What mags for a vintage soapbar P-90?

[belwar]

The thing is .. I cant find a history of Alnico.. and I dont know if the numbering was progessive as they came up with them.. From generally online reading it apears that Alnico came out in about 1940.. But when did each of the other recipes come out? I'd be most interested to know when A5 became readily comercially available. I'm guess that Alnico was first, followed by A2, then A3, and so on. *If* that was the case, the time line would make sense that A3 was used first in the fourties, then later when A5 became available they switched to that.

You know I dont normally subscribe to this "aged" magnet thing .. but I think in this case because the magnets are in constant oposition there *might* actually be something to it.

b.

[JGundry]

These also used a braided hookup with 4 strands per platt on the outer and an orange plastic insulated inner.

Hey Spence does the orange plastic insulation resemble this at all?. The color is bluer in this pic that it is in real life.

[JGundry]

The thing is .. I cant find a history of Alnico.. and I dont know if the numbering was progessive as they came up with them.. From generally online reading it apears that Alnico came out in about 1940.. But when did each of the other recipes come out?

General Electric owned and Patented the formulations for Alnico and companies paid a license fee to make it. My guess is you could do a patent search and maybe find some dates for different Alnico grades. I know Arnold started making Alnico in 1936 under GE license.

My guess is that one reason each magnetics house had their own mix for each Alnico grade was to side step Patents held by GE.

As far as the magnetic charge dropping in a P-90. I have a 1955 P-90's that I'm quite sure has A5 magnets and the charge of the magnets was in the high 600 gauss when I took it apart. I also have a PAF that never had the cover off. When I took it apart it had an A2 magnet that read 588 gauss. Both pickups seemed to still have a pretty healthy charge after all of these years. I did notice that the magnets lost quite a bit of charge once they were out of the pickup assembly for a few weeks. The keeper bar is actually in the pickup to help preserve the magnet's charge. I have two 52' P-90's and two 56' P'90's that I have yet to take apart. It will be interesting to see what charge those have when I pull the magnets out.

[LtKojak]

Man, this thread is the most interesting in I've seen lately... please, don't stop, keep'em coming!

[Spence]

Hey Spence does the orange plastic insulation resemble this at all?. The color is bluer in this pic that it is in real life.

No, it's as orange as a Jaffa.

[Spence]

The thing is .. I cant find a history of Alnico.. and I dont know if the numbering was progessive as they came up with them.. From generally online reading it apears that Alnico came out in about 1940.. But when did each of the other recipes come out? I'd be most interested to know when A5 became readily comercially available. I'm guess that Alnico was first, followed by A2, then A3, and so on. *If* that was the case, the time line would make sense that A3 was used first in the fourties, then later when A5 became available they switched to that.

You know I dont normally subscribe to this "aged" magnet thing .. but I think in this case because the magnets are in constant oposition there *might* actually be something to it.

b.

Mishima in Japan were very much ahead of the game when it came to magnet development. But it is generally accepted that AlNiCo as we now call it as a generic name, was introduced in 1936.
There's no question that early 50's P90s were A3 with A5 coming in later when it was commercially available. If you go to a magnet manufacturer today ( one who isn't already pandering to our needs) they will offer you the grage of AlNiCo that they currently make. So you'd be looking at cast and sintered A8 and probably A9. If you ask for A3 or A5 listen out for the sharp intaake of breath before the quote or outright refusal.
Gibson and Fender for that matter would have only been able to use whatever magnet that the suppliers were making at that time.
As a point of interest, there's a rather fine article by Shi Ming Hao, K. Ishida and T Nishizawa on the Role of alloying elements in phase decomposition in AlNiCo magnet alloys which will be of great interest to those who seek answers. It's of no use to the doubters.
It's available to purchase through Springer.
Here's their first page link :

http://resources.metapress.com/pdf-p...3&size=largest

[Possum]

...

I just repaired a 1960 PAF and the magnet in it was only 400 gauss, the edge was marked with five marker lines for alnico 5, so can show up pretty low sometimes. Also my P13's are about 450 guass, they are the same arrangement as P90s' repelling eachother.
Its not really "aging" it just what charge they were when installed and how much exposure the AC fields that can degauss them. I think some of them were never fully charged to begin with, I've never found any mention that Gibson had magnet chargers.

I too, tried to research the history of alnico but the only history there is when it was invented in the late 30s, there's no timeline for the other grades. During WWII is probably when it was perfected and commonly used from what I read. In the cold war and Korean war cobalt was used in war products and restricted for useage commercially so you find alnico 3 in early Fender stuff and also in the very early 60's supposedly. The magnet sales guys don't seem to know anything, they are just resellers....

[jonson]

patents

1933 William Ruder assigned to GE. 1947274
1934 " " " " " . 1968569
The only others I found were for casting alnico in 1939 225628 and 1948 2578407.
Never came up with the different grades and maybe they wern't patented but also maybe time to look again.
Hope your gleaning some good info from that old 90 Bruv.

[Spence]

1933 William Ruder assigned to GE. 1947274
1934 " " " " " . 1968569
The only others I found were for casting alnico in 1939 225628 and 1948 2578407.
Never came up with the different grades and maybe they wern't patented but also maybe time to look again.
Hope your gleaning some good info from that old 90 Bruv.

I'll let you know this week Jonson. Got a lot of info already. Looking to reproduce it within the next month or so but the finished article will have to wait for the magnet steel order.

[JGundry]

In the cold war and Korean war cobalt was used in war products and restricted for useage commercially so you find alnico 3 in early Fender stuff and also in the very early 60's supposedly.

I think this may be another myth. Cobalt was designated as a strategic commodity due to it's importance in military and industrial applications. It is considered vital to the military and the economy in general. But I have not found any evidence that its use was restricted. The price for Cobalt was pretty high at some point and it initiated the use of ceramic magnets as a substitute for things like speakers. But as far as restrictions on it's use I don't think that ever happened.

[Joe Gwinn]

1933 William Ruder assigned to GE. 1947274
1934 " " " " " . 1968569
The only others I found were for casting alnico in 1939 225628 and 1948 2578407.
Never came up with the different grades and maybe they wern't patented but also maybe time to look again.

The alnico alloys were all patented, but may not have used the word "alnico" anywhere. Some books on permanent magnet materials will give the history, with the names of the inventors, and possibly the patent numbers.

[voodoochild]

No disrespect but why really care what was used originally. It could have been A5, A3, whatever. My assumption has always been A3 but there is no definative proof. Magnets are made different today anyway so you won't ever be exact. Plus magnets are cheap enough to experiment with rather than waste time researching what could be complete garbage to begin with. When it comes to re-creating the wheel, its rather simple to change materials such as magnets and compare to an original sample until you hear the right sound. No rocket science or research needed beyond that I don't think. Please don't get me wrong as I think its very interesting to know these things but when it comes to making them it doesn't need to be that complicated.

[JGundry]

I think it's another myth that Alnico of today is different from what was made in the 50's. The main problem is finding a place that will make rough sand cast magnets the way you want them. The rest just comes down to the difference in formulations between different magnetics houses. Most of the places that supplied Gibson in the 50's are out of business so getting the same formulations comes down to custom ordering your magnets. Talk of purer raw metals being used in the 50's does not really make sense. Iron, aluminum etc.. has always had a value for scrap and has always been used and reused. There is a difference in foundry methods for steel now but magnets are pretty small scale in comparison and the processes of the 50's can still be duplicated.

[Possum]

...

Well, regardless cobalt disappeared from strat pickups briefly in the early 60s from reading I've done. Cobalt increased in price during war years so you know how cheap these guitar companies are. Early Fender stuff used A3 but simultaneously used A5 in the same time period. I have '51 Nocaster pickup here that reads 1200 gauss, no way is is A3.

The vintage magnets really are different enough, certainly from what China is making. the alnico 5 magnet in the '60 PAF would only charge up to 590 guass, thats pretty low compared to modern A5 which will charge up to 700+ guass.

The "pure" elements thing is not a myth, Arnold Magnetics in an issue of Tonequest wrote that they analyzed magnets from China and found alot of garbage in them that didn't belong, even "floor sweepings" according to them. But yeah, why spend alot of money and go nuts trying to make magnets like ye olde days. Arnold's magnets are vintage formula of their own and they are noticeably less bright than the Chinese stuff. But their magnets can yield dull sounding pickups too, I have some A2 bars that just don't seem to work well in anything so far.

[voodoochild]

I think it's another myth that Alnico of today is different from what was made in the 50's. The main problem is finding a place that will make rough sand cast magnets the way you want them. The rest just comes down to the difference in formulations between different magnetics houses. Most of the places that supplied Gibson in the 50's are out of business so getting the same formulations comes down to custom ordering your magnets. Talk of purer raw metals being used in the 50's does not really make sense. Iron, aluminum etc.. has always had a value for scrap and has always been used and reused. There is a difference in foundry methods for steel now but magnets are pretty small scale in comparison and the processes of the 50's can still be duplicated.

I can partially agree with that. Problem being that no one supplies rough cast like the old ones at a reasonable price and low MOQ. As a smaller operation, you are forced to work with what you can get. That said I could care less about having the exact formula made if I can get more than satisfactory results with "off the shelf" materials. BTW today China sand blasts one side of the magnet to fool you into thinking they are rough cast. I have seen this from one Chinese supplier and they admitted this was how they did it. Cool looking if someone is going to destroy your pickup and see, but makes no difference in sound for the extra cost involved.