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Post by bobbytouche on May 7, 2022 17:01:36 GMT -5
The JB bridge / Jazz neck combo has been marketed by Seymour Duncan as a good pairing, ever since they set was introduced in the very early 80's. The JB is essentially a highly over wound PAF, while the neck is essentially a PAF-like neck pickup. At 8 henries, the JB has around twice the inductance of the Jazz neck, which shows 3.9 henries inductance. It appears that all the same parts are used for the two pickups, including plastic spacers, AlNiCo 5 magnets, 4 conductor wire, a polyester tape, etc. The only difference appears to be the wire gauge used for the coils, and the wind count, achieving a great difference in inductance. Both appear to use the same wire insulation, which is fairly transparent, so the coils are copper-colored, probably a polyester or poly nylon. From the images below, they are impossible to tell apart, aside from the stickers that are affixed. I had previously measured a Jazz bridge and neck here , but that set from from the Custom Shop where as these are production floor pickups. The Custom Shop Jazz neck showed a slightly higher inductance. The electrical values of the Jazz neck are pretty close to that of the '59 neck, most likely within the range of production tolerance. The loaded peaks of both Jazz neck samples and the '59 I've tested land right around 3.0Hz. It appears that the idea was to have a neck pickup that performs like a PAF neck, but shares all the same production components of the JB, either for aesthetic reasons or cost reasons. The JB has a loaded peak frequency of 1.96kHz, which is similar to many of the P-90 style pickups measured. Having no metal cover should help increase the Q factor, but the higher DC resistance brings it down to 1.6dB, roughly the same amplitude at resonance you get when you put a nickel silver cover over a typical PAF pickup. The Jazz neck, by contrast, has a resonant amplitude of 2.9dB. Seymour Duncan JB I1IXQ SH-4 20161011
DC Resistance: K
- series: 16.80k ohms
- parallel: 4.20k ohms
= screw: 8.22k ohms (red & green)
- slug: 8.06k ohms (black & white)
Inductance:
- series: 8.059H
- parallel: 2.013H
= screw: 3.535H
- slug: 3.516H
Calculated C:
- series: 128pF (138-10)
- parallel: 243pF (253-10)
Resonant Peak:
- series: dV: 8.0dB f: 4.78kHz black
- parallel: dV: 8.7dB f: 7.05kHz red
- screw: dV: 8.7dB f: 6.89kHz green
- slug: dV: 10.0dB f: 6.97kHz gray
Loaded Peaks (200k ohms & 470pF):
- series: dV: 1.6dB f: 1.96kHz black
- parallel: dV: 4.6dB f: 4.08kHz red
- screw: dV: 3.1dB f: 3.28kHz green
- slug: dV: 4.1dB f: 3.28kHz gray
Gauss at screw / slug tops at center: 370G/365G
  Comparison of output voltages for different wiring modes:
product link: www.seymourduncan.com/pickup/hot-rodded-humbucker-set
Forgive me for the zombie post, but I’ve been studying pickups quite a bit and I’m utterly baffled by the relationship between turn count and inductance. On a JB for example, you’re looking at about 16.4k, 8H, from 6500 turns of 44 AWG. I’ve experimented with winding similar coils and for the life of me, I CAN’T get a reading over 5.6 or so H. It’s driving me mad. How do some manufacturers get such high L? Another manufacturer I saw has a 9k rocking 10H. Howwwww? |
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Post by antigua on May 8, 2022 15:35:24 GMT -5
Have you read this page www.allaboutcircuits.com/textbook/direct-current/chpt-15/factors-affecting-inductance/ ? In general, if you have a permeable core, like steel pole pieces, that will increase the inductance, and if you have more turns of wire, that will increase it also. I don't know how someone would get 9H from 9k ohms of wire that is no larger than 42AWG, but a ferrite core might do it. I'd have to know more of the specifics to make better predictions about why a particular coil is not reading as high of an inductance as you expect. Keep in mind that a high inductance is not the true goal. The real goal is a higher voltage, which comes from more turns of wire and a permeable core, and those same features cause a higher inductance, but it's not necessarily a desirable feature, as it causes a loss of treble. A tangential exception is that I suspect the "hot bridge" trend where the bridge pickup is only overwound by about 1k ohms of wire, I think the objective is probably more about reducing treble than it is increasing output. |
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ecmalmo
Apprentice Shielder
Posts: 46
Likes: 7
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Post by ecmalmo on May 12, 2022 12:51:42 GMT -5
The JB bridge / Jazz neck combo has been marketed by Seymour Duncan as a good pairing, ever since they set was introduced in the very early 80's. The JB is essentially a highly over wound PAF, while the neck is essentially a PAF-like neck pickup. At 8 henries, the JB has around twice the inductance of the Jazz neck, which shows 3.9 henries inductance. It appears that all the same parts are used for the two pickups, including plastic spacers, AlNiCo 5 magnets, 4 conductor wire, a polyester tape, etc. The only difference appears to be the wire gauge used for the coils, and the wind count, achieving a great difference in inductance. Both appear to use the same wire insulation, which is fairly transparent, so the coils are copper-colored, probably a polyester or poly nylon. From the images below, they are impossible to tell apart, aside from the stickers that are affixed. I had previously measured a Jazz bridge and neck here , but that set from from the Custom Shop where as these are production floor pickups. The Custom Shop Jazz neck showed a slightly higher inductance. The electrical values of the Jazz neck are pretty close to that of the '59 neck, most likely within the range of production tolerance. The loaded peaks of both Jazz neck samples and the '59 I've tested land right around 3.0Hz. It appears that the idea was to have a neck pickup that performs like a PAF neck, but shares all the same production components of the JB, either for aesthetic reasons or cost reasons. The JB has a loaded peak frequency of 1.96kHz, which is similar to many of the P-90 style pickups measured. Having no metal cover should help increase the Q factor, but the higher DC resistance brings it down to 1.6dB, roughly the same amplitude at resonance you get when you put a nickel silver cover over a typical PAF pickup. The Jazz neck, by contrast, has a resonant amplitude of 2.9dB. Seymour Duncan JB I1IXQ SH-4 20161011
DC Resistance: K
- series: 16.80k ohms
- parallel: 4.20k ohms
= screw: 8.22k ohms (red & green)
- slug: 8.06k ohms (black & white)
Inductance:
- series: 8.059H
- parallel: 2.013H
= screw: 3.535H
- slug: 3.516H
Calculated C:
- series: 128pF (138-10)
- parallel: 243pF (253-10)
Resonant Peak:
- series: dV: 8.0dB f: 4.78kHz black
- parallel: dV: 8.7dB f: 7.05kHz red
- screw: dV: 8.7dB f: 6.89kHz green
- slug: dV: 10.0dB f: 6.97kHz gray
Loaded Peaks (200k ohms & 470pF):
- series: dV: 1.6dB f: 1.96kHz black
- parallel: dV: 4.6dB f: 4.08kHz red
- screw: dV: 3.1dB f: 3.28kHz green
- slug: dV: 4.1dB f: 3.28kHz gray
Gauss at screw / slug tops at center: 370G/365G
Comparison of output voltages for different wiring modes:
product link: www.seymourduncan.com/pickup/hot-rodded-humbucker-set
Forgive me for the zombie post, but I’ve been studying pickups quite a bit and I’m utterly baffled by the relationship between turn count and inductance. On a JB for example, you’re looking at about 16.4k, 8H, from 6500 turns of 44 AWG. I’ve experimented with winding similar coils and for the life of me, I CAN’T get a reading over 5.6 or so H. It’s driving me mad. How do some manufacturers get such high L? Another manufacturer I saw has a 9k rocking 10H. Howwwww? What meter are you using and at what frequenzy is it set? |
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Post by antigua on May 12, 2022 13:11:59 GMT -5
Forgive me for the zombie post, but I’ve been studying pickups quite a bit and I’m utterly baffled by the relationship between turn count and inductance. On a JB for example, you’re looking at about 16.4k, 8H, from 6500 turns of 44 AWG. I’ve experimented with winding similar coils and for the life of me, I CAN’T get a reading over 5.6 or so H. It’s driving me mad. How do some manufacturers get such high L? Another manufacturer I saw has a 9k rocking 10H. Howwwww? What meter are you using and at what frequenzy is it set? I use a DE-5000, set to Ls at 100Hz for inductance and, Cp at 100kHz for capacitance, and 1kHz for the Q factor, when I collect that. |
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