Revisiting A Classic: The JB Model

The JB Model humbucker is one of Seymour’s earliest designs. It remains a seminal force in the realm of aftermarket, OEM, and upgrades for guitar pickups. Let’s unpack that for a second. I am using “seminal” for a reason. It can mean influential, formative, groundbreaking, innovative, important and the list goes on. That’s important to remember.

Seymour’s recipe for the JB model is the foundation for other models. The Distortion. The Mag (and Stag Mag). The Allan Holdworth (renamed Metal Fatigue) and the Jake E Lee variation. The Thrash Factor. The Dokkenbucker (renamed the Hunter). The Invader. It can also be considered the starting point for the RTM, the Super V, and the Alex Skolnick set.

A resurgence of interest hit the JB model almost 10 years ago with the Antiquity JB, the Concept JB, and the 35th Anniversary JB. My Fall 2016 series on the different iterations of the JB model is one of the most visited and searched for products on my website. And THAT is why I am talking about it again.

Not just any JB model. “The JB Model” from the late 70s and in to the very early 80s. It pre-dates the JBJ version that so many guitarists seem to chase. By the way, any JBx (i.e., JBL, JBM, etc.) label gives the same results as the JBJ and MJ will be the first to tell you so. HaHa! Anyway, The JB Model is the one it’s all trying to replicate.

Among the 4 (four!) The JB Model humbuckers that I have, there are interesting comparisons. And maybe not how one might expect.

Specs

The JB Model ex. #1
Series – 15.659 K
Inductance – 7.924 H
Split – 7.138 K
Split – 8.551 K
Parallel – 3.889 K
Magnet – Rough Cast Alnico 5

The JB Model ex. #2
Series – 15.968 K
Inductance – 7.888 H
Split – 8.137 K
Split – 7.861 K
Parallel – 3.995 K
Magnet – Polished Alnico 5

The JB Model ex. #3
Series – 15.717 K
Inductance – 7.757 H
Split – 7.867 K
Split – 7.889 K
Parallel – 3.936 K
Magnet – “Hybrid” Alnico 5

The JB Model ex. #4
Series – 16.165 K
Inductance – 7.746 H
Split – 8.073 K
Split – 8.122 K
Parallel – 4.047 K
Magnet – Polished Alnico 5

DC Resistance

Let’s start with the DCR. Those examples run a range from 15.717 k to 16.165 k. The coil offest ranges from 0.27% to 16.5%. That can mean different things and should not be an assumption of a secret recipe or other deliberate act. If anything, we should remember that tolerances on materials were not as tight as today. It was about 40 years ago, after all. LOL!

Here’s the deal. Matching DCR on two coils of the same humbucker is no guarantee of the coils being identical. Any more that uneven DCR readings might not mean there are more or less turns. How the wire is handled can affect coil geometry, as we should remember these were long before a CNC is put in to play on this model.

As such, there is an array of variances that can come in to play. Did the winding operator load one part of a coil thicker or thinner than the rest? Is one coil made in a Friday afternoon batch and the other made Monday morning after a fresh calibration to the winding machine or new felt for the tensioner? Maybe something is going on with the tolerance of the material that came from the wire vendor in use at that time? There’s no telling.

Why all that detail? It’s funny. One of my The JB Model humbuckers is confirmed to be Seymour’s own work. I get word a while back that some chump is selling one, using the online DCR specs from mine as a launching point to promote their item as also being from Seymour’s hands and asking stupid money for it. Except the seller is dead wrong about who wound it. How do I know? Sorry, that’s my earned knowledge to do with as I see fit.

Magnets

Magnets can be a sticking point. The 35th Anniversary JB, the Antiquity JB, and the Concept JB all facilitate rough cast Alnico 5 magnets. Self-proclaimed experts on the JB model have trashed keyboards and clutched pearls over the solid assertion that regular production JB models use the polished Alnico 5 magnet.

Yeah. About that. HaHa! You’ll see in the specs above. Half of The JB Model examples I have do use the polished magnets. However….. LOL! One has a rough cast magnet. And about the one I’m calling a “hybrid”. One side is polished and the other is rough cast.

Yes. One side is rough cast and the other is not. If you lay hands on examples of rough cast for any reasonable amount of time, you will see some that appear to be a mish-mash of rough and not so rough. Basically inconsistencies in production. This is not that. This is a full-on real-deal fully rough cast side. Flip it over, and you have a smoothly polished side. Talk about a unicorn!

Labels

Really a bit of a non-starter, but some of the inks are different colors. 2 (two) of the example have an ink that’s fairly red and can be seen in one of the images in this article. It is like the ink on my “The Mag” humbucker.

Another one is blue and can be seen in the header image of this article. This blue is the same color as the ink on the label of my old “Duncan Custom” pickup.

The other ink color is similar to a bold purple and almost black. As it stands, there is no real reason to think the different colors of ink have any real significance. Maybe the office supply was out of blue ink pads, but had red.

Comparison

Many a JB model is put to use in many a guitar of mine over the past 35 years. And even multiple versions in the same guitar. So I’m not some message board rat throwing darts blindfolded in his mom’s basement. HaHa! I do have to say that if you do not want to hunt down a The JB Model via online resources, I’d have to say that the Antiquity JB comes the closest. The Thrash Factor is alarmingly close but the accouterments might scare off purists. Either option is easier and may or may not save you a few bucks.

For reference, these Seymour Duncan The JB Model humbucker evaluations are conducted with a Fractal Axe-Fx II XL+ featuring Celestion Impluse Responses and Fractal MFC-101 MIDI Foot Controller.  Real cabs are Marshall 1960B cabs loaded with Celestion Vintage 30s and G12M Greenbacks.

Seymour Duncan Website | Facebook | Twitter | YouTube | Instagram

7 string 59 Alnico 2 Alnico 4 Alnico 5 Alnico 8 Bare Knuckle BKP Brandonwound Brass Brown Sound Celestion Ceramic Custom Shop Dean DiMarzio DMT EVH Falbo Guitars Fishman Floyd Rose Fluence Gibson Humbucker JB Jimmy Page John Petrucci Les Paul MJ Mojotone Nut P-90 PAF Pariah Pickup Professor Guitarism ReWind Satch Satriani Schaller Seymour Duncan Singlecoil Speaker Steve Vai Tech Tip