Pre-voicing

This entry is part 1 of 2 in the series Piano Tuning Matters

When confronted by tone problems, many piano technicians seem overly anxious to find a quick remedy by using voicing needles or lacquer. Both needling and lacquering are important elements in the over-all voicing picture; a skilled technician must know when and how to use voicing needles, as well as how to prepare and use lacquer solutions for hammer hardening. The point is this: both these methods are ultimately destructive to hammer felt, and shouldn’t be used until all other possible solutions have been explored. What are some of the things to check before we begin to needle or lacquer?

A. Before thinking about voicing we must make sure the piano is well tuned. We all have had clients comment upon the remarkable change in tone or volume after a good, solid tuning. A major pitch change will most assuredly change a piano’s voice, so tune it first. As part of our preliminary tuning procedure we must consider several areas which can affect tone:

  1. Tighten all plate screws.
  2. Seat strings properly, using a wooden or brass tool to tap them down on bridges, aliquots, duplex bars, and counter-bearing bars. This can clear up false beats, and clean up a muddy sounding tone.
  3. At this time, check and, if necessary, correct the tuning of the duplex scale – if the instrument has one. You may notice a brighter, louder tone when the duplex strings properly reinforce the harmonic structure of a given note.
  4. We also double check the location and tension of stringing braid. A minor point, but one which can either add or eliminate high partials without using needles.

B. Next, we consider the role of proper action regulation in piano tone-building. Perhaps this is an obvious point, but sometimes we overlook regulation problems and are quick to blame hard or soft hammers, old strings, etc., for tonal problems. Some areas of regulation seem to have a greater effect on the tone we hear:

  1. Of primary importance in this area is the bedding of the keyframe. This foundation for all our regulation has a very direct influence on what the artist hears, both physically and psychologically. Generally, an improperly bedded keyframe will cause loss of power and consequent loss of tone.
  2. Another major item to check here is the proper hammer striking point, especially in the high treble. Many a hammer has been unnecessarily hardened, when the problem was really an incorrect strike point. Check by experimenting- results here are immediately obvious.
  3. Travelling of hammers and shanks can affect tone, so do this work carefully.
  4. Of utmost importance is the actual hammer-string contact point: each hammer must hit its strings squarely and simultaneously. Space the hammers to the strings. File the hammers if necessary to remove dead felt, and to provide a perfectly level surface at the strike point. Later, we will discuss filing to bring up volume and brilliance.

After checking that the hammers are level, we check for level strings. String levelling is much over-looked, both by manufacturers and technicians. Here is an area that can dramatically improve tone. The symptom of an unlevel unison is an unclean, almost buzzing sound. It can also seem like a false beat, and can make tuning difficult.

Check all unisons by pulling the hammer up to the strings and blocking it there. Use either a hook to support the shank from the bottom, or use the method of pushing up on the bottom of the jack and not allowing let-off to occur.

When the hammer is blocked in such a fashion, the strings are individually plucked. It is immediately apparent if one or more strings is not level. The high strings will sound, while low strings will be deadened by the hammer. Carefully lift all low strings to the level of the high strings. Use a tool available from supply houses (string lifter) or make yourself a stringing hook using heavy gauge music wire epoxied into a handle of some sort. 

In string levelling we are actually pulling up and slightly bending the wire near the agraffe or cape bar. This technique is easily learned and is an important part of pre-voicing. (An added bonus of level strings comes when we regulate dampers- especially in fine adjustment of the tri-chord wedges.)

C. The piano can be well tuned and properly regulated, but still lack volume or brilliance. Don’t lacquer yet. If there is plenty of felt on the hammers, another filing can increase tone quickly. Getting down closer to the hammer molding, the layers of felt are harder and can create a more brilliant tone. This is especially useful to bring up sound in the high treble.

Some manufacturers count on the technician to remove layers of felt as the first important step in tone regulation. This is in addition to the removal of the outside layer of “dead,” slightly cupped felt found on all new hammers.

Finish your hammer filing with a fine garnet paper (220 or finer). This final filing is done in only one direction, and is commonly referred to as “polishing” the felt. Again, we can effect a major change in brightness by this last touch.

Now, if we still can’t get enough high-quality sound, we can lacquer to harden hammers. Lacquering is a major subject in itself, and won’t be discussed here. Now also, if we have uneven tone, we can get out our voicing needles. Again, this is a big subject and can’t be considered in this space.

A final bit of pre-voicing, obvious but often overlooked: room acoustics. A move of a few feet can alter a piano’s tone in many different ways. Placement of rugs, pillows, curtains, etc., also have a great influence on volume, sustaining power and quality of sound. , If these acoustic variables can be altered, do this first – hammer voicing must always be the last step, after everything else has been adjusted for ultimate piano tone.

So, next time you are anxious to get out the “juice” bottle, or to perform “acupuncture” on someone’s piano hammers, stop for a moment and consider all other possibilities first. Only then should you proceed to use your other voicing skills in a judicious and craftsmanlike manner.

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