JB/Jazz switch problem

[Inflames626]

Hey guys,
If you've followed my threads, you know I tried the JB/Jazz in dual master parallel mode in a Jackson KV3. Never got that to work, so I went back to splitting with the front coil of each pickup working (screw on Jazz, stud on JB).

I got an idea that I could simulate single coils in parallel for a best of both worlds sound by moving the toggle to the middle position and putting each humbucker in single mode. To my knowledge, middle position on a 3 way switch is always parallel. I turned the JB down all the way, as I want to isolate the Jazz's single in parallel mode.

The weird thing is, with both coils split and the toggle in the middle, if I cut the volume completely to the JB, the Jazz has no output. If I turn the JB back up, the Jazz comes back.

However, I can turn the Jazz down with both split, toggle in the middle, and the JB works fine.

I don't know if this is a factor, but I have the grounds mostly running all to the switch ground, and then from the switch to the ground screw. The bridge as ground well as the pickup cavity grounds go straight to the ground screw. The grounds for the pots go from the ground lug to switch ground. I do not have ground wires going straight from the pot bodies to the ground screw. The pickups are grounded to the switch portion of the pots on the DTDP push pulls. Everything is quiet and sounds okay in hum and single modes, but only when I try this does it not work, so I thought maybe trying to do what I'm doing somehow doesn't work electrically.

I resoldered all connections to the switch just to make sure. Same issue.

As an aside, any advice for a pickup with less bass and highs than the JB, but the same mids? For passives, I prefer the Distortion for full out high gain metal, and the standard Blackouts for active detuned stuff, but I like the JB for 80s Marshall type stuff. It's just a bit flubby in the bottom and shrill in the highs. I'm thinking about a bridge pickup to use with a 59 in the neck. I thought maybe the Custom Custom might do it, since it seems to have less bass and similar mids and highs to the JB.

I know a lot of people like the Custom/59 combo, but I fear that, if the JB is too flabby for me, the Custom definitely will be since it is modeled after a PAF for use in mahogany guitars.

I'm also considering the Custom/59 hybrid and the Custom 5.

Thanks.

[hamerfan]

Re: JB/Jazz switch problem

First of all standard sized JB are not the best choice for a FR guitar. It makes the flabby bass of FR guitar even flabbier. That why SD invented the Parallel Axis and the Tremolo spaced humbuckers. There are boutique winders that worked on that problem too and modified the JB like bareknucklepickups (holy diver or nailbomb).

Second show us your schematic - pic or drawing. My guess, without seeing it, is you must change the wiring of your volume pots.

[Inflames626]

Re: JB/Jazz switch problem

First of all standard sized JB are not the best choice for a FR guitar. It makes the flabby bass of FR guitar even flabbier. That why SD invented the Parallel Axis and the Tremolo spaced humbuckers. There are boutique winders that worked on that problem too and modified the JB like bareknucklepickups (holy diver or nailbomb).

Second show us your schematic - pic or drawing. My guess, without seeing it, is you must change the wiring of your volume pots.

Sorry for not being clearer. It is a TB-4.

The wiring is essentially a combination of the dual master volume diagram with 3 way toggle combined with the coil split. The only additional wires I have are from ground tabs in the pickup cavity. I tend to run everything to the switch and then to the ground tab so there are less wires. There's also less room on a PP pot to solder to.

I may try soldering from the PP pots directly to the ground tab to see if that helps.

[Inflames626]

Re: JB/Jazz switch problem

Here is the diagram I'm using for the split.

https://forum.seymourduncan.com/showthread.php?187159-How-to-Choose-Which-Coil-is-Active-When-Splitting

And for the wiring, again, the dual master volume, 3 way switch.

[AlexR]

Re: JB/Jazz switch problem

I would guess you've wired one pickup to work for dependent volumes, one for independent volume controls

[hamerfan]

Re: JB/Jazz switch problem

I would guess you've wired one pickup to work for dependent volumes, one for independent volume controls

Yep, that's what i thought, too.

[Inflames626]

Re: JB/Jazz switch problem

I would guess you've wired one pickup to work for dependent volumes, one for independent volume controls

Is that possible if they're not directly connected to each other in some way?

Here we go.

http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=2h_2v_3w

I'm thinking it has to be the ground. I don't have the pots grounded to each other. I tend not to be as thorough with grounding as many of the diagrams if the guitar isn't making noise.

[Inflames626]

Re: JB/Jazz switch problem

Something else to consider is this. I know Duncans are not EMGs but you would think the wiring principles would be the same.

http://www.sonic.net/~emgman/pdf/2%20EMG%202v%20no%20tone%203wt.pdf

It looks like the hot wire is in the middle on the EMG pots, but on the left side lug (when the terminals are facing up) on the Duncan diagram. I notice the Duncan diagram doesn't say "volumes independent" even though I assume it is, while the EMG does say it.

More a try out of desperation than anything.

I also soldered the pots to each other via a ground wire. No change. Neck pickup still cuts out completely when bridge pickup knob is turned down, toggle is in the middle, and both are split.

[Inflames626]

Re: JB/Jazz switch problem

Ah, here's the answer guys. Sorry for the long paste but I figured this would be important if you ever want to do what I'm doing.

http://www.stewmac.com/freeinfo/Electronics/Misc/i-4000/i-4000_4.html

Reversed (Jazz Bass) wiring for independent control of volume
If a guitar has two or more volume controls that are wired in the traditional manner (a Les Paul for example), an interesting thing occurs when the selector switch is in the middle position. The volume control for the neck or bridge pickup will turn down the whole guitar—not just its respective pickup. Yet, on a Fender Jazz bass, which doesn't have a selector switch, two volume controls somehow allow you to turn the pickups up or down independently, without affecting the output of the other. How is this possible?


The reason for this is simple. Since the volume controls are in parallel and the output of the volume pots is the sweeper, when either of the controls is turned down (applying signal to ground) the sum output (what the output jack and amp "see") is "short-circuited" to ground. To resolve this problem, simply swap the input to lug 2 and the output to lug 3.

This means that the output jack or the amp never really see or are shorted directly to ground—the pickup is shorted to ground instead. The overall tone of the instrument is not affected, since the DC resistance of the resistive strip that attenuates the high end is still present. Refer to diagram #5 for an example of this wiring.