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:


http://www.cs.dartmouth.edu/~lsa/associated/database/dbdetail.php?PID=228

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.

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.

http://www.youtube.com/watch?v=1TaI8G4OJ4U
http://www.youtube.com/watch?v=ol_ZY8i1uTs

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.

Building an Early Lacôte Guitar - Part 4

My replica

The original 1823 Lacôte has a mahogany body with black lacquered neck. The peghead, which is a later replacement, is a light colored wood with an ebony top and back plates. Although I built my model in curly maple I wanted to retain the black lacquer scheme for the neck. This made the finishing procedure a little tricky.

1823 Lacôte

You'll remember that in my last post I explained that the neck and body had to be assembled before I could complete the purfling because of the latter's delicacy. I knew these would create a problem in finishing because the guitar body, varnished with oil varnish, would share a joint with the neck that would be sprayed with black lacquer. I decided to proceed in the following manner even though the two finishes are incompatible.

When I build an instrument in curly maple I like to  give it a strong stain of roasted chicory tea. The maple for this guitar is actually English sycamore - I use the term "maple" generically - is quite light, so it needs some color, otherwise it apppears too washed out. I boil several teaspoons of chicory in a small container with about 60 milliliters of water for as long as it takes to produce the intensity of color that I want. I apply the stain in one coat with a new white shop cloth. Since the stain will raise the wood grain it is necessary to prepare for this in advance. After each sanding session I raise the grain by wiping the wood surface with a warm damp cloth. After the last sanding with #600 paper I scrape the area next to the binding with a thin steel scraper to remove any dis-coloration.

I have always varnished my instruments with oil varnish but it  will soon be impossible to buy oil based products because they are being phased out for environmental reasons. Last fall, a large old family run paint supplier closed and I was able to buy two gallons of varnish.
I find that oil varnish dries slowly on ebony, rosewood and other exotics so I seal these a with several coats of shellac.
To prepare the varnish I filter it through fine cheese cloth and add 5% thinner. Using a 1 inch wide natural bristle water color brush I cover a quarter of the back at a time using strokes across the direction of the grain and then brush out with the grain. In the photo you'll see that I masked the neck heel. Since black lacquer will be sprayed right to the edge of the varnished side rib I made sure the mask was accurate and firm.

 I sand lightly between coats with #400 paper or #1800 Micro Mesh. Heavy brush strokes or sags are removed carefully with a sanding block. Three coats will usually be enough. This is left to dry thoroughly in a cheese cloth tent. The maple dried well but even though I sealed the purfling it proved to be absorbent and needed an extra separate coat of varnish.

I had removed the masking after the last coat had dried over-night but I waited three or four days for the varnish to harden. Then I accurately masked the side ribs and protected the rest of the guitar from over-spray. There is always the risk of bleeding under the mask with sprays so I sealed the joint with clear lacquer by spraying several light coats (misting) right at the joint. If this does bleed, the clear coat will protect the under-lying varnish and make the clean-up easier. I proceeded to spray light coats of black lacquer at about 15 minute intervals until I had built up a thick enough finish.

The peghead of the original 1823 Lacôte had been replaced by one with side mounted tuners. The peghead core was capped top and back with thin plates of ebony. A maple like wood that had developed a beautiful patina  contrasted with the ebony. Chicory stain when heavily applied will collect in the pores of the wood and create an unattractive appearance on broad surfaces. But on small areas like those visible on the peghead it has an antiquing effect. I followed the same procedure in masking the appropriate areas of the peghead as I did around the neck joint. I finished the lacquering with several clear gloss coats. After allowing this to harden overnight I fitted the elegantly simple Rogers tuners and strung and tuned the guitar and then allowed the finish to harden for a week or more.

I varnished the soundboard of the guitar separately from the back and sides and the neck simply for the reason that I find it less cumbersome in handling the instrument.  While three coats of varnish were necessary to cover the back and sides I think that is too much finish on the top. Some makers would criticize me for varnishing my tops in the first place but soundboards need protection and I believe this can be achieved without inhibiting the response of the top. I thin the varnish a little more than 5% with solvent. This allows the varnish to penetrate the soft porous spruce enough that it doesn't lie on the surface. It also makes it easier to brush around the bridge and embedded frets.

The second and last coat is thinned by 2-3%. In comparison to the varnish on the back and sides, the two thinned coats creates a thin flexible film. If my hand is steady and my eye accurate, I can apply a smooth even coat in spite of the obstacles the bridge and belly frets present.  When all of the finishes have hardened I rub them out with rottenstone lubricated with mineral oil using a firm cotton ball wrapped in cheese cloth.

Pat Bianculli's original 1823 Lacôte is a beautiful, lovely sounding guitar. I enjoyed every minute that I spent building the replica.

                           

Building an Early Lacôte Guitar Part 3

Pat Bianculli's 1823 Lacote

The flush fingerboard of Pat Bianculli's Lacôte is a hold-over from baroque era in which it was important to keep the strings close to the soundboard. Utilizing a low bridge and a flush fingerboard accomplished this. I find it curious that this feature endured as long as it did. The transition to six single strings had started thirty years previous to this. The development of a saddle and fixed metal frets swiftly led to the raised fingerboard. Yet, guitar builders continued to use flush fingerboards even though it is a feature that made demands on musicians and luthiers alike. Perhaps guitarists and makers were hesitant to discard this feature because the aesthetics of both tone and sight were pleasing, evocative, intimate? I had not built this style of Lacôte before and that was the attraction for me.

Constructing a guitar with a flush fingerboard requires a particular sequence of assembly. This photo appeared in an earlier post but I am using it again to show that I had glued the fingerboard in place even before I started the purfling. This was necessary  because I needed to level the transition from the fingerboard to the soundboard before I assembled the purfling. Doing so afterward might have damaged the delicately mitred purfling corners. 

 I had also slotted the fingerboard previously and hamered in the frets. The edge of the last fingerboard fret is visible in the photo.

original bridge

The bridge on Pat's guitar was a replacement and seemed to be constructed a little larger than Lacôte's standard size.  

The front edge of Lacôte bridges are smoothly rounded with the saddle slot cut several millimeters in from the front edge. The saddle on the replacement bridge was cut considerably further in from the edge than normal.

I consulted my notes and museum plans and designed a bridge in the Lacôte size and style. When I make any bridge with a saddle I leave the front edge square and the top surface, where the saddle slot will be, flat.

I do this so I can work out the compensation of each string in order to achieve good intonation. I use triangular shaped pieces of nut  bone as movable saddles. Placing them on the surface that I had left flat I maneuvered them into positions that gave the correct intonation for each string. I duplicated these positions by angling the saddle slot from closest to the front of the bridge on the treble side to furtherest on the bass side. The finished saddle is 2mm wide so I will contour the top of the saddle to further refine the intonation on the finished instrument.

The last stage of the fretting was the most difficult to do, yet when finished, the most satisfying and visually one of the most pleasing features of this style of guitar.

On baroque era guitars the belly frets are slivers of ebony or boxwood glued on the surface, but sometimes inset, on the soundboard. Once metal frets were used on the fretboard they needed to be continued onto the soundboard for consistency of tone. Keep in mind that 19th century frets were not the T-shaped fret of our day but straight pieces of metal that were about 0.8mm thick. The spruce of the soundboard is too soft to support metal frets of any kind adequately. Lacôte bordered his bar frets with ebony. This ebony/metal fret/ebony sandwich is a little less than 3mm wide. I wanted to insure that my belly frets played in tune so my problem was how to inset a 3mm wide fret assembly in the soundboard precisely in the correct location.  

I laid out the fret positions in pencil and after double checking for accuracy I scribed over the pencil with a knife being careful to respect the length of each fret. Then I widened the scribe line with a razor saw and continued with successively thicker saws until I had broadened the original line to 0.9mm. This is the width necessary to press fit a T-fret into the soundboard. I still needed to add the ebony supports that were also 0.9mm wide. I cut pieces of a broken bandsaw that fit exactly in the fret slot but a little raised above the surface. I placed a piece of the ebony border against each side of the temporary metal "fret" and carefully scribed a thin knife line. This delineated the borders of the recess I would cut for the ebony/fret/ebony sandwich. The sequence of steps is demonstrated in the photo. Once everything was prepared I waxed the metal spacer and glued all three pieces into the slots.

When the glue dried I removed the metal spacers, planed the ebony flush with the soundboard and inserted the T-frets with a little glue.

Next time I'll explain the varnishing and post detail photos of the finished guitar.

Building an Early Lacôte Guitar - Part 2

In my last post I had assembled the guitar body and finished the neck and peghead. Before I glued the neck onto the body I checked the strength of the neck. Wedging the heel against a notch in my workbench I tried to bow the neck -- mimicing the pull of the strings -- by pressing against the back of the peghead with my thumbs and down on the face of the peghead with my other fingers. The neck bowed a little less than a millimeter from level. I was satisfied as this is what I expected. If it had bowed more than that I would have routed a recess in the top surface and installed a long rectangular ebony strengthening rod. I glued the neck to the body using a screw through the front block into the heel by maneuvering the screw driver through the soundhole. At this stage the neck is plain wood. Eventually I will lacquer it black like the original that I am copying.

1823 Lacôte

The purfling detail on the original guitar is composed of five bands of ebony and five of ivory that wrap around the perimeter of the guitar body in one piece. Each band is about 0.7mm thick. I substituted holly for ivory. I make my own banding by band sawing lengths of appropriate woods with widths of 30 or 40 millimeters. After smoothing and thinning to the required thickness I stack them one on the other, as many as 10 high, and glue them together. After they have dried I square the two rough edges and saw off several pieces and smoothed with a small plane. Each piece is then composed of multiple bands that only need to be soaked in warm water to dissolve the glue and then dried or bent while still damp.

Even though I carefully prepared the banding I found discrepancies in the thickness of a number of pieces. If I were using a decorative edging of 3 to 5 pieces of banding I wouldn't worry about a tenth of a millimeter here or there. But multiplied over 10 pieces a small error can cause problems. I use a home-made device to check and re-size each piece of banding. The tool is composed of a block of wood with a flat bottomed ramp cut into the block at a 45 degree angle. A scraping blade is clamped in a position over the exit of the ramp leaving a gap through which the thin strip of banding can be passed. High spots are scraped off by the blade. It is a primitive tool but with patience it will turn out perfect work.

The width of the purfling is a little wider than 8 mm composed of ten pieces of ebony/holly banding. A final band of ebony that is a little thicker and, of course, deeper is added to the edge.

I use a small router fitted with a simple guide to cut the rabbet. Setting the guide to the proper depth I make a series of passes gradually widening the recess. I test fit the 10 ebony/holly bands and stop when the wider ebony piece fits comfortably.

The purfling is intended to wrap around the soundboard tongue with four mitred corners. This is a tricky procedure that displays the luthier's skill. If it is well done it looks pretty classy.
In this photo I masked the corner of the  rabbet with cellophane tape and glued the last 30 - 40 mm of the pre-bent banding together. I wedged it temporarily into the recess so it would dry in the proper alignment.

I lifted the banding from the recess, peeled off the cellophane mask and cut the end of the assembled banding to the correct angle. Once that was done I could proceed to glue the entire assembly in place. It is necessary to work slowly and methodically making sure that each piece of banding is covered with a layer of thin glue and that each piece in turn is properly seated in the recess.

Fitting the mitred banding perfectly around the soundboard tongue was complicated by discrepancies in the thickness of the ends of each piece of banding.  I found it necessary to fit them individually -- each mitred piece matching its mate.

Once all of the banding was in place and well dried I scraped it flush with the soundboard.

The rosette is composed in the same style of multiple bands of ebony/holly except that they are narrower and present greater difficulty in making and assembling. There are 20 bands, plus the wider ebony band that edges the hole. It measures 13.5 wide.

I assembled the rosette before I finished thicknessing the soundboard. This allowed me a little lee-way with the depth of the recess and the process of levelling the face once I was finished or if something were to go wrong. I routed the recess to the maximum  outside diameter and took off a little extra toward the inside as well. This allowed for the expansion that the thickness of the glue might cause. Lacôte assembled his rosette rings so that the ends, which are faintly visible, were spaced randomly around the circumference in order to further obscure them and I did the same. Using pre-bent bands I started at outside  and worked in, one at a time, cutting the pieces to length with opposing bevels so as to avoid making a band either too long or too short. It was not easy going. I quickly developed sticky fingers which made it difficult to do everything including pressing the most recent ring in place against its neighbour. When I had all of the bands in place there was a little space left that I filled with thin strips of styrene until the glue dried. I wasn't happy with the result. Every imperfection showed up. A kink or two here and there and several gaps between bands as well. I routed it out and started over.

Next time, I'll fret the neck including the embedded soundboard frets. I'll also describe staining and varnishing the body and lacquering the neck.