I had to re-cone this speaker.

BEFORE

The NEW cone (shown below )was about 59 cents from www.electronix.com
http://www.electronix.com/catalog/advanced_search_result.php?ELECTRONIX_CATALOG_SESSID=ee646f8a9ec743b85012b926f96926f4&keywords=cones&x=0&y=0

... and it was NOT a perfect fit ....other than the outside diameter.
The pitch angle or slope was too deep. The outer edge was 1/2 inch above the basket.
So 1st I removed about 1/8" from the voice coil area... and that made it a little better/shorter. But the more I cut from that end made the opening too wide or too big for the voice coil diameter to fit properly.
More you cut the wider the opening gets... y'know?

Normally... on most other speakers that I do.. I don't worry too much about the narrow end getting wider as I trim it ...because when I remove the old cone, I usually leave a good sized diameter of old-cone around the voice coil. Typically about a silver-dollar size or maybe even twice that size or larger.

This usually allows me enough area to let me keep snipping away from the new cone's narrow opening until it drops down properly on the outer basket lip and then... where ever it fits, down at the narrow end, that's where I glue it.

But in this case most, if not all, of the old speaker cone close to the voice coil was destroyed already.

So I studied the problem a bit and realized that I really needed about a 1/4" spacer up at the wide end (top) ... to allow the outer lip to rest on "something" properly around the outside diameter of the basket.

Quite luckily... the cardboard gasket looked just right if it were 1/2 the thickness.

So I took a razor knife and slit the lamination of the gasket in half all around it.
That made 2 half-thickness gaskets.

I glued one down flat to the metal basket.
Then placed the cone in and it was resting perfectly on the new 1/2-thick gasket.

So I glued that in place too.. then glued the other gasket half on the top.
It came out perfectly!

Sounds so nice now too...lol

BTW.. you'll notice how the foam edge seems to extend upwards just past the gasket... so I'll need to use some stand-offs when remounting to prevent the foam from contact with the cabinet.