double thick magnets and keeper bars

ToneFiddler

ToneFiddler

New member
since i like what thick 1/4” rods in single coil bridges (e.g. the quarter pound) do for heavier stuff, i like to try double thick mags in low/med output pickups and of course Clint 55 relentless raving about them made me curious:D


spacers i can flip, print or make myself, but what about the keeper bar?

do i need a higher one and if yes, where do i get it?
 
Do a search for "hobby metals." There's all kinds of companies that make small dimensional metals for hobby projects. Micro-Mark is just one, for example.

https://www.micromark.com/hobby-supplies/metal?show=48

And hopefully, someone can correct me if I'm wrong, but I don't think that bar has any tonal characteristics. You could probably replace it with some maple. Or any easy to work material. (But I may be wrong.)
 
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ArtieToo said:
Do a search for "hobby metals." There's all kinds of companies that make small dimensional metals for hobby projects. Micro-Mark is just one, for example.

https://www.micromark.com/hobby-supplies/metal?show=48

And hopefully, someone can correct me if I'm wrong, but I don't think that bar has any tonal characteristics. You could probably replace it with some maple. Or any easy to work material. (But I may be wrong.)
Click to expand...

Hi Artie,

I'd find very pretentious and ungrateful to "correct" you.

Now and if i can simply share something with you and the community: in my humble experience, the keeper bar contributes to the overall inductance and Foucault currents, so it allows to "fine tune" a tone to some extent. Not sure its effect wouldn't / won't be hidden by a double thick mag but it's a part that I find more meaningful tonally than maple. YMMV. :-)

I think that with a double thick mag, I'd try a double decker keeper bar (= two stacked ones, sanded or not) , just to hear what it sounds like... :-P
 
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lol, thanks Clint 55 , ok if the SH-6/SH-7 only has ONE Standard sized keeper bar, then i will try it just like that. I was thinking like freefrog that the space between baseplate and Bobbin must be filled. And yes, I agree with freefrog that it will make a difference for one the size and the material of the keeper bar. How much? no f'ing glue. But there was a anecdote on this very forum:
https://forum.seymourduncan.com/for...etween-original-jb-and-current-jb#post4924121
A good example of a difference that I havent personally messed with but Frank Falbo related was the differences in keeper bars. He said they tried different vendors and the vendor was making the holes in the keeper bars a few thousandths! of inch too big. What difference would this make? Its just the bar that the screws go through shouldnt make any right? According to Frank it made enough of a difference that it was easily heard.
Click to expand...

and freefrog wrote about it here before:
https://forum.seymourduncan.com/for...fect-of-pole-screw-and-slug-alloy#post5689856
 
Don't know anything concerning various alloys and the keeper bar.
But AFAIK its function in a humbucker is to couple the magnetic field of the bar mag with the pole screws.
If so, it certainly isn't irrelevant - and replacing it with wood or plastic would more or less disable the screw coil.
It'd be almost like removing the screws.

This is also why bars with oversized holes could be an issue.
 
I think within this thread some people are just having misunderstanding of the meaning of words like spacer vs keeper bar. For this discussion the spacer is referring to the plastic or wooden piece that props the bobbins up so they don’t sag outward.

So when you use a double thick magnet you either make a special spacer, or flip the standard spacer onto its side so that it’s standing vertically. That would be tonally neutral.

The keeper bar, however; the metal bar that has holes in it that wraps the screws on the screw coil, does play a role in the sound of the pickup. But for the sake of this discussion the important thing to note is that most double thick magnet pickups only utilize 1 normal keeper bar, they don’t stack them, and it’s usually pushed to the top, just underneath the bobbin. Not sagged down toward the baseplate. Stacking another keeper bar could be a fun experiment though if you wanted to play with the inductance and flux return path.
 
Stack two keepers on top of each other. You can also get a low carbon steel bar and drill it, but that’s more work.

Here you see stacked keepers AND a drilled and tapped bar for the poles.
5dd550e6a0c36a550733d04d7b273673.jpg



Sent from my iPhone using Tapatalk
 
DavidRavenMoon said:
Stack two keepers on top of each other. You can also get a low carbon steel bar and drill it, but that’s more work.

Here you see stacked keepers AND a drilled and tapped bar for the poles.
Click to expand...
Cool, thanks David.
I have a couple of humbuckers that I've considered as candidates for double mags.
How much difference does using a second keeper make - does it change the output significantly? Lower the resonant frequency?
What's the overall effect on tone & response?
 
@DavidRavenMoon: thanks for the pic!
but for the first trial i go with a std. keeper bar
frankfalbo: thanks for the inside!

found some old post about double thick Alnicos and my motivation took a lil hit
https://forum.seymourduncan.com/for...4692-why-no-oversized-alnico-mags#post3686839
... Double tall A5 is a finicky beast and I wouldn't consider it a good mag swap for the forum crowd. It's more like something you would design a pickup around. Its also used on the Benedetto B6 another very unique pickup and recipe.
Click to expand...
... I'm telling you that it's a specialized use. It's not like these other Alnico grades and rough vs. polished, or degaussing, etc. If your brain has got you thinking you want a double tall A5 then you're probably better off trying A6 or A8 first. For example, a Custom 8 probably would sound "better" to most people than the Custom 5XL. (sweet name, huh?)
Click to expand...
 
Dumb. They solve one of the most common problems of filling out vintage or medium bridge hums. That's not a specialized use. Fun for high output, but you can simply stick a double thick alnico of your choice in a vintage output bridge and you get the openness of the wind without the clank.
 
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Maybe you guys can clarify something for me. And know that I only have a rudimentary understanding of magnetics. Since like poles oppose each other, wouldn't stacked magnets try to degauss each other? In other words, is a magnet that's manufactured as a 1/4" thick going to be the same as two 1/8" thick mags clamped together?
 
ArtieToo said:
Maybe you guys can clarify something for me. And know that I only have a rudimentary understanding of magnetics. Since like poles oppose each other, wouldn't stacked magnets try to degauss each other? In other words, is a magnet that's manufactured as a 1/4" thick going to be the same as two 1/8" thick mags clamped together?
Click to expand...

Cermag said if you force like poles together, they will partially degaus each other. So no it is not the same. It will work to force 2 together, but it is not ideal. The way I make mine is I epox 2 mags together and then remagnetize them as 1 magnet.
 
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