Posts tagged strike
You may have heard a piano technician talk about voicing saying “Well we can voice those hammers down for you if you’d like”. First of all, most don’t know what voicing entails. Second, manipulating the hammers ‘down’ (up or sideways for that matter) doesn’t exactly fit any kind of tonal response you would think of. But before we get carried away describing what is going on, let’s define voicing: Voicing is the manipulation of very hard pieces of felt called hammers which strike the strings on the piano. At that strike point (please refer to the blog called Bright and Brassy Sounding Pianos) the hammers can either create warm sound, brassy sound, nasal sound, thin sound, percussive sound – all from the strike point of the hammer. Voicing then changes or alters the support of that strike point to get the desired response out of the piano. Voicing ‘down’ means to make the piano mellow while voicing ‘up’ means to make the piano more strident.
So here’s the pseudo exhaustive (or exhausting… take yer pick) list of what goes on in the voicing world.
- Hammer hardener
- Hammer softener
- Steam voicing
- Methyl hydrate/water mix
So i’m not going to pass judgement on what i think is correct voicing and/or techniques, but i WILL describe what’s going on in each of those methods. Without further adieu, here’s the list on what technicians do to pianos.
1. Needling… needling is by far the most common process in voicing. Pictured to the right is a voicing tool that i own. You will see that it has a needle in the tip. When you poke holes in hammers, it releases some of the tension and almost… ‘fluffs’ up the hammer. In doing so, the hammer can support the crown – the very tip to bring out the optimal sound of the piano. Most often this is used in reducing ‘high’ points – where one note will stick out above it’s neighbours.
2. Filing… hammers over time with heavy use will eventually become grooved. These grooves quite often make undesirable tones. Filing the hammers reshapes the worn parts so that the grooves are minimized. Please see the picture on the left for a hammer file voicing tool.
3&4 Hammer hardener and softener are both commercially available substances which drastically alter tone by use of chemicals.
5&6 Both steam voicing and methyl hydrate/water change the hammers by fluffing up the hammers much like a piece of paper when it gets wet. When paper gets wet and then dries, it is no longer flat but ‘crinkled’. In like manner, hammers ‘puff up’ with the addition of methyl hydrate and water mixed or steam voicing.
So there you have it – the entire list (that i know of) to alter piano tone.
Indeed, friction is one of the piano technician’s worst nightmares. At best, the piano is a simple machine – you depress a key, it lifts a hammer to strike a string. At worst, it’s a complex mechanism where levers and joints are in contact all the time and each surface area is potential for friction to either be too loose or too great: too loose and the piano feels ‘warbly’ and too tight and it either doesn’t function properly or feels like you have to work too hard to compensate for the touch.
I learned this only a few years back but the formula for touch on a piano is relatively simple (operative word being ‘relatively’). There is a 5:1 ratio of hammer weight to key. What that means is, for every gram of weight at the hammer there is 5 grams at the keyboard. An average hammer weighs in at about 8 grams (multiply by 5 = 40 grams). So if average touch on a piano is 55 grams per key, where are the other 15 grams of resistance coming from?? Answer: friction.
Today i had the opportunity to redo key bushings on a fabulous grand piano owned by one of the best jazz musicians in the area. With a lot of playing (both from his own practice and from his students), the bushings around the contact points on the keys were completely worn making almost a ‘knocking’ feel from side to side. A bushing is nothing more than a substance used to reduce friction between two contact points. In pianos, bushings are almost exclusively made out of cloth (some people mistakenly call it felt but truly it is cloth – woven together). The cloth then allows the interaction of joints. Centre pins are made out of steel and they need to interact with wood. Without bushings these two hard substances would click and knock together. As well, friction can be taken up by cloth in varying degrees of thickness. So the cloth is the perfect substance for acting as the ‘spacer’ inbetween.
Next time you’re at a piano, test the bushings. Take one key and swivel it from side to side and see if you sense a knock or a thunk. This will tell you they need replacement. Simply steam out the old ones (see pictures) and glue in new ones and you’re good for years to come.