to see if there might be some junk / imperfections at the backplate end of things...

Yeah, if I had the equipment, I might have done that.
Truth be told though, I didn't inspect the magnetic gap as much as I should have. I only looked for loose wire in there, but didn't really look if any of the edges on the top plate had any sharp ends or if there was dirt/debris. At a glance, everything looked okay in there, so I forgot to inspect it again a second time.

Quite the opposite, I've been a fan of big speakers and quality sound for a long time but i've never really taken the time to understand the anatomy of them.
Your thread has been great. I'd probably attempt a repair in the future because of it, although whenever glue is involved it tends to get mostly in the places I don't want it.

Thanks! That's really good to hear, especially considering how many videos and info there is online on speakers from other people.
Actually at some point, I also thought about making a video on this repair (I was thinking of starting a YouTube channel someday.) But I am really not that good at explaining things in a video - I simply forget to mention too many things and my thoughts are rather disorganized. With typing, I can edit many times (like I did with this thread.) It also helps me improve/maintain my writing skills. I'm hopeless at oral communications.

Anyways, don't worry about messing up with the glue. I've seen people do quite a mess and still get a working speaker. Plus, IIRC, you do reballing... so if you can pull off that, you can surely do this.

Your audio "bug" is growing- soon you'll be building complete enclosures.

I want to, but that takes a lot of space. And I'd have to do some reading on enclosures... and at this point, after getting done with university, I just want to take some time off from learning and only apply what I have learned already... i.e. work. (I know this is a stupid excuse.)

Sometimes silicone won't stick unless your surfaces are *perfectly* clean- in this case, solvent based adhesives may work better.

For your edge gasket/cone, this works well for something available "locally and quickly." Should be good for those spiders also.

http://www.homedepot.com/p/Amazing-G...0211/202533796

Yup, I'm sure there is a good list of better adhesives I could have used. Not to mention there's two Home Depots about 5 minutes away from my house. I just had silicone in the garage already, so that's why I used it (okay, my laziness is really starting to show now. )

You are absolutely right that regular silicone doesn't hold too well on such surfaces (unless it's the clear silicone meant for glass - this stuff is much tougher). I can easily peel it off from the speaker basket/frame. But I guess it has just enough strength to hold the spider and surround alright, even near maximum cone excursion. Moreover, I actually can't push the speaker cone all the way due to the rubbing problem, so it should hold fine like this for my needs.

The nice thing about large speakers is you don't need much excursion to get loud bass
... that is, if you have the right enclosure, of course.

[diif]

Re: Eminence Kappa Pro-15A - speaker driver repair [VERY LONG POST]

I think it was the lack of video I liked. It was more like a detailed iFixit fix, which can be far more informative.
The last 2 subs I was given were a pair of Jamos but both cones were ripped. I should have saved them and attempted a repair but with 3 already in my front room I needed the space and the boxes went to a friend.