smallest alnico and retain charge?

[ShannonH]

I was going to build a strat rail pickup, and had the wild idea of putting an A8 in it. The problem is that the magnet would be about 1/4 wide, possibly 1/16 - 1/8 thick. Will an alnico magnet that size hold it's charge?
All the rail pickups I've seen use ceramic, although I've heard of using Neo magnets too.

[David King]

I suppose if you can set the rail to act as the magnet's keeper it might help the longevity of the charge.
A-8 probably sounds as close to ceramic as anything so I don't see what you'd gain other than having to pay 10x the C-8 price.

It would be so much easier to experiment with neodymium which already comes in those thicknesses, I'd start there.

[jonson]

I split A5 bucker mags to give me 2 at 5mm x3.4mm so just under a 1/4 by an 1/8. Cutting been dealt with in an earlier thread. They hold their charge fine.

[David King]

Which way are they magnetized? Through the 1/8 or the 1/4?

[jonson]

what I'm holding is a bucker mag split so they are now perfect for my mini Dearmond size p90 and dog ear p90s. Have used them for what Shannon is wanting to do but to fit in a lipstick. Through th 1/8th to the 1/8th face, those on the table are as Harry mags.

[ShannonH]

This makes me think...

When I was dinking around with mini humbuckers, the magnets didn't quite fit between the poles and the bar. I have a 2 x 72 sander with some fine zirconium wet belts. I think I'll see if I can use it to good effect on reshaping an A5. Thanks! I'll report my findings...

[frankfalbo]

Standard Alnico rule is 5:1 ratio is optimal, anything less and the magnet will quickly settle in to a degaussed state. Continue even further and the magnet can fully degauss itself.

I have some theories I can't express here due to my company affiliation, but on a basic, broad-brushed theoretical level, one might suppose that if the magnetism has somewhere to "go" that it will retain charge better or longer. So contrast strat slugs, or mini humbucker blade magnets which are simply "out there in the air" with a base magnet that comes in direct contact with magnetic material on either end, and produces a magnetic "circuit", and the results could differ. The magnet with somewhere to go on either end-think about it-is that draining the magnet, or is it maintaning direction? The reason shortie Alnicos degauss themselves is that their own north is too close to their south. (Somewhere in there is a hermaphrodite joke) if there is something on either end that technically extends the north and south "exit points" out to the point where they're no longer in self-conflict, perhaps the conflict is avoided?

[Possum]

...

Yes, those Harry magnets are a good example. There are .20" thick and I have boxes full of them. They are charged through the thickness. Those old pickups that used alnico with those relatively thin alnico magnets all had steel base plates, or the magnets probably won't stay charged too long. By themselves they hold a very low charge, put them on a steel plate and the gauss go up.

[David Schwab]

Frank, I have a questions for you (it can be a hypothetical question). I haven't seen any Strat sized humbuckers with alnico magnets... that's not to say there aren't any, but every example I've seen use ceramics.

So if you had to guess (as to not put you on the spot), would the use of ceramics in these pickups be because that's part of the desired tone, or for magnet stability issues?

[frankfalbo]

would the use of ceramics in these pickups be because that's part of the desired tone, or for magnet stability issues?

Both. The P-Rails powers the rail coil with Alnico 5, and it sounds different than a split Rails with Ceramic. But the Rails pickups we make aren't really intended to be split. I have lots of guitars where I do split them, especially for hum cancelling with other coils, and it's usable but there's a harshness present. The rail design makes for a very tight, "closed loop" magnetic field on top as well. The field jumps across quickly. Put a Rails pickup too far from the strings and it's pretty obvious by the dramatic output drop, moreso than traditional HB or SC designs. Ceramic in the Rails pickups, when used as humbuckers (series or parallel) do the job just fine, without a lot of what we consider to be the negative aspects of Ceramic. When split, not only do you have Ceramic, but you also have a nearby blade aggressively tugging the magnetic field to the other side.

All that being said, Maricela makes a Little Pearly Gates in the Custom Shop for Billy Gibbons and anyone else who wants one, and it has an Alnico magnet (not sure what grade) Again, in that case, are the rails "closing the loop" and therefore stabilizing the field? Does the magnet settle in to a mildly degaussed state? Does she degauss it in advance, in order to stablilize it? Those are the hypotheticals.

[Joe Gwinn]

I have some theories I can't express here due to my company affiliation, but on a basic, broad-brushed theoretical level, one might suppose that if the magnetism has somewhere to "go" that it will retain charge better or longer. So contrast strat slugs, or mini humbucker blade magnets which are simply "out there in the air" with a base magnet that comes in direct contact with magnetic material on either end, and produces a magnetic "circuit", and the results could differ. The magnet with somewhere to go on either end-think about it-is that draining the magnet, or is it maintaining direction? The reason shortie Alnicos degauss themselves is that their own north is too close to their south.

The theory of design of permanent magnet driven magnetic circuits is well understood, and no secret. Consult any textbook on the design of permanent magnet circuits for details. Math is required.

[Possum]

...

I did alot of work with steel blade pickups and frankly with blades ceramics sounded better than alnico. Alnico made the blades sound too dark. Alnico 8 though might be a good choice for smaller magnets and blades, but I've not really worked with this grade at all, plus you can't really just buy real small A8 magnets that I know of the shelf. I had my ceramics custom made to about the size of the ceramics you find on cheapo Fender strat junk. I don't make any double blade buckers, Barden's got that covered in my opinion, as does everyone else. Wasn't it Lawrence that pioneered blade pickups, everyone just copied him?

[ShannonH]

Math is required.

When it comes to math, I am not a smart man.... Thus my thanks to you who know....

[Joe Gwinn]

When it comes to math, I am not a smart man.... Thus my thanks to you who know....

There is still time...

Seriously, it's only algebra and slopes, using B-H curves of the material in use.

Magnet manufacturers publish magent circuit handbooks with the procedure. Confusing at first, but ultimately cut-and-dried.

Not required is membership in a mystery cult requiring sacrifice of virgin musicians.

[Possum]

...

There are virgin musicians??? I'm convinced some people's brains are wired wrong for certain kinds of math, I'm one of them....