Voicing: How do we change the tone of a piano?
1. Hammers are made of a piece of wood called the molding.
2. The wool overcoat is in the shape of a triangle and is bent BACKWARDS over the molding and glued and stapled into place.
3. The hammers are then sliced into individual pieces.
4. Remember the overtone series? 1-1-5-1-3-5 Flat7-1? Well, from the bottom of the piano to the tenor section, this is what we aim for. That happens when the strike point of the hammer hits the 7th node of the string. This creates 8 partials or one fundamental and 7 partials…it’s the same. As an example, it would be C-C-G-C-E-G Bflat-C. Basically, a pretty minor seventh. After that it gets dicey.
5. In order to change the voice of a piano, we subtract the upper dicey partials or add to the lower in order to sustain those 8 partials. Again, the technician can only achieve what the piano will allow.
6. There are considerations like hammer shape, contact time, density of the wool, and scale design, etc. A technician can change the density in either direction, hard or soft by needling or ironing. Needling softens and subtracts; ironing hardens and increases.
7. Voicing is done after regulation and tuning to be performed with efficiency.
8. The upper sections of the piano have the strike point at the 15th node which creates 16 partials. Although the upper partials are not “pretty” They do create volume which comes at a premium. The good news is the “ugly” upper partials go away so quickly as to be almost indiscernible leaving volume.
9. The process goes something like this: The technician has an idea, his idea, of what a piano should sound like…this is quite subjective. The good technician will find out what the pianist wants, use his idea as a baseline, and pivot on that baseline to give the pianist what they want. Again, unlike the academics of regulation, this is VERY subjective.
10. There are things that change the voicing of a piano:
a. Age of the wool
b. Regulation….movement efficiency
c. Humidity: remember the hammer is wool…it moves from day to day.
d. Hammer velocity: more velocity more overtones.
e. Shape of the hammer. Is it the correct shape to hit the node and no more? It is more difficult in the upper section where the nodes are smaller to get it right.
You may have noticed I left out the soundboard. A good soundboard is nervous. It picks up, through the bridge assembly, the early sine waves, they are more well defined, and translates that into larger air movement. The soundboard should not, like a good audio amplifier, get in the way of the sound producer: the strings, hammers, and scale design. The least total harmonic distortion is what we shoot for here!
Lecture: The Other Side of the Keyboard is now available again.
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