Building a Baroque Bass Guitar after Matteo Sellas - Edited for Content January 14, 2023

 

This past winter I built a large baroque guitar with a string length of 71 centimeters. The instrument is based on the Matteo Sellas 1614 that is conserved in  the University of Edinburgh Collection of Musical Instruments. The Original Sellas Guitar. My blog title "Bass Guitar", although an attention getting, is a misnomer. The guitar is tuned in standard e' b g d A and can be tuned comfortably to 440.

I took the guitar to Quebec City for David Jacques to try out. David is a busy performer, an authority on and a collector of early guitars. He previously owned one of my 67 centimeter Sellas style guitars. You can listen to David play that guitar here.

 The body is 48 cm long with the upper bout width at 20.8, the waist is 18.6 and the lower bout measures 25.9. These dimensions are slightly larger than the original guitar.

The wood that I chose for the back is special to me and I want to share its story. In the late 1970s when I was building a significant number  of viola da gambas I bought a large plank of curly hard maple that I  cut into backs and sides. Some of the pieces had long heavy iron stains and bore holes from having been tapped for sap to make maple syrup. I set those aside and when I was considering a good wood to use for the flat back I checked out the few pieces that I had put away to see if they were large enough.

Two pieces were just wide enough to accommodate the width of the larger Sellas guitar. It is difficult to make out in the photos but besides the obvious curl in the grain there is a long patch of bird's eye along the centre joint of the guitar and adjacent to the iron streak in the plank.

I glued two book-matched pieces together with a thin ebony spacer and thinned the back to slightly under 2mm.

The side ribs are Indian Rosewood inlaid with thin holly lines. The rib depth at the neck joint is 79mm which deepens to 92mm at the tail.

Edited January 14, 2023

A reader wrote and asked me to explain why I chose to build this guitar with a flat back rather than an arched one like the original guitar.  There were many factors involved in this decision. Foremost was that I had built a model of this guitar with its original arched back in 1995 specifically for use by the musicians of The Harp Concert for their recording Spanish Dances. It worked well in that context. The guitar was very good at playing rasgueado chords, but I felt that it could not stand alone. The prevailing opinion among a group of clients and other baroque guitarists was that arch backs were best for strumming while flat backs  excelled at punteado.  This assessment  became a guiding principle for me. Over the next 10 or 12 years I built several dozen models of a smaller ( 67 centimeter string length) anonymous arch back guitar mainly for use in continuo bands. David Jacques is playing the last of these in the above link.

When I received a commission to build a long scale (71cm) flat back baroque guitar I found that there were few options. Several Stradivari were considered but their string lengths are too long. A Domenico Sellas conserved in NMM Vermillion SD is the right size but the maximum rib depth of 117mm scared me off because I knew my client would require a guitar that was capable of supporting good punteado playing. In my opinion excessively deep body guitars are ill-suited to playing in this style.The University of Edinburgh 1614 Matteo Sellas came to mind and I started to think of the possibility of using it with a flat back. It is the right size both in string length, number of frets to the neck joint and width of the body. When I imagined a line from the bottom of the tail block to the bottom of the front block the measurements of 92mm and 79mm, essentially cutting off the arch, convinced me that the guitar configured as a flat back would produce the tonal effects I desired. Would Matteo Sellas have approved?

                                                          _________________________

                                          

I constructed an inside mold from several pieces of clear pine and drilled large holes around the perimeter to accommodate clamps that I would use to hold the bent sides in place. I shaped the rear block out of spruce with the grain direction on end and perpendicular to the gluing surface. The original guitar has a wider and slightly thicker front block to accommodate the extra torque of the longer string length. I built a model of this guitar in the 1990s and it needed a neck re-set after a few years. I decided to switch to a slipper foot construction that would counteract the string tension more effectively. I wedged both blocks snuggly into their respective locations. Once the ribs were bent and glued to the blocks I trimmed the height of the ribs close to their final contour. With the frame (the ribs and blocks) clamped securely in the mold I then rubbed the surface that was to be the front of the guitar on a rough sanding board. This procedure ensured that the top of the guitar would sit on a level plane. Then I used the same procedure to create the desired tilted plane of the back.

This shows the completed interior with the back glued on. My guitars get a lot of use both at home and on the road. Therefore I add reinforcements that I think will help to protect the integrity of the guitar but have little effect on their acoustical response. For example, I thinned the rosewood ribs to 1.1mm which helps to create a transparent tone, but this leaves them vulnerable to bumps and other hazards. The thin narrow spruce pillars placed at strategic locations help to protect them. Since the gluing edge of the back to ribs is so small I added short supports to the cross struts and covered the upper bouts and lower bout joints with 90 pound cold press watercolour paper. 

I decided not to use the barring of the original Edinburgh Sellas guitar. It consists of only two bars arranged about 3 centimeters above and below the rose and angled so that they are closer together on the treble side. Early in my baroque guitar building career I built many Sellas type guitars with this barring. They were very good in continuo where energetic strumming styles (rasgueado - love that word) were important. But to prevent the tops from sinking in the area around the bridge it was necessary to use a thickness of 2.2 to 2.5mm. Thicker tops always seemed to be a cover the treble tone a little. Eventually I used thinner tops and added a diagonal bar angled toward the treble side at various distances from the bridge. You can hear David Jacques play such a guitar that I built for him in 2009 Here .  

 

 

 

 

This photo shows the barring layout that I did use. It is based on the Stradivari guitar that is in the Ashmolean Museum (formerly part of the Hill Collection). The dimensions of the guitar's body, except the depth, are very close to the Edinburgh Sellas. Listening to  Rolf Lislevand's YouTube recording of the Sabionari convinced me that the barring pattern had merit. That is not to say that the Sabionari has the same pattern. In fact, very little information about the Sabionari is available so I was taking a leap of faith.  I added two small bars in the upper and lower bouts as well as the smaller tabs along the outline of the top. The guitar is bright and focused with a transparent tone.

The parchment rose is by Elena dal Cortivo. 

The top is finished with multiple applications of beeswax polish.

This section of the back shows both the curl and bird's eye grain patterns.

The back, sides and neck are finished with oil varnish.

The core of the neck is poplar veneered with 0.9 mm ebony.

The sides of the heel and neck are flat, and angled in slightly.

The core of the peg head is walnut with the faces in ebony. The joint is a  true V but the raised part was added after the joint was assembled. I concealed the glue line by fine sanding over the area, then carefully pressing the dust into the very narrow crevice and applying a thin coat of Crazy glue.  After many applications the joint disappeared.

All photos by the author.