For the "JB" Nerds... (Inductance and DC Resistance values for older JB models)

[Masta' C]

Thought a few of you might enjoy seeing the relative inductance and resistance values for some older '70s/'80s "The JB Model" and "JBJ" pickups.

Fairly certain I had one of the largest collections of truly vintage JB's out there at one point, but I've slowly thinned the herd over the past 7-8 years and only have a few examples of these original pickups left.

Here are a handful of measurements I took tonight:

"The JB Model" #1 - black, 4-conductor (circa '79-'82)
Inductance: 8.03H
Coil 1: 8.3K
Coil 2: 7.9K
Series: 16.2K

"The JB Model" #2 - black, 4-conductor (circa '79-'82)
Inductance: 8.13H
Coil 1: 8.0K
Coil 2: 8.1K
Series: 16.1K

"The JB Model" #3 - black, single-conductor (circa '78-'79)
Inductance: 8.49H
Series: 16.3K

"JBJ" #1 - black, large baseplate logo (circa '83-85)
Inductance: 8.24H
Coil 1: 8.6K
Coil 2: 8.4K
Series: 17.0K


Here are more DCR measurements from some older JB's I've sold in the relatively recent past. Unfortunately, I don't have inductance values for these:

• "The JB Model" (earliest production version): 16.2K
• "The JB Model" (earliest production version): 16.7K
• "The JB Model" (earliest production version): 16.9K
• "The JB Model": 16.2K (8.1K + 8.1K)
• "The JB Model": 16.1K (8.0K + 8.1K)
• "The JB Model": 16.6K (8.1K + 8.5K)
• "The JB Model": 16.8K (8.4K + 8.4K)
• "The JB Model": 16.4K (8.1K + 8.3K)
• "The JB Model": 15.2K (8.1K + 7.1K) *see Edit 1 below
• "JBJ" (early '80s, large baseplate logo): 16.0K (8.0K + 8.0K)
• "JBJ" (early '80s, large baseplate logo): 17.2K (8.3K + 8.9K)
• "JBJ" (late '80s, small baseplate logo): 16.2K (8.2K + 8.0K)

One thing I find interesting, even if not particularly important, is that most of the very early stuff was either quite low in the 16.0K-16.2K range or higher in the 16.7K-17K range compared to the "16.4K" spec. Not saying any of these are technically "out of tolerance", but it's interesting nonetheless.

I also think it's pretty clear from these measurements that the JB has always used symmetrical coils, at least in production.

The few that have suggested "offset" coils are definitely a rarity and unlikely to have been intentionally made that way. Also, my sampling is rather skewed, because I tend to hold onto the more interesting pickups and sell off the rest, so the "offset" coil phenomenon appears more common in my limited collection than it would have in actual production. I did have one example of an early production model that had a particularly notable disparity between the coils. I know I've posted about it before, but I'll see if I can dig up that info.

EDIT 1: In 2019, I posted about one of my early "The JB Model" pickups that came in at 15.2K with coils measuring 8.1K and 7.1K. What was interesting is that it appeared to be all-original with no obvious signs of having been tampered with, rewired, repotted, etc. Why that pickup exists is a mystery...did bobbins get mixed up at the factory? Was it a factory rewind of a damaged coil way back in the day? Odd batch of wire? Who knows! Either way, I've added the info to the list above. Also, I don't have Darth Phineas' particular pickup in hand to inspect (and he actually uses a picture of one of my pickups on his website rather than the one he actually measured in his article), but he provided details for one of his "The JB Model" pickups at 15.7K with 7.1K and 8.5K coils, which I found interestingly close to my own from that period.

EDIT 2: For those wondering, I don't currently have any regular-spaced versions of modern JB's to compare these with. Also, Trembucker versions (i.e. TB-4) are going to have considerably higher DCR and greater inductance values due to their longer coils requiring more wire, regardless if the turn counts are the same as the standard-spaced version. For example, I have a TB-4 in front of me that measures 18.1K and 8.98H. That may be a bit on the high side (most Trembuckers I've come across are in the low-to-mid 17K range), but this is exactly why the TB-4 shouldn't be compared against the standard (SH-4) versions.

I do have 2 more "JBJ" models on hand, including one early '80s large baseplate logo version and one later '80s NOS (new old stock) version. However, I wasn't getting a reading on one coil of the older pickup and I'm not sure I want to strip back the virgin leads on the NOS one to get the inductance (DCR is posted above), just in case I decide to sell it in the near future. We'll see...

If I can figure out what's going on with the older JBJ, I'll add it to the info above. Likewise, if I find any more of my records or get any more measurements to share with you guys, I'll update the list.

 

[beaubrummels]

FWIW My limited understanding is part of the DCR reading difference is the wire stock supplied at the time, e.g. min-nom-max. The turns per layer and tension should be the same so they should sound very similar. There's threads on here about it.

 

[Rex_Rocker]

That's interesting, thanks for posting!

Do you have any current-day off-the-shelf examples to compare?

 

[Chistopher]

What are you anecdotes between them?

 

[Mincer]

So, which one sounds the best? They all seem close enough that someone who like the JB wind would probably dig any of them, and those who don't...won't.

 

[GrooveHT]

Masta C, this is actually of some interest to me; have you compared the F spaced Trembuckers to these at all? Or are there any differences in magnets (roughcast/polished/UO) in any of these? I'm kind of trying to tie down in my brain which variables affect what.

Thanks so much for the cool comparison!

 

[jeremy]

id guess all production trembucker jb are polished. by them time they came around, i think all production pups used polished mags. not sure if the cs model trembuckers use something different

 

[GrooveHT]

id guess all production trembucker jb are polished. by them time they came around, i think all production pups used polished mags. not sure if the cs model trembuckers use something different

Jeremy, I had seemed to remember at one point reading that they went from roughcast to polished, but I'm not sure?

 

[Rex_Rocker]

Jeremy, I had seemed to remember at one point reading that they went from roughcast to polished, but I'm not sure?

Yeah, I think Jeremy means by the time the Trembuckers came out, they had gone from roughcast to polished on all pups.

 

[jeremy]

correct. i know they used roughcast back in the day, but by the time the trembucker came out, all production pups used polished magnets

 

[Mincer]

Does a roughcast JB sound much different than a polished one? I've compared roughcast to polished in vintage output pickups, and you can hear/feel a difference, but I never compared them in higher output pickups.

 

[Rex_Rocker]

Does a roughcast JB sound much different than a polished one? I've compared roughcast to polished in vintage output pickups, and you can hear/feel a difference, but I never compared them in higher output pickups.

I've be interested in that as well.

I've heard comparisons of the regular production JB to the 35th anni JB, but I don't think the roughcast magnet is the only thing that's different between them.