Friday, April 19, 2013

The Christoph Koch Theorbo Berlin

This past week I visited the Musikinstrumenten Museum of Berlin's Staatliches Institut für Musikforschung to study, photograph and measure the theorbo by Christoph Koch, Venezia 1650, No.3581.

This is an important example of a medium size, mid-century theorbo. Its construction combines features typical of early 17th century Italian theorbos with elements usually associated with later instruments. Also, the fingerboard, neck and extension are stunningly and masterfully inlaid with ivory arabesques, whorls and engraved figures.

I have been interested in building a model of this lute for some time. It is slightly smaller but with a flatter bowl than the Kaiser theorbo (Musee de la musique, E.24) that has proved so popular for me.  However little information about it, other than the essentials, is available. See Klaus Martius' lute database:

Therefore, a trip to Berlin was essential.

I recorded details of the belly, neck and theorbo extension with measurements and photos which I will describe later in this post, but my principal interest was in the design in the construction of the bowl. This is the feature that tonally distinguishes one model of theorbo from another.

The bowl is built with fifteen ribs of kingwood (dalbergia cearensis) separated by 2mm wide spacers composed of narrow bands of ivory/kingwood/ivory. The rib wood is "flat-sawn" rather than quartered in order to display the its intense figure.
 Using the same technique, as I did with the Unverdorben lute in Dean Castle, Scotland (post from October 2,2012) I traced the face contour of the bowl on a paper grid and made templates of the central axis and five cross-sections.

The bowl is noticeably flattened as is the norm for larger Italian theorbos. It is constructed with wider ribs while its compatriots, the multi-rib bowls, are assembled from many more narrower ribs -- a technique that actually simplifies construction because narrow ribs can be bent side-ways to conform to the odd rib shape that results from flattening the bowl.

I noted the size of the end clasp and the width of the ribs as they disappeared under it.

Also, I measured the width of the ribs at the neck joint and the angle of the joint itself. So by combining the measurements from both ends of the bowl with the  positions of the ribs derived from plotting the cross-sections, I will be able to assemble an accurate mould of the bowl.

The soundboard is 375mm wide and 594mm from the end to the neck joint and is constructed from very fine grain spruce. The contour is pleasing; full in the lower third and sloping gracefully toward the neck. The triple rose whose size, top to bottom, equals one quarter of the length is placed in the third quarter of the total length. The border is a combination of thin ivory and kingwood (in places repaired with ebony) bands with a wider strip of ivory on the outer edge. However, there are two disruptive elements. The contour in the  lower third of the face is asymmetrical; the treble side contour forms a sharper curve than the bass side. And the bridge is off-center. This in itself is not unusual, but the placement is extreme. The total string width on the bridge is 161mm. The first treble string is placed 60mm from the center line of the bowl, leaving the last bass string significantly close to the edge.

 Whether this was by design or error is difficult to decide. The fretted neck has been shortened which would have resulted in repositioning the extension. Perhaps it was repositioned at the wrong angle, necessitating moving the bridge. However I could discern no marks on the soundboard to support this hypothesis. Presumably, Koch chose this placement expecting a particular tonal reward.
Contrary to the appearance of the quality of work in the photo of the triple rose it is well done. A patina, which appears to be an accumulation of wax has collected between elements of the design and in the incised areas obscuring the detail.
One of the features of this lute that separates it from its earlier predecessors is the noticeably cambered fingerboard. I couldn't remove the strings in order to measure the camber accurately nor could I take an adequate photo due to the glare produced by the strings, but I estimated the camber to be nearly 4mm at the nut, diminishing to nearly 3mm at the joint to the neck. To put this in perspective however, the neck is 108mm wide at the joint to the bowl and 91mm wide at the nut,

The ebony fingerboard with the inlay is thin (around 1mm) stretched over a cambered spruce (?) core. You can see that the whorl has been truncated at the nut leading to the speculation that the neck had been shortened.

The arabesques on the back of both the neck and theorbo extension are superb. This is the most beautiful inlay work I have seen. Usually I find such things too elaborate, but the lines are delicate and graceful. The veneer for the back of the neck
and the extension, front and back as well as the lute bowl is a light colored kingwood. The tiny gap that remains between the ivory and the wood veneer is filled with a darker colored mastic glue that accents the over-all design. I think the combination of these factors adds to a perception of lightness of design. As a point of interest, Joël Dugot, Musée de la musique, notes that this design is the reverse (dark wood inlaid into an ivory panel) of the one that Koch created for his archlute built in 1654 and conserved in Paris, E. 546. 
The theorbo head is constructed in the recognizable style that folds back on itself. The front is decorated with an attractive checkerboard. The unusual feature is that it contains nine holes. But that is not all.

There is also a cluster of plugged peg holes at the end of the peg cavity. The vertical black lines are not shadows but an inlaid design. The tops of these pieces are visible in the previously shown photo of the fingerboard inlay. 

An additional plugged hole is located mid-way along the length of the extension level with the inlaid emblem.
The top surface of the extension shows a restored area contiguous with the cluster of holes shown previously.
Obviously, this area had been used to expand the compass of the shorter neck.  Whether this represents a legitimate or an invented use could be investigated further.

Dr. Otterstedt lends a hand for a final photo
I have only touched the many interesting features found in this instrument. But my trip to Berlin and this report is only the beginning of a lengthy project to document and to build replicas of this important theorbo. I plan to report my future progress in this blog.

I would like to thank Heide von Rüden for her assistance during my study and Dr. Annette Otterstedt for arranging my visit and graciously agreeing to extend it for an extra day when I found that I needed more time to complete it.

All photographs by the author.

Friday, April 5, 2013

Jerry Willard's 1831 Panormo Guitar

Jerry Willard Photo

New York City guitarist Jerry Willard sent me his 1831 Louis Panormo explaining that it had serious intonation and tuning problems.  In spite of this it is a dynamic and lovely sounding guitar.
Here are two of Jerry's recordings with his Panormo.

Once I had the guitar in my shop I spent a considerable amount of time analyzing the problem before I decided what to do about it. It was complicated.

Intonation problems are not unusual for nineteenth century guitars as many builders did not adjust the design of their bridge to compensate for the intonation problem that arises because of the physical difference in each of the guitar's six strings. Generally, the stopping point of each string has to be positioned on the bridge so that the string length becomes progressively longer from treble to bass by a total of one or two millimeters.  Otherwise, the guitar will not play in tune. Panormo built a raised edge, a raised wood saddle, on the front of this bridge to provide a clear stopping point for each string but no attempt was made to "compensate" for the characteristics of string physics. This fact would account for a portion of the tuning problems but not for all of the false notes. 

Next, I turned my attention to the relationship between the length of the strings and the fretboard. I measured the the distance from the nut to the twelfth fret and compared this measurement with the distance from the nut to the bridge.  

For a guitar play to pay in tune the latter measurement must be twice the distance from the nut to the twelfth fret plus one or two millimeters. It wasn't. In fact, the distance from the nut to the bridge was less than twice the twelfth fret distance.  I was astonished. Legendary guitar makers don't make this type of error. This guitar could never play in tune.

 I continued my analysis using an electronic tuner. By testing one string at a time and muting the others I was able to get accurate readings free of string harmonics. The results gave me a clear idea of the scope of the problem. Not only did every fret position on every string sound slightly out of tune, which was expected because the string length was wrong, but some fret positions were worse than others. Using the measured distance from the nut to the twelfth fret I calculated the position for each fret and compared this with the fret positions on the guitar. I found many discrepancies of misplaced and even misaligned frets.

I wasn't happy with this discovery. The guitar appears to be in nearly original condition and I believe it is important to preserve original work. But there were fundamental problems with both the bridge and the fretboard that prevented the guitar from being used in professional concerts and recordings.

 There was enough wood in the peaked front edge of the bridge so I knew I could treat it like a classical guitar saddle and reshape it to a contour that would accurately compensate for intonation. As you can see in the photo, the side of the front edge of the bridge has previously been altered as a glue joint is visible where the peaked front piece joins the curved contour where the bridge pins are placed. Either the piece had broken off and been re-glued or some other remedial work had been done to it.

But re-shaping the front of the bridge would only  be useful if the fretboard were substantially altered. Since there were so many problems with fret placement I decided there was no other alternative than to replace it. The fretboard was 6.5mm thick at the nut tapering to 4.5mm at the sound hole and had been re-fretted with modern, medium size T frets. My plan was to plane the it down to a minimum thickness and then use a warm iron to loosen the glue and remove the remainder of the board without damaging the neck material or its finish. As I worked down through the board I could see that it had most likely been slotted for bar frets because the slots were shimmed with ebony slivers, as you can see in the photo. Original bar frets are about 0.8mm wide and that is what the slots measured when the shims were removed.
As I continued planing I was surprised to discover that a very poor quality piece of Indian rosewood had been used for the fret board. Would Panormo have used such material? And would he have made such a mess of the fret placement? I would like to think not. But modern assumptions about historical instrument building are often at odds with the evidence. I don't have an answer but at least this is an opportunity to describe such findings and to ponder their significance.

Before I completely removed the fretboard I strung and tuned the guitar. I did this in order to acoustically determine the position of the twelfth fret. Using this information I calculated all of the fret  positions.
I prepared the new fretboard and made a caul that would fit under the neck so I could use spring clamps positioned on the edges of both boards with the neck and fret board sandwiched in between. Other clamps placed through the sound hole secured the end of the board.  I then cambered the surface of the fretboard to a 25 inch radius and hammered in the frets.  I use small modern fret wire that is intended for mandolins as it is about the same size as the various types of frets that were used in the nineteenth century.

In order to complete the alterations to the guitar I  reshaped the front of the bridge in a way that compensated for the physical characteristic of each string as I discussed earlier in this post. In the photo I highlighted the crown of the saddle with chalk to display its contour. The first and second  strings are closest to the front while the third abruptly needs to be longer. The fourth and particularly the fifth move back toward the front while the sixth is about in the middle of the range.

Jerry told me he intends to spend the summer preparing and recording with his Panormo. I'll look forward to hearing the results.