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January
25, 2008: New Project - Electric Upright Bass Number 2
This bass is a refinement of
the design I used for the first EURB I built in October 2006.
General characteristics:
- The body is a three layer
sandwich of Sitka spruce, black swamp ash, and flamed hard maple.
The body is chambered to reduce weight.
- The body shape is based on
the shape of a Bass Viol, but narrower for compactness and to
keep the weight down - essentially the same design as EURB Number
1, but a little wider
- The neck is laminated from
two pieces of birdseye maple with a 3/16" center stripe
of black walnut
- The neck design is a somewhat
stylized version of what you'd find on an upright bass, but the
shaft of the neck is about 2 inches longer
- The fingerboard is ebony.
I bought this one from an Ebay merchant
- The neck will be bolted on,
this time with six brass inserts in the neck itself, and six
1/4x20x2-inch steel screws with wide flat heads and allen sockets.
The neck can be easily removed for storage and transport
- The bass will be equipped
with the same type of bridge that upright basses use.
- The scale length is approximately
41 inches, approximately the same as a 3/4-size upright bass
- The electronics consists of
a Pure Western pickup system made by K
& K Sound, with an Artec 2-band preamp
- The bass will be equipped
with an Upright-bass style adjustable end pin
I've used the K & K transducers
in five of the six acoustic instruments I've built so far, and
found them to be excellent at REPRODUCING the sound of acoustic
instruments.
Lessons
Learned from EURB Number 1:
The following is a list of
things I'll do differently on the next one (assuming there IS
a next one!):
- I'll hollow out the body to
reduce weight - this thing is pretty heavy - although I'm pretty
sure it's lighter than a 3/4 size URB. Making the body semi-hollow
would have some other benefits:
- Wiring would be simplified
with no need to drill passages between control cavity, battery
compartment, output jack, and the bridge location
- Wouldn't have to drill a 1/2"
diameter hole 10 inches into the body from the bottom for the
endpin
- I'll make the dimensions more
compatible with 3/4-size strings, since the choices are vastly
greater for that size (this one needs 1/2-size strings; 3/4-size
strings are WAY too long)
- I'll tilt the neck back a
little more so that the bridge height can be a little taller
so I don't have to cut the bridge down so much
- Probably won't bother with
a truss rod. :-) The neck is absolutely straight, and I've never
touched or adjusted the truss rod.
- I'll use a larger neck block
so I can better approximate the scroll shape of a URB
- Use 4 spot transducers instead
of 3
- Buy the fingerboard instead
of making one - it's a lot of work, and the ebony is so bloody
expensive anyway. Other possibility is to use Bolivian rosewood
(which was the original plan for this one)
- I'll use a set of tuning machines
designed for an URB. The electric bass tuners don't have the
right type of posts (they're not long enough), and the gear ratio
isn't high enough
Thanks to
the guys on ALT.GUITAR.BASS, REC.MUSIC.MAKERS.BUILDERS, and BASS
BUILDERS for their comments, suggestions, and advice on the design
and construction of EURB Number 1!
This is the first picture of
this project. The body has been glued together using three layers
of wood:
- The top is Sitka spruce from
Bob Tibbetts
- The chambered center layer
is black swamp ash from Ross
Hebeisen
- The back is tightly flamed
hard rock maple
Once the body was glued up,
I carved the top as shown in these pictures:
This is my first carved-top
instrument! More on how it was done below.
I used the sanding disks shown
below with the Random Orbital Sander to do the carving. They
are made from stainless steel, and they work quite well - the
one on the left (coarse) did most of the work - then I used the
other one (medium) to smooth it down before I went to sandpaper.
I started by marking a pencil line all the way around the body
1/4" from the glue line between the spruce and the ash.
Then I carved the top down to that line all the way around, trying
to make sure the curve of the body was smooth and symmetrical
from side-to-side.
The neck pocket was pre-cut
into the top before it was glued to the rest of the body:
Here's part of the back of
the body - note the very tight figure in this piece of maple:
Here's the neck (which I made
last summer) with the new body. I've spent some time over the
last few days sanding the neck and installing the side-marker
dots on the edge of the fingerboard:
A couple of weeks later - the
neck has been given about 4 coats of General Finishes Semigloss
oil/poly:
The body has been trimmed to
final shape and sanded to 150-grit:
October
8, 2008: Major assembly
of the bass is completed:
As you can see from the picture
above, the wiring has not been completed yet - the potentiometers
are mounted, and the K&K transducers have been glued to the
bridge, but nothing connected up yet.
I had the bass tuned up a couple
of days ago to check playability and make adjustments to the
bridge height. It plays nice! Even has some acoustic tone to
it, although very weak compared to an upright bass - the sound
chamber is just too small.
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