Wiring a Mono Tractor Bass?

[Cadfael]

If you buy a completely new J-Set or have "real J-Set", it would be better to place the neck PU to the "normal bridge" and the bridge to the "between bridge-PU and real-bridge".

Why? The bridge PU normally has some more windings and has more output. It wouldn't be good to put the "weaker J" nearer to the bridge. The amplitude of the string gets smaller and smaller ...

If you have out-of-phase problems with the neck PU, you can change (twist) both J-wires! Black would be HOT then, White/Yellow GND.

But keep that the wire from the "middle/upper J" (then black instead of white/yellow) is connected to the On/On/On switch an the "lower J" (then with white/yellow instead of black) is directly connected to GND.

I think it is much better to keep the "middle/upper J" on in SC-mode ...

 

[Stranger Danger]

OK now the really inportant question:
"Where the hell did you find a Dark Star?"

 

[RaniBrandt]

Thanks, Cad--I'll give it a shot!

OK now the really inportant question:
"Where the hell did you find a Dark Star?"

I had a want-to-buy ad in the TB classifieds for months, but only recently started bumping it up every day. I did that for about a week or so, and I somehow got a hit!

 

[SGD Lutherie]

Could I then flip the DS so that the poles are closer to the neck, or will I run into polarity issues?

You can have the poles facing any way you want, and that does not affect the polarity.

I would also put the longer J closer to the bridge, or even get two long Jazz pickups that are RWRP.

 

[Stranger Danger]

Thanks, Cad--I'll give it a shot!



I had a want-to-buy ad in the TB classifieds for months, but only recently started bumping it up every day. I did that for about a week or so, and I somehow got a hit!

I had one of those too. Guess I shoulda bumped it. Congrats!

 

[RaniBrandt]

Okay, I'm taking this show to the Luthier's Corner!

http://www.talkbass.com/forum/f57/modding-p-into-p-tractor-956859/

 

[xk49w]

I have an RS Guitar works Tractor replica. V/T on the DS, V/V/T on the two J pups. J tone pulls for stereo, in for mono. I always run it mono. In mono DS and Js are in parallel. Tried series on the Js, loss of highs resulted.

 

[h60]

I'm building a Tractor tribute as well. In my case I will be running the J's into a 4 way rotary for S Bridge soloed, Both Parallel, Both Series, N Bridge Soloed. Both the switch output and the DS ouput will branch off to a Passive Tone control for each and into a custom Buffer/Mixer circuit with Blend and master Vol.

The body and neck are Warmoth and arriving today. The DS is sitting at my house and and the J's are Nordstrands custom ordered as a RWRP set, but both bridge spacing.

Not exactly a historically correct replica, but it'll get the job done.

 

[h60]

I unded up wiring the J's to Passive Vol/Vol/Tone and the DS to Vol/Tone
Then each output feeds a 2 channel buffer then to a mono out.

The buffer is a AGDB so I set the gain of each channel to get the best mix.



Then finished it all off with a custom engraved neck plate.

 

[sunbeast]

You can make a route for the Darkstar such that you can have its orientation reversible at any time using the same 4 mounting screws.

Some considerations coming from someone who owns and loves a dual-Darkstar'd J bass:
-I'm assuming the Darkstar you have is one of the variety built with Fender string spacing? Fred made 2 kinds, one of which was to fit the narrower Guild/Hagstrom spacing and one to fit the more "standard" wider Fender spacing. The Guild-style one may still work in the neck position anyway (just something to be aware of). My bass has a bridge with adjustable string spacing, so I just use it to fine tune alignment of the strings with the polepieces and the neck, and I would recommend looking into a bridge with adjustable string spacing on any sort of DIY pickup installation for this reason!


- What is your string clearance where you plan to mount the DS pickup? I have found my DS's to be very sensitive to string clearance (the original basses that had the BiSonic pickups that the DSs were modeled after usually had a whole lot of clearance between the body and strings as compared to a Fender-style bass). When I first installed my DSs the strings were close enough to the magnets that their response was fairly harsh and prone to huge dynamic jumps (as opposed to their characteristic warm + smooth vibe), and even affected intonation- and they did have what I would consider "normal" clearance for something like a J or P pickup, but it wasn't enough for the DS in my experience (obviously you can adjust polepiece height with the DSs, but the height of the magnets isn't adjustable as on a P or J). They really do sound better to me with a fair amount of distance from the strings! I ended up shimming my neck a bit to give me more clearance and it worked wonders, even a little bit of extra clearance makes a world of difference (you could also route through the pickguard and mount the pickup directly to the bass body to gain a little extra clearance, which I didn't do). With only one DS, you might not have quite the same sensitivity issue, as they do seem to have a fair amount of magnetic pull compared to many other pickups. Just another consideration that may or may not apply to your bass...

- If I were in your position, and able to mount just about any pickup in the bridge position, I would look into something like a G&L MFD humbucker which could be wired series/parallel/single coil and would definitely have enough output to match the DS. Some other cool options would be a Nordstrand Big Single, Lakland Chi-Sonic (which was inspired by the Darkstar/BiSonic)- or even better yet.....another Darkstar! The bridge Darkstar in my bass is a beast, and is plenty thick on its own soloed for Rock music- it almost has a rounded Rickenbacker vibe to it.

 

[h60]

If your intent is to build a replica of the "tractor" bass

Played by The Allman Brothers Band original bass player Berry Oakley,


Then you double up the J pickups at the bridge as he did back then.

That being said, a double Bi-sonic/ Dark Star Jazz bass is no doubt easier to wire. It also probably has more usable tones. You won't find me soloing the twin J's on mine. But, Oakley didn't have access to a bi-sonic that had wide enough spacing.

Fred made more then 2 models. He had pole spacings that matched string spacing at the neck and bridge for DeArmond and Guild (they were different) Starfires, as well as neck (original Lakland Decade) Bridge and Middle (Fender P) positions.

Novak is recreating the classic Guild/Hagstrom spacing of 15 and 17 mm.
The avg fender style 34" scale bass has string spacing at 19-20mm.

 

[sunbeast]

Fred made more then 2 models. He had pole spacings that matched string spacing at the neck and bridge for DeArmond and Guild (they were different) Starfires, as well as neck (original Lakland Decade) Bridge and Middle (Fender P) positions.

Novak is recreating the classic Guild/Hagstrom spacing of 15 and 17 mm.
The avg fender style 34" scale bass has string spacing at 19-20mm.

My DS set for a Fender has the 19mm spacing at the bridge pickup and 17mm on the neck pickup, so my guess is the neck pickup is the same as the bridge one used for the Guilds. My assumption was that anyone selling a single pickup was probably selling a neck position pickup for one of the two models. The only complete incompatibility for a Fender bass in the neck position would probably be the Guild style neck pickup, as the outside strings would sit close edge to or completely outside of the polepieces (with a Fender spaced bridge pickup the strings might not sit over the polepieces, but at least they'd all still be well within the magnetic field).

I'm not so sure that the OP was necessarily originally planning to recreate THE "Tractor"- he just planned to install a DS in his P-bass and happened to have two J pickups on hand. That's why I suggested he consider other options (obviously the original Tractor also used a Jazz body as opposed to a P, so there's already an inherent difference!). The beauty of a second DS is that you don't have to worry about volume balance issues, and if you can get a RWRP set you can get hum cancelling with both on together...on the other hand a J pickup at the bridge definitely has a different tonality/response than a DS- so if you really dig a solo J bridge pickup honk you will probably prefer a J there (personally I prefer the thicker/rounder nature of the DS in the bridge position most of the time, but I still keep a J-bass around because its just better at a certain things). Obviously getting ahold of a second DS might be a tall order, especially one in the correct string spacing and reverse wound from the one he already has, but you never know...

 

[h60]

The Adjustable Gain Dual channel Buffer has trim pots that takes care of the volume balance issue between the J's and the DS on mine. However, I find the J's best turned down a bit so they compliment the DS.

Like I said, if I could find a DS in 19mm (please Curtis Novak... Please) I would likely re rout my bass as a dual DS.
I'm just not impressed with the tone I get from the J's alone. But I wanted a Tractor... So I built a Tractor.

 

[Ryan Donahue]

Apologies for resurrecting this thread but there is a ton of good info in here and my question is just a tweak to wiring scheme devised here. I am planning the same build and Ronald but will be using one of Curt's BS-DS pickups. Since this pickup can be tapped I'd like to add another switch to activate the tap. Would someone be able to help me modify the below wiring diagram to add this tapping functionality?

 

[bobkingbass]

Hi guys, thanks a lot everybody for all the interesting informations on this forum.
I just finished my Rumbleberry, which is to be considered my personal tribute to Berry Oakley rather than a Tractor’s replica. You’ll see why.
After 25 years playing regular Jazz Basses and making my sound only from the neck pickup I decided to try new solutions and I falled in love with the Tractor. So my goal was to do something strange, with a couple of different sounds and most of all I wanted to have fun!
Most of the parts are from a cheap (very cheap) DIY kit I bought at the most important european music online store. I kept almost everything (the neck, though cheap, is amazing) except the pu’s.
The two Js are from an early 80’s Fernandes (which I made fretless with two Bartolini) and I added a DiMarzio Model One for different reasons: 1. not easy to find a DarkStar; 2. the Curtis Novak is too much for my pocket; 3. I’d like to experience the mud bucker sound. Ok let’s go to the wiring!
The two Js are wired in series and can be considered a single bridge pickup. The mudbucker is in series configuration and is the neck pickup. My first attempt lead me to wire the pickups in standard jazz bass mode but it worked fine only with a pickup at time: very strong Jazz sound with the bridge Js, very fat gibsonish sound with the mudbucker. But as I tried to have sound from both… no volume and no tone, only a weak sound with no bass… Very bad! Ok I learned from you guys that the problem was to have the two pickups paralleled, so I tried to rewire them in series, bypassing a volume pot, and there it was! A kind of heartquake come out of my amp! I reached the goal but I needed to have the three sounds available: Js only, Mudbucker only, Js + Mudbucker in series. It has been quite easy, with only a very simple SPDT on-off-on switch. I hope that my diagram (sorry for bad graphics) can explain. What I can say is that I have a very simple configuration and three powerful and well defined different sounds.

On the funny side… the artwork is related to a small winery located in Monferrato - Italy, we are close friends, they love good music and we love good wine. The pot knobs are made from a couple of used corks and the pickguard is part of a carton bottle box. A relic finish was compulsory
The pic below was taken before the switch installation.

 

[bobkingbass]

Sorry I wasn't able to resize the pics on this board...