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Post by reTrEaD on Dec 20, 2016 9:24:46 GMT -5
They are a very special ceramic, a so-called ferrite. Although it is true that ceramic (ferrite) permanent magnets tend to have low permeability, the soft magnetic versions can have very high permeability. They also can be very lossy at higher frequencies (used to suppress rf pickup) or not. In the audio range ferrites in general are quite low loss, and permeabilities can be as high as several thousand. My original thoughts were regarding ceramic permanent magnets in the shape of slugs. Since they aren't electrically conductive, the eddy current issue is mitigated. And the low permeability suggests that the inductance would be lower than that of steel and perhaps lower than AlNiCo? But the idea of highly permeable ferrite as pole-pieces with external magnets sounds interesting as well.
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Post by stratotarts on Dec 22, 2016 20:42:56 GMT -5
They are a very special ceramic, a so-called ferrite. Although it is true that ceramic (ferrite) permanent magnets tend to have low permeability, the soft magnetic versions can have very high permeability. They also can be very lossy at higher frequencies (used to suppress rf pickup) or not. In the audio range ferrites in general are quite low loss, and permeabilities can be as high as several thousand. My original thoughts were regarding ceramic permanent magnets in the shape of slugs. Since they aren't electrically conductive, the eddy current issue is mitigated. And the low permeability suggests that the inductance would be lower than that of steel and perhaps lower than AlNiCo? But the idea of highly permeable ferrite as pole-pieces with external magnets sounds interesting as well. I think that would be really great, but the question is, where to find them? Or any magnets in the right size, for that matter. The strat magnets fit the holes, but they're way too long. I'd like to ditch the bar magnet because I think it would be great to make pickups flatter.
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Post by reTrEaD on Dec 22, 2016 21:15:24 GMT -5
I agree. At approximately 1/2 inch, the A5 rod magnets on Jazzmaster pickups are pretty short. But I have no clue as to where you could buy just the magnets without the rest of the pickup.
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Post by antigua on Dec 22, 2016 22:08:26 GMT -5
If you had beeds of various materials, such as neo, steel, AlNiCo, ferrite, you could stack them to get various outcomes. A single neo, or several ferrite at the top of the stack would give you all the flux density you require, while steel or another high permeability material on the bottom would push the coil's inductance up or down, to taste.
Taking things further (and I wish someone would), you could mechanically change the core makeup by raising or lowering the material in or out of the core from below, or even move a PAF's bar magnet near or far from the poles and screws to tweak the flux density at the strings. Some little lever or push-n-click could allow for the change to happen from outside of the pickup without having to unmount it, unscrew it, etc.
I think the problem with a lot of these ideas is that if you don't get a celebrity guitarist to get on board, nobody else will either. Where would the Lace Sensor be without Clapton? Or EMG's without hair metal?
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Post by ms on Dec 23, 2016 5:54:00 GMT -5
My original thoughts were regarding ceramic permanent magnets in the shape of slugs. Since they aren't electrically conductive, the eddy current issue is mitigated. And the low permeability suggests that the inductance would be lower than that of steel and perhaps lower than AlNiCo? But the idea of highly permeable ferrite as pole-pieces with external magnets sounds interesting as well. I think that would be really great, but the question is, where to find them? Or any magnets in the right size, for that matter. The strat magnets fit the holes, but they're way too long. I'd like to ditch the bar magnet because I think it would be great to make pickups flatter. Neo magnets are cheap and available in many many sizes, suitable for putting on the backs of individual pole pieces (or even on top, but be careful, even the plated ones corrode if exposed to guitar players). They are very small for the field strength. Ferrite beads are available shaped and sized like pole pieces.
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Post by newey on Dec 23, 2016 6:50:26 GMT -5
I got a laugh out of equating "celebrity guitarist" and "hair metal", sounds like an oxymoron to me . . .
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Post by reTrEaD on Dec 23, 2016 12:14:16 GMT -5
Neo magnets are cheap and available in many many sizes I did a bit of googling. Seems like the sizes would be reasonable to design around (1/8" and 1/4 diameter) but I couldn't find the Goldilocks size (3/16" diameter like a Strat magnet or HB slug).
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Post by ms on Dec 23, 2016 13:41:36 GMT -5
Neo magnets are cheap and available in many many sizes I did a bit of googling. Seems like the sizes would be reasonable to design around (1/8" and 1/4 diameter) but I couldn't find the Goldilocks size (3/16" diameter like a Strat magnet or HB slug). www.kjmagnetics.com/products.asp?cat=1
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Post by reTrEaD on Dec 31, 2016 5:20:53 GMT -5
Very nice!
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