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[Dan Brandesky]

I have a pair of EV model 848 horns, one of which had a blown diaphragm when I bought it. I purchased a new replacement diaphragm online, and I'm in the process of installing it now, but I ran into a slight problem: while removing the old diaphragm, I had to heat and peel away the old gasket (apppears to be some sort of flexible fiberboard-type stuff). While peeling it off, I didn't notice that the gasket seems to have 2 layers, and only one of them peeled off, so basically I destroyed the other layer while trying to get the diaphragm out (which was also glued in).

So basically I only have half the gasket thickness for the replacement diaphragm. Is this going to be a major problem if I just put it in as-is, or should I hunt down a new gasket?

Also, what kind of glue should I be using to put these in? I was thinking of something mild like Elmer's so it doesn't take a heat gun to get it back out like it did this time.

Thanks,
Dan

[Mike Smith]

Dan,

It's been a lot of years since I was inside one of those old EV drivers, but here are some thoughts:

Do NOT reassemble without gaskets or shims of the correct thickness. The bottom one sets the voice coil winding at the right depth into the magnetic gap, and the upper one helps the top cover clamp down on the diaphragm mounting "lip", holding it in place and preventing spurious vibrations.

I don't think Elmer's is what you want to use. EV probably used their go-to adhesive, Scotch 847. It is the brown rubber cement they applied to everything from speaker assembly soft parts to name tags. It is quite tenacious and sticks to metal, paper, and everything in between.

Alternatively, we also used to see non-hardening cements or sealants used on the diaphragm shims, especially in later drivers that had plastic shim rings instead of fiber. The modern equivalent would be Hylomar, which is also used in the repair and reconditioning of old British sports cars! It stays sticky forever. You can find Hylomar at better car parts stores.

That's all I can remember right now.

[Dan Brandesky]

Thanks, that was what I was afraid of. The diaphragm actually was glued directly to the flange, with the 2-ply gasket glued on top of that, between the diaphragm and the magnet. I suppose I'll call EV tomorrow and see how many limbs I'll have to sell to get a gasket out of them...

-Dan