Friday, November 25, 2011

Bracing a gourd banjo head

The image above was taken earlier this week, showing a nearly-finished banjo spine. One idea I have had about this sort of banjo is that the head needs a brace, here seen just right of center, the ridge that connects to the rim section (and from there to the tailpiece/tuners). It extends under the head a portion of the way towards the neck, supporting the head, and stopping a bit before the bridge. Another view (the brace is on the left this time), showing how the spine fits into the gourd.

My first gourd banjo originally had no such brace, with the stick from the neck running underneath the head without touching it. This has been the standard system in banjos since the mid-19th century and I didn't consider other options when designing that instrument. But without adjustable head tension, humidity could lower the action until the instrument wouldn't play, and I noticed a more significant problem that has bothered me in banjos for decades, the "ring" of the head. In bluegrass music, this has become integrated into the sound of the music and the sound of a plastic head in a 20-pound Mastertone snaps more than it rings. Many clawhammer banjo players like to mute the back with a cloth, effectively cancelling the ringing of the diaphragm bell of a banjo head. On my gourd banjo with an actual skin head, the effect muddied the sound, which was sounding even muddier because I was tuning down to low G (now I'm up to A).

At this point, my brother-in-law Tom sent me a video of an akonting player. Since I didn't keep my finger on the academic musicology pulse, I had not been aware of Ulf Jagfors' introduction of Daniel Jatta and the music of the akonting to the West; this occurred after my article on Gottschalk had been published and I never had traveled in musicological circles anyway. I agree with what seems to be the consensus in the field that this music tradition is the closest thing to an African banjo ancestor, and obviously anyone interested in the gourd banjo had to sit up and take notice. Also, the music was wonderful. And there in plain sight was the original instrument design, found throughout the plucked lutes of West Africa, with the spine neck running right under the head, supporting it. Besides mitigating to some degree the movement of the bridge of the instrument in changing humidity, it also would serve to cancel the dreaded ring.

I resolved at that point to remove the first head from my gourd banjo, widen the opening while I was at it (trying to increase volume), and install a brace, running in this case from the rim on the neck side to the bridge, which on this banjo is in the center of the head. It was a piece of maple that I glued to the stick running underneath. I suppose I could have run it the entire length, but I wondered whether I would get the effect I wanted with the partial brace, and then I would have greater volume by leaving the rest of the head free to vibrate. Between this and tuning up to a low A, I ended up with a richer sound, with more clarity. The experiment was a success, but this instrument was still pretty quiet, unable to play with other instruments comfortably. I had to admit that the akonting obviously has plenty of volume and a lovely rich tone acoustically, and that I would need to redesign my banjo to take advantage of what I had learned--the primary agenda being to increase the size of the head, but also to make use of the partial brace.

In my new banjo, to increase downward pressure on the bridge (hopefully increasing volume and enriching the tone), I have moved the bridge towards the tailpiece, which been the standard configuration on banjos since the 19th century. In this case I think the American innovation makes sense, especially because I have increased the head size and I think the bridge would be most efficient on the stiffer surface nearer the rim. Because of the shift of the bridge location, I can run a shorter brace from the tailpiece end, and that way I hope to maximize the potential of the vibrating surface while still canceling the "ring."

Tuesday, November 8, 2011

Gourd banjo, part five

I am at last focused on spending some time working on this instrument, so things should happen pretty fast. For me, anyway. I have just finished an arrangement of the Vivaldi D major lute concerto where I play the orchestra to Richard Kriehn's mandolin playing the lead, and I need this more powerful (I sure hope) instrument to be able to hold its own with other instruments.

First, I built a maple rim for the gourd, leaving two gaps for the spine to fit. I made six angled pieces like the one on the right, each piece was put on the gourd rim and marked from below, then cut out on the bandsaw (see my previous post) and sanded to an approximate finished shape on the belt sander. Because the gourd is so irregular, I made each piece, glued it on (with the masking tape clamp method you can see above), and then fitted the next piece to it. I had marked locations on the rim of the gourd for each piece, but I assumed (and this turned out to be the case) that once I started fitting them, the marks would change.

Next came fitting the spine. Cutting a precise fit into a gourd is very satisfying since the material is so easy to work. I got pretty close just marking things and cutting the basic shape with a coping saw, and it was easy to file a tighter fit. I have the square end at the tailpiece, and a small rounded heel for the neck.

I don't know of any African instruments that have a wooden rim like this, and I don't know if other modern makers use them, so I think of it as my idea. I did this on my first gourd banjo, though through several alterations not much of it remains. I think it significantly stiffens and strengthens the gourd, and I guess some part of me likes the idea of a "tone ring." Because I intend to glue the head (instead of attaching it with nails), I think that it will become very strong when reinforced with glued skin.

Now I can file the final maple rim shape and prepare the gourd for finishing, finish the tailpiece shape, create the rim sections in the spine, and make the head brace, which will be the subject of a future post.