PSN-L Email List Message

Subject: Re: Speaker magnet replacement
From: "Charles R. Patton" patton@..........
Date: Thu, 14 Oct 1999 16:07:08 -0700


A quick comment on this thread.  If you find thin, single poled
crescents as opposed to dual-poled crescents (i.e., if you check one
face of the crescent, and it has one N or S pole it is single poled as
opposed to having a N on one end of the face and a S on the other end of
the same crescent face which would be a dual poled unit.), you could
easily use them to replace the ferrite magnets in the speaker if you
just place a flux bar (soft iron, cast iron, steel, basically any
ferrous, relatively high permeability metal) to fill the vertical height
to make the combination height equal to the old ferrites being replaced.

(look at following in fixed spacing type such as Courier or Line
Printer)
Sliced view from side of only 1/2 of a symmetrical structure
            +--Voice Coil Gap
            |
            V
 +--------+   +----------+
 |        |   |          | <---Original flux plate
 |        |   +----------|
 |        |     |        |
 |        |     |        | <---added flux conductor/spacer
 |        |     |        |
 |        |     |        |
 |        |     +--------+
 |        |     |        | <---new high energy magnet
 |        +-----+--------+-+
 |        |                | <-orginal lower flux plate
 +-------------------------+

P.S. You could use the dual-poled units by grinding a line on the face
to mark two equal halves then snapping the magnet into two pieces by
using a vise and a hammer or board.  The magnets are brittle and don=92t
bend, they break.  Then you could lay up the magnet pieces with the
poles all in one direction.

Charles R. Patton



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Larry Cochrane <cochrane@..............>