Humbuckers - Coil Split - Preamp

[Double E]

Hi, I am looking to connect two humbuckers to my new Audere preamp with a single on/on mini-toggle to split the coils on both pickups simultaneously. My desired result is to have either two humbuckers or two single coils...nothing fancy really.

I will follow the diagram below and just use the second set of contacts on the same switch for the second humbucker. I am not 100% sure I am not overlooking something.

Which of the two grounds should I attach to the common input of the preamp?

I figure that since all of the pickup blending is done in the preamp that I just need to feed in the single coil or humbucking signal to the preamp as dictated by the position of the toggle. I shouldn't need to worry about any other trickery, should I?

Thanks in advance for any and all help!

 

[line6man]

Firstly, that's splitting, not tapping.

You probably don't want to copy the wiring exactly for the second pickup's switching. You will want to ensure that the coils you choose are RWRP, to allow humcancellation. This generally means choosing either inner or outer coil pairs. You may rotate one pickup so that its north coil becomes its south coil, and vice versa. A better option is to wire one pole to split to a north coil, and the other pole to split to a south coil. As far as choosing between inner and outer coils goes, that's a personal preference, and either option will work fine, if you enjoy the tonality.

Which of the two grounds should I attach to the common input of the preamp?

Follow Audere's instructions for grounding.

 

[Double E]

Firstly, that's splitting, not tapping.

Gah...I know that, that was a slip in my thread title, I fixed it.

You will want to ensure that the coils you choose are RWRP, to allow humcancellation.

Oh yes, I get this too. Thanks for the heads-up!

Follow Audere's instructions for grounding.

I am assuming that one of the two grounds on the diagram above would become the pickup common that is required to be attached to preamp...I am just not sure which one I should use.

Audere's instructions:

 

[Double E]

Okay...so here is a draft of my diagram. The the main pickup coil "start" wire (shown as pickup "output") will connect to the preamp's pickup "Hot" input...this the one that should be activated in single coil mode. The series connections will land on the on/on toggle switch common.

I assume the opposite coil "start" wire (shown as the pickup "ground") would connect to the preamp's pickup "Common" input...I guess I am curious how lifting the series connection wires off ground splits the coils.

 

[line6man]

Okay...so here is a draft of my diagram. The the main pickup coil "start" wire (shown as pickup "output") will connect to the preamp's pickup "Hot" input...this the one that should be activated in single coil mode. The series connections will land on the on/on toggle switch common.

I assume the opposite coil "start" wire (shown as the pickup "ground") would connect to the preamp's pickup "Common" input...I guess I am curious how lifting the series connection wires off ground splits the coils.

Now you have a pickup out of phase. Be mindful of the positive and negative phase leads. You are switching the order in which two coils connect in series, such that one coil is closer to the ground potential, and the other is closer to hot. You are NOT, however, inverting the polarity of any coil.

 

[Double E]

Does it work if i re-label the sketch this way or am a still off base?

 

[line6man]

For the bridge pickup, white is the ground, and black is the hot. Red and green go together, to the switch. Also, you need to switch the north and south coil labels on the bridge pickup.

 

[Double E]

So swapping the white/black pair with the green/red pair reverses the polarity, safe to assume?

I think the north and south coils are inverted on the existing bridge pickup...judging by the way they were wired before removing the factory electronics, which had both greens attached to the pickup selector switch and both reds to ground. The coil tapping feature integrated with the rotary selector switch provided single coil operation of the outer single coils (neck p/u neck coil and bridge p/u bridge coil).

It also would seem, based on your advice, that Fender (this is a Fender Modern Player Jazz) did not have the polarity reversed. Alternately, maybe the factory wiring was completely wrong! Here is a couple pictures of the back of the original, wired control plate:

 

[Double E]

Does anybody else have any input here? Was Fenders factory wiring goofed up?

I don't know if I should I pay any attention at all to the way it was wired before.

Both green wires and both black/white series connections were tied to the four way rotary switch and both red wires were connected to the volume pot housing (ground)...much in the same way I propose to connect to the preamp inputs in my last diagram. It makes sense to me to wire it this way because of how it was wired from the factory.

Am I wrong in thinking that the bridge pickup has the north & south coils inverted? I believe this is so, again, based on the factory wiring and the confirmed behavior of the rotary selector which switched both pickups in and out of single coil mode. When in single coil mode, the "outer" pickup coils were active (neck p/u neck coil and bridge p/u bridge coil).

 

[Double E]

Here's what the diagram would look like if I take line6man's advice and reverse the polarity of the bridge pickup coils...but stick with my assumption that the bridge pickup is inverted.

@line6man - am I crazy to think that the bridge pickup is inverted? Is this done? If not, why did it behave the way it did with the factory setup?

 

[line6man]

I'll redraw your diagram properly when I have time. It still is not correct.

 

[Double E]

Without any consideration to my obviously wild theories considering the existing wiring, this should be the closest version to what @line6man laid out in post #7... will this work?

Also...what to do with the bare ground wire that is not shown in the diagram? does it connect to ground or to the preamp common along with the respective red or white wire?

 

[line6man]

 

[Double E]

Thanks.

The Audere pre has inputs not just for positive, but also common. Do I connect the negative leads that you show going straight to ground to the common inputs of the preamp or just keep them on ground and ignore the common inputs on the preamp?

 

[line6man]

Thanks.

The Audere pre has inputs not just for positive, but also common. Do I connect the negative leads that you show going straight to ground to the common inputs of the preamp or just keep them on ground and ignore the common inputs on the preamp?

Like I said, follow the directions for your preamp. If it wants the pickups' negative phase leads seperate from ground, then connect the ground terminal in the diagram to the common terminal.

 

[Double E]

Like I said, follow the directions for your preamp. If it wants the pickups' negative phase leads seperate from ground, then connect the ground terminal in the diagram to the common terminal.

Thanks again line6man! I certainly appreciate you taking time out of your day to help.

Though you haven't said so directly, I guess you are deeming Fender's factory wiring on this bass to be deficient. They apparently did not reverse the polarity on the bridge pickup as you are clearly recommending.

By the way...I deleted all of my bad sketches so that some poor soul does not stumble on to them and use them for their project.

 

[Double E]

Like I said, follow the directions for your preamp. If it wants the pickups' negative phase leads seperate from ground, then connect the ground terminal in the diagram to the common terminal.

Wait a minute...are you saying I should still land the pickup negatives to ground first and then extend wires from that point to the preamp inputs?

 

[line6man]

Though you haven't said so directly, I guess you are deeming Fender's factory wiring on this bass to be deficient. They apparently did not reverse the polarity on the bridge pickup as you are clearly recommending.

I am not recommending any reversals of polarity. Failure to observe proper polarity will result in out of phase pickups that sound thin when used together. I recommended switching the order in which the two coils on one pickup connect in series, so that one pickup splits to the north coil while the other pickup splits to the south coil. The reason for this is that you want to split to oppositely directed coils in order to be able to humcancel. If the two pickups are wound in the same fashion, then splitting both of them to their north coils will not result in humcancellation.

As far as Fender's wiring goes, I have not translated it to a schematic to check, but if you observe that both pickups split to the same coil, then it is possible that the pickups were not wound in an identical fashion. It may be that Fender designed the north coils on their neck pickups to be RWRP from the north coils on their bridge pickups, without any change in the color code. If this is the case, then you can use the original diagram.

Wait a minute...are you saying I should still land the pickup negatives to ground first and then extend wires from that point to the preamp inputs?

I can see that this is beginning to become confusing, so I am going to draw up a second diagram, with a detailed account of the grounding scheme with the Audere preamp, as well as an alternate switching scheme to use, if it turns out that the pickups wound as I described above. Give me another day and I'll post it up.

In any case, no, you wouldn't ground the common input on an Audere preamp.

 

[line6man]

Ok, here is a more detailed diagram, specific to your Audere preamp. There are two options. The top diagram splits to the outer coils. If the north coils on your pickups are NOT RWRP with respect to each other, this is the diagram to use. If, on the other hand, the north coils on your pickups ARE RWRP with respect to each other, then the bottom diagram is the one to use. To determine whether or not the north coils of the pickups are RWRP with respect to each other, you will probably need to analyze the stock wiring to see how the coils were split, and note whether or not humcancellation occurs in split mode.

 

[Double E]

Thanks @line6man !

This makes perfect sense to me now. I am glad I posted my plans here for critique.

I will definitely be double checking how these pickups are wired before proceeding.

I found this great video on analyzing humbucking pickup coils, he does a great job explaining the how's and the why's... plus it has a little surprise lesson in not making assumptions about the color codes of the pickups, even when both pickups are OEM equipment! The pickups he used for his video were out of a Peavey guitar and the neck and the bridge pickup's coils were not color coded identically.