Ceramics vs Alnico
When I read that
ceramic magnets sound harsh and alnico magnets sound sweet, I ask myself,
" Who the hell preaches such nonsense?" There are harsh-sounding pickups
with alnico magnets and sweet-sounding pickups with ceramic magnets and
vice-versa! A magnet by itself has no sound, and as a part of a
pickup, the magnet is simply the source to provide the magnetic field
for the strings. The important factor is the design of a magnetic circuit
which establishes what magnet to use.
Though ceramic magnets cost less than alnico magnets of equal size, a
well-designed magnetic circuit using ceramic magnets costs much more than
the six Alnico 5 magnets of a traditional single coil pickup!
Before the introduction of alnico magnets in 1935, permanent magnets were
not quite that permanent. During a certain time, they lost a good amount
of magnetism till they finally reached a stable condition. The process
to accelerate this decay was called in the industry, "magnetic aging."
In modern science, it is called "stabilizing." Since the ‘50's, we use
Alnico 5 magnets which lose, under normal conditions, less then half a
percent per 100 years.
How do we achieve normal conditions?
Alnico magnets are shipped by the manufacturer in a non-magnetized condition
and will not be magnetized until a pickup is completed.
How to maintain normal conditions?
avoid any close contact with other pickups or magnets facing either north
to north or south to south with their magnetic poles. Don't ever throw
pickups random in a drawer; you may either use a keeper on each side of
the magnetic poles or carefully place them with the north facing the south
pole of the other magnet. ( For tele players, remember that the iron backplate
of a traditional tele pickup functions as a keeper which increases the
stability of the magnets.)
Once pickups are in a guitar, there is very little to worry about. That
your pickups lose some of their magnetism when you lean your guitar against
an amp is nothing but a fairy tale. Or, that pickups lose some of their
magnetism when you drop them on a concrete floor is just another fairy
tale -- alnicos and ferrites will break before they have any measurable
losses. Magnets are sensitive to heat, but so is your guitar. However,
heat can be a severe problem when an Alnico 5 magnet is exposed to temperatures
above 1000 F, approaching its Curie temperature of 1634 F. At these temperatures,
Alnico 5 undergoes structural changes and cannot be re-magnetized. Why
do I mention this? Because it happens quite often, when someone doesn't
like the unbalance in output of a pickup with staggered magnets and goes
to a bench grinder or a belt sander to grind a magnet down. You take a
chance that a magnet gets too hot and becomes damaged.
© 1996-2010 Bill Lawrence