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OT (?) installing air-core inductors

There's an obvious answer to the following question, but I thought it might be a good idea to see if someone had an even better idea.

I'm restoring a pair of the original Advent speakers. These were made in late '75 and have the first version of the crossover. The crossover and amplifier terminals are on a board that's glued to a hole cut in the back of the speaker. Other than breaking the board loose, there's no way to remove it.

All parts will be upgraded. The original iron-core inductors will be replaced with Alpha-Core 14ga air-core inductors. I doubt this will have much of an effect on the sound -- but the inductors can't saturate at high levels.

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There are two obvious ways to install them. One is to simply glue them to the board. The larger one weighs 1 pound, 7 ounces (!!!) so it has to be glued down tightly. The smaller one has to be mounted on its "side", so it's at right angles to the larger. This doesn't provide much surface area for a tight attachment.

There's no guarantee even the best adhesive won't eventually give way. I don't want to have to open the speaker in a few years and re-glue the inductors.

The other obvious way to mount them is with locking cable ties passed through small holes drilled in the crossover board. This alters the speaker in a visible way -- but it's hardly a big deal.

Any thoughts? Am I missing something obvious?

Thanks in advance.

"We already know the answers -- we just haven't asked the right questions."

-- Edwin Land

Reply to
William Sommerwerck
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Yeah, I wouldn't trust glue to hold that much mass safely... and it would be hellish to remove if you ever needed to swap them out again.

How about making some endplates out of good-quality plywood, between which you would sandwich the inductors? For the one mounted end-on to the board, make 'em circular discs, and run a non-magnetic screw down through the center into the mounting board. For the one mounted side-on, you could make the endplates with flanges which would then be screwed to the crossover board.

Reply to
David Platt

Not a bad idea. I'll give it some thought.

Reply to
William Sommerwerck

"William Sommerwerck" wrote in news:l49i6f$6ke$ snipped-for-privacy@dont-email.me:

I would be cautious about coupling between the coils. The core material in the originals would have helped to keep the flux contained. Mounting them at right angles is good, but the further apart (within reason), the better.

I haven't messed with crossover inductors, but I've seen small signal audio frequency filters do odd things when the inductors were butted up in parallel. These were unshielded ferrite core solenoid inductors (the ones that look like big carbon composition resistors).

Doug White

Reply to
Doug White

Would the Xovers ever get hotter than 50 or 60 degree C ? If never then hot melt glue. Heat the coils and the other surface with hot air gun at a low setting and then apply hotmelt glue, forms a much stronger bond than if applied to unheated surfaces. If you have to remove them later then just apply hot air and leverage

Reply to
N_Cook

They'd barely rise above ambient.

I'll consider that. The manufacturer recommends using hot-melt adhesives, so it should be okay.

Reply to
William Sommerwerck

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