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Post by antigua on Oct 14, 2016 23:37:05 GMT -5
DiMarzio fills many of their humbucker bobbins with additional permeable material in order to increase the inductance. They filed a patent covering the specific manner in which they go about doing this, and it can be viewed here: www.google.com/patents/US5908998 . The claimed benefit of this invention is exactly the same reason anyone adds a permeable core to an inductor: to increase inductance without requiring additional wire, which leads to higher resistance and unwanted capacitance. The end result is that you can achieve a higher peak resonance, due to the lesser capacitance, and a higher output voltage, due to the higher inductance. So what so they put in the bobbin? It's a small slug, about half the size of a regular slug. Here are some technical comparisons between the two: Embedded slugs:
height: 7.88mm
radius: 2.16mm
weight: 0.8 grams
volume: 115.5 mm^3
density: 0.0069 g/cm^3
Standard steel slugs:
height: 12.71mm
radius: 2.38m
weight: 1.8 grams
volume: 226.3 mm^3
density: 0.0079 g/cm^3
I'm not sure what material the embedded slugs are made of, but it's a dull gray color, and it's of a lower density than the steel slugs:  How much effect do the embedded slugs have on the inductance? Not by as much as the screws and slugs that are already in coil. The embedded slugs alone only increase the inductance by 150mH to 170mH. When the humbucker is full assembled and wired in series, the embedded slugs only increased the overall inductance by 150mH, or 3.6%. The traditional slugs and screws increase the inductance by 250mH for the screws (not counting the keeper bar) and over 700mH for the traditional steel slugs: Screw coil:
- with no metal: 0.918H
- with only imbedded slugs: 1.087H
- with only screws: 1.164H
- with screws and embedded slugs: 1.700H
Slug coil:
- with no metal: 0.924H
- with only imbedded slugs: 1.077H
- with only six regular slugs: 1.650H
- with screws and embedded slugs: 1.683
Fully assembled, in series:
- with embedded slugs: 4.256H
- without embedded slugs: 4.106H
Each coil of the DiMarzio PAF Master neck only has three embedded slugs, and I suspect this is the case for most of their pickups that contain embedded slugs, since the otherwise generic plastic bobbin only reserves space for three embedded slugs:  Increasing the inductance without also adding capacitance is generally a good thing, but these embedded slugs seem to have a minimal effect, overall. I bet they could get more permeable metal in there if they made a custom shaped metal piece that spanned the center of the bobbin, and left holes that were only large enough for the slugs and screws to pass through them. |
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Post by straylight on May 22, 2018 5:55:31 GMT -5
They, use large bars on some of the other pickups, the density is intriguing though, it's a bit light for drawn steel rod as per conventional pole pieces, my first guess would be cast iron. Have you investigated magnetic properties?
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Post by antigua on May 23, 2018 14:26:12 GMT -5
They, use large bars on some of the other pickups, the density is intriguing though, it's a bit light for drawn steel rod as per conventional pole pieces, my first guess would be cast iron. Have you investigated magnetic properties? They're "soft iron", apparently. Along with the dual wire gauge coils, it doesn't really enhance the pickup in any particular way. The goal is just to have features which supposedly makes their product better than someone else's, regardless of how effective it actually is. This happens in lots of areas of commerce, though, it's marketing 101. |
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Post by straylight on May 24, 2018 16:24:36 GMT -5
Surely the marketing is when you parade the feature, not hide it. Is it also a half "air" or is that your modification?
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Post by antigua on May 24, 2018 16:41:46 GMT -5
Surely the marketing is when you parade the feature, not hide it. Is it also a half "air" or is that your modification? DiMarzio doesn't hide it, they refer to those slugs as "Virtual Vintage" technology. DiMarzio doesn't go into detail about what these "technologies" are or how they work, probably because the truth of the matter would leave buyers underwhelmed. Which is ironic, considering they're the only pickup maker to have a second set of marketing copy title "tech talk" on all their product pages. It tends to be as non-technical as the copy at the top of the web page. The pickup in question is a "air bucker" in stock form, that is nothing I did. |
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yanyan
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Posts: 52 
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Post by yanyan on Dec 29, 2019 10:36:49 GMT -5
Those bobbins look like they could accommodate at least two more holes to embed slugs in, in between the 1st-2nd and 5th-6th polepieces. Perhaps it might be worth experimenting drilling out holes and inserting more slugs?
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Post by antigua on Dec 29, 2019 10:58:55 GMT -5
Those bobbins look like they could accommodate at least two more holes to embed slugs in, in between the 1st-2nd and 5th-6th polepieces. Perhaps it might be worth experimenting drilling out holes and inserting more slugs? Those spots are reserved for the mounting screws. I don't think adding the slugs is really a productive thing to do from a manufacturing stand point. It would be cheaper to increase the inductance with more turns of wire, and while the ferrite doesn't increase the capacitance or resistance, the amount of capacitance and resistance added by extra turns of wire is negligible. I think DiMarzio just likes to distinguish themselves any way they can, and then patent that distinction, give it trade name, and then use it as a selling point in their marketing material. Even if there were no patent on the idea, I don't think any other pickup maker would bother doing it. |
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yanyan
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Posts: 52
Likes: 2
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Post by yanyan on Dec 29, 2019 11:41:13 GMT -5
Those spots are reserved for the mounting screws. I don't think adding the slugs is really a productive thing to do from a manufacturing stand point. It would be cheaper to increase the inductance with more turns of wire, and while the ferrite doesn't increase the capacitance or resistance, the amount of capacitance and resistance added by extra turns of wire is negligible. I think DiMarzio just likes to distinguish themselves any way they can, and then patent that distinction, give it trade name, and then use it as a selling point in their marketing material. Even if there were no patent on the idea, I don't think any other pickup maker would bother doing it. But then we haven't really established what material the slugs are made of. Perhaps Dimarzio hasn't found the right metal or alloy that would make a bigger contribution to overall inductance with only 3 slugs? |
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Post by antigua on Dec 29, 2019 14:23:49 GMT -5
Those spots are reserved for the mounting screws. I don't think adding the slugs is really a productive thing to do from a manufacturing stand point. It would be cheaper to increase the inductance with more turns of wire, and while the ferrite doesn't increase the capacitance or resistance, the amount of capacitance and resistance added by extra turns of wire is negligible. I think DiMarzio just likes to distinguish themselves any way they can, and then patent that distinction, give it trade name, and then use it as a selling point in their marketing material. Even if there were no patent on the idea, I don't think any other pickup maker would bother doing it. But then we haven't really established what material the slugs are made of. Perhaps Dimarzio hasn't found the right metal or alloy that would make a bigger contribution to overall inductance with only 3 slugs? The material itself doesn't matter much because the amount of air gap is so great. To know that the slugs are highly ferrous and is all that's of importance. If they're highly conductive they could increase eddy currents slightly. The goal of pickup makers is more about increasing output voltage. The increase in inductance has almost always been a negative side effect of attempting to bump up the output. The patent states with some nonsensical logic that the goal was to increase inductance: patents.google.com/patent/US5908998 " It is a primary object of the present invention to provide an electromagnetic pickup having a reduced sonic harshness due to an increased inductance without a corresponding increased DC resistance or capacitance."Even though it's not the intention of the patent, a better question to ask is whether the beads reduce the magnetic reluctance path enough to increase the output of the pickup, but even if they succeeded, the slugs are not evenly distributed across the coil, and there is significant air gap above and below them. It's like a very half hearted attempt at gaining the advantages of a blade style humbucker with the appearance of pole pieces, I dont think they would even increase the output voltage by much. That's easy to test, it's just takes some time out of someone's day. The funny thing is that increased DC resistance would reduce harshness, it would lower the Q factor, just as a tone control does. |
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Post by ms on Jan 6, 2020 6:53:54 GMT -5
But then we haven't really established what material the slugs are made of. Perhaps Dimarzio hasn't found the right metal or alloy that would make a bigger contribution to overall inductance with only 3 slugs? The material itself doesn't matter much because the amount of air gap is so great. To know that the slugs are highly ferrous and is all that's of importance. If they're highly conductive they could increase eddy currents slightly. The goal of pickup makers is more about increasing output voltage. The increase in inductance has almost always been a negative side effect of attempting to bump up the output. The patent states with some nonsensical logic that the goal was to increase inductance: patents.google.com/patent/US5908998 " It is a primary object of the present invention to provide an electromagnetic pickup having a reduced sonic harshness due to an increased inductance without a corresponding increased DC resistance or capacitance."Even though it's not the intention of the patent, a better question to ask is whether the beads reduce the magnetic reluctance path enough to increase the output of the pickup, but even if they succeeded, the slugs are not evenly distributed across the coil, and there is significant air gap above and below them. It's like a very half hearted attempt at gaining the advantages of a blade style humbucker with the appearance of pole pieces, I dont think they would even increase the output voltage by much. That's easy to test, it's just takes some time out of someone's day. The funny thing is that increased DC resistance would reduce harshness, it would lower the Q factor, just as a tone control does.  Well, you could just make the slugs a bit longer if this was anything but fins. Measure an SD SH1N: 1.755 and 1.813. So close because the screws extend out the back (and the heads have an effect). That is done on purpose, right? So that the inductances match to give good hum cancelation while the slugs and screws seem very different and might have very different effects. (The two together give 4.136 due to the mutual inductance.) The DM patent reads like a technical version of a skit from SNL, but that is normal for pickup patents. |
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