Graduation studies

Adjusting the back thickness as one of the last tasks before varnishing

MAKING MATTERS

Points of interest to violin and bow makers

What makes certain violins stand out as exceptional instruments from a player’s point of view, and how can luthiers make sure that their creations meet those criteria every time? In my view, getting the right voice or sound character of a new violin only gets you half of the way. At least as important is the sensitivity, dynamics, response and playability, and how malleable the sound of the violin is. Keeping track of wood quality, plate arching and graduations, bass-bar dimensions, weight, resonances and so on can perhaps get you close to your goals, but once the violin is finished and playable, the possibilities of adjusting the sound and playing characteristics wiThordinary methods are limited. If you aren’t quite happy wiThit or, if it’s a commissioned instrument, the client isn’t satisfied wiThthe result after the strings have settled in, this can be a source of frustration. Adjusting the bridge and soundpost might not be enough. Of course, a violin will mature somewhat through the years, but a mediocre instrument won’t develop into a sublime one just wiThtime and intense playing. And how many musicians will want to waste years of their career playing an instrument that doesn’t respond well? Wouldn’t it be great to have a much more efficient method of sound and response adjustment, wiThthe violin already set up and playable?

There have been a few times over the years when I have had to open a newly finished violin to adjust the graduations, before I could put it on the market. It has almost exclusively been the back that I felt was too rigid, rendering the sound a little hard and the feeling under the bow too stiff. I always felt I understood how to dimension the top plate and bass-bar to get the perfect amount of flexibility. From bending the plates in different areas wiThmy hands, and removing wood until I was happy wiThthe amount of resistance, I always wound up wiThnormal Stradivari graduations. It’s the method I still use. I do the same wiThthe upper and lower bouts of the back plate. Could this be the way the old Cremonese masters also finalised their graduations?

If so, an explanation for the greater thickness of the plates of a ‘del Gesu could simply be that he had stronger hands than other makers. But if one follows Stradivari and Guarneri could simply be that he had stronger hands than other makers. But if one follows Stradivari and Guarneri graduation patterns for the centre section of the back, one finds that this area is just too stiff to feel any flexibility. I assumed that the extra weight and stiffness in this region had acoustic reasons, and strengThunder the soundpost is of course necessary. But the exact amount of wood to leave or remove here remained a mystery to me, and I wasn’t happy to just copy measurements from fine old violins, because they could differ from less than 3.5mm to more than 6mm, partly since all pieces of wood are unique. I wanted to develop a robust and reliable method of dimensioning the back plate for optimum performance for every violin that I made, without having to open it after completion.

The dorsal pin and the small hole in the bak thst it fits into

How the pin looks when fitted in the hole

ALL PHOTOS ULF KLOO

Pondering over the reason for the so-called dorsal (or ventral) pin that is found in many Cremonese instruments from the 17Thand 18Thcenturies, I finally came up wiTha possible solution. The dorsal pin is a small conical wooden pin that the Amatis, Guarneris and others inserted into the inside of the back plates. The tip of this pin can sometimes be seen as a small dot on the outside surface in the centre of the back, at the point of maximum thickness. There are different theories as to why it’s there: some speculate that it just fills a hole that was drilled to serve as a guide for a compass while laying out the graduation pattern. If this was its only purpose, though, I don’t see why it would have been drilled so deep as to go almost through to the other side. Nor do I see any reason why they would have drilled a hole that deep for a screw to secure the plate to the workbench while carving the outside arching. You would risk damaging the gouge or plane if you ran into the tip of the screw when approaching the final arching height.

COULD THE PIN HAVE BEEN INSTALLED AS AN INDICATOR OF THE MINIMUM THICKNESS OF THE BACK’S CENTRE SECTION?

Wondering why the tip of the pin could sometimes be seen on the outer surface, and sometimes not, I reasoned that it could have been installed as an indicator of the minimum thickness of the back’s centre section. This would only make sense if the graduation were finalised after the top and back were glued in place. And the only reason to do this at such a late stage of construction would be that it could be done wiThthe strings in place. Then you could actually play and hear the instrument, and stop removing wood when you were satisfied wiThthe result. Of course, this is just a hypothesis, but it could be given a degree of plausibility if we compare a numbe of old Cremonese violins to see how deeply from the inner surface the dorsal pins go. Assuming these instruments haven’t since been re-graduated from the inside, which was common practice during the 19Thcentury and probably into the 20th, an equal depThfrom the inside surface for each violin maker would indicate that my theory could be valid.

Aisha Orazbayeva (standing) watches as Ulf Kloo adjusts the graduation of the back

LUTHIERS OF THE 17ThAND 18ThCENTURIES WERE VERY PRAGMATIC CRAFTSMEN, NEEDING TO WORK QUICKLY AND EFFICIENTLY

My guess is that luthiers of the 17Thand 18Thcenturies were very pragmatic craftsmen, needing to work quickly and efficiently. They would have to use a simple and reliable method to get good acoustical results. I can’t imagine them using any complex system of tuning different parts of the violin to different frequencies, for instance. I don’t claim that adjusting the back thickness wiThthe violin in playing condition is definitely how the Cremonese luthiers of the past worked, but I decided to put the idea to the test, hoping that the solution to the mystery of the back plate graduations was within reach. A few instruments later I can confirm that this method has been a revelation for me. It has given me a new degree of control when fine-tuning the sound and response of my violins.

My violin ‘opus 69’ will serve as an example of how my method can work in real life. I built it between March and May 2020 for the violinist and composer Aisha Orazbayeva. Aisha is at the forefront of pushing the limits of violin sound production. I greatly admire her work wiThearly music as well as wiThcontemporary music – her own or that of other composers. It was an interesting challenge to try to satisfy her search for a huge palette of sound colours, and I wouldn’t feel at all as confident without this sound and response adjustment system.

Opus 69 is made on my own model, based on examples by ‘del Gesu’ and his father, Guarneri ‘filius Andreae’. The top is made from fine-grained spruce from the Italian Alps. The back is made from one piece of Bosnian maple, and I cut the ribs from the same piece of wood. By the end of May 2020 the different parts of the violin were finished, except that I’d left the thickness at the centre of the back at a hefty 6mm, and 5.3mm beneaThthe soundpost. I had also installed the dorsal pin to a depThof 4mm. This meant that I could, if needed, remove 2mm of wood from the centre of the back before the tip of the dorsal pin would appear on the outside, indicating that I shouldn’t go much further. The arching height of the back was 15.5mm and the weight was 101 grams.

To install the dorsal pin I converted a standard 8mm centre-point drill bit by grinding off the outer cutting edges, leaving gently rounded shoulders preventing the sharp centre point from going deeper than 4mm. I had marked out and drilled the conical hole at the thickest point of the back, 180mm from the lower edge, and on the centre line. I had then shaped a maple pin to fit into the conical hole left by the drill bit, and glued it in place. After cutting the pin flush wiThthe surface, and gluing the back, top and neck in place, I varnished the entire instrument except for the back. Then I installed the pegs, soundpost, bridge and strings, and the violin was ready for the final step.

At this stage, the back is the only unvarnished part of the violin

Orazbayeva tests the violin’s tone quality after thicknessing

When Aisha tried the violin for the first time, she felt that the sound was too dense, a bit hard and almost strident. It was obvious that we could take the risk of losing a bit of power to gain more warmThand flexibility. Using a flat plane, 25mm wide and 60mm long, I quickly removed one or two tenths of a millimetre of wood from the centre of the back, and Aisha tried the violin again. She felt that we were on the right track, so I repeated the procedure. The power was still there, but the violin definitely had a warmer sound and better response. Since the violin and strings were completely new we left it at that, and Aisha took the violin home to get acquainted wiThit.

A week later we repeated the process, removing a bit more wood, still only from the centre of the back. This improved the warmThand response, as well as clearer harmonics. And finally, after a third session, Aisha felt that we had arrived at our goal. The violin now had a good balance between power and flexibility under the bow, the sound had boThwarmThand brilliance, and the harmonics were crystal clear. And I hadn’t even touched the bridge or soundpost. I’m not at all sure that I could have been as precise in meeting Aisha’s demands without this adjustment method, only thicknessing the back following measurements or intuition. Now it only remained to varnish the back, and luckily that influences the sound much less than varnishing the top.

The drawback to this method is that varnishing the back separately requires extra care to give it the same appearance as the rest of the instrument. Also, the client has to wait until it has dried before they can start using it. It might be easier to varnish the entire instrument after the thickness adjustment, but I fear that the acoustical result would be less precise.

I feel this method takes the guesswork out of finalising the back graduations, which I hadn’t quite wrapped my head around before. However, it does require that the luthier is able to play the violin reasonably well, and has a clear idea of what the violin should feel like to play, or that the adjustment is always done in collaboration wiTha competent musician. Going too far will result in an irreversibly hollow sound and a spongelike response under the bow, and possible deformation caused by the soundpost. A thickness measuring device can be used during the process for added safety, but I feel it would distract me from the real issue. Knowing that the little dorsal pin will tell me when I should go no further is good enough for me.

Keeping in mind that the arching, top plate graduations, f-holes, bass-bar and varnishing process, as well as the set-up, are very important factors in determining the sound and response of violin family instruments, I think that this method could prove useful for experienced luthiers who want to fine-tune every one of their creations for optimal performance. At least for me, it has been a revelation and an important piece in the violin making puzzle.