Did my 1st ever speaker re-cone!

[tubeswell]

I have a dead 12" Jensen speaker, dated 1946 and pulled from a 16mm projector labelled US Navy, go figure, where I still couldnīt wind a voice coil that fits comfortably.

FWIW Weber has a range of coils, spiders and cones on their recone parts page something of which may well fit your old Jensen. Get the cone number off the back of the old cone and the coil number from inside the old coil and email Brian Spane in the email linked above.

[tubeswell]

FWIW, I thought I'd document the process I followed, in case anyone wants to try this at home (since this question came up on another forum):

From the Weber re-cone parts page, the parts you will need for each re-cone are:
Coil
Spider
Cone
Gasket set (you might as well have this because you'll destroy the old gasket in removing it)
dust cover dome
tinsel wire for the flying leads (2 x lengths are needed for a 15" speaker)

Email Brian Spane at Weber if they haven't got the specific part you are looking for listed on their parts page. They don't always keep all their part types listed on the page. (e.g. I know they stock cones with all paper surrounds for the JBL D-series re-cones, even though the parts pages only seems to have the JBL cones with the cloth surrounds listed - although this changes from time to time)
Ensure you have everything trimmed and dry-fit everything first before doing any gluing, to make sure that everything is resting flat with no pressure or warping.
For the adhesives, I use:
1) Fast drying superglue for bonding the spider perimeter to the basket frame. You need to apply a bead to both surfaces and then get the spider in place quickly (once you have the coil former centred properly over the gap with the correct shimming all around the gap).
2) Ados F2 for bonding the cone outer perimeter to the basket and for bonding the gasket over the top of this. Any decent multi-purpose contact cement where you can glue metal to paper should work for this
3) 5 minute epoxy for bonding the spider (and then the cone) to the coil former and for bonding the coil leads to the cone afterward (mixed up in separate batches as the work-steps dictate)
4) fast drying all purpose glue (I use Weldbond adhesive) for bonding the dust cover to the cone.

A tip for getting the coil evenly-spaced round the pole piece gap is to make a shim out of a piece of typewriter paper cut into a long strip that can go several times around the circumference of the pole piece gap (like in that 'Uncle Doug' video). The gap in these vintage speakers is somewhat narrower than more modern versions, which is what gives these speakers their efficiency, so its important to get the gap as even as you can for a good re-cone, as there isn't much room for error. The other thing is don't over-goop when you epoxy the spider to the coil. You only want a thin even bead of glue right at the perimeter of the hole in the spider to ensure the spider retains maximum flex. (This takes a patient and steady hand, so ensure you have something at the right height to rest your elbow on). The shim should be able to slide in and out evenly. Don't get the shim crooked, or the resulting gap won't be even. When cutting the shim its best to try and make it a perfect rectangular shape, so that when you roll it into a cylinder, it easily squares up. The shim rectangle should be long enough to go around the pole piece perimeter several times leaving a hair short of 2 or 3 times the exact circumferential length. The number of rolls of this paper will need to be adjusted - usually 2 or 3 circumference lengths - to make sure the shim is snug, but not so tight that it can't be removed when the gluing is finished. The depth of this cylindrical shim should be about 1" deeper than the coil former. Make sure the coil leads line up with the terminals on the basket, and make sure the coil former is positioned depth-wise into the pole piece gap so that there is enough clearance between the bottom of the former and the back of the speaker magnet so that the coil former won't knock into the back of the magnet when the cone is in maximum incursion, but deep enough so the the former doesn't pop right out of the gap when the cone is in maximum excursion.
Also, when you cut the old cone and spider out, cut around the outer perimeter of the cone and the inner perimeter of the cone (where it joins onto the voice coil) to remove the bulk of the cone first. Then you will see the spider better. Then cut around the edge of the spider near the outer perimeter with a sharp xacto blade. Don't try and scrape the spider off the basket at this stage (that comes later). The coil (along with most of the spider) should lift out once you clip away the old tinsel wire leads. Then, before you start scraping anything, cover the pole piece gap thoroughly over with masking tape (to avoid getting any particles inside the gap once to start scraping off the remanent of the spider and cone etc from the basket). You want to get all gluing surfaces perfectly clean and flat, and using a bit of coarse grit and then fine grit sandpaper is a good way to proceed (once you have finished with the scraper). Doesn't matter if you chip some paint off and go right back to the bare metal when doing this. You can always sand and touch that up with a bit of paint if you want. It really helps to keep the gap taped up during this time to avoid surplus crap getting into it. Vacuum the basket throughly before removing the tape. Then vacuum inside the gap and use the card-backed tape trick to clean out any stuff that might happen to be in the gap. You don't want anything inside the gap.


The work order is
1) removal of the old cone
2) removal of the spider and coil
3) masking tape over the pole piece gap
4) scraping and sanding all contact surfaces of the basket flat. and vacuuming everything, then thoroughly cleaning out the pole piece gap.
5) dry fitting and 'trimming' everything incrementally. (Don't over trim) including aligning the coil in the pole piece gap with the correct shimming. You can rub your thumbnail around the inner gap in the cone to incrementally burr it out to the appropriate diameter so it fits over the coil former and spider evenly without any pressure. Its better to trim parts a little bit at a time and fit incrementally, rather than trying to trim too much off all at once. The better you can get the parts fitting without any pressure twisting or warping, the better the result.
6) remove all parts and align the coil former to the correct height and spacing in the pole piece gap with the shim. The shim should be wrapped into a cylindrical shape that fits squarely into the gap between the coil former and the pole piece gap.
7) superglue the spider perimeter to the basket ensuring it is centred evenly around the coil former (some Weber coils and spiders are designed to match without trimming, but this cannot be guaranteed. Where these pieces match, the spider will fit snugly over the former, and then its a matter of ensuring the coil is shimmed properly around the pole-piece gap before gluing anything).
epoxy the spider to the coil former with a thin even bead of epoxy. Don't get any epoxy on the shim otherwise you'll feck everything up.
9) pierce 2 small holes in the cone for the tinsel wire leads (using a largish sharp sewing needle). Don't make these holes too big. They should only be barely big enough for the tinsel wire to pass through.
10) use a small dab of epoxy to hold each tinsel lead onto the back of the cone.
11) adhere the cone perimeter to the basket perimeter, ensuring the cone is centred evenly around the coil former and the tinsel leads are lined up with the coil leads/basket terminals.
12) adhere and clamp the gasket over the top of the cone perimeter ensuring the gasket spaces line up with the bolt holes
13) epoxy the centre of the cone to the coil former with the thin even bead of epoxy. Avoid getting any epoxy on the shim.
14) attach each of the coil leads to the ends of the tinsel leads inside the cone and electrically secure these connections a small dab of solder with a fine pointed soldering iron
15) epoxy each coil lead onto the cone surface with a thin bead of epoxy
16) remove the shim only when everything is totally dry
17) glue the dust cover to the cone ensuring it is aligned over the coil
18) solder the tinsel wire leads to the basket terminals and test the speaker

[Enzo]

Email Brian Spane at Weber if they haven't got the specific part you are looking for listed on their parts page. They don't always keep all their part types listed on the page.

This is a good approach for any company selling parts. The exception being those vintage/collector sites that specifically state, if you don;t see it here, we don;t have it.