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Vintage threads from the first ten years

about alnico speakers

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5/10/2000 2:16 AM
JC	about alnico speakers Is it true that all speakers with square back and square magnet were alnico's? JC

5/10/2000 2:39 AM
JC	I just read in the EIA thread a post about that some CTS speakers had ceramic magnets, and exhibited square back designs. So I would re-ask: How could I distinguish alnico magnets externally? Thank you. JC

5/10/2000 3:20 AM
eric	if it has a horseshoe type magent its alnico, now if its square it could be either as could the circular ones. I beleive that the horeshoe type were only alnico. by horseshoe i mean a metal u shaped magnet

5/10/2000 8:36 PM

There are a couple types of alnico magnet structures I've seen. The high end speakers, like JBL, and some of Weber's, have a huge concentric magnet sructure. The dome on the back is part of the magnet. But the most common type you will encounter has a small cylindrical alnico magnet, about as tall as its diameter, on the voice coil centerline, held in place by a surrounding steel box with 4 sides and two open ends. Some speakers have a removable domed dust cover attached over this structure, like typical vintage Jensen, which must be removed to see what you actually have underneath.

Ceramic magnet speakers usually have a cylindrical ring magnet, usually less than 1' thick or tall, held between two circular flat steel plates. Some of the CTS, and others like Advent, have the magnet in the shape of a square rather than a circle. Some ceramic magnet speakers can also have a domed dust cover fitted over the magnet structure.

Hope this clarifies.
Doc

5/11/2000 2:29 AM
JC	So alnico magnets do allways look like the alnico pole pieces on guitar pickups? I mean, is it allways "old steel" looking? No black coloured like ceramic magnets... I would like to find an url with pictures and maybe data on old speakers. That would be nice, but I haven't find any for the momment. JC

5/11/2000 3:58 AM

So alnico magnets do allways look like the alnico pole pieces on guitar pickups?
I mean, is it allways "old steel" looking?
No black coloured like ceramic magnets...

Here's the deal. Most users of AlNiCo, particularly the plug type, which is inside the horseshoe, and looks like a very large pickup magnet, specify the AlNiCo magnets with ground ends but the circumference "as cast". That means the foundry slag and 'crust' is left on the magnet. Why? Because it doesn't cause any harm and it saves them about 20 cents per magnet. Some do grind the circumference, just because it looks pretty. For instance, our R and Q plug magnets are 'as cast' but our big expensive ring magnet gets ground on the ends and the circumference. We do this despite the fact that we use a magnet cover. It just looks impressive when a person removes the cover. Commodity speaker manufacturers wouldn't bother.

Ted
WeberVST

5/11/2000 4:12 PM
Matthew Springer	>Ted >WeberVST Hey Ted, Welcome to Ampage. Maybe I should just ask you directly... I'm curious where your chassis prooducts went and if you're still planning on expanding the line. I'd REALLY like a nice Vibro-King clone chassis pre-punched and everything. -Matthew

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