Recommendations on best practices: pickup storage

[Audiotexan]

Apologies if this has been covered already:

Seeing as I've collected a crap load of pickups over the last 30+ years and virtually never sell or trash them...

What's the best way to store them (magnetically speaking)?

They're all kept in house, so 'room temperature' shouldn't be an issue. As well as the majority of them (anything with any value to me) have been stored in old SD plastic cases (as anytime I did an install and the customer didn't want the case, I put it in my collection...as they make great parts boxes too lol).

I'm thinking more along the lines of, vertical stacking issues (weakening magnetic poles??), or adjacent (less of a concern WRT pole interaction, but would there be other issues I'm not thinking of?). Or is there a good way to go vertical, by perhaps using something in between layers to isolate the magnetic field interaction?

Thoughts? Tips?
TIA!

[Magnut]

Best is to stack them. When the height to width ratio is high, it is best for the magnets. They will act as their own keeper this way and be less prone to demagnetizing from external forces. Stack them in the way that the magnets want to naturally orient themselves. This will create a strong magnetic circuit.

[Audiotexan]

Appreciate the reply!

Best is to stack them. When the height to width ratio is high, it is best for the magnets. They will act as their own keeper this way and be less prone to demagnetizing from external forces. Stack them in the way that the magnets want to naturally orient themselves. This will create a strong magnetic circuit.

So take them out of the cases they're in, see which way they're magnetically inclined, return them to the case, and then stack them accordingly?

humbuckers:
N/S stacked over
N/S

singles:
N over
N

Not quite sure what you mean by "When the height to width ratio is high, it is best for the magnets"...but I'll take a stab in the dark and guess that you mean stack humbuckers on humbuckers, and singles on singles. Which incidently, is what I've always done. Unfortunately however, I can't say with certainty that I've always observed N/S correlation. I wonder how much difference it would make on the magnets over the years (being kept in stacked/adjacent cases as such)...though I always maintained a divide between hums/singles.

I guess what made me ask to start with, is about the importance of A2 vs A5 etc, and have no clue as to which pickups have which type of magnets. Especially the offbrand stuff I have.

How much room should I leave between stacks of the same type?

For reference, the cases I was referring to are mostly this type:

except that they have foam that surrounds the upper portion of the pickup as well (see pic 2) as the 1/2" or so of foam that's under the pickup.

Also, some are offset at an angle /, and others line the pickup up straight | inside the case.

[big_teee]

As long as you have some reasonable space between them you should be fine.
You don't want strong Ceramic pickups real close to weaker Alnico pickups.
T

[SonnyW]

I agree with Magnut. Stack them oriented. I have for years kept my inventory of finished boxed pickups stacked, with no problems. Since I always box up my sets the same way, the magnetic orientation is the same and like with your boxes, there is a pad between them. In my case that separation is maybe 1/4 to 3/8 inches on each side. I do take care to separate the single pickups that are RWRP and stack them together, in a stack separately from the others. I also try to orient humbuckers in boxes the same way if I am going to stack the boxes, and I stack similar pickups together, in different stacks for each major design. single coils on single coils, humbuckers on humbuckers. I think the problem you are concerned about applies more to single coils like strat pickups than to humbuckers. In a humbucker the demagnetizing effect has to go through the polepieces and slugs to get to the bar magnet. That reduces the effect significantly. Even with single coils, I wouldn't worry at all about stacking A2 on top of A5 or other alnico alloys, if they are oriented the same. In fact, even if you have a stronger magnet like a ceramic as long as it is oriented correctly to the one stacked on top of it, then like Magnut said it acts like a keeper. It reinforces the charge. Another similar magnet even if stronger, isn't typically going to increase the charge. An A5 stacked on an A2 won't change either one. But if they are oriented opposite, that can't be too good. On the other hand, if they are close enough to have much demagnetizing effect they will naturally want to repel and you should be able to detect that if it is going to have much effect.

I also have a fairly large "library" of reference pickups. This is the equivalent of your 'crap load of pickups' collection. I have most of those in their original boxes if I have them and just try to stack them up the same way. But the boxes are not always similar. I try never to store those pups loose out of boxes and together, but sometimes the boxes do get randomly oriented in the pile. I have never seen any significant change in magnetic strength if from time to time I check back on any of them that I have previously measured. Not advising it, but even if you just jumble them in a pile or a toolbox or drawer they are naturally going to want to orient themselves in a way that preserves magnetic charge. It is only the repulsive force that causes degradation. Even this takes a long time if the magnets are similar in strength. Consider the opposing magnets in 1950's P90's for a case in point.

If I am making a large batch of say strat pickups, I often stack them directly in contact one on top of the other, after they have been magnetized, and if needed just put the RWRP ones upside down in the stack. This is for convenience and to avoid any changes in charge. I've left them that way for weeks or months with no issues. This is like what Magnut was saying about the width to height thing. For example a rod magnet that is too short will be more likely to lose magnetic charge over time than one that is above a critical length to diameter ratio. A couple or several magnets stacked oriented has effectively the same effect on keeping charge as a longer magnet would have. The higher the length to diameter ratio the less likely the magnet is going to lose charge over time. One number that is sometimes quoted by magnet manufacturers for stability of alnico magnets is a ratio of 5 times length to diameter. IMO, this 5:1 ratio is very conservative, and alnico magnets are available in length to diameter ratios much less that that even 1:1. But there is some truth to it, for example, I have observed significant loss of charge in doing rewinds of old DeArmond monkey on a stick pickups that by design have very short alnico rod magnets. It may have taken them 50 years to lose maybe a third of their original charge just in a guitar. Hope this helps, sorry for being a little longwinded about it.

[Audiotexan]

Pleased to meet ya Sonny! Also, thanks for chiming in here as you cleared up what I wasn't getting on the heighth to width ratio, in addition to all the other info. A great help and is appreciated!!

I do take care to separate the single pickups that are RWRP and stack them together, in a stack separately from the others.

Good tip! TY!

I think the problem you are concerned about applies more to single coils like strat pickups than to humbuckers. In a humbucker the demagnetizing effect has to go through the polepieces and slugs to get to the bar magnet. That reduces the effect significantly.

Hadn't even thought about that. TY again!

...even if you just jumble them in a pile or a toolbox or drawer...

My 'obsession for detail' would never allow this for anything I remotely considered usable/valuable. LOL
(barring the absolute garbage, ie: things that I would literally give away to a 6yr old who just starting playing, but spilled coke on his guitar and ruined a pickup)

If I am making a large batch of say strat pickups, I often stack them directly in contact one on top of the other, after they have been magnetized, and if needed just put the RWRP ones upside down in the stack. This is for convenience and to avoid any changes in charge.

Your 'explaining in detail' just saved me asking another question. Well done! *chuckles & grins* In my book, there's almost never a need to apologise for "being a little longwinded about it".

I have observed significant loss of charge in doing rewinds of old DeArmond monkey on a stick pickups that by design have very short alnico rod magnets. It may have taken them 50 years to lose maybe a third of their original charge just in a guitar.

ROFL @ "monkey on a stick". That's a new one by me!
I've only worked on a scant few DeArmonds over the years, but I can't place what you're referring to. Pics or links would be appreciated!
Also, no idea why...but the type of pickup that comes to mind (for whatever reason lol) is the old "humbuckers" that I had in an old 65-66 Tiesco Del Rey ET-220.

pics by oaktreevintage.com

[side note/curiosity: Are there any other humbuckers that anyone's aware of that use rod magnets as opposed to bar magnets, and would they be more apt to be a 'rarity' (oddball), custom, or just vintage?]

[SonnyW]

ROFL @ "monkey on a stick". That's a new one by me!
I've only worked on a scant few DeArmonds over the years, but I can't place what you're referring to. Pics or links would be appreciated!

The Monkey on a stick is the nickname for a DeArmond Rythm Chief 1000. They are called that because of the resemblance to a kid's toy that had a monkey shaped part that would climb up a stick when you shake it. They are a real pain to work on because they have the first part of the coil going around only four of the magnets, then you have to glue in the other two magnets to wind the outside part of the coil. The top of the bobbin is made of really thin linnen-phenolic material about 1/32 inch thick, and you have to glue in those other two magnets without breaking it.

[Audiotexan]

They are a real pain to work on because they have the first part of the coil going around only four of the magnets, then you have to glue in the other two magnets to wind the outside part of the coil. The top of the bobbin is made of really thin linnen-phenolic material about 1/32 inch thick, and you have to glue in those other two magnets without breaking it.

Oh yeah. That sounds like a real joy to work on... >.>