Setting Up & Tonal Adjustments, Part III

In Part II of this blog series, we discussed briefly how the bridge and sound post work together as a fulcrum and lever system.  In this continued discussion, we will outline a few of the guidelines and considerations I give to the sound post.

Some of this information may seem arbitrary, but is based on a combination of my training and 40 years of experience observing and setting up countless instruments from all schools, countries, and periods of violin making.

When choosing the wood for a sound post, there are a number of considerations that should be given thought.  First, one must determine the grain pattern of the top wood, i.e. how close are the annual rings, and how stiff or flexible the arching appears to be from both side to side, and neck to saddle.  It seems to work best if you can match the grain pattern of the sound post to that of the table.  But there are certainly other considerations when choosing the particular piece of sound post material for a particular instrument.

From young Engelmann spruce, to 16^th century Italian spruce

I have a collection of sound post wood which varies from high-altitude, 35+ year old Engelmann spruce, to 16^th century Italian spruce which came from the floor joists of a 16^th century house in Italy.   I like to use Engelmann because it is incredibly lightweight and has all of the properties I seek for the transmission of vibration from the top to the back.  It is extremely fast, and allows me great variability in choosing both the grain pattern and the actual width or thickness that I have determined to be ideal for a particular instrument.  Hardness of the particular piece of spruce chosen for the sound post is also one of my many considerations when setting up an instrument.

For a 17^th or 18^th century instrument, I sometimes like to use my very old and well-aged wood, if I can find a sample where the grain pattern and the apparent hardness of the wood seems to match the top wood in the particular instrument I am working on.  But if I determine that the lighter weight and flexible Engelmann is more appropriate, I don’t hesitate to use it, no matter how old or how “important” the instrument happens to be.  Again, I can’t emphasize enough how important the choice of wood is to a successful result.  This is just as important as placement in relation to the bridge which will be the subject of our next discussion.

Instrument Setup Part 3: The Soundpost

The sound post in a violin family instrument is often referred to as the “soul of the instrument”. As I explained in an earlier blog, the sound post transmits vibrations from the table to the back in order to initiate the pumping action of the back arching. This assists the table in getting the air inside the instrument to vibrate to the frequency of the pitch being played at that instant.

There are many factors to consider when choosing the wood one uses for the sound post. Age, diameter, length, grain pattern and hardness of the wood itself are all important. All of these characteristics must be taken into consideration and applied to the perceived characteristics of the instrument being worked on. Then, its position in relation to the bridge and bass bar has to be determined. Whenever possible, I try to utilize spruce that has a similar distance between the grain lines as one finds in the spruce of the table. But more importantly, I try to match the hardness or softness of the sound post material with that of the table.

Another variable one must consider is the thickness of the plates. If the thicknesses are too thin in relation to the design of the arch and density of the wood, then one should utilize a slightly thicker diameter post and fit it somewhat closer the the back of the bridge foot, and possibly one or two millimeters closer to the bass bar in order to more properly support the arching.

Conversely, when the plates are determined to be somewhat or too thick and or too hard for the design of the arch, one can place the top of the sound post further away from the bridge foot in order to allow the top to flex more to initiate the pumping action than it can if the post is too close to the bridge foot.

There are also numerous variables that can be explored with the angle of the sound post – front to back and side to side. These movements can be used to fine-tune an adjustment for a particular instrument. The preferred starting position is for the post to be fit and set to be perpendicular in all directions. From this neutral position, if the treble needs more support, the top of the sound post can be moved slightly toward the outside of the treble bridge foot. Conversely, if the bass needs more support, the top of post is moved slightly toward the bass side of the bridge. If the instrument needs more smoothness in the sound, the bottom of the post should be moved slightly from the vertical toward the end block. Conversely if the instrument needs more edge, the bottom of the post is moved slightly toward the neck block. Sometimes the bottom of the post can also be moved toward the outside to stiffen up and support the arch and to quicken the response. These are all 3very subtle movements.

Keep in mind that all of these changes have to reflect not only the construction of the instrument itself, but also the skill and/or approach of the person who owns and performs on the instrument-different styles of playing often require different approaches to adjustment to get the best results.

In the next segment, we will talk about how different string choice and tensions can affect adjustment.
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Setting Up & Tonal Adjustments, Part II

In my last discussion concerning tonal adjustment of violin family instruments, I touched on a number of topics, mostly dealing with different aspects of the bridge and sound post.  More specifically, one needs to understand that the bridge and sound post work together as a fulcrum and lever system, and need to be approached as such, in order to allow them to do their job in the most efficient manner.

To best understand how this system works, try to visualize the following:  When the bow strikes, or pulls on the string, the string vibrates along its length to a certain frequency.  That mechanical energy is transmitted to and through the bridge, which then begins to rock from side to side, with the bass foot of the bridge actually lifting up and then striking down on the top which then begins to move both side to side across the arching, as well as up and down along the length of the top, until those vibrations created by the vibrating string and bridge are also being transmitted through the bass bar and the entire system is vibrating to the frequency of the vibrating string.  Next, as I mentioned before, the arching is also moving from side to side, pushing downward on the sound post which in turn is also pushing downward on the back until the back is also pumping and that pumping action between the table and the back are exciting the air within the body until it is also vibrating to the same frequency and then escapes through the sound holes forming the pitch of the tone that one hears.

How a Violin Produces a Sound

What I just outlined is just the very basic overview of how a violin produces a sound.  Keep in mind that this process happens instantaneously, and all that I just discussed is what a string player or a luthier refers to as an instrument’s response.   So obviously, the choice of wood both for the bridge and the sound post, as well as the width and thickness of the bridge and the hardness, length and position of the sound post are very critical to the quality of the tone, and the quickness with it is produced.

This is why it is so important for the luthier to spend his/her life carefully studying the different schools of making with the goal of always trying understand and remember how the different concepts of arching design coupled with graduation of the plates and their attendant thicknesses affect the tone which is produced.  My master told me numerous times that the “holy grail” of violin making is the combination of those three elements-the arching, the graduations, and the specific density of the wood chosen by the maker.  Before any successful “set up” can be done on any given instrument, be it a violin, viola, or cello, these three elements must be thoroughly understood and taken into consideration.

Only a Starting Point

Even for the most talented luthier, this kind of understanding doesn’t happen overnight.  Most importantly, it must be accepted that whatever set of measurements one is taught in violinmaking school are only a starting point, and one has to be open to doing whatever the instrument is asking of you to help it work its best.

This approach is not “voodoo” violin set up and adjustment.  To be both artistic and efficient in assisting the player, a deep understanding of the elements discussed above does truly need to be assimilated by the luthier.   In our next discussion, I will offer some insight into the sound post, which in earlier times was referred to as “the soul” of the violin.  For each of these discussions, I welcome your comments and any insights you wish to offer, as I consider the learning process to be ever open-ended.

Violin Tonal Adjustment

As a working luthier, I was lucky enough to have a number of experiences that led to a fairly unique position in the violin trade.  First, I started learning to play the cello at age 11 and then went on to a professional career as a cellist, which I still maintain  to this day, more than 50 years later.  During the 1970’s, I had the good fortune to study violinmaking and repair with master maker David Caron.  Through my years of apprenticeship with him, I was taught to adjust violin family instruments so they could sound their best.  Adjusting an instrument to sound its best involves a complex assessment from a number of points of view: structural, architectural, design, and tonal.

The first thing I do when a player brings in their instrument for a tonal adjustment — even before I study the instrument to assess the elements set forth above — is to listen to them play.  Through listening, I can figure out their style and approach to their instrument and assess how it functions.  As an experienced player myself, I am in a position to make these assessments, which many of my colleagues who have only a traditional violinmaking school background are not in a position to do.

The Performer’s Relationship with Their Instrument

While listening to my client, I not only can understand their relationship with their instrument, but also am able to hear and observe its response. I then take the instrument and study it to ascertain its various characteristics.  To me, it is very important to recognize, through identifying the school of making from which it came, or which it is trying to copy, a number of variables:  the thickness of the plates in relation to the design of the model, the arching of the top and the back both side to side and along its length, the neck angle in relation to that arching, and the consistency (hardness) of the varnish.

My main goal in the set up and adjusting of an instrument is quickness and evenness of response throughout the frequency range of the overtone series.  For example, French instruments made from the late 19^th century onward throughout a great deal of the 20^th century often had a hard, brittle spirit-based varnish, and the necks were set with a very high projection, with a very low over stand.  These factors inevitably tend to emphasize mostly the upper partials of the overtone series, which sound very bright and harsh to the ear, and often create a certain amount of “white noise”, or static which also exaggerates the perception of harshness, especially on the bass strings, and an often piercing edge on the treble side.

Several Considerations

My approach to such an instrument has several considerations.  If I am only being asked to adjust the sound post, I ascertain how close it is to the bridge, both to the back of the bridge foot, and the edge of the bridge foot in relation to its treble edge.  If I feel that I can improve the tone by moving the post in a certain direction, as soon as I move the post, I am able to discern both how it fits, and whether or not is too loose or to tight.  If an arching is too stiff, and the hardness or inflexibility of the varnish are present, then I often ask permission to remove the sound post to study its own hardness and thickness in relation to the instrument it is in, and may start by simply shortening the post.

If I determine that the post is too thin, or the wood too hard for this particular instrument, I make a new one, usually from Engelmann spruce which I have found to be very strong, light and generally somewhat broader in grain than other spruces which makes it particular suited to French instruments. I also try to fit the post further away from the bridge foot than many of my colleagues in order to give the arching as much flexibility as it needs to function properly.  If I feel the need and am given permission to make a new bridge to help a particular instrument sound its best, I incorporate that into the process.  I try to choose a bridge of suitable hardness for this instrument, and make sure that it is of a correct width for where the bass bar is located in relation to both the bass sound hole and the center joint.

The Bridge

Once I have determined the proper location and width, (not thickness) of the bridge, I try to remove as little off the bottom of the bridge feet as possible to properly fit the arching as a way to help mitigate the often super high neck projection of a French school instrument from the period as discussed above.  This is done, by fitting the bridge feet in such a way that there is the least amount of wood left over the heart of the bridge given the (usual) high projection of the neck.  As a rule, the less amount of wood over the heart, the darker the sound, which emphasizes the fundamental and midrange of the overtone series.  Conversely, the more wood over the heart, the more emphasis there is on mostly the upper partials.

Also, it is very important that the overall thickness of the bridge should correspond to the hardness of the bride blank that I have chosen. The other thing I do is to make the bass side of the bridge thinner than the treble side.  If you remember, I mentioned that French instruments from this period tend to create white noise in the sound, and this is often reflected by a certain amount of fuzziness and lack of clarity in bass, and a very nasal, often piercing tone on the e string.  If one leaves a little more wood on the treble side of the bridge, and less on the bass side, it helps to mitigate this tendency and lead to a more balanced tone.

In future discussions I will explore the methods I use for other schools of violin making when I am setting up or simply adjusting an instrument.