Variation on JH's Jimmy page with P90 + HB, the JDJHJP

[JD]

Someone on this forum asked how many JP wiring do we need?
Well apparently one more.

There are a lot of variations out there, but I've found very few that would match my project.
So I started looking around and, with a lot of help from JohnH, We've come up with this design.

Let's go back to the beginning:
After buying a couple of new guitars, I wanted to repurpose my 20+ years old Epiphone LP and to occupy my time during these locdowned days... (apology for the neologism if the word doesn't exist)
So I had an old LP, with dead pots and time on my hand. First I wanted see what was out there in terms of pickups that could spice things up. It had old modern Epiphone humbuckers in, fine but not very exciting in terms of identity.
After some research I settled on a vintage voiced PAH humbucker in the bridge and a P90 in the neck. Once that was sorted, I heard about treble bleed mods, 50's wiring and Jimmy Page wiring. Let's mention here that I had never modified a guitar at that point.
So, more research and surprisingly very few JP wiring with a P90 option, and those who had one had an unused spot for a push pull mod (Can't exactly split a single coil...).
I could have gone for that but, you know, why make things simple when you can make them complicated...

In my research for a good JP wiring I happened to stumble upon JohnH's design (here) which was the first one with an actual electrical diagram, and the engineer in me found it far easier to understand and adapt than a simple wiring.
So I had now a starting point and a lot to learn to arrive where I wanted. My luck was John was patient enough to answer my questions and give me some insights (discussion can be found on his thread starting here unless a Mod or Admin can move the posts to this thread) so I could reach a point where I was confident enough to undertake this project.

Enough foreword, let me introduce to you the JDJHJP wiring ! (I know so very pompous, right ? And I hope JohnH will allow me modding his design's name as well as his design !):

Features: "Jimmy Page" modern wiring with Treble bleed (no 50's wiring)

    2 Pick Ups: Neck P90 (modded to have 2 wires + Shield) + Bridge HB (4 wires + Shield)
    4 Push Pull Pots
        - Neck Volume : Neck and Bridge Out of Phase
        - Neck Tone : Global Parallel / Series
        - Bridge Volume : HB Coil Split
        - Bridge Tone : Local HB Parallel Series

Electrical schematic:

Wiring Diagram:

Configuration Table:

Special configs: Parallel HB with coil split engaged:

I am not sure exactly what's going on with the In phase config, maybe i messed up the wiring, but it's much darker than the split HB in normal config (not parallel).
Out of phase the inline RC circuit is acting as a high pass circuit as expected and the sound is brighter than the Split HB

Now this is by no means carved in stone (This is my 5th version after all...), I welcome any comments and input to keep making it better !
Once again, credit to where credit is due: This was based on JohnH's design, and most of the modifications come from his advice, so Thanks !

In the end, I hope this will help someone, if not for the actual thing, but for knowing that even if you've never modded the electronic of your guitar and even if you're clumsy (at my best) with a soldering iron, with some help and some work you could have fun with a brand new (old) guitar !!

PS: I've used DIY Layout Creator to render the wiring diagram, a nice little freeware by Bancika. You can find it here: bancika.github.io/diy-layout-creator/ (Copy/paste the url, the link doesn't seem to be working)

[dmh]

Hi I've been looking for a P90 neck and Humbucker bridge wiring diagram that included phase and coil split, and I like the series/phase options you have here.

I'm new to rewiring guitars and have not come across the extra shield wires before and struggling to find out much about them - hoping you can give me a hand? I'm not an engineer or electrician so hope it can be explained fairly simply!

I assume the shield wire is shown in light blue, in which case:

• What is their purpose, I assume something to do with shielding/to reduce hum but not sure why it is necessary compared to other circuits?
• If my other wires are shielded are your shield wires still beneficial? Would the circuit still work without the shielding wires, or would it need adjusting?
• It looks like they are just soldered to the pickup frame? 
  
• Does the shield wiring need to be any special type of cable?

Any other comments, links etc would be greatly appreciated!

Many thanks

Dan

[JD]

Hello and welcome Dan,

Tricky little devils to find those P90/HB wiring, right ?

So shielding.... I am an engineer but rather new to guitar wiring, so I'll explain to the best of my knowledge, which might not be optimal...

First, Shielding is connecting all the metal parts of your guitars and cavities to form a protective cage against electromagnetic radiation you might find yourself into. It may not be a problem where you are, but it might be hell in other places, so don't cheap out on that part !

Second, if you haven't noticed it on other circuits, it's because it's usually the same as grounding. Most of the time they have the same role and one of the wire of your pickup is connected to the frame and plays both roles.

Now it gets tricky when you want an out of Phase configuration. If one of the wire is always connected to ground and to the rest of the shielding, when you're inverting them, you may have both wire connected to ground in the end which means no sound.
So Basically you need to have both wire of your pickup kind of floating from the shield/ground parts of your circuit. On the schematic above you'll notice that both pickups are not connected to ground directly, only after switches, which allow to always have the right side connected to ground and never short any pickups.
That means that on HBs with splitting capacities, you'll need 5 wire (2 for each coil and 1 shield, connected to the frame, most come that way), and on HBs with no split and SCs, 3 wires (2 for the coil and 1 on the frame. If you are missing that shield wire as I was on my P90, You'll need to desolder the ground wire from the frame (careful not to break it, but it's not that difficult) and add another wire soldered to the frame.

You can use basically any type of wire for you shield circuit, even bare ones (as often found on pickups) as they are easy to connect to the cavities shielding (just be careful not to touch any connectors on the pots)
Also on the wiring above (yes, in light blue), you'll notice that you could safely remove one of the grounding connection between a pair of pots. I just added a redundancy and I liked the symmetry of it ^^
What's not on the wiring diagram though, is the connection to the shielding cavity somewhere. Whether you use conductive paint or copper tape, you'll need to have a contact with one of those wire (solder on copper, or bare wire hooked on the conductive paint or whatever clever solution that exists out there...).
And don't forget to shield the cover as well to seal the cage. I personally used conductive paint on the cavity and copper tape on the cover but more experienced people may have a better approach.

All that being said, that was (and still is) my first wiring experience and there are far more experienced people around here with probably better answers.
Good luck with your build, if you prepare well, there's no reason it shouldn't work !
And if you try this design, with the shunting module, I'd like to hear from you about the two weird configs (the dark sounding one in particular)... If it's the design or if I messed up somewhere. Everything is working and I really don't want to get everything out to check ^^'
Also, last tip, use connectors for your pickups...if it sound thin or not as it should in normal mode, maybe one pickup or one coil isn't in the right way, and with a connector it's easier to correct it rather than desolder and resolder... At least personally, I rarely get it right the first time ^^

That's it, have fun !

[newey]

dmh-

Hello and Welcome to G-Nutz2!

JD has already dealt with most of your questions, but let me "zero in" a little on some of the questions.

Also, last tip, use connectors for your pickups...if it sound thin or not as it should in normal mode, maybe one pickup or one coil isn't in the right way, and with a connector it's easier to correct it rather than desolder and resolder... At least personally, I rarely get it right the first time ^^

Nothing wrong with using connectors, but what JD is talking about when he says "maybe one coil isn't in the right way" is that you might wire one or more coils out-of-phase with others. This usually isn't an issue if you are using pickups from the same manufacturer, as the wire colors should be consistent for in-phase wiring.

As far as between the 2 pickups is concerned, you have a phase switch to flip the phase anyway, so you're really only concerned with getting the 2 coils of the HB in phase. If you follow the wire colors for the HB, you should be OK there. As for the phase switch, you would want the push/pull phase switch to operate with the in-phase setting "down", probably. You can check for phase beforehand, we have a tutorial in the references section on how to do that, using a PC or a analog multimeter. Better to test beforehand if there is any question. And not all connectors you will find can be flipped over and reconnected- some of them only go one way, for use with DC circuits.

Now it gets tricky when you want an out of Phase configuration.

I assume the P90 doesn't have a metal cover, but if the HB does, what JD is referencing here is the need to be sure the cover isn't grounded to the frame. If so, you'll have to break that connection and wire a separate (i.e., light blue as per the diagram) wire. If there is any question, a multimeter can quickly tell you if the cover is grounded.

I assume the shield wire is shown in light blue, in which case:

What is their purpose, I assume something to do with shielding/to reduce hum but not sure why it is necessary compared to other circuits?
If my other wires are shielded are your shield wires still beneficial? Would the circuit still work without the shielding wires, or would it need adjusting?
It looks like they are just soldered to the pickup frame?
Does the shield wiring need to be any special type of cable?

Yes, they are to reduce hum. The circuit would work fine without them, but might be noisier. Many diagrams, here and elsewhere, omit grounding/shielding wires between components for clarity's sake. They are understood to be used even if not shown on a particular diagram. Same with the bridge/string ground wire, it's often omitted as understood.

I don't know exactly what you mean by "if my other wires are shielded". First of all, if you mean that you are using cables with a braided shield to do all your connections, those braided wires won't do anything unless they are connected to ground in some fashion. JD's diagram shows one way of doing the grounding, by daisy-chaining the various pots, switches together. This is fine, and is commonly done, but there are other ways to do it. For one example, I use copper foil (with conductive adhesive, so you don't have to solder the strips together) to shield the cavity; with that, you can use the shielding to ground the pot cases, since the copper foil is then connected to ground. And I typically don't bother grounding the frames of switches, as the frame of a switch is unlikely to generate any noise in your circuit. But "best practices" would suggest doing so just to be sure.

No special type of cable is needed to run ground wires, I just use the same wire I'm using to wire the rest of the guitar, albeit in a different color so I can see what's what.

[dmh]

Thanks both, awesome replies and I (think) I understand - certainly enough to go ahead and give it a try!

I've got a busy couple of months coming up but I'll let you know how I get on.

Thanks again

Dan