One String Willie
Building a Unitar

When Shane Speal first showed me a picture of Willie Joe Duncan standing next to his Unitar (Living Blues Magazine issue 156, March/April 2001, page 50), I thought "Wow—that is one serious diddley bow!"  My next thought was that it would be a cool instrument to try to build.  I had previously built a replica of Eddie "One String" Jones' diddley bow with a paint can as a resonator (perhaps a good subject for a future Uncle Enos article), and thought the Unitar would be a good building project. 

The Unitar was a diddley bow writ large—it was made from a board taller than Willie Joe, with the nut above his head, and the bridge halfway to his knees, both apparently made from pieces of pipe.  The tailpiece appeared to be a hinge from a cabinet door.  The instrument was hinged in the middle so it could be transported, and was locked into playing position with two barrel bolts mounted on the front.  It also used a turnbuckle as a tuning device—a technological advance.


It was a big instrument, but the question was, how big?  One night, looking closely at the photograph, I noticed that the board the instrument was made from had been originally attached to a metal fitting, and I then realized that the Unitar had been built from a wooden bed-frame rail.  Twin and full sized mattresses are 75" long, and a bed rail is a little longer.  From this number, the overall size of the instrument was established, and measurements taken from the photo permitted good estimates of string length (44" from nut to bridge) and the sizes of the other components.


The next day, I found a pair of wooden bed-rails (5-1/2" x 76") at the local thrift shop, and bought the rest of the components at the hardware store.  These included:

·        two 4" steel strap hinges to enable the Unitar to be folded for transportation

·        12 #8 5/8" Philips head wood screws to install the strap hinges

·        two 4" steel barrel bolts to lock the unfolded Unitar into playing position

·        a decorative brass hinge for the tailpiece

·        two pieces of pipe, one 1"diameter (nut), the other 1-1/2" diameter (bridge).   I bought several types:  galvanized steel pipe nipples and copper pipe unions to have a selection to try.  For the bridge, glass such as a jelly jar would be good, and for the nut, a short length of closet pole or another piece of wood would work.  Maintaining tuning will be slightly easier if the bridge and nut do not have tapered sides.

·        one small turnbuckle for the tuning mechanism

·        two small S-hooks to attach the string to the instrument

·        a slide—I like a heavy, flat glass bottle, but other choices are equally good—a long beef bone from the pet store or butcher shop, a large socket wrench, a smooth rock and a heavy pocket knife are all tried and true slides.  Each has a slightly different feel and gives a slightly different sound.

·        a beater—I have tried a wooden stick, the wrench used to tighten the turnbuckle, and a folded leather belt.

The traditional string for diddley-bows is broom-wire, the wire that holds the broom straw onto the handle of a broom.  It is likely that Willie Joe first used broomwire on the Unitar.  He apparently switched to steel trolling wire (used for deep-sea fishing) when he lived in California.  The brooms that I have cannibalized have yielded 7 to 9 feet of wire each, at about 0.050" diameter.  To ensure domestic tranquility (my wife doesn't want any more brooms disassembled for their wire), I have obtained new unused broom wire (see the page on wire).  Music wire is available in 72" lengths from


Willie Joe apparently used several kinds of electromagnetic pickups on his Unitar.  To decrease cost, and because I have more experience with piezoelectric pickups, I decided to go with a piezo under the bridge.  Radio Shack yielded a piezo buzzer (P/N 273-073) and a ¼" mono phono jack (P/N 274/252).



The pair of bedrails I found had metal fittings inserted into a slot at the end of each rail that were used to attach them to the head- and foot-boards.  The first order of business was to get these out.  The fittings were held in place by two short metal pins inserted through holes on the inside of the rail.  After removing the strip of wood used to support the cross-boards for the mattress, I spent a long time trying to hacksaw the pins out, until I realized that they were only held in by the snug fit of the wood.  I whacked the edge of the metal fitting with a small crowbar a couple of times to loosen things up.  While I rested the end of the rail on my legs, I followed up with some blows with the crowbar on the inside face of the wood next to the pins.  (PHOTO)  This caused the pins to stand a little proud of the wood.  I then used pliers to pull the pins out.


Willie Joe's Unitar looks like it is finished wood, but my bed rails were painted, so I decided to leave the paint on.  I did clean up the paint a little bit, and sanded the back side of the rails to prevent splinters.  To allow the Unitar to fold, I cut the one of the bed rails into two 38" pieces, using a hand saw and miter box.  I sanded the cut ends so they were fairly smooth and would fit together snugly.  The two pieces were then butted together flat on the floor with the "good" side facing down, and, using a combination square,  the hinge positions were laid out on the back side of the rail (about 1/4" from each edge) so the hinge pins were right over the cut.  The screw holes were carefully marked, and the screw holes were drilled with an electric drill.  I used a piece of masking tape marker on the drill bit so I would not drill through the rail to the good side.  I then screwed the hinges onto the back of the rail halves with the #8 5/8" wood screws.  Flipping the assembly over, and supporting it with a small piece of wood under each end so the pieces were completely butted together, I laid out the barrel bolts, marking the screw holes, drilling them, and finally screwing them onto the rail halves.  With the bolts engaged, the rail is not very rigid.  Not to worry—the string tension will take care of this.

Installing Components:

The next steps were to lay out the locations of the rest of the components go on the Unitar.  Using a combination square I drew a centerline down the length of the instrument.  I installed a #8 1" roundhead screw on the centerline 1-1/2" from the top end to hold the string, passing almost all the way through the rail, and avoiding the end-slot that held the bed-rail hardware.  Taking measurements from the photograph, I used the combination square to draw lines 7'' and 51" from the top end of the instrument to establish the nut and bridge positions.  I installed a couple of small roundhead screws on either side of the centerline at these positions as "speed bumps" to allow accurate and repeated positioning of the nut and bridge.  I then installed the hinge used as a tailpiece on the centerline below the bridge.  I should have given myself a little more room for the fully extended turnbuckle—I did not have it fully extended when I did the measurement.

Stringing Up:

A WORD OF WARNING/DISCLAIMER:  If you decide to try to build a diddley bow of any sort including this Unitar, be aware that the wire may be of unknown tensile strength and is being brought to unknown tension; in addition, the board being used is under tension.  Be careful to keep your face out of the way of the wire—I do not know what would happen if the wire should break (it has not happened to me—so far) but please use sense when building, tuning and playing these instruments.

I decided to string up the Unitar to make sure everything was working acoustically before installing a pickup.  I used 16 gauge fence wire because I had a big roll of it and could experiment with it a bit.  I first extended the turnbuckle almost as far as it would go, and attached it to the tailpiece hinge using an S-hook.  I then cut off a 5 foot piece of wire, attached it to another S-hook, hooked the S-hook onto the screw at the top of the instrument and ran the wire through the upper eye of the turnbuckle.  I pulled the wire fairly tight, and then twisted the wire to attach it to the eye.  I then slipped the nut and bridge underneath the wire and slid them toward their respective ends until they went past their "speed bumps."  The wire was pretty slack at this point, so I started tightening the turnbuckle to tension the wire.

As I tightened the turnbuckle, the wire stopped sounding like it was flapping around when plucked and started to sound a little brighter (more harmonic overtones).  I tightened the turnbuckle several more half-turns beyond this point and stopped.  The rail was starting to get a noticeable bow, which appeared to limit the highest pitch that I could achieve.  A test play with a glass bottle slide and a stick as a beater showed that the barrel bolts had an annoying rattle.  This was solved by cutting a fat rubber band in half and jamming the pieces between the bolts and the metal fixtures.  After that I got a pretty clear tone.

Position marks:

Before disassembling the Unitar to install the pickup, I laid out some of the note positions along the centerline and tried a couple of playing positions. 

Please see the page on position marks.

 A word on playing position: 

Willie Joe played the Unitar standing up.  In my short experience, the instrument plays well leaned against a wall, leaned against the player's shoulder, or horizontally.  If played against a wall, the player can easily see the position of the slide and can clearly hear the strong tone when the string is struck between the slide and the bridge (this apparently is the way Willie Joe played it).  If played against the shoulder, it is not as easy to see the position of the slide for the lowest notes.  In addition, the tone coming from the "wrong" side of the string (between the nut and the slide) is right next to the player's ear, making it very difficult to hear what is being played on the "right" side, once the slide goes beyond the midway point of the string.  Playing with the Unitar against the shoulder almost demands playing amplified so the player can hear what is going on.  I am most used to playing larger diddley bows horizontally.  The Unitar is far too long to rest on my knees, so I have tried supporting it between the backs of two chairs.  As an interesting aside, the length, and possibly the cut in the middle, allows the Unitar player to perform the equivalent of a "neck-bend" as done on an electric guitar with a bolt-on neck.  By pressing against the face of the Unitar near the middle, the string pitch can be lowered—when the pressure is released, the string pitch returns to normal—a cool "twangy guitar" effect.  Willie Joe apparently used a leather strap to strike the string with, and I have included one in my eclectic collection of strikers.  Experimentation suggests that a belt (even a fairly heavy one) is too flexible for rhythmically accurate playing unless it is doubled.  If you fold the belt so that both ends are together, and hold it so the center of the belt forms a loop, this loop forms a nice, relatively firm string beater with a softer timbre than a stick.

Pickup installation: 

I disassembled the Unitar to install a pickup under the bridge, and while doing this I moved the tailpiece about 4 inches lower on the instrument to provide more room for the turnbuckle.  One thing to consider when choosing between piezoelectric and electromagnetic pickups is that the piezo, while very inexpensive, requires a preamplifier to boost the signal.  I have used piezos on all my instruments, and for the preamp, I use a SignalFlex SF1000.  This is a small unit that plugs directly into the output jack of the instrument, and provides three channels of EQ plus gain control.  The cord to the amp plugs into the side of the unit, which turns it on—it is not a good idea to leave the amp cord plugged into the unit when it is not in use, because it will drain the batteries.  Other options are undoubtedly available.  It is possible to wind your own electromagnetic pickup on a sewing machine bobbin, but I have not yet tried this.

The pickup I initially used is a piezo buzzer from Radio Shack.  If you apply current to it, it will vibrate—on the other hand, if you vibrate it, current will flow, which is why we use it as a pickup.  Being careful not to break the wires, I cracked the "ears" off the plastic case with needle nose pliers, and then shoved a small screwdriver under the top (the side that has the label) to pry it off.  The piezo is the brass-colored disk inside the case.  Then with the needle nose pliers, I cracked the edge of the case that is higher than the piezo, being careful not to break the wires.  I slipped a very thin blade under the piezo to pry it up from the case, and finally levered it up with a small screwdriver.  I stripped a little more insulation off the wires.  Using a small soldering iron and acid-free solder for electrical applications, I soldered the black and red leads to the terminals of a ¼" mono phono jack.  Black went to the body terminal (attached to the center) and red went to the prong terminal (although with a piezo, I do not think it makes a difference which goes where).  In order to determine where the phono jack should go, I laid this assembly out on the Unitar so the piezo (brass side up) was where the bridge would be.  I marked the position where the phono jack would fit, and drilled a ¾" hole to the left of the centerline as one faces the Unitar.  I then cut a small piece of very thin plywood used for the backs of cabinets so it would act as a cover plate.  I drilled a 3/8" hole in the center, and small holes on each of the corners.  I installed the phono jack in the plate, and then screwed the plate down onto the face of the Unitar.  The piezo wires came out one edge of the plate, and the piezo was held in place with a loop of masking tape.  I was uneasy about the back of the plug being exposed, so I removed the top from a half-gallon paper orange juice container with a screw-top pouring spout, tore all the paper away from the plastic fitting, cleaned it up, and then epoxied this onto the back of the Unitar around the phono jack hole.  The lid screws down onto this, protecting the phono jack.  I then restrung the Unitar as described previously.  The bridge rests directly on the piezo.  The loose wires are covered with tape so they don't catch on anything.

I now use homemade electromagnetic pickups for all my diddley bows.

Plugging in:

I tuned up the Unitar to E (the same as the 6th string on a guitar), plugged it into my small amp, and tried it out.  The Unitar has a primal growl that changes to a throaty howl as I slid my glass bottle slide up the string—in other words, perfect.  I was really pleased with the sound—I am still fiddling with different amp settings, but in general, it sounded really good in both the clean and lead channels, and a variety of tonal shaping could be done through the EQ on the preamp.  I think this instrument would also sound good with a lot of reverb.


The Unitar was a great building project, and it sounds great too!  I am really excited that I now have a faithful working replica of Willie Joe Duncan's one-string wonder in my collection of homemade instruments.  It will be fun to learn this instrument—I sure don't sound like Willie Joe.  That will take some more work!

This page copyright 2009 David L Williams Jr.