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.

Today saw the birth of a new bass: The Brooks EXB-4-SA A semi-acoustic Explorer shaped bass with 4 strings. - Mahogany body. Two large tone chambers - Quilted Maple top, bookmatched - Three piece Mahogany set neck. Glued in - Cherry Burst finish. Dark Mahogany back and sides - Pearloid binding - Ebony fretboard - Pearl position dots. Aluminium ring in 12th position - Jumbo frets - 34" scale - Buffalo horn nut - Babicz FCH-4 bridge. Gold plated - Spokewheel double action trussrod. Titanium - Lace Alumitone Bass Bars 3.5 - Pure Tone output - On-on Toggle switch - Gotoh GB 350 lightweight bass tuners, Gold plated - La Bella Flatwound Low Tension strings - Weight: 3.2 kg (!) I'll post pics of the build process in separate posts below

Are you sure about the neck-through? Looks like a set neck to me.

Here's a cool pic of Tom Petersson on stage with the bass Pic by Alive Coverage

It's really a matter of personal preference. Most 12-string players prefer the octave strings above the bass strings. This has become the standard over time. When playing downstrokes with a pick, you hit the octave strings first. But not a lot of players use only downstrokes when playing with a pick. And there are some players who prefer it the other way around; the octave string below the bass string. It is called reversed triplets. When you play finger style you'd hit the octave string first. But the difference is hardly noticeable. Since you really hit all three strings at once. The biggest difference you'll notice between the two is actually on your fretting hand. Pressing three strings down with your finger feels quite different when they are reversed.

The "lost" bass that finally showed up two days ago is out on tour with Tom Petersson now. It got its maiden flight in Atlanta yesterday. And I see Tom decided to mount the pearloid pickguard that I put in the case with the bass.

***UPDATE*** The bass was found. And delivered at Tom Petersson's address today! It appears to be undamaged.

Here are the two bass guitars together, side by side like they should be...

While the lacquer cured, I started to prepare the tuners for installment. Like I mentioned in the thread of the other bass that I built for Tom Petersson I modified the Schaller tuners a little bit. Two reasons: Save weight. And to make them shorter in order to keep the headstock as small as possible (without sacrificing strength of the wood). After I had wet sanded and polished the bass, I installed al the hardware and electronics. Initially the bass was designed with a pearloid pickguard (which matches the pearloid buttons of the octave tuners) But when I saw the beautiful quilted maple top I got second thoughts. And suggested we'd leave the pickguard off. Tom agreed to leave it off. But I did make some pics with the pickguard that I already had cut out. I used cut off head of phillips crews to make it look as if it was really mounted. So no holes were drilled in that quilted maple top. I put the pickguard inside the case. So if Tom should change his mind he can always decide to mount it after all.

After the neck was glued in I stained the bass in the desired color. Tom asked for a dark Lemon Burst. Which was a first for me. But it turned out great. After a few coats of clear lacquer Applied the decals

Routed the profiel for the controls cover on the back of the body Routed the neck pocket Shaped the heel of the neck to fot the neck pocket Then routed the pickup cavities