Basvarken

You're forgetting one very important aspect: A carbon rod is passive. A truss rod is an active part. If you dial a curve into a truss rod it compensates the tension of the neck much more than a carbon rod that just sits there.

I think that should be doable, if the neck pocket is wide enough for the string spacing of the ETS bridge.

Two carbon strips and just one truss rod would not be enough to withstand the string pull. You really need two truss rods and one carbon strip to compensate the enormous pull of the 12 strings.

Wow! The Black EXB-12-TP that I built for Tom Petersson is Bass Of The Week @ NoTreble! Check it out: https://www.notreble.com/buzz/2025/09/08/bass-of-the-week-tom-peterssons-custom-12-string-bass-from-brooks-bass-guitars/

And the question was ?

Normally when I'm working my day job, it takes between 2 and 3 months. Since I have to do the lutherie in the evenings and weekends. And my little tool shed is a limiting factor too. I can't saw and sand while I'm in the middle of the lacquer process. 😉

The actual build of this bass (together with one other bass) was done during my summer vacation of 4 weeks. But the finishing process (of endless building up and sanding) took another 4 weeks. So all in all 8 weeks. I have three more bass guitars planned to build this year. And I am working on the finish of the other bass that I built this summer. I hope to close that off in two weeks from now.

And of course I made the mandatory video demo of the newborn bass 😉 All kidding aside: With the Laballa Low Tension Flatwound Strings the bass sounds very round and even all across the board.

And after endless checking an fine tuning of the neck fit, I glued it in All of a sudden it looks like a bass... Fine tuned the pickup cavities I stained the top. Yellow first And red for the burst effect After many coats of clear and sanding in between, I applied the decals Shielded the controls cavity.

Routed the profile for the binding Glued the binding in. I seldom use glue. But I use acetone instead. This softens/dissolves the binding, so it adheres to the wood without leaving glue spill. This is essential because I use waterbased stain. And watyerbased stain does not work on glue... When the binding was done I routed the neck pocket Shaped the neck heel. Always checking the alignment. See the blue line on the purple tape. Routed the pickup cavities Drilled the holes for the potentiometers and switch And the output hole on the side of the body

Filled the gaps underneath the fret ends with a mix of ebony saw dust and wood glue. The shifted my attention to the body. Routed the tone chambers. And routed the controls cavity Routed the profile for the cover The bookmatched set of quilted maple was thickness to the desired thickness of 4mm by my wood supplier. And when that was done, I sawed the triangular "F"-holes. Ready to clamp the top down onto the chambered body And when that was done I cut out the outline shape and routed it along the template (sorry no pics)

Before I glued the fretboard on, I cut the headstock angle and planed it nice and smooth. Then cut out the rough outline of the neck And glued the fretboard in place. Using tied together strips of inner bicycle tubes for even pressure clamping. The result As you can see I left quite a bit of wood at the end of the neck. Which is really handy when you want to clamp the neck down to the work bench to work on the neck profile 😉 The headstock surface and angle had not been fine tuned yet. And you can see it still had a slight tilt I got rid of the tilt by scraping the headstock face. Always checking the two straight edges till they were parallel. After that hurdle had been taken I gave the headstock its outline shape The drilled the tuner holes. I never drill all the way through. But drill till the pointy bit in the middle comes out the back. And then flip the headstock and drill from he back with a smaller drill. Next I drilled the holes for the side markers Glued the side markers in. And sanded them flush

At the end of the fretboard I made the truss rod acces slot. Plus the matching ebony cover.

As with most of my builds I made a ring ilays for the 12th position. Cut of part off an aluminum tube and put a 6mm black position dot inside Drilled the holes in the fretboard for the position markers Glued the ring in and the mother of pearl dots for the other markers Sanded it flush with the fretboard using the 16" radius block Prepared the frets for their slots. And the slots for the frets 😉 And hammered (and pressed) them in.

The build started with finding some slabs of very light weight Khaya. For the neck I made a three piece blank. And for the body a two piece blank. Plus a nice bookmatched set if quilted maple. I routed the truss rod slot. I tried something new for the spokewheel truss rod. Normally the choice of spokewheel truss rods is very limited. On a Spanish website I found a separate spokewheel part with a hex pin. Instead of a female hex that you see most of the time. And this opens up a wide choice of regular truss rods that you adjust witha hex key. As you may now I build quite a lot of 12-string bass guitars and the truss rods really are a big part of the weight of the neck. Which is always a challenge in the battle against neck dive. With this new spoke wheel part I suddenly had the opportunity to use titanium double action truss rods. These are substantially lighter than regular truss rods. So I bought a couple of titanium truss rods. And some blue shrink tube. And made my own titanium spokewheel truss rods. The new (4-string) bass that I was going to build would be the first to get this new truss rod.