LE5-2 AlNiCo vs LE5-5 Ferrite
Ferrite magnets are ceramics made primarily from iron and boron with a small amount of strontium. By weight they are stronger than steel or Alnico equivalents but less so than neodymium magnets. Like all ceramics, they are quite brittle & will easily break if dropped onto a hard surface. They are the most economical for their strength.
Can anyone comment on the truth as to why JBL dropped the AlNiCo magnet and went into production with the ferrite magnets?
Cost or greater magnet strength w/less distoration?
JBL Marketing seemed to focus on the later...
What was the JBL Development / Engineering scoop?
Re: LE5-2 AlNiCo vs LE5-5 Ferrite
Quote:
Originally posted by magnet
Can anyone comment on the truth as to why JBL dropped the AlNiCo magnet and went into production with the ferrite magnets?
This has been discussed at length on previous threads. The reason JBL retooled their entire line was due to a civil war in Zaire where most of the world's cobalt comes from.
Here is a post Don made on the subject.
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Here's the skinny on the Alnico crisis of 1978. The geographic center of this situation was the Kolwezi mining region of Zaire. At the time, Zaire accounted for over 60% of the world’s production of cobalt. In 1977, rebels calling themselves the Front for the National Liberation of the Congo, invaded from Angola. In May 1978, the cobalt mines in Kolwezi were taken by the rebels and flooded. Zaire’s cobalt production was effectively shut down. Considering that most of the remaining cobalt producers were either behind the iron curtain, or tied up by the defence industry due to the strategic value of the metal, the net result was that cobalt was pretty much eliminated from the commercial market.
Regarding JBL (and I assume the other speaker manufacturers), they were told by their magnet suppliers that Alnico magnets would not be available once the current stock was depleted. Greg Timbers (who was at JBL at the time) stated it wasn’t a matter of cost. Their magnet suppliers could not provide any new quantity of Alnico magnets. There was enough stock to continue production for a limited time, but a rush program was developed to convert the bass drivers to ferrite magnets since they represented the largest consumption of magnets. In less than a year, the SFG magnet topology was developed and put into production.
By 1979, France, Belgium and the USA had interceded in the civil war and the cobalt mines were back in production – albeit at reduced output. Alnico magnets became available again at higher cost. JBL continued the manufacture of Alnico compression drivers until 1981, when it was decided that the economies of switching to ferrite could no longer be ignored.
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Regards
Don McRitchie
