FOR THE CURIOUS CELLIST

Point of Contact of the Bow with the String

The term “point of contact” refers to the position of the bow relative to the bridge or, more precisely, the distance from the bridge (or from the edge of the fingerboard) at which the bow is touching the string at any given moment. If we continue with the painting analogy that we used to describe the effects of bow speed and pressure, we could say that the distance of the bow from the bridge determines the “gloss” or brilliance of the sound. The closer our bow is to the bridge, the more brilliant, glossy, sharp and penetrating our sound will be. But, as with paints, the more shiny (brilliant, glossy) they are, the more careful we need to be with our brush-strokes as, just like with glossy paints, even the smallest defects are visible.

Our choice of the bow’s point of contact at any one moment is always intimately related to our choices of its speed and pressure, and very often these choices are made almost automatically, unconsciously, instinctively: the result of our many hours of practice. As we bow closer to the bridge, the strings become exponentially tighter and more rigid, which makes them more difficult to move (to set in vibration and to keep in vibration). This means that, as our bow gets closer to the bridge, it becomes more and more difficult to find the right mix of bow speed and pressure necessary to make a good sound. The permissible margin of error diminishes rapidly as we near the bridge, and if we lose this “right mix”, the increasingly shiny (but increasingly brittle) mirror risks sudden disintegration into 1000 razor-sharp pieces (sul ponticello or the “cracking” of the sound).

We all know which types of sounds (timbres) result from using the two extremes of point of contact (sul ponticello and sul tasto) but it’s fun to look for other analogys to describe and illustrate this phenomenon. Apart from the paint analogy that we used above, here are some others:

THE LANE ANALOGY

We could look on the space between the fingerboard and the bridge as if it were a multi-lane highway. Nearest the bridge is the slowest lane: this is the lane for tractors and slow-moving heavy vehicules. Furthest from the bridge is the lane for the fastest, lightest vehicles while the lanes between the two are a gradual progression between these two extremes. If the light, fast vehicles try to drive in the lane near the bridge they can’t get enough traction and just skate and slip on on the ultra-hard, smooth surface. If the heavy vehicles try and drive in the lane over the fingerboard they just sink into the soft surface and get stuck.

Our highway doesn’t have to be only for road vehicles. We could also imagine the lanes being for different animals. Nearest the bridge go the hippos, elephants and the rhinos (all in a peaceful mood) while near the fingerboard race the rabbits, barely touching the ground as they fly along, with the antelopes, gazelles and racehorses in the next lane.

THE BIKE ANALOGY: THICK SAND OR SPIKY BUSH

Let’s now use a slightly different analogy, that of a motorbike videogame, in which we now only have one type of vehicle. In this game we are riding a motorbike along a narrow lane. On the right side of the lane is a thick impenetrable hedge with nasty prickly branches sticking out (the cello-bridge with its warning signs of cracking sound) but on the left side, the road surface becomes quickly and dangerously softer, ultimately becoming thick sand. We have to find just the right trajectory between these two dangers, staying on the hard road near the wall, but not so close that we hit it (sul ponticello). If, for safety’s sake, we choose a trajectory that is too far away from the wall, we can get stuck in the deep sand (sul tasto).

OUR CHOICE OF LANE: CONSCIOUS OR INTUITIVE ? APPROPRIATE OR INAPPROPRIATE?

In good, expressive playing, the point of contact varies constantly, but this is a very tricky element to control. A small variation makes a big difference in sound quality – the bike lane is very narrow – and too often our point of contact varies not because we want it to, but rather because we just don’t have enough automated fine control to really know where our bow is. If we are not in control of our bow’s point of contact then it’s as though we, on our motorbike, were permanently alternating between bouncing off the wall towards the thick sand and then skidding back towards the wall again. And, of course, the faster we drive (the greater the difficulty of the passage) the harder it is to consciously control this trajectory.

Often, to avoid the dangers associated with driving close to the prickly edge, we can be tempted to stay permanently on the “safe route”. Bowing is so much easier (more forgiving) when the bow’s point of contact is in the softer sand, nearer (or over) the fingerboard. Here, the sound is “sweet”, it doesn’t “break” at the slightest miscalculation, and we can use faster and lighter bow strokes. This is an intimate, gentle style of playing, especially suitable for small, resonant rooms or close microphones. But it is not appropriate for loud, powerful, strongly-projecting music, nor for large halls. Playing louder, projecting more and using slower bowspeeds all require that our bow moves closer to the bridge.

RAILS AND VIDEO

There is a lot to be said in favour of “rails” for learning and automating a good trajectory because the most basic skill in this domain is just to be able to maintain a steady, unvarying point of contact. Mechanical bow-trajectory-guides (rails) exist. Some of the finest string teachers guide their student’s bowhands with their own hand, sometimes for years, in order to create and reinforce the physical memory of a healthy, stable (but also responsive) bow trajectory in the player from the youngest age.

Past a certain age however, it can become more embarrassing to ask someone to hold our hand at the cello. In that case, watching our bowing is perhaps the best way to see whether the changes in point of contact are the result of our musical intentions or simply the result of our lack of awareness/control of the bow trajectory. We can see this better in a mirror than just by looking down the fingerboard. But the very best way to see what our bow is really doing is in a video recording, preferably one where we are playing a piece of music in which we are thinking only about the music (and not about our bowing technique). It is at these times of total musical immersion that our bow often starts to do have a secret life of its own that we never imagined!

Once we know how to maintain a stable and constant point of contact, then we can practice varying it for musical and technical reasons. Let’s now look in more detail at these reasons:

1: POINT OF CONTACT AND DYNAMICS

As a general rule we will need to move our bow’s point of contact closer to the bridge when we want to play louder, and closer to the fingerboard when we want to play softer. So in a crescendo our bow will normally go closer to the bridge and in a decrescendo it will do the opposite. Choose any one note for the following exercises which can be done starting on either downbow or upbow.

The above exercise is a laboratory experiment. We can have more fun by playing around with musical examples, playing any one passage sometimes loudly and sometimes softly, at first simply observing what our bow does “intuitively” and then consciously experimenting with deliberate changes to the point of contact.

2: POINT OF CONTACT AND VIBRATING STRING LENGTH

As our left hand moves up the fingerboard (towards the bridge), the length of vibrating string becomes shorter. As this happens, unless the bow is moved closer to the bridge, the sound will eventually become so unstable and unfocused that not only will our sustained notes sound “dead”, but also our bow changes will simply not speak (sound) as clean pitched notes: they will just squeak instead.

Not bringing the bow closer to the bridge for high passages is a common phenomenon (error) because when playing up high (which occurs most frequently on the A-string) it is very easy to fall into the trap of concentrating exclusively on our lefthand difficulties and consequently forgetting about our point of contact. Also, if we are a little scared of those high passages then automatically our bow will tend to pull away from the bridge in our involuntary and unconscious attempt to hide. For all these reasons, one way to get used to playing with the bow closer to the bridge is simply to practice more “up high” (see Repertoire Compilation Of High Thumbposition Passages).

After getting used to playing with our point of contact closer to the bridge during high passages, we can then progress to the skill of changing our point of contact as we climb up and down the fingerboard. Passages in which the left hand makes enormous changes of register are ideal study material because they show up this problem (requirement) in its most extreme form.

One-octave scales on one string are good study material. We can do them slurred (starting on both down and upbows) or, in fact, with any type of bowing:

We can even do our one-octave scales as glissandi:

Perhaps the best way to automatise our point of contact adjustment with the distance of the left hand from the bridge is by practicing huge aimless (targetless) glissandos up and down the strings (first legato, then with separate bows and finally with spiccato). As the left hand goes higher up the fingerboard, we must bring the bow closer to the bridge and vice versa. If we do our glissando without a specific target note then we can concentrate exclusively on our point of contact  because we don’t have to think at all about intonation, rhythm or coordination.

We can also do the following exercise, in which the very high lefthand alternates with a lower openstring. Here, the lefthand doesn’t move from its position high up the fingerboard, requiring a point of contact near the bridge. But every second note (lower open string) requires the bow to move further away from the bridge in order to be in the correct “lane” for the open string to sound cleanly.

One of the consequences of having the point of contact too far from the bridge in high passages is that the notes may not speak cleanly, giving us a scratch or a squeak instead of the true pitch. The greatest high-register scratch risks, caused by a point of contact too far from the bridge, occur in spiccato passages. This is because each note not only starts with a bowchange but also with a landing from the air. Therefore, passages that race up any string in spiccato are like “the canary in the coal mine”: they will tell us (by squeaking) when our bow is not moving close enough to the bridge. Because of this “alarm signal”, these types of passages are not only a very good diagnostic tool but also a very good training tool for the automatisation of our bow’s movement towards the bridge as we go up the fingerboard. And if they have a crescendo then this is even better because the increased loudness during our race upwards requires that we bring our bow point of contact even more towards the bridge in order to avoid the squeak/scratch:

COMBINATIONS OF DYNAMICS WITH VIBRATING STRING LENGTH

If we do a crescendo to a lefthand position higher up the string, or a descrescendo to a lefthand position lower down the string, then our movements of the bow’s point of contact towards and away from the bridge are motivated/driven/reinforced simultaneously and in the same direction by both factors: dynamics and vibrating string length. In these situations both of these factors coincide with the identical requirements for our point of contact. Here, it is as though we have “double the need” to move our point of contact, therefore passages and excercises that have this very natural combination will serve to reinforce and automate these healthy point-of-contact movements.

The Elgar, Lalo and Tchaikovsky excerpts shown above are all played with a big crescendo as we go up the scale, which is a very standard, common musical phenomenon. This type of phrase gives us this  “normal”, comfortable, standard point-of-contact transition in which our bow moves towards the bridge in a passage that gets louder and goes higher. But doing the exact opposite (a diminuendo as we go to a LH position higher up the string and a crescendo as we go to a lower position) is a very good subsequent practice phase because this now requires the conscious and deliberate overriding of our natural (learned) urge to bring the bow away from the bridge as we get softer and vice versa as we get louder. Practicing all of our point-of-contact material in this counterintuitive, “unnatural” way makes us greatly aware of what we are doing with our bow and is therefore a very useful practice technique.

SOME TYPICAL POINT OF CONTACT ERRORS:

1: POINT OF CONTACT AND BOW DIRECTION

Because it is so natural to play downbows with decrescendos, and upbows with crescendos, we also tend naturally to move our bow’s point of contact away from the bridge as we go out towards the tip, and then closer to the bridge as we come back towards the frog. If our bowing directions coincide with this natural ebbing and surging dynamic then we are lucky: we can allow our natural tendencies free rein and everything fits together quite naturally.

But in those many musical situations in which we have unavoidable crescendos on downbows (and diminuendos on upbows) we will need to do the exact opposite of this, bringing the bow towards the bridge as we go out on the downbow towards the tip, and then closer to the fingerboard as we come back in towards the frog. It is these “unnatural, reverse, upside-down” situations that we will need to practice the most in order to learn to control our point of contact rather than letting it control us.

In the above examples not only do we have crescendos on the downbows but also the lefthand shifts higher up the string, which gives us even more need for our bow to go nearer the bridge as we go out towards the tip.

A less extreme version of this need to avoid moving the point of contact away from the bridge on a downbow occurs in long legato phrases in which, in order to maintain the musical line over the different bowstrokes, we will need to consciously override the tendency to relax the point of contact on the downbow.

Here is an exercise to play around with different bowdirections combining in various ways with the ebb-and-surge of crescendos and diminuendos. To allow us to concentrate entirely on our bow’s point of contact we will choose any one note for the left hand and just stay on it for the entire exercise.

2: POINT OF CONTACT IN STRING CROSSINGS TO THE A-STRING

We can easily find our bow moving away from the bridge as we go from the lower strings across to the A-string. This is an involuntary, unconscious reaction which, by bringing the bow over the fingerboard avoids the sudden increases in volume and brightness of timbre (harshness) that occur on the A-string compared to the lower strings. Occasionally this can be useful, but more often than not it is a spontaneous “cringe” reflex of fright and avoidance that does not help us at all to get a good ringing sound out of the A-string. In this sense we could use the analogy of a tiger tamer in a circus: we have to “dominate our tiger” (A-string,) making it sing for us rather than cringeing in fear from its potential “violence”!

POINT OF CONTACT AND SPIKE LENGTH

Changing our spike length can have an immediate effect on point of contact. If we have a tendency to play excessively “sul tasto” (with the bow over the fingerboard) one way to immediately and automatically start playing closer to the bridge would to lengthen the spike (endpin) without changing its point of fixation on the floor. This raises the cello up on our body and brings the bridge closer to us. Automatically our bow is closer to the bridge (unless we compensate for the new cello position). And if we have the opposite problem, that of playing with a point of contact too close to the bridge, then we can do exactly the opposite: by shortening the spike length (without changing the point of fixation at the floor) the bridge will now be further away from the bow.

These changes-of-spikelength experiments are very revealing because they can show to what degree our point of contact is chosen intuitively and unconsciously by our inner ear as compared to how much it is determined by simple mechanical and ergonomic factors. If our inner ear’s conception of the desired sound quality is primordial, then no matter what changes we make to the spikelength we will quickly revert to our original point of contact. If, on the other hand it is the simple ergonomics and biomechanics of arm length and cello height that are determining our basic point of contact, then any change in spikelength will have a lasting effect on our “choice of lane”.

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We could design our own little exercises, based on the following sequence of exercise models which are presented in order of increasing complexity, to practice and automatize our”point of contact ” control. While playing long held notes (or anything extremely simple), we can play around (experiment) with the effect of varying the point of contact, first on its own, then progressively adding other variables to the mix (pressure, speed, hair angle, left hand distance from bridge etc). This is like an artist experimenting with the mixing of colours. This is our palette.

1. Vary the point of contact without changing any of the other variables (pressure, speed, bowhair angle, left hand position)

2. Vary the point of contact while simultaneously varying  one other variable, for example:

 ………. left hand distance from bridge
……….. bow pressure
……….. bow speed

3. Vary the point of contact while simultaneously varying two other variables, for example:

………. left hand distance from bridge AND bow pressure
………  left hand distance from bridge AND bow speed
………. bow pressure AND bow speed