Mystery Humbucker. is there any way to determine what kind of magnet

[Snoogles]

is underneath?

 

[freefrog]

Beside their look that a trained eye can recognize rapidly, it's relatively easy to tell if a magnet under the coils is ceramic or AlNi(Co): ceramic is not conductive, AlNi(Co) is. Checking this just requires a multimeter able to measure resistance / continuity between both ends of the bar.
Differentiating AlNi(Co) alloys is much more difficult albeit measurements with a magnetometer + an inductance meter can give a clue.

 

[uOpt]

You put the magnet into a pickup where you know the magnet type and see whether the sound of that pickup changes.

 

[freefrog]

In my own experience, ceramic is relatively consistent but bars of a "same" AlNi(Co) alloy can differ noticeably according to the era and foundry involved. For instance, the dark blueish RC A5's in my SH1's from 45 years ago don't shape the tone in the same way than light grey polished A5 bars as those sold nowadays... Only lab tests could confirm these vintage bars are A5, in fact.
YMMV.

 

[Chistopher]

If you know its alnico and have a known a5 and a known a2, you can make assumptions based off how hard it is to pull off a fridge compared to those two. A5 is a stronger magnet, A2 is weaker. These are the most common magnets. There's also probably a 5% chance it could an A3, A4, or A8

What brand is it? Can you measure DCR?

 

[Señor Verde]

If there's a colored sharpie mark on the magnet, in my experiences Alnico 5 has a black mark, Alnico 2 is blue, Alnico 4 is yellow. I don't know if that is universally true though

 

[Rex_Rocker]

I think it's pretty easy to tell if it's ceramic vs. Alnico. But other than that, regarding which specific Alnico, it might be easier to find other context clues as to what pickup it is.

 

[jeremy]

i cant tell alnicos apart unless they are marked. they look the same. you can guess if you have the gauss strength, but its just a guess

 

[nienturi]

If you don't have access to a device like an XRF that can reveal the elemental composition, there is strictly no ideal way to distinguish between these metallic magnets. When I have doubts about the bar magnets I have, or if I come across an unknown magnet, here is what I do: I have very powerful Neodymium N52 magnets that I use for charging. I magnetize the magnet with them, and once I remove the strong magnets, I measure how much charge it retains. For bar magnets, if the general values are around 1200/1400G, I assume it’s likely A8; if it's around 1000G, it's likely A5; around 700/800G is A4; 500/600G is A2; and if it’s slightly below that, I consider it A3. In other words, I make an assumption based on how much magnetic load it can hold.

 

[freefrog]

A problem is that a "degaussed" (not fully charged) A5 might exhibit the same flux strength than a fully charged A2, for example. I have that kind of blurry measurements in my data. It doesn't deny the differences due to anisotropic vs isotropic alloy / less iron decreasing a wee bit eddy currents and inductance... but flux strenght alone doesn't suffice to show which AlNi(Co) is involved IME - unless one tries what nienturi explains in his post above.

Another problem is the variability of AlNi(Co)'s. I've already mentioned Zollner counting 8 kinds of A5 in his PhD thesis on pickups and concluding that "Obviously, a 'typical' Alnico 5 material does not exist". I'll add that I'm almost sure to have handled in my life vintage pickups whose magnets were made of "hybrid" alloys - as if the operator in a foundry had not poured the right percentage of such or such component in the mix, considering that it would give a magnet anyway...

At the end of the day, a destructive lab analysis appears to me as the only way to be totally sure about an AlNi(Co). And my ears as well as my measurements keep noticing differences between magnets confirmed as being of a same alloy but of different origins...

YMMV, as usual.

 

[Snoogles]

TL;DR: "no, except for ceramic"
HA!
these are 100% mystery pickups. no indication anywhere
here's my next question without starting a new post.
do certain magnet types pair better with particular DCr ranges?
and will replacing old, oxidized/tarnished pole pieces and magnet (and base-plate with threaded holes in the case of double-row slugs) with quality parts significantly improve tone using the same generic-brand coils?

 

[freefrog]

do certain magnet types pair better with particular DCr ranges?

Low DCR pickups are often paired with AlNi(Co) (lower grades, principally) and ceramic often goes with higher DCR values but for various reasons that I won't develop here, it's not a rule. DCR means nothing in itself, anyway.

and will replacing old, oxidized/tarnished pole pieces and magnet (and base-plate with threaded holes in the case of double-row slugs) with quality parts significantly improve tone using the same generic-brand coils?

Subtle tonal changes can happen with "same" parts of concretely different alloys, sizes and mass. For several reasons, a longer screw pole made of low carbon steel should give a warmer tone than a shorter screw pole made of high carbon steel, for instance. And coils won't react in the same way on baseplates made of brass, nickel silver or other materials.
Now, the exact tonal effects of such parts depend on some specs of the coils (like inductance and stray capacitance).
And the related changes can be cumulative or deny each others: that's where fine-tuning magnetic transducers becomes complex (but instructive / funny / potentially rewarding).
Oxydation in itself shouldn't make a perceptible difference unless a screw pole crumbles in rust - albeit it can bring subtle but measurable changes in eddy currents, for example.

 

[ehdwuld]

Ibanez uses ceramics in their higher wound bridge pickups

And Alnico in their lower wound neck pickups

Changing the baseplate and polepieces may help
But at that point just buying a new pickup would make more sense

 

[freefrog]

IME of these last 45 years, changing the parts of a pickup can bring a noticeable tonal improvement if the mods are based on conscious and rational choices.

 

[ehdwuld]

IME of these last 45 years, changing the parts of a pickup can bring a noticeable tonal improvement if the mods are based on conscious and rational choices.

My point was the cost of swapping to a nickel siver baseplate and premium sluga and screws may be more than just buying another one with those pieces already on it