The whole reason magnets work is because the atoms inside are aligned so that N and S are in the same direction, or at least that's my understanding.
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Replacing ceramic magnets with neodymium?
- Thread starter Will_White
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The whole reason magnets work is because the atoms inside are aligned so that N and S are in the same direction, or at least that's my understanding.
I think the misunderstanding here is one of orientation. Like you said, if you take two magnets and arrange them in series, you'll end up with a stronger magnet:
N-------S N-------S
It'll be a little less strong than an equivalent single magnet of the same length and composition. That's not very practical for a pickup, though. What I believe Coolhandjjl and megafiddle are saying is that they'll need to be arranged in parallel like so:
N-------S
N-------S
Again, you end up with a magnet that's slightly weaker than the a magnet of the same length/width of the two combined, but much stronger than either of the single magnets by themselves. Because the north and south poles are adjacent to each other, they'll have to be bonded together mechanically somehow. Flipping them around the other way:
N--------S
S--------N
effectively shorts the field, and isn't useful.
If I'm misunderstanding something, someone please let me know.
I also had a thought that they were thinking of some static mechanical system and a "pushing force". Then the magnets like this :
N------S S------N
Would have more "pushing force" (for lack of a term I can think of, been awhile since I took physics or circuits in college) because one is repelling the other.
However if you want to "sum" the magnetic fields you'd would need to do this :
N------S N------S
I understand it's not a linear relationship hence the quotes on the "sum".
Magnetic fields are what is required for pickups to work. A mechanical "pushing force" is not the mechanism used to induce a current in the coil. The strings are within a magnetic field, and when they vibrate mechanically they are changing the magnetic field. This induces a current in the coil, creating a voltage difference across your hot and ground wire that your amp can detect and turn into sound.
I don't see how putting magnets side by side (parallel) instead of stacking them (series) is practical for modding pickups though. I guess that was the confusing part. I assumed nobody would be putting them in "parallel" like this :
N------S
N------S
I think piezo pickups might work the other way though. They sense some change in pressure, acceleration, etc. and convert that to an electrical charge. You might be able to make one with two magnets stacked with their N's facing each other for all I know.
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Actually, one more thought, I don't actually know what way the magnets are oriented in pickups. So maybe parallel is the way it is. I was assuming the N or S is facing the strings.
Actually, I think *I* was mistaken on how the magnets are oriented in a pickup, and was thinking the N/S axis went across the pickup instead of vertically through it. To quote Gilda Radner, "Never mind!"
If you place them end to end with opposite poles facing eachother so they attract, you get a longer, but not much stronger, magnet.
Try taking a compass and holding it over a pickup. The compass will point N or S directly down at the pickup. At least it has for every pickup I've tried, both ceramic and alnico. The magnetic field lines are passing vertically through the strings. This suggests that the magnets are oriented top to bottom and not along the length of the pickup, and that adding another magnet will increase the field strength. This is natural for alnico slugs oriented vertically, and maybe a little weird for ceramic bar magnets, which in other applications are usually magnetized along the bar length, but it seems like a reasonable way to design a pickup.
For more analysis of magnetic fields in pickups see Link Removed
For more analysis of magnetic fields in pickups see Link Removed
It's not a matter of them being expensive, it's a matter of wanting to experiment.
When you add another magnet to the stack, each added one is now further away from the area you want to have a magnetic field.
When you make a stack to create a stronger field, and add them like to lilke poles, you get a stronger field, but it is now primarily in just one direction.
When you make a stack to create a stronger field, and add them like to lilke poles, you get a stronger field, but it is now primarily in just one direction.
Where's all this talk about stacking magnets coming from? I'm wanting to replace the ceramic magnets that are on a pickup with a single neodymium magnet per pole, not add another magnet to the pickup. Besides it's easily verifiable that if you stack magnets
N
S
N
S etc.
That it's stronger then a single magnet otherwise a stack of eleven magnets would have only slightly more pulling power then a single which isn't the case the stack of eleven acts (basically) like a single magnet 11 times the height of the single magnet.
Back on topic, I'm wanting to experiment on this pickup because in the future I want to wind a set of extremely hot multi coils with steel poles and I want to get the magnets figured before I do that.
N
S
N
S etc.
That it's stronger then a single magnet otherwise a stack of eleven magnets would have only slightly more pulling power then a single which isn't the case the stack of eleven acts (basically) like a single magnet 11 times the height of the single magnet.
Back on topic, I'm wanting to experiment on this pickup because in the future I want to wind a set of extremely hot multi coils with steel poles and I want to get the magnets figured before I do that.
Post # 2 ( you did ask)
I would take a look at this before you build anything:
Link Removed
You can skip over the theory in the beginning, but there are some good descriptions of the various types later on and why things like stacking up magnets gain you very little.
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Yeah, if you remove the ceramic mag, the neo mags will "stick" to the remaining unmagnetised poles in any which way, so I'm not sure why there's so much "combining magnets" talk going on here.
Just make sure the neo mags are all orientated the same way. They will probably come in a little stack, so just put them on one by one straight from the stack without flipping any by mistake.
If you have a compass, then yeah check the magnetic orientation of the pickup before you remove the old ceramic mag, and place the new neos the same way.
Or, if you have a multimeter, you can check the phase by pulling off a little screwdriver from the top of the bobbins and checking the polarity of the voltage that's enduced.
Or, if you have neither of these, then yeah, just put the neos all in the same orientation, wire the J back in, and if it is out of phase when combined with the P, simply swap the hot and cold wires on either pickup.
FWIW, I play a PJ that has well balanced pickups, and it is my main bass. I have a hot (dimarzio) J and an underwound alnico P. Tweaking the outputs for a PJ is a really great mod. My blend pot morphs seemlessly from one pickup to the other. I use it as a mid control.
Just make sure the neo mags are all orientated the same way. They will probably come in a little stack, so just put them on one by one straight from the stack without flipping any by mistake.
If you have a compass, then yeah check the magnetic orientation of the pickup before you remove the old ceramic mag, and place the new neos the same way.
Or, if you have a multimeter, you can check the phase by pulling off a little screwdriver from the top of the bobbins and checking the polarity of the voltage that's enduced.
Or, if you have neither of these, then yeah, just put the neos all in the same orientation, wire the J back in, and if it is out of phase when combined with the P, simply swap the hot and cold wires on either pickup.
FWIW, I play a PJ that has well balanced pickups, and it is my main bass. I have a hot (dimarzio) J and an underwound alnico P. Tweaking the outputs for a PJ is a really great mod. My blend pot morphs seemlessly from one pickup to the other. I use it as a mid control.
Yes, that's the result I got from swapping my Rickenbacker 4001's neck pickup rubber magnet for neodymium discs.
Buy a few sets of neo magnets from KJ Magnetics on the web. They are inexpensive, and you can try different sizes to see the difference.
But, adding a stronger magnet will add to the field strength of the entire field, altho more in the location of the stronger magnet.
Update, I've abandoned the J for now but I'm still going foward with this idea. I have two cheap ceramic P pickups coming along with 100 6x1.5mm n52 neodymium disc magnets. I'm putting it in a Double P Bass so my plan is to put two on each bridge pickup pole and one on each neck pickup pole.
