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): 16.7K
• "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)
• "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)

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 once I have those measurements.

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. 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.

If I find any more of my records or get any more measurements to share with you guys, I'll try to 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.