Twelve-string bass with built-in tube pre-amp

[Basvarken]

I've done something foolish...

The Brooks EXB-12-QB - the construction of which was already completed in August 2024(!) - is finally completed and ready to ship.
The installation of the electronics took about a year and a half for all kinds of reasons that I will not bore you with.

I solemnly promise that I will never build a thing like this again. 😵‍💫

 

Anyway: Here it is!
- Mahogany body. Explorer shape
- Quilted Maple top. Sunburst. High gloss
- Body back, sides and neck: Clear gloss
- Pearloid Binding
- Neck through, mahogany/maple/purple heart five piece laminate.
- Two spoke-wheel type double action truss-rods.
  Plus one carbon stiffening rod.
- Ebony Fretboard. Pearl dot inlays. 12th position circle
- Sintoms Jumbo frets. Nickel-silver
- 32” Scale
- Buffalo horn nut/ string guide
- Custom made 12 string bridge and tailpiece. Inverted triplets. Gold
- 4 x Gotoh GB 350 bass tuners. Lightweight. Gold
- 8 x Gotoh ST-31 Octave string tuners. Lightweight. Gold
- Custom D’Addario string set
- Gotoh large gold strapnuts

- Pickup 1: Ubertar Sliding Pole Piece pickup
- Pickup 2: 2x Nordstrand NM4
- 1 x 5-pin XLR.
- 2 x Volume.
- 2 x Tone
- 2 x On/off switch with led light for each effect
- 1 Master volume trimpot
- Weight: 5,1 kg

 

Custom made electronics:
- Built-in effect 1: Frog FX1 pre-amp with sub-mini tube.
- Built-in effect 2: Aguilar TLC Compressor.
- External power supply

 

 

 

 

 

 

I will post pics of the build process in several separate posts below.

[Basvarken]

My customer asked for a neck of the highest janka number possible.
I did not want to ruin my router bits and saw blades on something too ridiculous. So I came up with a compromise:
A five piece laminate of Khaya mahogany, Maple and Purple heart.

 

Here's the neck blank:

 

Plus Khaya Mahogany body wings

 

Routed the slot in the middle for the carbon reinforcement strip:

 

Drilled the holes for the position markers in the ebony fretboard:

 

Made the ring for the 12th position marker:

 

And glued in the mother-of-pearl dots for the rest:

 

Sanded them flush, using the 16" radius block:

 

Prepared the fret slots for the frets. By filing with a triangular file I get better results with seating the frets.

 

[Basvarken]

Prepared the frets. Cut off the fret ends with a tang nibbler:

 

Hammered the frets in:

 

And cut off the excess on the sides:

 

Routed and cut the slots for the two spokewheel truss rods:

 

Made the truss rod cover in the 21st position:

 

Routed the part of the centerpiece where the Quilted Maple top should go later in the build process.
Also made sure this part had the desired neck body angle of 1.5°.

 

Also sawed the headstock angle.
In this pic I had not planed it nice and smooth yet.

 

Worked on the neck jont area. With some chisels and scraping steel:

 

The neck taking shape:

 

Made the side position markers:

 

And worked on the neck profile:

 

Edited 2 hours ago by Basvarken

[Basvarken]

And shaped the volute:

 

Next I shifted my attention to the body and its shape. Snd all the crazy wiring that it would require.
Made some vector files for the laser cutter to make templates:

 

I had already glued the body wings to the center piece and cut them in their rough outline shape:

 

I also laser cut the effects panel in Quilted Maple top. But forgot to make pictures

Glued the quilted maple top on:

 

The steps are handy when you want to clamp to two bookmatched pieces sideways. You can't clamp a diagonal line 😉

 

Routed the body outline shape along one of the laser cut templates:

 

Routed the controls cavity at the back of the body:

 

Plus the profile for the cover (different template):

 

 

Did the same for the effects cavity:

 

And the profile for its cover:

 

Turned over to the front side and routed the channel for the binding:

 

Notice I couldn't routed too close to the fretboard of course. Had to chisel that last bit out by hand:

 

[Basvarken]

Glued the pearloid binding in the channel:

 

Route the big cavity for the sliding pickup:

 

And the other one for the Quad Bucker:

 

Test fitted the Ubertar sliding pickup system.
This pickup contraption was provided to me by my customer.

 

[Basvarken]

Drilled a big hole for the 5 -pin XLR:

 

Made a thin metal plate for the effects panel:

 

Put the Quilted Maple panel inside to check if it had the right height:

 

Cut a little recess hole in the metal sheet, for the pickup wires:

 

Drilled holes in the metal sheet. And glued the quilted maple cover on:

 

Checked the bridge alignment:

 

Drilled the holes in the Quilted Maple panel following the holes in the metal plate:

 

[Basvarken]

The Ubertar contraption was not height adjustable. 
So I had to come up with a solution. 
I made a pickup ring and a base plate. With a screw in each corner I could tilt the base plate to the desired height.

 

The other pickup was my own design. So no surprises there:

 

Then stained the top:

 

Stained the back and sides too:

 

And sprayed several layers of clear:

 

 

Edited 2 hours ago by Basvarken

[Basvarken]

Applied the lettering to the effects panel:

 

Sprayed a couple of layers clear lacquer:

 

Applied the logo decals:

 

Put it all in place:

 

Polished it:

 

Mounted the hardware:

 

Customer provided the Goto ST-31 Stealth tuners. Around that time these were already pretty hard to find since Gotoh had stopped making them.
Not sure if the difference in buttons was an ergonomical choice? Or maybe he couldn't find two identical sets of four?

 

[2pods]

Absolutely amazing.

 

[Richard R]

 That is jaw-dropping and mind-boggling at the same time!

Fabulous work!

[Basvarken]

In August 2024 I handed over the bass to the guy who always did the electronics for my builds. He was going to build the tube pre-amp and modify the Aguilar TKC compressor to fit into the effects cavity. We had already discussed this back and forth with the customer and myself. The electronics guy had also built a Frog FX1 as a test case for this project.

 

But all this took way too long. I started to fear this bass would never see the light of day.
After more than 14 months I asked the bass back.
The electronics were not completely ready yet.
But my patience (and faith) had run out.

I brought it to a friend of mine who has a degree in electronics.
He checked the electronics and cleaned up the mess.

Now it is finally ready.
Everything works.

 

[Basvarken]

I thought I was not going to make a video demo. Because I wouldn't know where to begin. 😉 
But I finally succumbed and made a (very short) video demo.

Showing all options woulld take up a whole week. So this will have to do...

 

 

 

 

[JPJ]

Beautiful, mad, bonkers, crazy etc. The bass looks tremendous, personally, a simpler pickup and preamp arrangement would suit me. Fascinated to know how the customer intends to use this unique bass. 

[Basvarken]

12 minutes ago, JPJ said:

personally, a simpler pickup and preamp arrangement would suit me. Fascinated to know how the customer intends to use this unique bass. 

Yeah I can't fathom what use all the options could have.
I much prefer a simple bass myself.
 

And I would love to build something like this again:
Four strings and no controls!

Edited 1 hour ago by Basvarken

[Hellzero]

Fantastic work as usual, Rob!

 

I also don't understand this kind of electronics in an instrument, but the customer is king...

 

Once again, congratulations for this masterpiece!

 

Do you have a link to the Ubertar pickup(s) used as all I could find is this: https://www.ubertar.com/hexaphonic/

 

[Basvarken]

I'm afraid not. The Ubertar was provided by the customer.
I don't think I would have chosen the Ubertar myself.
 

The sliding pole-piece pickup the 13 Ghost (Thorsten Behrens) made seems much nicer to me.

 

https://www.notreble.com/buzz/2024/12/30/bass-of-the-week-meet-the-anachronist-13-ghosts-handmade-marvel-from-germany/