Dummy coils!

[Alanko]

My OLP bass is about to enter the next phase of modding. My goal here has always been to make the bass sound something like a robust Rickenbacker and, to that end, I've kitted it out with different pickups over time.

My next plan is to fit two Jazz-style pickups, in the virtual 24th and 36th fret locations. I plan to wire it with a 3-way switch, master volume, master tone and bass roll of control on the bridge pickup alone to give me the equivalent of the cap in older Rickenbackers. As I'm using single coils, and a 3-way switch, I'm wondering if there is any way of getting a dummy coil in to the proceedings. I have scads of cheap single coil pickups I could use for the job, once shod of their magnets. From what I gather, dummy coils have to be reverse-wound from their accompanying pickup to work. However Jazz pickups are wound in opposite directions so that they cancel hum when both turned up. Therefore does each pickup need an accompanying dummy coil, and will this kill all the high end when both pickups, and their dummies, are selected at the same time? I want to keep the bass easy to play, so I don't really want to be working with microswitches to flip the phase on the dummy coil, which is the only solution I've seen online thus far.

[Dave W]

Jazz pickups traditionally aren't wound in opposite directions. It's become more common in the past 20 years. You'll need to know one way or the other.

If they're traditional -- wound in the same direction -- then you only need one dummy coil, RWRP with respect to the other two. You could stash it in the control cavity if you have enough room.

I'm not sure how to wire it (my brain hurts thinking about complex wiring diagrams), maybe someone else here can show you. But I know it can be made to work, b/c of the way my Fender Rascal Bass works. The middle lipstick pickup is RW/RP in relation to the other two. In addition to being noiseless in positions 2 and 4 of the 5-way switch, it has two more options when you pull up the volume pot. One of those gives you all three pickups, and it's noiseless in that position. Hope that makes sense.

If your Jazz pickups are RW/RP to each other, then I'm almost sure you would need a dummy coil for each one.

[BTL]

Mojotone has released a new "quiet coil" design for guitar.

You may consider checking in with them after NAMM to see if they will be offering a version for Jazz Bass.

The core of each coil is an alnico rod magnet, presumably with rounded ends, and the center slugs are "dummies":

[Lightyear]

John (Redbird/Barkless Dog) Fertig built a bass with an dummy coil, Uwe has it now I do believe.   I'm sure the thread could be found easily enough.

[chromium]

John (Redbird/Barkless Dog) Fertig built a bass with an dummy coil, Uwe has it now I do believe.   I'm sure the thread could be found easily enough.

That was a cool build.

http://bassoutpost.com/index.php?topic=419.0

[Granny Gremlin]

Ideally, the dummy coil has to be RWRP (as Dave pointed out) AND the same in terms of specs (e.g. basically the same pup) AND is as close to the same location as the pup it is to bnuck the hum of.  This last point is the least vital (Alembic didn't care and put the dummy for both neck and bridge pups in the middle, but Gibson did it right proper with the LP LoZ pups which are stacked humbuckers, dummy on the bottom).

You might be able to get away with a random J pup; might be similar enough, but you will have to figure out if any of the ones you have are reverse to the ones you want to use in the bass.  Fortunately, there is no standard so despite what Dave said about Js not coming in RWRP sets, pups from different manufacturers may very well be.  You can look up how to test/check this on youtube; there's a ton of vids about it.

[Alanko]

Thanks all for the advice. I'm going to use some of this stuff for beta testing;



I really don't know what is going on with either my candidate dummy coils or the pickups I intend to use. I might scrap the dummy idea all together!

[Highlander]

Choccy-blocks...!

[Dave W]

Fortunately, there is no standard so despite what Dave said about Js not coming in RWRP sets, pups from different manufacturers may very well be.  You can look up how to test/check this on youtube; there's a ton of vids about it.

I thought I made this clear when I said that RWRP sets have become more common in the past 20 years, and that you need to know one way or the other. RWRP pairs were unheard of back when I started playing, IIRC Seymour Duncan was the first to offer them and now they are common, but not every set is that way, and not everyone buys in sets anyway.

[Granny Gremlin]

Oh sorry; I misread that then. 

[Alanko]

If I need to use two coils, is there any reason not to use a de-magnetised humbucker with 4 wires, and simply using each coil as the dummy? I have some sort of hideous Schaller X2N clone I'm never going to use, so I might use that if it works.

[Granny Gremlin]

Yep.  You couldn't use it if it was 2 wire.  And you gotta watch out for which coil is wound in which direction vs your proper pups.

[Alanko]

Thanks! I'm going to be trying out various wiring permutations to get the right fit. One idea I have is to fit my Fender WRHB pickup in the neck position... again, only testing will reveal if this is a good idea!