Bass
I can be a bit obsessive – if I get an idea in my head I can have a hard time letting it go. So when Leah told me a bass version of my guitar would be really cool, she might as well have incepted me. Paul made it worse when he said a lot of people would be interested in a lightweight resonant bass. I know nothing about basses but it was just a matter of time before I got working on one.
Once I got the guitar pretty far along and became confident in the process I headed up to Leah’s place and got a primer on basses by studying her collection. I learned that it’s a wild west of non standardized scale lengths, string spacings, pickup mountings…you name it. We decided to base mine off the iconic Fender Precision, and, like the guitar, use existing Fender necks.
‘Research’.
I wanted to use Graphtech Ghost piezo saddles again, so I started by modeling a bridge, then dropping it into the file. I also ordered a neck so I could get measurements accurate enough to make a snug fitting neck pocket.
The bridge of a Precision is pretty close to the rear edge of the body. My design would be an arch top, so the bridge needs some distance from that edge, enough room for the top to sweep up gradually to the bridge. That means my body would have a bit of an extended butt compared to the Precision.
Since mine will be a lighter hollowbody I extended the top horn a tiny bit to help fight neck dive. With the stretching I offset the hips a tiny bit and I had my basic profile.
Then I dropped in the neck and found the neck angle that would put the strings in the middle of the saddles’ height adjustment range. There was a bit of trial and error on the guitar, and I was hoping that the lessons learned there would help me nail this first try.
That guide line tracks the top of the frets at the edge of the neck, and it lines up just below the minimum height of the saddles.
With that done it was time for the worst part of the whole process, surfacing the arch top. I thought I had this pretty well mastered after the guitar but I wasn’t able to get the sections to maintain a continuous curvature. Then I realized that I had to section them with cuts that were normal to the curves. Once I figured that out it went fairly seamlessly (pun!).
The offset hips meant that the surfaces had to be sectioned with a curve, so that the corners had perpendicular edges. That allows the next surface to flow into it smoothly.
The zebra stripes verify that the sections flow into each other.
It’s hard to visualize the curves of the top, so I droppped an STL into Simplify 3d so I could look at it like a relief map. It’s just another way to verify that there are no hard breaks in the transitions.
With Leah’s help I settled on EMG GZR’s, so I ordered them and modeled them, dropping them in the same position as the Precision’s pickup.
Bass pickups mount downward into the body instead of upwards into the pickguard. I wanted to mount these to the carbon top, so I needed to add brackets for them. They are split so each half can be independently tilted to follow the radius of the strings.
Threaded aluminum brackets. The pickups screw onto them, and then they screw on to the top.
I refined the bridge a bit. I added two holes for each saddle so the adjustment screw can be offset to either side of the string. I slotted the string holes so they can be slightly offset to get past the adjustment screws. Since this is effectively an acoustic instrument, I wanted to run Graphtech Ghost piezo saddles for more tone options. I added holes for the wires from the piezo saddles to go into the body. Then I added holes in the top for the jack, tone and volume controls, and a 3 way switch.
Next it was time to work on the back. I added a belly cut, ribs for strength, and cutaways for access panels.
And finally I added an aluminum anchor for the strings, material for the strap button screws to screw into, and carbon fiber panels for the back. The lower panel has a couple extra holes for a battery holder for the 9v.
OMG I think it’s done.
I 3d printed the neck pocket to verify the fit.
And lastly a drill jig for the neck mounting holes. The holes can’t be cnc’d since they’re angled, and I don’t want to incur the expense of a 5 axis machine. The jig sits in the pocket and guides the bit in to match the neck angle.
This will be 3d printed. There’s a slot for a c clamp. The pointer helps verify that the jig is properly aligned in the pocket.
Build Time
The parts came in and everything came together without a hitch, amazingly. The EMG’s and the Graphtech’s are both mostly solderless systems, so the majority of the wiring was just plugging things in. The only soldering needed was the at the output jack, and splicing the EMG output to the Graphtech mag input.
So easy, almost everything is plug-in. On the bottom row, left to right, are two EMG pots, the Graphtech push/pull pot, Graphtech 3 way switch, output jack. The Graphtech preamp is the board to the right of the pickups.
The hardest part of the design is nailing the neck angle. Having gone through it a few times with the guitar, I was able to get it right first try this time. The saddles end up in the middle of their range. A massive relief.
Just like the guitar, the piezos have a brighter tone than the magnetics. With them both on, you can blend the sounds using their respective volume knobs for a huge range of tones. And just like the guitar, the bass is much brighter than traditional wooden basses. The carbon top really gives it a brightness and immediacy, you really do lose less of the high end.
As for weight and balance, it came in nice and light at 8 pounds, and it’s perfectly balanced on a strap. If nothing else that’s a big plus for a bass.
No neck dive! Very cool for such a light instrument. It’s lighter than a Les Paul!
I brought the bass to guitarist extraordinaire Paul Carbonara, bassist extraordinaire Adam Bernstein, and gearhead extraordinaire Leah Druckerman for feedback.
Paul’s been testing the guitars, so he was already familiar with the form factor. He liked the piezos, and found many usable tones. He especially liked blending both pickups.
Adam prefers a more traditional dark bass tone – he starts liking strings after using them for years. One of his Precisions has flatwounds that’s worlds away from my bass. He played the piezos for a second and switched them off – way too bright. He found the Super Slinky Ernie Ball’s to be too heavy, and he wanted higher action so he could attack it like a standup bass. Even though it was totally not to his taste, Adam did start to take a liking to it. He just wanted the strings to be a few years old, and he wanted a neck with a rosewood fingerboard. And of course, you can darken the tone of an instrument, but you can’t pull brightness out of a dull instrument.
Next I compared it to Leah’s numerous basses. It was almost as loud acoustically as her Taylor acoustic bass (though with much less of the bottom end), and once again, it was brighter than all her basses. Unlike Adam, Leah wanted the action lower.
To be continued…