timtam
Meter Reader 1st Class
Posts: 61
Likes: 30
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Post by timtam on Jul 17, 2024 0:53:57 GMT -5
I am not sure if the magnetic field viewer below is just a cute school science demonstration or a useful pickup visualization tool. This video recently came up on my youtube feed. Magnetics is not really a field in which I have any particular knowledge, but I wondered if this gadget actually has any practical use in understanding anything important about pickups in general, or characterizing particular pickups ? I am familiar with more complex ways of analyzing pickup magnetic fields (eg Zollner's work), but tools for doing that are not easily accessible (other than a simple magnetometer like the WT10A, which is very useful). Obviously the viewer doesn't allow you to measure anything quantitatively, but does it provide any practically useful qualititative indicators as he suggests ? (eg direction, density, length, separation of flux lines ?). If nothing else, maybe a visualization of an A5 bar magnet against an A2 magnet would help direct people's thinking towards these being fundamentally different strength magnets. Instead of dubious notions we hear from pickup manufacturers of them having a different intrinsic "sound". You can apparently become a member of his site in order to get the instructions for putting a viewer together, but similar resources are readily available from other sources, such as those below. Basically you need a flat (water) bottle, some (washed?) iron filings, and a suitable suspension oil (eg mineral oil). Or you can buy one ready-made. www.amazon.com/Magnetic-Lines-Force-Field-Demonstrator/dp/B00ICOD6ZWwww.kevingittemeier.com/521-2/www.amazon.com/s?k=Flat+Water+Bottlewww.amazon.com/gp/product/B000BJRLTIwww.amazon.com/gp/product/B01NBT0KD5 |
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Post by antigua on Jul 17, 2024 11:53:33 GMT -5
The video is useful for the visualizations, but he said a number of things that are not true. He says the ceramic pickups tend to be under wound and have stronger magnetism, but that's the opposite of what is usually true.
The video demonstrates what is already known about magnets, that the flux pattern has to do with the shape of the magnet, not the strength, but if the magnet is stronger, it will cause more of the iron filings to overcome friction and clump together. He seemed to want to believe that the different pickups showed different flux patterns based on strength differences, but the patterns were all the same, the difference was just in how the iron filings respond to magnetic saturation.
The AlNiCo and steel ceramic pickups have different magnetic shapes, because the AlNiCo has six magnets and ceramic is a bar magnet with six slugs along the face of the bar magnet, but by visualizing the magnetic field on axis from the top down, that difference is obfuscated. He could have laid these pickups sideways and visualized the difference that way. Same with clipping the screw on a humbucker, he visualized it in a way in which you'd not expect to see a difference. But if you use a Gaussmeter, you can measure the difference in strength at the screw top after you have clipped the screw short.
The comparison between the AlNiCo and steel ceramic pickup looked strange. He says the ceramic steel is stronger than the AlNiCo, based on the higher density of iron filings, but that looks more like a testing error, as if you look around the periphery, it appears that there are just a lot less iron filings in the test field overall.
I'm sad to say that this yet another YouTube video that will probably contribute to the misunderstanding of how pickups work, based on the presenter's emphatic misinterpretation of the experiment results. I think he wanted to talk a lot about strength, and if he had a Gaussmeter on hand, he could have contrasted the Gauss reading with the iron filing visualization, and come up with some better conclusions.
It would be cool if someone could make a YouTube video showing how the guitar string is magnetized along it's length through cancelling out the sound by holding AlNiCo pole pieces close the the guitar string as it rings out. I should get over my hang up about making videos and get to it.
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Post by gckelloch on Jul 17, 2024 23:48:28 GMT -5
Yeah, antigua. That would be interesting to hear if it alters the sound of a wide coil P90 or JM pickup.
Regarding the results of the magnetic field viewer, I was thinking the higher iron grain density in the Steel pole pickup result might be due to the much more permeable poles drawing more of the magnetized grains to the poles than the A5 result.
Incidentally, a set of cheap ceramic Steel pole pickups wound to ~4.5k came stock in my 2012 SX guitar.
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Post by antigua on Jul 18, 2024 15:15:00 GMT -5
Yeah, antigua. That would be interesting to hear if it alters the sound of a wide coil P90 or JM pickup. Regarding the results of the magnetic field viewer, I was thinking the higher iron grain density in the Steel pole pickup result might be due to the much more permeable poles drawing more of the magnetized grains to the poles than the A5 result. Incidentally, a set of cheap ceramic Steel pole pickups wound to ~4.5k came stock in my 2012 SX guitar. The iron filings only know what's happening at their point in space, so if the iron filings experience a stronger magnetic field, it would have to be that the permeable steel pole pieces were creating what is in fact a stronger magnetic field. Based on testing with the Gauss meters, I've never seen steel pole pieces with under magnets have a higher strength at a given point in space above the pole piece than AlNiCo poles. The fact that his iron field looks more dense for the steel pole test suggests to me that he's just not accounting for the fact that there was more iron in the field for that particular test, creating the appearance of there being more of something. |
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Post by ms on Jul 18, 2024 15:55:23 GMT -5
Yeah, antigua. That would be interesting to hear if it alters the sound of a wide coil P90 or JM pickup. Regarding the results of the magnetic field viewer, I was thinking the higher iron grain density in the Steel pole pickup result might be due to the much more permeable poles drawing more of the magnetized grains to the poles than the A5 result. Incidentally, a set of cheap ceramic Steel pole pickups wound to ~4.5k came stock in my 2012 SX guitar. The iron filings only know what's happening at their point in space, so if the iron filings experience a stronger magnetic field, it would have to be that the permeable steel pole pieces were creating what is in fact a stronger magnetic field. Based on testing with the Gauss meters, I've never seen steel pole pieces with under magnets have a higher strength at a given point in space above the pole piece than AlNiCo poles. The fact that his iron field looks more dense for the steel pole test suggests to me that he's just not accounting for the fact that there was more iron in the field for that particular test, creating the appearance of there being more of something. Right, An A5 pole piece at its surface could be 1300 Gauss. At the top surface of screws and slugs of a humbucker it is more like 300 Gauss. Maybe this viewer would be of some use if you first measured the B field at points on the surface of the magnetic structure, thus calibrating it at those locations. |
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