Explanation of Voicing or Tone Regulating a Piano by Rich Van Slooten – A440 Precision Piano Tuning

Often pianists will ask me to explain the differences between the regulation and voicing of a piano.  These are important questions to address and understand since they will ultimately affect the overall performance of the piano in terms of tonal quality, evenness and controllable dynamic range.

  • Normally, voicing is performed on individual hammers by changing the density, resiliency and hardness of the hammer felt.  Voicing is only performed after the piano action has been carefully regulated or verified to be in proper regulation, and the piano has been fine-tuned. (i.e., verifying proper hammer blow distance to key-dip depression, proper jack to knuckle placement, hammer let-off, optimum repetition lever spring adjustment, correct back-checking, hammer drop and damper engagement – quite a mouth full).

Once the piano has undergone fine regulation, one can be reasonably confident that playing individual keys with equal blows will deliver uniform fairly uniform hammer velocities.  Provided that the hammers are uniformly dense and resilient, this should in-turn should yield fairly consistent tonal quality and dynamic range, assuming the piano is in tune.  However, in practice, technicians seldom find pianos that have hammers that are uniformly resilient.

  • So the voicing or tone regulation of the piano is the fine adjustment of the hammer head felt shoulder, crown and strike point surfaces in order to slightly modify the density or hardness of the hammer and its resilient characteristics as it impacts piano strings.

For hard or dense hammers that produce overly bright, loud, or shorter sustain tones, shoulder and upper crown areas are softened, keeping strike surfaces very resilient.  Conversely, soft hammers such as N.Y. Steinway, or older, grooved hammers may require resurfacing, reshaping or incremental hardening.  Voicing hard hammers requires a robust voicing tool with anywhere from 1 – 6 sharp needles.  The needles are carefully forced into various sections of the hammer, i.e., allowing for small changes to be made to the hammer felt density.  Then the piano is played over  a period of days or weeks to allow for tonal quality to settle out and stabilize.  If further voicing is deemed necessary to achieve uniform tone, small incremental changes are again made to those particular hammers.

  • Voicing normally is done over 2 or 3 individual sessions, separated by 2-3 weeks.   Voicing fees typically vary between $60 – $80 per session, depending on the quantity of hammers involved.

Some important qualifications should be noted about the surroundings that a piano is located in prior to the start of hammer voicing.

  • The particular acoustics of a room will have a dramatic affect on the tonal quality of a piano.
  • Also the size of the piano compared to the room size and acoustics will have a dramatic affect.
  • Rooms that are small relative to the size of the piano or have hard reflective surfaces will contribute to bright, loud, maybe even harsh tonal qualities.  Hammer voicing (softening) may not be able to fully compensate for the live, bright acoustic qualities of the room.
  • Large rooms with small pianos, or rooms with carpeted floors, curtains on walls, irregular wall surfaces or acoustic ceiling tiles or texture will tend to dampen hammer tonal quality.   If desired, hammers can be shoulder and surface hardened to achieve a somewhat brighter sound with a comparative longer sustain tone.
  • Dramatic humidity changes, especially in Colorado, will have a tendency to change the hammer strike surface characteristics, with higher humidity levels often causing hard nodules on the strike surface which will cause sharp or brittle tonal sounds.  These anomalies usually resolve themselves when humidity levels drop back to normal.
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