Wiring a Mono Tractor Bass?

**ronaldpdbrandt** · #1 01-30-2013, 01:10 PM

Okay, so I have this great no-name P-bass that I got for nearly nothing. I just picked up a Dark Star pickup that's going to go in place of the P pickup. Simple enough.

But then I got to thinking about some extra jazz pickups I have laying around, and I thought, "Hey I could kinda do a P-bass version of Berry Oakley's Tractor Bass (Two jazz pickups close together at the bridge, Dark Star in the sweet spot).

However, the Tractor Bass was done in stereo, which I don't want. Also, I just want the same number of knobs I have now (one volume, one tone) and a switch.

So should I go with a Strat-style 5-way, or a 3-toggle? Or is there a better way that I'm overlooking?

Cadfael · #2 01-30-2013, 01:23 PM

Depends on what you want ...

Together with a P PU, most Js are too weak ...

You can wire both Js in series to get a higher output ...
Then via 3 way with the P PU ...

Or a 4 way switch ...
Upper J alone, both Js in series, PJJ, P ...

Or a SPECIAL 5 way ...

I would NOT recommend a normal Strat 5-way ...
The bridge J will be much too weak - and the parallel Js would also be weak ...

**ronaldpdbrandt** · #3 01-31-2013, 04:32 AM

Okay, the your first option sounds feasible.

Does anybody know of a schematic that would show me how to have master volume, master tone, and a 3-way switch that would give me JJ only, JJ+DS, and DS only?

Or, could I maybe do it similar to the passive Stu Hamm schematic by Stealth, and add a blend for the Jazzes, like this?:

Stealth · #4 01-31-2013, 05:22 AM

If you want JJ/JJ+DS/DS only, the only difference from my wiring is, if you want the JJs in parallel, you drop the blend pot and solder the blue and red to the purple (bottom right) contact on the switch.

If you want JJs permanently in series, connect the blue to the black of the first pickup, then the red to the purple contact on the switch.

If you want JJs in parallel in JJ mode and in series in JJ+DS mode or vice-versa, I can't guarantee that it can be achieved with a regular DPDT on-on-on.

**ronaldpdbrandt** · #5 01-31-2013, 05:43 AM

Quote:

Originally Posted by Stealth

If you want JJ/JJ+DS/DS only, the only difference from my wiring is, if you want the JJs in parallel, you drop the blend pot and solder the blue and red to the purple (bottom right) contact on the switch.

If you want JJs permanently in series, connect the blue to the black of the first pickup, then the red to the purple contact on the switch.

If you want JJs in parallel in JJ mode and in series in JJ+DS mode or vice-versa, I can't guarantee that it can be achieved with a regular DPDT on-on-on.

Thanks, Stealth! Your answer leads me to one more question, though. Would a three-toggle switch be a better solution, so that I could turn each pickup on and off at will, or would that cause other problems I'm not privy to?

Stealth · #6 01-31-2013, 06:33 AM

It would neither be a better nor a worse solution. It's just a different switching setup and only you can know if you'd like that kind of switch-work on your bass or not.

Functionally, it'd give you more combinations than the three-way, but it's debatable if you'd get any useful out of it. I mean useful in the sense of truly different enough from the other combinations to warrant a switch position.

Of course, you could also keep the above combination ALONG with series/parallel between the Jazzes.

This would naturally necessitate another DPDT (this time a two-position on-on), or a push-pull/push-push (which are all of the DPDT on-on type).

**ronaldpdbrandt** · #7 01-31-2013, 11:36 AM

Okay, I'm liking the options here. Thanks, Stealth. OTOH, I'm thinking that the Jazz blend wouldn't be super useful, as they would be so close to each other anyway. I do like the idea of switching from parallel to series, though.

So here's the new wish list:

Ability to switch from JJ to JJ+DS to DS
Ability to switch Js from parallel to series

So, essentially, the schematic above, but without the blend pot. Does anybody know how that would look? I'm trying to figure this out myself, but my brain is starting to hurt!

Cadfael · #8 01-31-2013, 12:06 PM

Are you really such a "hum enemy"?
Switching from series JJ to J would sound more useful to me ...
Js are weak - and parallel "double Js" woulkd be even weaker.

Impedance is not output ...
But a parallel JJ has 1/4 of the impedance of a serial JJ ...
The output might be 1/3???

I have a DiMarzio X2N as bridge PU in my Rockinger Telecaster guitar - and even this murder PU is wired series or SC - not series/parallel ...

In the 1980s when everything was switched which could be switched parallel Ps or "J HBs" could be found in many basses. But who really used these options? It was much too weak!

Two switches JJ/JJ+DS/DS plus JJ/J makes sense to me.
Instead of a JJ/J switch also a blend pot can be used!
But JJ serial / JJ parallel makes no sense to me ...

**ronaldpdbrandt** · #9 01-31-2013, 12:24 PM

I was more thinking about different tones, rather than output, but you make a good point Cadfael. I also don't necessarily want this thing to look like a cockpit panel.

Maybe the best thing is one ON-ON-ON switch (for JJ/All-in/DS), one volume, one tone, and to heck with the rest.

Now, does anybody know what THAT looks like? I'm trying to sketch it out now, but I foresee a mental breakdown...

Cadfael · #10 01-31-2013, 01:22 PM

Just look at the first wiring (made by Stealth) you posted yorself!

The "green HOT" is the serial JJs (serial JJs = black > white > black > white).
The "purple HOT" is the P PU (DS).

That's it!

It would be simple to make the tonepot a Push/Pull. Pulling the P/P would cause to put GND onto the first J PU and the second J would work alone then. The P/P doesn't make it look like a cockpit and you see in a 1/10 second what's going on (VERY important point to my mind).
Tone Pot down means two HBs (JJ+DS), P/P up means the bridge is SC ...

With a On/On/On + P/P you would have five different sounds without long thinking what's going on ...

**ronaldpdbrandt** · #11 01-31-2013, 02:24 PM

Okay, I think I've got what you're saying, Cadfael. Before I saw your post, I drew this up:

Does that look right (obviously without the push/pull at the moment)? If so, I think I've got a good handle on how the switches work, and I could probably figure out how to plug the push/pull into this schematic.

Cadfael · #12 01-31-2013, 02:45 PM

Nearly right!

The DS has to go to the upper right (or better lower left)
and the JJs to the lower left (or better upper right).

When you tilt the switch 90°, there has to be a "Z", not an "S".
That's why these switches are called "On/On/On" or "On/Z/On".

In the middle position, the "upper right" and "lower left" are connected to the middle.

And when the switch points up / to the neck, the "lower left" is connected! That's why I wrote "or better ...".

But you got the principle!

ADD ON !!!
You COULD add a P/P pot.
The middle connected to ground.
The upper two connectors would go to "HOT J-Brigde" and "GND J-Mid".
If you pull the pot, "J-Bridge would get GND from both sides, "J-Mid" would get GND at the GND side and HOT would still go to the On/On/On switch ...
But this was just an add-on!

**ronaldpdbrandt** · #13 01-31-2013, 04:01 PM

Thanks, Cadfael! I'll draw this up tomorrow and run it up the flagpole again. The Dark Star just arrived in the mail today, so this will be a reality really soon!

**ronaldpdbrandt** · #14 02-01-2013, 11:28 AM

Okay, I started trying to follow what you said, and I got this far and got stumped:

Now I'm lost. I think I have the input to the 3-way right now, but I'm not sure where the output should go from there. The push/pull has me baffled.

Cadfael · #15 02-01-2013, 11:37 AM

The upper On/On/On is correct now!

The lower P/P isnt ...
Put the "black" cable of the "J-Middle" to the same contact as the "red J-Bridge" (sop that they are connected. Then put a GND cable to the middle connector(s) of the P/P switch.

When the switch is down, there is no connection between middle (GND) and the two PU cables. So, the signal can pass both PUs in series.
When the P/P is pulled up, GND is connected to to both cables. So, the "J-Bridge" gets GND from both sides, the "J-Middle" gets GND on its "black" side and goes to the upper switch with its red side ...

EDIT: Like this:

**ronaldpdbrandt** · #16 02-01-2013, 12:09 PM

Okay, got it. and the pots themselves would be wired just as I already had them, right?

Cadfael · #17 02-01-2013, 12:33 PM

Right!
Your pot wiring was correct from the beginning.

**ronaldpdbrandt** · #18 02-02-2013, 03:34 AM

So, just to clarify, here's what I've got:

Thanks for the help, Cadfael & Stealth!

Cadfael · #19 02-02-2013, 04:49 AM

Everything correct!

**ronaldpdbrandt** · #20 02-08-2013, 10:10 AM

Okay, I started laying things out, and a new question arose.

I know that Oakley left the J-bridge pickup in its normal spot and just placed the J-neck in between it and the bridge, so that the narrower pickup was closer to the bridge. Then the Dark Star was placed in the J-neck's old spot, with its pole side facing the bridge.

But, considering that I can rout that area any way I want on my P-bass, I could potentially put the J-bridge closest to the bridge, then the J-neck in the normal J-bridge spot. Could I then flip the DS so that the poles are closer to the neck, or will I run into polarity issues?