|
October
6, 2006: New Project! This
one is something entirely new for me: an Electric Upright Bass.
I've been showing the guitars and basses at Blugrass Festivals
lately, and wanted to participate in the jam sessions that go
on there at all hours of the day and night, but the Bluegrass
folks don't (as a rule) use electric basses. When I was at the
Father's Day Bluegrass Festival in Grass Valley in June, I actually
tried out one of Bruce Sexauer's upright basses -the first and
ONLY time I've ever played one. Since then I've been considering
acquiring one, but I thought I would try this first.
General characteristics:
- The body is solid swamp ash
with a 3/8" bookmatched flame maple top
- The body shape is based on
the shape of a Bass Viol, but narrower for compactness and to
keep the weight down
- 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 Macassar
Ebony. The original plan was to use Bolivian rosewood, but a
friend (an upright bass player) advised me to use Ebony if I
could
- The neck has a two-piece single-action
truss rod assembly
- The neck is bolted on, with
4 brass inserts in the neck itself, and four 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 (This one
came from Bob Gollihur)
- The scale length is approximately
41-1/4 inches, pretty much standard for a 3/4-size upright bass
- The electronics consists of
a Pure Western pickup system made by K
& K Sound, with a Bartolini 2-band battery-powered
preamp
- The endpin is of the type
used in Kay and Englehardt basses from Bob
Gollihur
I've used the K & K transducers
in three of the five acoustic instruments I've built so far,
and found them to be excellent at REPRODUCING the sound of acoustic
instruments. I was planning to use a Belcat preamp of the type
used on acoustic guitars, but I didn't have one handy, so I used
a Bartolini 2-band preamp that I DID have on hand instead.
Lessons
Learned:
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, and the gear ratio isn't high enough
Keep in mind that some of the
decisions I made on the design of this bass were made in the
interest of economy - in most cases I used what I had on hand,
or used what I could get for a low price. If and when I build
one of these for a customer, I'll do what yields the maximum
quality for a fair and reasonable price.
Thanks to
the guys on ALT.GUITAR.BASS, REC.MUSIC.MAKERS.BUILDERS, and BASS
BUILDERS for their comments, suggestions, and advice!
For the first picture, I set
the body on its edge to show the figure of the flame maple top.
This top was a 7/8" thick piece that I originally bought
to make a couple of bass necks, but instead I sliced it on the
band saw to make the top for the EUB:
The top and body core (a single
piece of swamp ash) have been glued. The body and top were cut
to shape, and the body sanded to final shape on the oscillating
drum sander. The top needs to be trimmed, and I'll use the router
for that. Then I'll rout the neck pocket and the cavity for the
preamp. Finally, the edges of the body will be rounded over with
the 3/8" roundover bit in the router.
The neck has been carved from
the glued up neck block. The block started out as a 1-1/2"
x 5-5/8" x 32" block of flatsawn birdseye maple. I
ripped it into 2 pieces 2-3/4" wide each, then glued them
together with a 3/16" piece of black walnut between them.
The result was then shaped on the bandsaw to look like the picture
below. Note that you can see the channel for the truss rod in
this picture. At this point I didn't have the piece of Macassar
ebony that I needed for the fingerboard.
The headstock area has been
shaped to be a stylized version of that on an upright bass. I
cut it to shape on the bandsaw, then used a 1-1/4-inch Forstner
bit to cut the opening for the tuning pegs. The opening was then
sanded smooth and true using a 1-inch drum in the oscillating
drum sander. I have a set of Fender-style bass tuning machines
that I'll use with this neck. They're an aftermarket set, but
pretty much identical to wht Fender uses on the standard model
(made in Mexico) basses.
This picture shows the under
side of the headstock:
The heel end of the neck has
been shaped to provide a significant tilt-back to the neck: I've
worked it out so that the height at the bridge will be between
4-1/2 and 5 inches above the surface of the body. Since a 3/4-size
upright bass bridge is made 7-1/2" tall, I'll have to modify
it to reduce its height a little.
This picture shows how the
neck and body will go together, once I've cut the neck pocket,
which will be approximately 7/8" deep. The fingerboard will
extend almost 12 inches beyond the heel end of the neck., and
the truss rod adjustment nut will be accessible from the heel
under the fingerboard. Also, you can see the truss rod channel
pretty well in this picture:
October
8, 2006: I spent yesterday
refining the shape and dimensions of the neck, and then I cut
the neck pocket. The neck is 2-3/4" wide at the heel, and
tapers to "Jazz Bass" width at the nut: 1-1/2".
Once the neck was done, I routed the neck pocket to 1" deep,
then fitted the neck into the pocket by rounding the corners
to match the 1/4" radius of the corners of the neck pocket.
Once this was done, the next
step was to complete the shaping of the body. As you can see
in the picture above, the flame maple top overhangs the body
a little. This was cleaned up with a 3/8" diameter flush
trim bit in the router. That was followed by a trip around the
top and back of the body with a 3/8" roundover bit.
Here's a picture of the neck
and body together:
The neck loosely fitted into
its pocket:
The headstock:
The next steps will be:
- Cut the cavity for the electronics
in the side of the body. I plan to do this with a drill and chisel.
Guess I'd better make sure the chisels are sharp!
- Drill a hole in the bottom
end of the body for the end pin
- Install the mechanism (yet
to be designed) for attaching the neck to the body so that it
will be removable
- Once that's done, the body
will be ready for final sanding
Yesterday I also took a trip
down to Woodcraft in Rancho Cordova and picked up a nice piece
of Macassar Ebony - 3-1/2" x 1" x 48" to be used
as the fingerboard. I was advised that Ebony would be a better
choice for the fingerboard than the Bolivian rosewood I was planning
to use.
For the neck attachment mechanism,
I'm thinking along these lines: 2 brass thumbscrews of the type
used to attach the backs on Hammond organs, with brass inserts
in the neck itself. In addition, some thin brass plates attached
to the mating surfaces on the sides of the neck and the sides
October
10, 2006: Tonight was
fingerboard-carving time. Yesterday I used the bandsaw to rough-cut
the fingerboard to shape (just over 1-1/2" wide at the nut,
3-1/2" wide at the other end), then used the table saw to
bevel the top surface, leaving the edges about 3/8" thick.
Then I carved it to about a 6" radius using the oscillating
drum sander and the belt sander. Finally, I glued it to the neck,
with the truss rod in place. These pictures show the glue-up:
The neck has been romoved from
the clamps, and is ready for final shaping and sanding. I plan
to make this neck somewhat slimmer than a traditional upright
bass neck. That's the main reason I installed a truss rod. Here
are five views, showing the beatiful grain and color of the Macassar
ebony. Note that the wood is not pure black like Gaboon ebony
would be, but it still makes black sawdust. Very weird.
October
14, 2006: Last night
I mounted the neck to the body. I made four holes for the bolts
in the neck pocket, then located the spots on the back of the
neck to drill the corresponding holes. The next step was to drill
holes for the brass threaded inserts that would go in the back
of the neck. Finally, I mounted the neck. The bolts use 1/8"
allen wrench, thus making the neck easily removable.
The two pictures below were
taken at the First Annual Auburn Bluegrass Fest, held at the
Gold Country Fairgrounds in Auburn CA:
October
18, 2006: The finish
has been applied to the neck: about 10 coats of General Finishes
Satin tung oil/polyurethane, and the tuning machines have been
installed. The tuners are the same type used by Fender on the
Made-In-Mexico basses. I am also in the process of applying the
finish to the body. I started with two coats of the General Finishes
sealer, and I've put about six coats of the gloss topcoat on
so far.
Here's a picture of the neck
heel - it shows the brass inserts I used, as well as the bolts:
October
19, 2006: I made up
the tailpiece and installed strings this evening. Well, three
strings, anyway. I broke the low E string, so it's only got three
strings on it. :-)
October
20, 2006: Tonight I
installed the electronics and tried out the bass through my Peavey
bass rig. Now I see why piezo type pickups need a special preamp.
The sound is thin and nasal, and distorted if I turn the volume
up. The bass will need a buffer stage to match the high impedance
of the piezo K&K pickups. I will place the order for that
this evening. In the meantime, here are some pictures of the
assembled bass. The first one shows the overall size of the bass:
just about 64 inches top to bottom, not including the end pin.
More of the whole bass and
the body:
Headstock detail shots:
The backside. I haven't made
a cover plate for the control cavity yet:
Detail shots of the controls
and the bridge. These two pictures really show off the figure
in the flame maple top, as well as the deep rich color and grain
of the fingerboard. Note the three K & K piezo transducers
super-glued to the bridge:
Detail shot of the bridge.
I haven't cut the slots for the strings yet - I'll do those after
the replacement E string arrives next week.
October
27, 2006: The bass
is now complete. Here's another set of pictures, with all four
strings AND the end pin installed. First a couple of shots of
the bass:
The headstock and the back
of the bass, showing the cover plate for the control cavity,
as well as the battery compartment:
Whereas electric basses typically
have the controls mounted on the lower right quadrant of the
body, I decided to put them on the upper left to make them more
accessible to the player. I've seen some where they're mounted
on the edge of the body, or even on the back. But this placement
of the controls made the most sense to me. The controls consist
of a master volume (a 1-meg audio-taper potentiometer), plus
active bass and treble controls (both are 25K-ohm pots). The
output of the volume pot feeds the input of a Bartolini 2-band
EQ/preamp, with the bass and treble pots wired to that. The preamp
is powered by a single 9-volt battery, which is switched on when
a cord is plugged into the input jack.
The pickup system consists
of a Pure Western system, made by K & K Sound, based in Coos
Bay Oregon, the location made famous by Ray Stevens' Haircut
Song a number of years ago. When I first put the pickups
on, the middle one was mounted below the heart-shaped cutout
in the bridge, but that caused some phasing problems. The result
was a very nasal tone that lacked bottom end response. I moved
them to their present locations, and the tone is now quite good
- well balanced, and plenty of bottom end.
This picture is a detail shot
of the bottom end of the bass body. It shows the tailpiece attachment,
as well as the end pin, which is the same type one would find
on an Englehardt upright bass.
This is a closeup shot of the
bridge, showing the placement of the K&K pickups. The bridge
is an adjustable-height model purchased from Bob Gollihur, and
modified extensively (reshaped, the feet removed, and the heightshaved
down to about 4-1/2" to conform with the geometry of the
bass.
Although I said the bass was
complete, there's still one thing I'm going to do. I will be
installing walnut 5/64" diameter side marker dots on the
fingerboard at the "fret" locations, so I'll know where
to put my fingers for proper intonation as I'm learning to play
this thing. I'm going to use walnut so I can see 'em, but they
won't stand out like a sore thumb, which they would if I were
to use maple or white plastic.
One of the guys on the ALT.GUITAR.BASS
newsgroup was concerned that the control knobs might get in the
way while you're playing this bass, and I realized that none
of the pictures clearly show how much clearance there is from
the top of the control knobs to the under side of the fingerboard.
So this picture shows how much space there is (It's exactly 1-1/2
inches, BTW):
I've also gotten some negative
comments about my use of the Gibson-style speed knobs I used.
There are some things I like about these knobs:
- I like what they look like,
and
- The numbers give me clear
information about where the controls are set, and
- The settings are repeatable
That being said, I have to
agree that they don't quite fit the asthetics of this bass, so
I've ordered some replacements. I'm not sure what the wood is,
but it looks somewhat like zebrawood. Anyway, here's a sample:
 |