Tuning is the adjustment of the tension of all of your piano's 220 (or more) strings to the correct pitch or frequency. This ensures that notes played in a musical interval (octaves, chords, etc.) will sound in harmony.

Voicing is the adjustment of a piano's tone or quality of sound. Tone can be changed without affecting the pitch. For example, turning the bass or treble knobs on your stereo changes the tone but does not alter the notes the musician recorded. A skilled piano technician can voice a piano to change its tonal personality from mellow to bright or robust to delicate. The degree of change possible depends upon the piano's design and condition. Voicing is done after the piano is tuned, the hammers are softened with a tool that has a series of needles. It refreshes the piano's sound.


A piano cannot be voiced well unless the action is carefully regulated first. The action must be capable of carrying the pianistís nuance through to the hammer, while losing a minimum of energy during powerful passages. Every aspect of the action should be evaluated for proper performance before hammer voicing is begun. If the action is not performing well, the time working with the hammers will be spent attempting to overcome the shortcomings in the action.

Prior to regulation and voicing of the instrument the following areas should be evaluated and problems corrected:

Voicing Circle of refinement

All piano service should progress through ever finer circles of refinement. At the outermost circles, serious matters must be addressed, with rough tuning and repairs being made to eliminate the effects of wear on the action. Then the first regulation should space, travel and align the parts, and the action should be regulated to specifications. The next level is tuning and string spacing, then in the next the action spacing and regulation should be refined, then the first rough voicing can be done, and so on until the piano has been brought to its potential.

These voicing instructions commence with one of the inner circles of refinement, after the condition of the action is correct, the regulation and spacing of the action has been refined, the hammers have been filed to remove string grooves caused by wear, and the piano is ready for the first voicing steps.

A. Evaluate the overall tone. Keeping in mind the environment and use for the instrument, listen to the tone of the piano, playing chords or music at different volume levels. Listen for harsh or brittle tone, listen for excessive high harmonics in the bass, listen for dullness and lack of power.

B. Pre-voicing. Hammers are pressed for high compression of the felt. This compression should remain unchanged under the strike point, where it will give brightness and power during Forte passages. Some of the tension in the shoulder areas is released by deep needling the hammers in the factory.

If the high treble is too bright, the same procedure may be used, but with fewer and shallower penetrations of the needles, closer to the strike point than in the tenor and bass. If some part of the scale is too dull, those hammers should be tested for hardness by needling low down on the shoulders (below 3 0' clock). If the hammers feel soft and resilient in the low shoulders, needling in this area should not be necessary. Next, file the hammers on the upper shoulders and at the strike point to present a harder surface to the strings.

C. Testing / needling again. This process may need to be repeated a few times until the overall tone of the piano is at the approximate level desired. Be aware that too much needling will ruin the hammers, especially if they are needled too close to the strike point. Once the hammers feel resilient and soft in the shoulders, further needling in that area is not necessarily going to improve the tone, so moving to a different type of needling process in a different area should be tried to achieve the results you are seeking.

D. Shaping. The hammers must now be shaped to remove the excess outer felt which has been loosened by the voicing process. Only the outermost layer of felt should be removed, from the low shoulders all the way up over the strike point. Special attention should be paid to the smoothness of the strike point surface. Using fine sandpaper (400 - 1,000 grit) for the final shaping will allow the surface to be smooth and firm, making the later voicing process simpler. In some cases the use of 1000 grit emery cloth strips to "buff' the surface of the hammers, especially in the treble, will give the best final results and may help brighten the tone somewhat.

3 - Brightness, Tone Range

2 - Fullness, tone bloom

1.- Preparation of the hammers
This deep needling is done in two stages in the factory; the first is done mechanically just prior to mounting the hammers on the shanks.


Sample hammers are tested for hardness and rebound, and the shoulders are deep-needled by machine accordingly. The shoulders are then deep needled again in the voicing department according to their sound. It is not normally necessary for the hammers to be extensively deep-needled on the shoulders once the piano leaves the factory, although some deep needling may be called for to increase sustain or improve the sound of hammers that have been re-shaped. If you are Detail installing new hammers, of course, then this deep pre-needling of the hammer shoulders would be required. Be careful to maintain the proper shape of the hammer, not too round at the top, with slightly flattened shoulders. If the tone needs to be brightened more, then a liquid hardener may be applied to the hammer to add support under the strike point.

Most all piano hammers are made of 100% felt that has been compressed to 10 pounds weight, 12 lbs, 14 lbs, 15 lbs, 17 lbs and 19 lbs.  (Some manufacturers use felt as much as 22 lbs and more!)  These weights are the total weight of the felt prior to shaping it over the wood molding.

The wood molding used as the hammer core itself was beachwood, walnut, maple and even pine.



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