Vintage Jazzmaster pickup questions

[sangtlee]

Hi everyone -- new to the group, have been reading many of the posts on vintage JMs and restoration projects...such an amazing resource of info!

I'm the 3rd owner of a '65 JM -- and one of the prior owners swapped out the bridge pickup for what appears to be a Seymour Duncan quarter pounder -- having said, that the neck pickup is original to the guitar (pictures below). I have a few questions for the group:

1. If you were to looking to buy a single JM vintage pickup, how would you go about identifying whether it was originally the bridge or neck? Purely via resistance measurement?

2. Given that pickup resistance measurements can vary widely...is there a general range of accepted Ohm values for grey bobbin pickups? Or stated in another way, was there a factory approved range of Ohm values for the neck and bridge pickups back in the grey bobbin era?

3. I understand that the bridge pickup should have a higher resistance value than the neck...was there a specific delta (difference) that one would see between the bridge and neck pickups? e.g. 1.5k -- meaning that a pair of pickups could have left the factory as 7k neck + 8.5k bridge....or 6k neck and 7.5k bridge, etc.

Thanks in advance everyone...and happy holidays!

[will]

1. I check by seeing if the faces of the pickups stick together or repel when they are held close to one another. I believe that Jazzmaster pickups have reverse magnet polarity (and reverse winding direction) between neck and bridge, so the magnets should stick together and not repel one another.

2. Most of the ones I've encountered are around 6.5-8.5K

3. I'm pretty sure no. (though I could be wrong here.)

[mbene085]

The scientific way for checking magnet polarity s with one of these but I admit I often do the "do they stick together?" test.

Depending on the pickup and the era, sometimes the colour of the leads indicates polarity and winding direction, eg on the Mustang where one pickup has black and white leads and the other has blue and yellow.

Fender pickups were never wound by a targeted resistance. There was a designated number of turns that changed as often as one year to the next, but they were wound by hand so there was a wide tolerance and mistakes were made.

There was absolutely no difference in the number of intended turns of wire between neck and bridge pickups, only winding direction and magnet polarity. If one pickup is hotter than the other, it's random luck as to whether the neck or bridge was hotter. The concept of an overwound bridge pickup is a much more recent invention.

[Veitchy]

As I understand it, the wound pickups were set in bins and grabbed more or less at random and put into guitars. I believe the pickups were balanced moreso by height, rather than making sure the bridge was a bit hotter to match the neck, and as such the 'neck' and 'bridge' pickups were whatever that put in on the day.

[sangtlee]

1. I check by seeing if the faces of the pickups stick together or repel when they are held close to one another. I believe that Jazzmaster pickups have reverse magnet polarity (and reverse winding direction) between neck and bridge, so the magnets should stick together and not repel one another.

There was absolutely no difference in the number of intended turns of wire between neck and bridge pickups, only winding direction and magnet polarity. If one pickup is hotter than the other, it's random luck as to whether the neck or bridge was hotter. The concept of an overwound bridge pickup is a much more recent invention.

Thanks for the replies guys...follow up question then...if you're not able to physical inspect the pickup, then how can you determine if it was the neck or bridge pickup? I've seen several ads on ebay and reverb showing the pickup and the ohm reading...but no indication of polarity. If I can't physically hold it up face-to-face to my presumed vintage neck pickup...then how can I be sure which pickup I'm buying?

I'm happy to spend $6 on the magnetic polarity reader...but does anyone out there know what polarity the bridge (or neck) pickup should be on a late '65 JM?

[Todd Connelly]

Greetings all. So I just took a compass to all of the pick ups in my guitars and found that the bridge pickups on all of them are north polarity. (Attract the north needle). A Jazzmaster, a Telecaster, a Stratocaster and the bridge side of the two + two pickup in my P bass style washburn. I'd say that's a pretty compelling argument that that is pretty much an industry standard. In any case pretty much everyone has a compass in their house somewhere right? I'd just check yours and ask any potential seller to check for you.

Cheers.............................Todd

[sangtlee]

Greetings all. So I just took a compass to all of the pick ups in my guitars and found that the bridge pickups on all of them are north polarity. (Attract the north needle). A Jazzmaster, a Telecaster, a Stratocaster and the bridge side of the two + two pickup in my P bass style washburn. I'd say that's a pretty compelling argument that that is pretty much an industry standard. In any case pretty much everyone has a compass in their house somewhere right? I'd just check yours and ask any potential seller to check for you.

Thanks for sharing that info Todd! Do all of your NECK pickups exhibit south polarity then? (i.e. attracts the south needle). Of course, I'm the only person in the world without a compass, so I purchased the polarity tester from Amazon and can confirm similar results with my pickups: black bridge pickup attracts north needle -- grey neck pickup attracts south needle.





So...based on the info from everyone, looks like I should be looking for a pickup that has north polarity (i.e. a compass's north needle is attracted)...and that the exact ohm reading isn't too important, but that I might want to measure the resistance of my neck pickup and attempt to find a bridge pickup with something similar (if not higher). Would people agree with this?

Cheers,
Sang

[timtam]

I have one of these polarity testers. Avoids mental conundrums when using a compass-based gizmo ... "so the pickup attracts the north-labelled end, so that means it's south-up polarity right ? .. or maybe that's already taken into account with this particular gizmo and it's showing me the actual polarity, ie the pickup is actually north-up" .... second-guessing. This thing just lights up as North or South. And I know that's the actual polarity.

[sangtlee]

I have one of these polarity testers. Avoids mental conundrums when using a compass-based gizmo ... "so the pickup attracts the north-labelled end, so that means it's south-up polarity right ? .. or maybe that's already taken into account with this particular gizmo and it's showing me the actual polarity, ie the pickup is actually north-up" .... second-guessing. This thing just lights up as North or South. And I know that's the actual polarity.

Isn't it backwards for you in the southern hemisphere? Just kidding...

[timtam]

Isn't it backwards for you in the southern hemisphere? Just kidding...

Kind of ... this is how the world looks to us ... 'right' way up.

[Todd Connelly]

Do all of your NECK pickups exhibit south polarity then? (i.e. attracts the south needle).

All of the ones that would be expected to do. My Jazzmaster neck pickup does. The middle pickup in my Strat does. (Seymour Duncan SL1s) The neck pickup is the same as the bridge as you would expect. However the neck pickup in my Telecaster is the same as the bridge. (Seymour Duncan Broadcaster set) No RWRP in that set so no hum canceling.

Cheers..............................Todd

[sangtlee]

All of the ones that would be expected to do. My Jazzmaster neck pickup does. The middle pickup in my Strat does. (Seymour Duncan SL1s) The neck pickup is the same as the bridge as you would expect. However the neck pickup in my Telecaster is the same as the bridge. (Seymour Duncan Broadcaster set) No RWRP in that set so no hum canceling.

Roger that -- thanks again for checking and following up. Much appreciated.

[sangtlee]

Continuing my previous question about how to visually identify whether a pickup is bridge or neck (other than checking for polarity)...

Do we know if there is any pattern to the position of the hot lead vs ground lead? Every photo of authentic internal wiring shows that sets of neck & bridge pickups will have swapped lead positions...i.e. white lead on left on one pickup and white lead on right on the other. This makes sense since JM pickups sets are RWRP.

So assuming that someone hasn't messed with the leads...can we confidently say that a pickup was neck or bridge based on the hot / ground lead positions? For example, the image below is of my neck pickup...hot lead on right. If I was to orient another JM pickup of similar vintage in the same position and the white lead was on the left, could we be confident that it's a bridge pickup with opposite polarity and winding direction? Or is there really no base rule for this...and can differ from pair to pair?

[Unicorn Warrior]

Isn't it backwards for you in the southern hemisphere? Just kidding...

Kind of ... this is how the world looks to us ... 'right' way up.

Interesting fact, orientation is a man made concept. We’re merely a floating mass in space. Only humanity has identified portions of the earth as “top (north) and bottom (south)”. If you’ll notice, the countries in the northern “top” hemisphere are predominately more well developed/white than those in the Southern Hemisphere. That isn’t by chance folks. Self centered bias has been taught to us and the rest of the world since the beginning of map making...

Sorry for thread derail