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Tempering


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3/5/2004 12:58 AM
Jeff
Tempering
Awhile back, there was a discussion here regarding the tempering of magnets. I can't seem to find it (gonna have to start saving the stuff on my 'puter).  
 
Could someone describe how and why this is done? I think I understand tempering/annealing as a concept, but I'd like to apply it if it can have a positive effect on tone.  
 
Do y'all think this is what a "famous pickup maker" is referring to when they claim to be using "aged" magnets?
 
3/5/2004 3:07 PM
RobB
I believe the purpose of tempering pole pieces is to even out the magnetic strength of each pole so you end up with a more even sounding pickup. The initial question which started that thread, went something like this…  
 
Will placing alnico poles in simmering water for an hour or so temper them?  
 
I can't remember who asked it.  
 
Although a number of people here say they temper their magnets, nobody gave a straight answer to that question. I’d like to know how tempering is achieved but I got the impression it was some kind of secret.  
 
When I get hold of a Gauss meter I plan to experiment with some mild heat treatment and see if it makes a difference.  
 
Hope to see an answer to your question before then.
 
3/6/2004 1:46 AM
Dave Stephens
Well, from what little I know this is kind of a pointless thing to do. If you want all your magnets to be equally charged use a magnet charger for one thing. Duncan has this deal he calls "dun-aged" magnets. He doesn't say what he's doing but I suspect he's deguassing them slightly, reading between the lines. You can do that by putting your magnets together with repelling poles, that will knock them down if you want weaker magnets. The whole idea of magnets aging is a farce from what I've been able to discover. They don't age , they get demangetized over time. You can take an old Fender pickup and charge it to new in an instant for instance. There's alot of pickup mythology that is basically sales bull. There was a discussion awhile back about cryogenic treatment its a nice sales gimmick, is damn expensive to do and gets so nearly unoticeable effects that its a waste in my opinion. I just had an experience with a guitar wired with really thick pure copper wire that is used in very expensive microphones, its costs $100 to wire one strat. The player that did it says it made his vintage wound strat pickups come alive. Problem is the stuff is so thick you coulnd't get the pickguard back on without crushing the switch which made one or two pickups go dead. So even sometimes stuff that DOES work is a pain in the butt. Don't forget Leo Fender never did any fancy stuff or made any weird sales claims, he made his pickups in a very crude way with little consistency and they worked. Simple is better IMHO...Dave
 
3/6/2004 2:34 AM
Jeff

Dave,  
 
I agree that most of what is printed with respect to "aging" and such is probably hype. However, in terms of the physical micro-structure of the magnets there absolutely will be an effect as a result of tempering. Whether or not that ultimately effects the tone, I couldn't say at this point.  
 
In fact, one of the reasons I'm curious about this is that tempering is generally a part of the sintering process when the AlNiCo slugs are made. I'm not sure if it's done with cast slugs or not. The tempering is done to reduce the brittleness of the material and stabilize it which is supposed to improve the overall "magnetic" characteristics and performance.  
 
So, one of my thoughts is why temper if it's a part of the process to begin with? Having asked that, if you look at SK's site he describes how it appears to equalize the strength of the two poles of a magnet that was initially uneven.  
 
I'm inclined to believe Steven's analysis, and therefore wonder if ... even though tempering is a part of the sintering process (casting too?) ... magnetizing the material might create internal stresses otherwise not present in the un-magnetized slug. If so, re-tempering might in fact be worthwhile ... that is, assuming magnets that are more or less equalized sound better.  
 
I couldn't agree more that there's a ton of hype surrounding pickups. From a mechanical/chemical engineering standpoint though, the effects of tempering couldn't be more real.  
 
All I want to know is ... how do I do it at home? Anybody?
 
3/6/2004 4:28 AM
Jason Lollar

the guy that everyone quotes that says aged magnets is sales hype-well its just a matter of terminology.  
OK they dont really age but they do seem to degauss just sitting in the guitar (Fender single coils) Look at any old Fender pickup with an accurate and sensitive gaussmeter the two outside poles normally read about 15- 20% higher.  
anyone else ever noticed that?  
also they generally read quite lower than if you recharge them again.
 
3/6/2004 8:58 AM
Owen

Jeff, as you can tell, this is a complex subject with not only varied technical support, but it also arouses this debate of whether tempering is really a viable factor in simulating a vintage pickup. Alnico, as far as I understand, has a half life of fifty years, though no doubt that was a mere hypothesis as 100 years would not render a magnet dead, though it may have been a time gauge to represent a magnet's specific integrity accurately, which as Jason pointed out, is realistic number given his data. Magnets, as a rule, are not all linear in their properties and are affected in strength by so many factors.  
 
To temper a magnet, you would simply have to decrease it's magnetic strength. Whether one puts them in a sack in the dryer, boils them for an hour, hammers them, or weakens them in any way, this still will not make them all equal in strength. One would simply choose a weaker magnet in a pickup to get a mellower sound, or just lower the pickup to yield the same result as deguassing, or tempering. I believe that was acutally mentioned in the old thread to which you were referring. Keep in mind, magnets vary by the batch, and a guass meter will be invaluable as you attempt to equalize your magnet strength in a pickup (though my ear can't tell much difference, it appeals to our meticulous natures). Most likely, as others have illustrated, we chase oue own tails and the benefits would not necessarily be audible in a fair, honest, A-B test.  
 
As Dave and others mentioned, there is a lot of hype and mythology surrounding pickups and pickup makers, which is frustrating to those of us who do not wish to pander to a non-techncal "audience". The bottom line, IMHO, is that most of those old Fender pickups have chipped up magnets and were made with far less consideration and love than anyone on this forum makes their pickups, and yet they sound amazing.  
 
Most of the other factors in pickup making are going to have a greater impact than the tempering process, and though the effect of of the tempering process may result in different technical readings, I honestly doubt that one could differentiate two identical pickups with tempered and non tempered mags.
 
3/6/2004 2:27 PM
Jeff

Owen,  
 
Agreed it's complex, and I certainly don't wish to promote the hype in any way. My concern stems in part from the meticulous nature that you mention and the fact that some folks have expressed interest in having me re-wind pickups for them. Up to now, I've been trying to send them to other, more knowledgeable folks from this board as I work on my skills. Now that I'm getting better at the winding process, and have at least one satisfied customer (heh, more like "trusting soul"), I think I might like to try to make some money at this as a side business but I have to feel I'm doing the best I can for people. From that perspective, if tempering could somehow provide more uniform results ... I'm interested (of course, uniform might not actually be good too, I guess).  
 
The only thing I really know about it is what I studied in college in a Chem-E class ... so I'm pretty ignorant in that respect. It's a well known process though, and not a fantasy in terms of it's effect on an alloy. I don't plan to move into the "slightly de-gaussing" or "cookin' them just because" realm ... again, just looking to be informed and provide the best effort possible for anyone seeking my services.  
 
I really appreciate the thoughtful response. I'm getting the sense that any improvement may be marginal at best and that I really need a gauss meter, etc., to look into it.  
 
So, let's say I decide not to temper mags but just ensure that the slugs are as fully magnetized as possible. I now have in my possession two 2"x2"x1" N42 Neodymium magnets (almost three inches on the diagonal). Is this a better way to go?  
 
If I make a jig with the two magnets set up to attract but rigidly separated, how do I insert/remove the AlNiCo magnet from the gap? Does it matter?  
 
Thanks again for all the good responses. There's no other place to get this kind of information.
 

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