This term refers to the distance from the bridge (or from the edge of the fingerboard) at which the bow is touching the string at any given moment. Our bow’s point of contact is always intimately related to the bow’s speed and pressure. Continuing with the painting analogy that we used to describe the effects of bow-speed and bow-pressure, 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.
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).
Let’s now use a different analogy: that of a motorbike video game. In this game we are riding a motorbike along a very narrow road. On one side of this lane is a wall with nasty prickly branches sticking out (the cello-bridge with its warning signs of cracking sound) but towards the other 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, however, 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).
In good, musical 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. On our bike, it’s as though we were permanently alternating between bouncing off the wall into the thick sand and then skidding back towards the wall again. And, of course, the faster we drive (the faster our bow-stroke) the harder it is to control this trajectory.
Often, to avoid the dangers associated with driving close to the 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 and also using a slower bow both require that our bow moves closer to the bridge.
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 the learner’s bowhands with their own hand, sometimes for years, in order to create and reinforce the physical memory of a healthy and stable 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). That is when 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:
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 we go higher up the fingerboard, unless the bow is moved closer to the bridge, the sound will eventually become so unstable and unfocussed that not only will our sustained notes sound “dead”, but also our bow changes will simply not sound as clean pitched notes: we will make squeaks instead. This is a common phenomenon because in high passages (which occur most frequently on the A-string) we usually concentrate exclusively on our left hand difficulties and consequently tend to forget about bringing the bow closer to the bridge. Also, if we are a little scared of those high passages then automatically our bow tends to pull away from the bridge in our spontaneous 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 “up high”.
After getting used to playing with a point of contact closer to the bridge in high passages, we can then progress to the skill of changing our point of contact in response to changes in vibrating string length. Passages in which the left hand makes an enormous change of register are ideal study material because they show up this problem (requirement) in its most extreme form.
The greatest high-register scratch risks, caused by a point of contact too far from the bridge, occur in spiccato passages because each note not only start with a bowchange but also with a landing from the air. Passages that race up any string in spiccato are thus a very good test for the automatisation of our bow’s movement towards the bridge:
Another way to automatise our point of contact adjustment with the distance of the left hand from the bridge is by practicing huge glissandos up and down the strings (legato, with separate bows and spiccato). As the left hand goes higher up the fingerboard, bring the bow closer to the bridge and vice versa. This is “easy” because we don’t have to concentrate hard on the left hand for a glissando (no intonation, rhythm or coordination to worry about).
SPIKE LENGTH AND POINT OF CONTACT
Another way to immediately and automatically start playing closer to the bridge is to lengthen the spike (endpin) without changing its point of contact with 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).
Look at the following sequence of exercise models, in order of increasing complexity, to practice and automatize our control of this “point of contact.” While playing long held notes (or anything extremely simple), 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 mixing 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