How to ID bar magnet?

moshuajusic

moshuajusic

New member
I found a humbucker pickup magnet in the drawer. No recollection of where it came from. It's probably A5 or ceramic. Any way to determine magnet type before installing? It's dark grey, with white paint (or marker?) on one of the long edges, and what looks to be a small, faint blotch of the same white paint on one of the wide surfaces.
 
Re: How to ID bar magnet?

Ceramics are black and Alnicos are gray. Between the Alnicos the only way to test them is by comparing the strength of the magnet to that of known magnets by pulling off the side of a fridge or something else magnetic.
 
Re: How to ID bar magnet?

I found another one. lol Looking at these, my guess would be ceramic + alnico 2. Is that right?

IMG_0501.jpg
 
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Re: How to ID bar magnet?

There's a simple way to be sure about ceramic (ferrite): a digital multimeter set for resistance measurements shouldn't show any reading with the magnet between the probes (while an AlNiCo bar would allow a resistance reading since it's made of a conductive alloy).

There's no way to be sure about AlNiCo grades but some COMPARATIVE measurements might give a clue. For example, A3 typically hosts the weakest charge and gives the highest inductance while it's the contrary with A5. A2 and A4 are in between... Now, these explanations hold the water ONLY if the mags have strictly the same mass and have been magnetized in the same way. :-)
 
Re: How to ID bar magnet?

freefrog said:
There's a simple way to be sure about ceramic (ferrite): a digital multimeter set for resistance measurements shouldn't show any reading with the magnet between the probes (while an AlNiCo bar would allow a resistance reading since it's made of a conductive alloy).
Click to expand...

"allow a resistance reading"? Not sure what you mean by that.

I think you're using the term "resistance" incorrectly. What you said would be correct if you were talking about "continuity"...just the opposite of resistance. Ceramic will measure a very high resistance (no or low continuity), and the alnico would show little or no resistance (depending on the multi setting)...the meter display would probably show "--" indicating continuity (no resistance).
 
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Re: How to ID bar magnet?

freefrog said:
A3 typically hosts the weakest charge and gives the highest inductance while it's the contrary with A5. A2 and A4 are in between...
Click to expand...

And that's exactly what we HEAR when we put them in a humbucker: alnico 3 is the weakest and alnico 5 the strongest with A2 and A4 being between.

I wonder why alnico 2 isn't called alnico 3? And alnico 3 called alnico 2?
 
Re: How to ID bar magnet?

GuitarDoc said:
"allow a resistance reading"? Not sure what you mean by that.

I think you're using the term "resistance" incorrectly. What you said would be correct if you were talking about "continuity"...just the opposite of resistance. Ceramic will measure a very high resistance (no or low continuity), and the alnico would show little or no resistance (depending on the multi setting)...the meter display would probably show "--" indicating continuity (no resistance).
Click to expand...

This is the equivalent of saying not to measure how cold something is because temperature is measured in heat.
 
Re: How to ID bar magnet?

why is alnico3 even called alnico since there isnt any cobalt in it
 
Re: How to ID bar magnet?

jeremy said:
why is alnico3 even called alnico since there isnt any cobalt in it
Click to expand...

Totally agreed.
Reason why I've wrote "A3" in my previous message, in fact.
I write "AlNi(Co)", with "Co" between brackets, when I don't post on a hurry like this morning (and when I find lexical precision constructively useful). :-)

GuitarDoc said:
"allow a resistance reading"? Not sure what you mean by that.

I think you're using the term "resistance" incorrectly. What you said would be correct if you were talking about "continuity"...just the opposite of resistance. Ceramic will measure a very high resistance (no or low continuity), and the alnico would show little or no resistance (depending on the multi setting)...the meter display would probably show "--" indicating continuity (no resistance).
Click to expand...

Possible answer, if I wanted to argue: "I meant exactly what I said: under normal physical conditions, every normal material has a resistance, even AlNiCo (it's very, very low... but it's not "continuity", which would be possible only with a SUPRAconductor). If a DMM reads 0.00, it's due to the limitations of the measuring tool and/or to a simplification of the result."

Actual answer: would it be fructful to fall in such an argument? I’ve too little free time for that (like you, I guess) and my only goal when I post here is to share, anyway... so, any imperfect wording due to my hasty answers in a foreign language isn't really a problem as long as my messages are understood - as it appears to be the case below with my previous post… :-)
 
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Re: How to ID bar magnet?

freefrog said:
There's a simple way to be sure about ceramic (ferrite): a digital multimeter set for resistance measurements shouldn't show any reading with the magnet between the probes (while an AlNiCo bar would allow a resistance reading since it's made of a conductive alloy).
Click to expand...

I never realized that. I just tested it and it works. My known ceramic reads in the mega-ohms, while my alnico reads a dead short. Good info.

Lewguitar said:
And that's exactly what we HEAR when we put them in a humbucker: alnico 3 is the weakest and alnico 5 the strongest with A2 and A4 being between.

I wonder why alnico 2 isn't called alnico 3? And alnico 3 called alnico 2?
Click to expand...

My understanding is that the "alnico" number comes from its creation date. Not it's magnetic strength. I've a got a "white paper" on that around here somewhere. I'll see if I can find it.
 
Re: How to ID bar magnet?

ArtieToo said:
I never realized that. I just tested it and it works. My known ceramic reads in the mega-ohms, while my alnico reads a dead short. Good info.



My understanding is that the "alnico" number comes from its creation date. Not it's magnetic strength. I've a got a "white paper" on that around here somewhere. I'll see if I can find it.
Click to expand...

Just in terms of how they make a humbucker sound, they do make the pickup sound stronger as you progress from alnico 2 to alnico 4 to alnico 5.

Alnico 3, though, makes a humbucker sound weaker than alnico 2.

They each seem impart their own tone or EQ curve to a humbucker too.
 
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Re: How to ID bar magnet?

Take it to Paul Reed Smith. He can rap on it with his middle knuckle and tell you exactly what the magnet is going to sound like...
 
Re: How to ID bar magnet?

Last question: they look like they're from a 7-string. Could I use a rotary tool (or something else?) to cut them to 6-string length? Or would that somehow screw up the magnetism?

They're cheap enough I can get new, but I don't mind a little handiwork.
 
Re: How to ID bar magnet?

magnets dont usually like to be cut once charged. how long are they? 2.5" is typical but there have been slightly longer mags used in 6 strings too.

ive heard a3 rods are stronger than a2 rods of the same size but dont have actual evidence of this.
 
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