Monday, November 7, 2011

Harmonic Barring for the Kaiser Theorbo

Many lutes that I examine are intact so unless a drawing has been made of the the interior, perhaps during a restoration, I must find other means to discover what the barring is like. Such was the case when I examined the Kaiser theorbo in Paris. No drawing was available but I knew from visiting the lute on the museum's website that there were several long, wide cracks in the belly that were wide enough to see several bar locations. When I had the theorbo in front of me I could clearly determine the location of all of the major bars. Since I had prepared paper probes that I could slip through the cracks I was able to measure their size.

Although I do not have a photo of the inside of the Kaiser soundboard I do have this photo of a large triple rose lute belly by Magno Tieffenbrucker that is in the Metropolitan Museum of Art. This lute and the Kaiser are similar in length, width and position of the triple rose so the layout of the bars is similar.

But the position of the bars is only one of my concerns. Even if I copy the bar locations of original lute - which I don't necessarily do - I am concerned about the quality of wood that I use. This, I think, is one of the most important elements in instrument construction. I cut up blemished soundboards from my stock which works fine for smaller lutes and guitars but some of my larger theorbos need bars that are thicker than the normal thickness of stock belly wood. To solve this dilemma I buy cello tops. This allows me to cut whatever size of bar I need. An additional advantage is that from instrument to instrument I am assured of uniformity in density and strength of my bar wood.

The photo on the right shows some of the bars already glued in place and others still under the clamps. I start by gluing the small  rose bars. One of them is visible just to the right of the clamps in the center of the belly. The side that is visible through the rose is stained black. I usually place four of these bars under each rose. Three larger bars that span the width of the belly are placed through the centers of the pair of large roses, one bar through the center of the small rose and a third bar across the area in between. Note that I clamp the bars in five locations across their width. My bellies are thinnest in the center at each bar location along the belly's length and it is necessary to press each bar firmly into this slight depression. I glue the bars in groups that are the same height so I can minimize the number of clamps.  I adjust the height of individual bars in the next step.

Although I vary the basic bar layout from one Kaiser to the next very little I will alter their size. This is not because one soundboard may be stiffer than another but because each of my clients attack the theorbo a little differently. One may like a little stiffer instrument, another one a more compliant instrument. I accommodate these differences by adjusting the bar sizes. In this photo I am rounding the top of the two harmonic bars. Once this is done for all of the bars I will cut the slope at their ends. Historical lutes show different treatments of the bar ends in height and angle.

This photo shows the ends of bars from the Epp theorbo (formerly attributed to Hoss) in the collection of Harvard University. They are left high but are cut at an angle that prevents the full height of the bar from contacting the inside of the rib. This frees the edge and results in a very resonate but less powerful instrument. I prefer to balance the resonate / power by leaving the bar ends from 5  to 7 mm high and in full contact with the inside of the rib. This is an example of one of the methods that I use to personalize my instruments for my clients' playing style.

In my next post I will fit the top to the bowl, make the bridge, glue it on the belly, tune the J bar and the small finger bars that support the bridge area and then glue the belly to the bowl.

All photographs by the author.

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