Exploring bow sound

THE SOUND OF BOWS

Senior bow makers explain some of the mysteries of bow sound.

Our first experience of the sheer magic of bows was during our inaugural Take a Bow exhibition in 2002 when we exhibited 50 cello bows by renowned makers from around the world. We were stunned by the way that some bows had such distinctive personalities that we could identify their sound in a blind testing; also that while one bow might be attractive to large numbers of cellists, another more unusual bow might have an extraordinarily positive interaction with just one player and instrument. This growing fascination has inspired us to repeat the exhibition on a regular basis, but has also left us with a growing number of questions about the mysterious bow.The result can be magical

To mark our 2011 exhibition, we decided to interview a number of senior bow makers to try to find answers to some of our abiding questions. All the bow makers we spoke to have practiced their craft for many years and have made a significant contribution to contemporary bow making through their making, research and teaching. Our questions centred on the issue of sound: what makes some bows sound so beautiful and interesting? Why do bows sound so different to each other? And how controllable is the end result when a bow is being made?

Charles Espey was quick to remind us that bows do not have a voice of their own: ‘Bows do not make sound themselves, but they accentuate different ranges of an instrument’s potential sound spectrum as well as simply mobilizing more or less sound from the instrument. The bow is in a partnership with the instrument and can only generate sound within the instrument’s potential to create it.’ However, although bows do not make a sound themselves, most of us have discovered that some bows make darker sounds on cellos and some make brighter sounds. According to Yung Chin this is because of the overtones (or partials) that the bow encourages. ‘You can divide bows in a very general way into those which will pull higher partials and those which will pull lower partials. The great bow will pull throughout the sound spectrum, and that’s what you really want to find, especially on the cello – because of the big range between upper and lower strings.’

All the bow makers we spoke to believe that the choice of the pernambuco wood used to make the bow is absolutely crucial for its sound. Morgan Anderson explains: ‘One of the biggest effects a maker has on the sound is at the very beginning, in choosing the wood. If a maker has a good selection of high quality pernambuco of different types and is familiar with their characteristics, he or she can influence the sound a great deal. The word “influence” is probably a more accurate representation than “control”.’ Espey agrees: ‘First and foremost is the wood; its density, its grain structure, presence of perturbations in the grain, its stiffness and the quantity of extractives such as pigments and waxes in the wood.’

Klaus Grünke quotes a study of pernambuco which discovered not only that it is an exceptionally stable material, but its most unusual quality is that it has least damping factor on vibration at room temperature than any other wood tested. ‘This is the reason that it carries sound better than any other wood,’

Thomas Gerbeth often copies fine old classical bows and he finds that in order to make bows sound like the original, the most important factor – in addition to the bending of the stick – is the wood selection: ‘Pernambuco wood, which is used to make the stick of most bows, has 125 sub‐species. Of these only about 12 are used for bow making.’ Morgan Andersen is equally clear that not all types of pernambuco will make good bows: ‘While there are many types of pernambuco with a variety of characteristics from which good bows can be made, there is such a thing as bad wood. Most pernambuco is not suited to making good bows. Bad wood will never produce a bow with complex tonal colour.’

There is a general consensus amongst most bow makers that you can control or influence the sound of a bow through wood selection. Yung Chin is able to discern certain characteristics in pernambuco which indicate the general sound qualities of a bow made from that blank. Espey finds it very helpful to have a stock of wood from one region that he has come to know over the years through trial and error. For instance, when a stick from a particular board has certain qualities he can assume the sister sticks on the same board will be similar. Other makers emphasise the variability of wood. William Salchow once made two bows using wood from the same plank: ‘These two sticks were right next to each other in the plank and I made two bows, but they were totally different. I was shocked! Of course there have to be great similarities from the same piece of wood, but you can’t always predict the result.’ John Stagg concurs: ‘A bow maker will find that four sticks from the same plank of wood, although possibly having the same overall weight, stiffness or balance, will each produce a different colour on the same instrument.’ Yung Chin believes that wood is not as uniform as people think and it always holds a mystery for the maker. He also points out that new wood needs to season for at least 10-12 years. ‘New wood needs laying down like wine.’

The design of the bow is also of fundamental significance. Espey believes the following factors in a bow’s structure will contribute to the bow’s sound generating potential: ‘…its camber, its graduations or diameter from tip to butt, the height of frog and head, the weight of frog and winding. Of course the qualities of the wood are reflected in the bow’s structure; strong wood will permit finer stick diameters for example.’

Salchow, who studied cello at the Juilliard School in his youth, is very aware of how some aspects of a bow’s design affect the cellist: ‘The height of the frog and of the head is very important. A very high head will give a lot more range of volume/dynamics, but a high head is uncomfortable for a player as it feels as if you are walking on a tightrope – that’s why people love Sartory bows because the head and frog are low. With Tourte the head is quite high, the frog less so and Peccatte usually had a higher frog and people like that a lot, as it affects the feel of the playing but not the sound that much, other than giving you further distance to go when you are pushing the bow right down on the string.’

The design of the stick also dictates the tension of the bow hair, as Gerbeth explains: ‘If the hair tension is high, this reduces the area of contact with the string, and vertical pressure has to be used to compensate for this loss. That is the reason why some players ask for heavier bows, as they do some of this work for them. With less tension the bow hairs are more willing to ‘caress’ the string. The player is able to set the string in motion without much pressure.’

For many cellists, part of the quest for a suitable bow is to find one that complements their cello. This seems to be a time honoured strategy as William Salchow relates: ‘Years ago when I first started out there was a little booklet by a wonderful cellist about how to choose a bow and he said you have to fit the bow to the instrument so that if your instrument is very bright you need a bow with a darker sound to make it a little less bright – if dark, you need a bow to brighten it up.’

Is it possible for a bow maker to set out to make a bright or dark sounding bow? Klaus Grünke says: ‘If trying to make a bright or dark sounding bow, I would take into consideration the pitch of the wood and the specific weight – if you have a very dense, dark wood it tends to have a dense, dark sound – but it is not a general rule.’ Salchow doesn’t believe that he can control the brightness or darkness of a bow. ‘My point of view is, I want to make a bow that will bring out the utmost projection of sound with more overtones than anything and it’s probably the overtones that give brightness and colour to a sound, and the way I try to do that is to make an absolutely full curve – the stick must be curved right down to the hair and must also be even, tightening up to a straight line. These are the things I really work for and I believe that they do work very well.’

Some bow makers are also experienced string players and are sensitive to the way in which the bow is used by the player and the resulting effect on the sound. Salchow recommends a bow hold which doesn’t cramp the bow: ‘With the thumb under the stick and the first finger on top of the stick you form a little lever which pushes the bow down on to the string, but if the other fingers grip down onto the bow I think that tends to mute the sound.’ Yung Chin is well aware that there are some important issues in the bow hold which affect a bow’s performance. ‘I think that too many players hold the bow at too much of a severe angle to the string so they play forte with a hard martillé stroke. If you flatten the hair slightly you can find a sweet spot and you will get a very different sound but more importantly, the bow response will be very different. With the bow angled too far over, there is a certain kind of delay to its performance and bows aren’t meant to be played that way, it’s a bad habit. When you find the sweet spot it takes less effort to make the stroke.’

Why do some bows sound much more interesting than others? Charles Espey believes that richness or complexity of sound is achieved by matching the right stick and the right dimensions. ‘But there is always some magic to the overall sound signature a bow can produce; there is no simple formula and the maker is inevitably going to use their intuition as well as their knowledge.’ Morgan Anderson finds that with most good pernambuco, the sound keeps opening up the more wood you remove from the stick. ‘But there is a point at which taking more off makes the bow too soft to play or starts to erode other qualities that need to be present in a good bow such as response time and stability. Where this “edge” is varies from piece of wood to piece of wood and requires individual attention. A bow stick can have harder and softer spots in it which require changes in graduation designed for that particular piece. Sometimes I will put hair in a bow and play it while still in the process of removing wood. Most often I find the sound becomes more interesting and complex the closer I take it to that “edge”….the trick is to stop before you fall over it.’

Extended versions of interviews with bow makers quoted in this article can be found below:

Interview with Charles Espey

What makes bows sound so different?

‘Bows of course do not make sound themselves but they accentuate different ranges of an instrument’s potential sound spectrum as well as simply mobilizing more or less sound from the instrument. There are a number of elements contributing to the bow’s sound generating potential. First and foremost is the wood; it’s density, it’s grain structure, presence of perturbations in the grain, it’s stiffness and the quantity of extractives such as pigments and waxes in the wood. Secondly there is the bow’s structure; it’s camber, it’s graduations or diameter from tip to butt, the height of frog and head, weight of frog and winding. Of course the qualities of the wood are reflected in the bow’s structure, strong wood will permit finer stick diameters for example. In addition the quality and quantity of hair has an effect. All these qualities of wood and structure are combined in an infinitely variable way in a given bow.’

As a maker, how much control do you have over the sound of a bow during its manufacture? (for example, if a player asked for a bright sounding bow, would you be confident of fulfilling his/her request?)

‘As a maker one can definitely affect the bow’s sound generating potential. It helps greatly to have a stock of wood from one region that one comes to know over the years through trial and error. For instance when a stick from a particular board has certain qualities one can assume the sister sticks on the same board will be similar. Also one associates a certain look in the wood to a certain result. In the same way through experience one associates the mass of the frog or the amount and type of camber with a certain result. Brilliance in the sound can be achieved through choice of wood and other physical traits one puts in the bow. But the bow is in a partnership with the instrument and can only generate sound within the instrument’s potential to create it.’

What makes the tone of some bows so much more interesting/complex in tone colour than others?

‘Richness or complexity of sound is a result of matching the right stick and the right dimensions. But there is always some magic to the overall sound signature a bow can produce; there is no simple formula and the maker is inevitably going to use their intuition as well as their knowledge. Players are also likely to have difficulty articulating or defining the sound quality they are hoping for. When players use poetic metaphors like ‘chocolatey’ or my favorite, ‘buttery’, the maker is going to mine all their experience to search out a stick in their stocks that simply feels right in addition to having qualities that in their experience will produce the desired result.’

Interview with Morgan Andersen:

1. What makes bows sound so different?

Just about everything. Wood choice; how the wood is shaped; camber; hair tension; how comfortable the player is with a bow etc… It’s a big question and a hard one to answer with a brief definitive statement. I think an analogy to wine comes close to explaining why something that seems so simple produces such a wide variety of results.

What makes red wines taste so different? It’s a very simple process of pressing the juice out of grapes, letting it ferment, and aging it. The process is similar the world over, and yet the variations of the finished product are almost endless.

Anyone with the least interest in the subject of wine knows that different areas use different varieties of grapes. Even with the same variety in a particular area changes in soil, drainage and slope can produce differences in flavor and quality. Each wine maker, while repeating the age old process, has their own sense of when it is optimal to pick the fruit, how long to leave the juice on the leas, when to bottle the fermented juice, how long to age, etc…

Pernambuco varies as much as grapes do. And bow makers, while basically repeating the age old process, have their own sense of what they are looking for in a piece of wood and make a multitude of subtle individual choice in crafting that piece of wood. Making methods vary, the opinions and decisions of each maker are influenced by their teachers, the players they have worked with, the old bows they have studied. Their talents are then honed with the materials that are available to them. All these factors account for the uniqueness of a particular makers work.

You can also carry the analogy of wine through to include the consumer. Some people just want a glass of wine with their dinner and are happy buying the same local product forever. It works for their taste and budget and that is the extent of their interest in the subject. Others become fascinated with the subtle differences in wine, and for them it becomes a life long journey of exploration and taste experience.

Some string players have a bow that works for them and their interest stops there. Others become fascinated with the differences and are always trying new things exploring the subtle variations that bows produce.

2. How much control does the maker have over the sound of the bow?

If a maker has a good selection of high quality pernambuco of different types and is familiar with their characteristics, he or she can influence the sound a great deal. The word “influence” is probably a more accurate representation than “control”. One of the biggest effects a maker has on the sound is at the very beginning in choosing the wood.

Once the wood is chosen, the maker’s training and experience comes into play as to the decisions they make in shaping that particular piece of wood to maximize the sound it is capable of producing within the limits imposed by other factors such as weight, balance and handling qualities.

With most good pernambuco the sound keeps opening up the more you take off. But there is a point at which taking more off makes the bow too soft to play or starts to erode other qualities that need to be present in a good bow such as response time and stability. Where this “edge” is varies from piece of wood to piece of wood and requires individual attention. A bow stick can have harder and softer spots in it which require changes in graduation designed for that particular piece. This is one of the reasons that producing bows of a consistently high quality using factory production methods does not work very well.

One also needs to keep in mind that there is no one ideal bow that will suit all players and instruments. There are some bow makers who have done their best to obtain a wood supply that is consistently of one type, and try to make one kind of bow. There are others that try to produce a variety of bows to suit players of different types.

Adjustments to the bend or camber of a finished bow can sometimes change its sound and performance as dramatically as the changes made to a violin by adjusting the sound post.

3. If a player asks for a bright sounding bow how much confidence would I have in fulfilling their request?

If I set out to make two bows, one brighter and one darker sounding, I have complete confidence of being able to do so. This is something different than having complete confidence in fulfilling the request of the client.

Is the client’s idea of the brightness required to pull the sparkling higher over tones out of their particular violin exactly the same as the sound of the brighter of the two bows I have just made? One never knows if you are using terms in the same way or even hearing sounds the same as someone else.

If I have not yet shown bows to someone and we are talking about sound, I may get an idea that becomes a theme or guiding principle I refer to when making them a bow, but it is very subjective. Back to the wine analogy for a moment: If someone tells me they like a wine with a lot of blackberry fruit overtones and a stony dry Italian finish, I get an impression of what that means to me, but will our taste buds agree?

If on the other hand, I have shown someone two of my bows and they are describing their reaction to them, this type of information gives me an impression to work with which is better gauged to their preferences. For example, sometimes neither bow is quite right and they may say something like, “this one has the sound I’m looking for but I’m having trouble handling it near the frog. The other bow feels great in my hand but is a little too bright for my violin.” This type of information gives me an impression to work with which is better gauged to their personal technique and their violin. Sometimes all that is required to achieve the desired result is an adjustment to the camber, and other times I will show them another bow. While I can’t guarantee the next bow I show them will be exactly what they are looking for, with the information I now have I can be pretty confident that next bow will be closer to what they are looking for.

4. What makes the tone of some bows more interesting/complex than other bows?

Part of the answer to this question is covered under the first and second questions. Another part of the answer to this question is that this question can never be completely answered and there in lies the reason that bows are interesting and somewhat mysterious. This is a craft that defies simple explanations. As soon as you think you have discovered the few basic principles that define great bows, you will see exceptions to your new rules. Makers who have the most confidence that they have all the answers tend to be those with little experience, lesser powers of observation, those who have not had the opportunity to study many great old bows, or are simply taking that position for marketing purposes.

If someone forced me to dare and take a stab at providing a more specific answer to this question, I would refer back to two things I have already discussed: wood quality and the “edge” mention in my answer to question two.

While there are many types of pernambuco with a variety of characteristics from which good bows can be made, there is such a thing as bad wood. Most pernambuco is not suited to making good bows. Bad wood will never produce a bow with complex tonal colour.

Sometime I will put hair in a bow and can play it while still in the process of removing wood. Most often I find the sound becomes more interesting and complex the closer I take it to that “edge”….the trick is to stop before you fall over it.

© Robin Aitchison and Sarah Mnatzaganian 2008