Twelve string Thunderbird

Today I completed the build of a twelve string Thunderbird.
The Brooks TB-12

Specifications:
- Mahogany body wings
- Nine ply Mahogany/Walnut set neck. Neck through
- Opaque white (blonde) high gloss finish
- Abalonoid binding
- Ebony fretboard
- Circle position dots
- Jumbo frets
- 34" scale
- Buffalo horn nut
- Three ply black/white/black pickguard
- ETS twelve string brass bridge set
- Two spokewheel double action trussrods
- Carbon reinforcement strip in the neck
- Lace Alumitone Bass Bar in the neck position
- Lace Alumitone DeathBar in the bridge position
- Allparts stacked pots (volume/tone volume/tone)
- Mullard capacitors
- MEC on-on switch for coil split (humbucker-single coil)
- Gotoh GB 350 lightweight bass tuners
- Gotoh Stealth ST 31 guitar tuners
- 2 xPure Tone Multi Contact jack output
- d'Addario EXL 170 - 12 strings
- Weight: 4.2 kg

Electronics circuit were done by my good friend Bas Becu (BQ Music)
















I'll post pics of the build process in several posts below.

 

Like all builds, it starts with finding the right slabs of wood.

Mahogany Khaya body wings


Made a laminated neck blank of Mahogany with Walnut strips


Routed a slot for the carbon reinforcement strip in the middle of the neck


Glued it in and scraped it flush


Then routed the two truss rod channels


Chiseled the part where the spoke wheel goes out by hand

 

Bought a nice pre-radiused fretboard at Holz Faszination in Germany.
Drilled holes for the position markers.



Glued in the position markers that I made out of an aluminium tube and black inlays dots



After I sanded the inlays flush to the desired radius, I recut the fretlines to the right width and depth.


I always file off the top edges with a triangular file to make the fret seat properly


Then hammered in the frets




Also made side position markers


Made some filler with ebony sawdust and glue to fill the little gaps on the side of the fretboard



And cut out the truss rod acces slot

 

After I glued the fretboard on (sorry no pix)
I started shaping the neck






Building a bass like this requires some thinking ahead. I drilled holes for the pickup wires in the lower wing, prior to glueing it to the centerpiece



Then glued the upper wing


Routed the body shape (again sorry no pix)
And routed the pickup cavities



Then the tricky part of routing the binding profile. The body can't be detached, so I had to come up with a plan.
I made and extra template with a profile that compensates the raised center piece.
So the router could route up to the neck.



Found out I had drilled the output holes too early. So I temporarily filled them up ;-)


The glued the abalonoid binding in place

 

Carved the belly cut on the back of the body



I cut a piece off the giant buffalo horn that I sawed in pieces last summer.



And copied the brass template that ETS made for me



Test fitted all the tuners before I started the pore filling

 

I used Z-poxy as a porefiller on this one. Works great if the wood does not have to be stained.


After I sanded it smooth, I sprayed the white blonde nitrocellulose.
My goal was to keep the nine ply laminate of the neck visible



Then did a very thin coat of pale yellow to make it less white


Scraped the binding clean


And I cut a pickguard at the FabLab


After lots of sanding and a few top coats of clear finish, I polished the finish. And mounted the hardware. Bridge set was custom made by ETS Hardware in Germany. It took forever, but it was worth the wait.



Stringed her up for the fist time


And decided against the white pickguard. Opted for the black one that I also made.

 

The bass weighs 4.2 kilograms.
And the tuners are very lightweight.
No neck dive!

 

Yeah, the big difference with the previous TB-12 is that that one had a glued in neck. Whereas this new one is truly neck through (like a proper Thunderbird ;-) )

 

As you can see in the specifications in the opening post and in the build report below, the neck has two truss rods and a carbon reinforcement strip.

 

None of the twelve string bass guitars that I have built, suffer neck dive. So it can't be just luck ;-)