Jensen's

[Barry Schaede <barrys@xxxxxxxxxxxxxxxxxxxxxxx>]

Alnico has a relatively high gauss for it's weight.  It does have a 
relatively short half life as magnets go. The reason that Jensen and 
other speaker manufacturers stopped using it in the early 60's was the 
cold war. Cobalt became a strategic metal. The price went through the 
roof.  Cheaper ceramic magnets became available.  They have a half life 
of several hundred years.  BTW the P designation for the Jensen's means 
alnico.  as in P12R.  If they're ceramic speakers they're designated 
C12R.  After Jensen stopped making the alnicoIV type speakers they 
switched to using the P designation for ceramics.  The only reliable way 
to know anything positively  about Jensens is through context.  What amp 
did they come out of?  How old was it etc.  FJM