How to recone a K-33 woofer

[mustang guy]

All together, I did five K-33 recones to arrive at what I have determined to be the best overall method and adhesives. I DO NOT like using the gel superglue at all. I much prefer the Instant Mix epoxy made by Loctite. The only two places I use epoxy are on the spider glue joints (spider/frame, spider/voice coil/cone). Be sure to read through these steps before you begin.

Cut surround away from frame:

Fold back cone to reveal spider:

Cut away spider from frame:

Cut leads:

Pull out cone and spider:

Mask off former slots:

Cut gasket away from frame:

Edited December 9, 2019 by mustang guy
Moved images from photobucket to Imgur

[mustang guy]

Clean frame where gasket was removed:

Clean frame where spider was:

Wipe down entire speaker with micro fiber towel and thinner or equivalent. If you have any particles of metal from scraping, duct tape works very well to get them up. Remember, this speaker is magnetic, so a regular towel will NOT remove scrapings:

Remove masking tape, and clean out former slot with card stock:

Put some masking tape on the card stock backwards and go around again to get little bits you missed. Use a flashlight to inspect that everything is out of there!

Insert voice coil into former slot. Find something to make shims with. I used ordinary business cards. Be careful, all business cards are not the same thickness! Also, make sure they are a fairly tight fit.:

Edited December 9, 2019 by mustang guy
moved images from photobucket to Imgur

[mustang guy]

Dry fit spider onto the voice coil. If it looks good, take the spider off and apply Loctite Instant Mix 5 minute epoxy to the bottom of the spider where you glue it to the frame. This is the most critical step! It must be positioned perfectly into the frame. The voice coil will center it. Let it dry 15 minutes.

You now have a short amount of time to do the next two steps together. Pull the voice coil up into the spider, so about ¼” is protruding. Glue the spider to the voice coil and spin the voice coil around so the leads are pointing toward the speaker terminals.

Before the glue dries, shimmy the cone onto the voice coil delicately so it touches the spider. Glue the cone to the voice coil. Spin the cone a little and it will center better. Let glue dry an hour.

The next 2 steps are also done together before the glue dries. With a small paintbrush, paint Parts-Express BC-1 Black Rubber Adhesive onto the frame under the surround. Press it down with the back of a pen or something to get the surround flat against the frame.

Paint the bottom of the gasket pieces with BC-1 and stick them to the frame/cone so they lign up with the holes. Be sure to glue the BOTTOMS of the gaskets.

Invert the speaker onto a hard flat surface to let it dry evenly:

You can also clamp another speaker upside down onto it:

[mustang guy]

After it dries about 30 minutes, use an awl to make holes for the leads through the cone:

Use some BC-1 to paint the leads down onto the cone. You don’t want those vibrating! :

Center the dust cap onto the cone. Carefully measure from the surrounds that you are centered. Use a pen or pencil to trace the outline of the dust cap:

Remove the dust cap and paint BC-1 directly onto the cone just below the pencil line you just made.

Stick the dust cap onto the cone, and press it down on the edges with something like the back of a pen:

Solder the leads into the terminals being sure the wires are loose enough to not hit the spider or the cone, and tight enough to not short circuit against the frame:

Trim the leads:

Your done!

Before and after:

Edited December 9, 2019 by mustang guy
moved images from photobucket to Imgur

[CECAA850]

Great write up and pics! I've done some surrounds but never a recone, kudos.

[MikeFord]

I think the lesson for me is don't do it. I think I could manage doing a surround, maybe even a cone and surround, but spider and voice coil, not a chance.

I am curious about how the TS parameter compare before and after. Sonically is it a good move, or better to opt for a new modern speaker

What were the parts costs like?

Want some more broken speakers? (I'm in SoCal).

[mustang guy]

Thank you Carl. The drivers turned out great.

Mike. Slow and steady wins the race. This isn't a hard thing to do at all. It was scary at first. Mostly because I could not find a single source of complete information for doing one from scratch like this. That is why I made this tutorial.

The total cost to rebuild these speakers was about $50 each. I used genuine Klipsch K-33 recone kits, so they will have the same specs as factory. That is the key. Most people don't know that these are 4 ohm drivers. The Eminence 15" recone kits for these are 8 ohm.

[mustang guy]

Here is a comparison of an old square magnet K-33E woofer I reconed to a newer round magnet K-33. I removed the round magnet driver, put new seal on access port, installed square magnet driver. The yellow line represents the square magnet driver in speaker A, and the green line represents the sister speaker with the round magnet driver, and nothing done. I know the seal must have had a lot to do with the comparison, so I intend on installing a new seal on a speaker, measuring it, replacing the driver with one of my reconed ones, and posting that measurement.

[mustang guy]

OK I failed miserably on testing the before and after of the speakers. Instead, here is a comparison of the low frequency of one of my reconed woofers to the best Lascala I own.

My reconed K-33:

My best lascala:

Here's an overlay:

Both sporting an AL-3 crossover. Keep in mind, the yellow represents a K-33 which is about 10 years newer, and a 10 year newer AL-3 network.

[Don Richard]

Great tutorial on reconing, the best I,ve seen anywhere. Good work!

[djk]

The new tinsel lead should never be soldered to the eylet.

Insted, run it through the eyelet, then run it over to the side tab and solder. Then put a drop of Weldbond on the eyelet.

This is how Eminence does it now, it's much better.

[mustang guy]

Great tutorial on reconing, the best I,ve seen anywhere. Good work!

Thank you very much. It was great fun... all except for the one that I had to rip back apart. I actually did one where I glued the spider and cone to the voicecoil first. I did it that way, because most of the recone kits I see sold have those components pre-glued. I found that to be a bit problematic, as the cone didn't line up as well to the frame at the top for whatever reason. The speaker is 100% OK, but it just seemed like it inceased the likelyhood of misalignment, as you have to remove the voicecoil after glueing so as to apply glue to the spider base.

Make it a good night,

Craig

[mustang guy]

The new tinsel lead should never be soldered to the eylet.

Insted, run it through the eyelet, then run it over to the side tab and solder. Then put a drop of Weldbond on the eyelet.

This is how Eminence does it now, it's much better.

Thanks for the info. I soldered them back the way they were when I took them apart.

Could you show me a picture of one as you described to help me see what you just described?

[djk]

http://www.eminence.com/pdf/Alpha_6A.pdf

Blow up the pdf and look at the terminals.

They actually don't solder it, it's crimped. You can't do this with the old terminal style, but you can duplicate the rest.

The problem with soldering to the eyelet is that the solder wicks down the tinsel lead and that is where it usually goes open at (or at the ferrule under the dustcap). If you run it through the eyelet and solder it on the side terminal it won't wick down to the part that flexes. Don't forget the Weldbond dot on the eyelet.

[mustang guy]

http://www.eminence.com/pdf/Alpha_6A.pdf

Blow up the pdf and look at the terminals.

They actually don't solder it, it's crimped. You can't do this with the old terminal style, but you can duplicate the rest.

The problem with soldering to the eyelet is that the solder wicks down the tinsel lead and that is where it usually goes open at (or at the ferrule under the dustcap). If you run it through the eyelet and solder it on the side terminal it won't wick down to the part that flexes. Don't forget the Weldbond dot on the eyelet.

In the pictures above, there are a couple of different pictures that show the terminals before I soldered them (one where I am snipping the old leads, and a K-33B which is already cleaned). As you can see in the picture with the leads, the lead went right through the middle of the terminal. The K33B doesn't even have redundant terminals. Even the round K-33 I removed (pictured above) had the tinsel going through that little hole with solder. I cannot figure out how you could duplicate the picture in the PDF you posted with the crimp/weldbond. Do you have any pics of a vintage driver soldered in this manner? Sorry if I am being a do-do.

[djk]

Now bend the lead over to the left and run it through the hole in the terminal. Solder at the terminal only. Put the Weldbond on the eyelet.

[mustang guy]

Got it! As they say, a picture is worth a thousend words. Thanks!

[BEC]

To complicate this a bit more, looks like now Eminence uses a different terminal that gives an extra place to solder the tinsel lead. On this recent Eminence made woofer, notice the crimp terminal that the tinsel lead is bent up into. The lead is soldered to the crimp terminal and not soldered where it comes through the eyelet. Seems to be some clear adhesive in the eyelet hole.

Bob Crites

[mustang guy]

I did notice that the solder crept up the tinsel about a cm. When I get back to the shop, I'll check the two round magnet K-33's to see if they also have that problem, as I believe they are soldered the way mine are. I'll report my findings and try to take a close up to see if there are any potential fray points. With the relatively low xmax of these drivers, the tinsel really doesn't move way back at the terminal end.

[djk]

It may not be a big issue for the average home user, but it can make a big difference for high-power use.

It's easy to terminate the leads this new way so it doesn't hurt to play it safe.

I actually run a small meniscus of Weldbond from the eyelet up the tinsel lead about 3/8" or so.

The double-tab terminal Bob shows (with the new tinsel crimp) is really handy for manufacturers that parallel woofers, or wire the mids and highs (through a simple cap) from a woofer running full-range (no inductor). You would be surprised how many inexpensive speakers are wired this way.