Breaking up is hard to do (Mudbucker Coil Split)

[chromium]

I completed the pickup surgery on my EB-0 today.  It now sports a mudbucker with four output wires - a pair for each coil - making it possible to create different coil combinations, each with some unique sound characteristics.  I built a new wiring harness to allow series/parallel switching of the humbucker coils, and also coil-tap for running it in single-coil mode.

The coils in a stock mudbucker are hardwired in series.  My pickup had a reasonable amount of slack in the wires coming out of the coils.  Not sure if they are all like that, but this was a welcome suprise, and made the job fairly simple.  Here's a shot of the pickup once I carefully extracted the wires out from under the coils:




In order to perform this mod, I had to run a four-conductor wire to the pickup.  I chose to use some shielded cable that I had handy, and I grounded the shield to the pickup casing.  I also ran a wire (not pictured) up to the pickup cover to ground it and keep it from buzzing when touched (I think I need to do that to my EB-3 too - buzzes like the dickens).  Here are some shots of the 4-wire mud, before I tucked the extra slack back under the coils:






In order to accomplish all of the switching permutations, I used two push/pull pots in the following configuration:




The volume pot switches between humbucking and single-coil mode, and the tone pot's switch changes the relationship of the pickup coils from series to parallel wiring.  This has a marked effect on the impedance and sound of the pickup.  In normal series-mode, the pickup measured about 30K.  Single-coil mode cuts that in half, and parallel-mode drops the impedance down to about 7.5K.

The most difficult part of this whole thing wasn't splitting the pickup coils - it was fitting those pots in the control cavity.  I couldn't get the cover back on because the pots are so tall!  I ended up taking out the brass shield insert and sanding down a couple of high spots in the wood.  Barely got everything to fit!  This is the finished product:



(Dig my super rare capacitor too.  I'll have it paid off next year.  It's totally vintage - out of a sweet '68 Teisco.  )


So hows it all sound?  Well- the differences between the various settings are subtle, but were immediately obvious to me.  As you drop to single-coil and parallel mode, the characteristic mud washes away, and the sound becomes more clear, and less "saturated".  I made a clip to try and demonstrate the differences:



The clip just repeats the same passage, iterating thru the following settings:

1.  Stock mudbucker w/coils in series
2.  Coils in parallel
3.  Single coil
4.  Single coil w/tone rolled off
5.  Stock mud w/tone rolled off a bit

I tried to record that as raw as possible.  It's just bass -> Alembic preamp (set flat) -> computer.  You probably need to listen thru phones or some decent monitors to fully appreciate the subtle differences in tone.

[Chris P.]

I'll listen to it ASAP, but it sounds promising. I guess the parallel/series switch will sound a bit the same like an EB3?

[Dave W]

Well, it was worth it to do the experiment, and I'm glad you posted the mp3 because it lets people know what to expect.

If I were doing it I'd just have series/parallel. But no doubt I'd be content just to leave it stock. 

[chromium]

Dave -those are my sentiments exactly.  The single coil and parallel humbucking mode differ so slightly, its probably not even worth messsing with the coil tap.  The nice thing about parallel mode is that you don't have the hum/buzzing that you get in single coil mode (only a trace amount - but it is there).

The other nice thing about all of this is that it can be put back to stock (well, aside from my sanding under the control cavity shield    -our little secret ).  I didn't have to make a single cut on the pickup wires - just desoldered them.  Still, I probably wouldn't have tried this if my EB-0 hadn't already been subject to prior cruelties.

@Chris- it's a different sound than an EB-3.  EB-3 mud is subject to the varitone filtering in all modes:  choked in position 4, and filtered highs in position 1 (same thing the stock EB-2 suffers from).  The effect of the new settings on my EB-0 is more subtle in nature - its' like like full-bore, wide-open mud versus slightly more gentle/articulate mud - but still unmistakably mudbucker in every setting.

[Chris P.]

Thanks, good to know!