Fine Tuning

I have completed my 30th year of tuning and general piano service and during all of that time it has been my aim to improve the quality of my work in any way possible. I believe most tuners have this same aim.

I have been successful and my work has been acceptable to my customers all along, but I have come to realise during the last five years that there are many things to be learned about fine tuning. And many of them are not taught to the students who study the theory and practice of tuning.

This is not to say the theory of tuning, as taught in the best schools, is faulty. On the contrary, it is a theory which has developed into an exact science.

It has been correctly described as a closed mathematical system which, if followed faithfully, will result in tuning all intervals, correctly tempered, and all octaves tuned as “dead” or perfect octave intervals. But even this result, if it could be achieved, would not necessarily be entirely pleasing to the critical musician.

There are several reasons why this is true and every tuner should know all he can about them, and about how he can best overcome the difficulties they present.

First: -All tuning, except unison tuning, is done indirectly; that is, in tuning any interval, octave included, we are comparing coincident harmonics of the two tones being sounded.

Second: - The harmonics of a piano string, which is under high tension, are not exact multiples, in frequency, of the frequency at which the entire length of the string vibrates.

Third: - To tones which are either very high or very low in frequency, the human ear does not assign pitches which are directly proportional to their frequencies when compared with tones in the middle frequency range. In other words, our sense of pitch is a subjective discernment for each individual, and it may be considerably different from true pitch theoretically determined by the correct frequency for that pitch.

Fourth:- I doubt it’s possible to set an absolutely perfect equal temperament, probably because the harmonics on which we depend are not true harmonics of the fundamentals from which they arise. This should not, however, prevent any of us from setting Bach temperament as perfectly as possible and, on a good piano, it is possible to set a very good temperament indeed.

Fifth: - I also doubt it’s possible to tune a perfect octave without resorting to tests other than our evaluation of a “dead” or beatless interval. A number of years ago, a technical editor for a piano trade magazine warned all tuners “never trust an octave.” My experience has borne out the value of his warning. In fact, I have found that there is a considerable range of frequency over which an octave is acceptable to my ears, but the same octave will often be found to be less than perfect when one of its members is made a part of some other interval which is known to be correctly tuned.

We must recognize that perfection in tuning is not possible, but we should always strive for it. And as nearly perfect an equal temperament as we can set is a must, for it determines the harmonic pattern upon which all of the rest of the tuning depends. The quality of the piano is a limiting factor, as is our skill, but in the matter of skill it is our responsibility to do all we can to improve it constantly.

We recognize also that we are dependent upon coincident harmonics for practically every step in tuning. And also, that coincident harmonics may create some of our worst problems when they result in dissonant intervals. Therefore, they become the basis for some of our most useful tests, especially when they are coupled with some knowledge of chord structure. With this background of recognition of the possibilities and the problems we face I would offer these suggestions for achieving what we term “fine tuning.”

First: - Become familiar with the piano keyboard so that you may test any combination of tones likely to be used in piano music. Those who play the piano may not know how careful the tuner may have been with his temperament or how much attention he has given to tuning perfect octaves, but they will be quick to notice any interval which is dissonant to the degree that it offends the ear. So, we must know what degree of dissonance is correct in the equally tempered scale, for it is, after all, a compromise whose greatest advantage is that all scales in all keys are equally acceptable, though none may be said to be perfect.

Intervals used in polyphonic music include seconds, major and minor thirds, fourths, fifths, major and minor sixths, minor sevenths, octaves, ninths, tenths, twelfths, and so on. And most of these intervals, as well as others, have their uses as tests of accurate tuning.

Second: - Do not expect to leave a piano accurately tuned with a once-over tuning if any considerable pitch change is to be made, because the change in down bearing on the bridges during tuning will defeat your best efforts to achieve accuracy.

With a reasonably acceptable scale at the proper pitch, I strip mute the middle and treble sections of the piano. On uprights, above the treble break, the loops in the muting felt must be pushed down behind or preferably below the dampers, but this is not too difficult.

Then I set as perfect a temperament as possible, realizing that not only are fourths and fifths important intervals, but that major and minor thirds and sixths, while more dissonant, must also be acceptable intervals within the temperament octave. Also that fourths, fifths, thirds and sixths, both major and minor, have their proper beat rates and that these rates increase in frequency as we ascend the scale. This is true, of course, throughout the entire piano scale. The progression of .beat rates and its evenness is one of our best tests of the equal temperament we try to achieve.

Third: - When I am satisfied with my temperament, and sometimes I must be satisfied with a compromise on spinets and small grands, I proceed with the bass tuning. My reason for doing this is, that...

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Grand Regulation – part XXX

Step no46 Check string level / damper seating  

Most technicians know that piano wire, even after being strung  and pulled up to tension, still retains a natural curve as a result of being reeled upon a spool during manufacturing. Because of this natural curve, the three strings (or two) which make a unison may or may not be perfectly level at the point where the hammers strike and where the dampers seat. Irregularities in string level may also be caused by the holes in the agraffes not being perfect.  Whatever the cause they must be corrected.  If one string in a unison is higher or lower than the others, problems in voicing and damper sealing are sure to result.

Since the string level affects both voicing and correct dampening, I find it easiest to match the string level to the dampers, then alter the tops of the hammers to finish matching the hammers to the strings. Theoretically, all strings should be perfectly level, with all of the tops of the hammers also perfectly level, and correct dampening on every note. However, being one who is more practical than theoretical, I have a tendency to leave the dampers alone if they are working fine! Play each note staccato, listening for the familiar “after ring” which tells that the dampers are not seating correctly. Don’t forget also to try the dampers using a lighter, legato touch, as well as using the sustain pedal. If any dampers are heard to “ring through,” feel the string directly in front of the damper head and check for a problem in the level of the strings. 

Not all problems with dampening are caused by string level. Sometimes the damper head is bent side to side or front to rear. Maybe the damper-to-string alignment is off. On trichords, if the middle string is dampened but one of the outer strings is not, try cutting the middle of the trichord a little deeper. There are numerous other reasons for incorrect dampening besides these. But if the strings are felt and one of the unisons seems to be too low or too high, try leveling the strings. When one string is low and the others are high, the obvious solution is to raise the low one. However, some technicians   would rather not raise two low ones to match one high string when one is high It is possible to lower one string. Whatever your preference, the end result should be to get all three unisons level.

To raise a low string, take a string hook, as used in restringing, and place it under the offending string between the agraffe and the damper. Slide it back and forth with a slight upwards motion a couple of times. This process is much like voicing in that you can always do a little more if needed, but it becomes a problem when you’ve gone too far. Don’t run the string hook too close to the agraffe as you want to put a slight bend in the wire rather than a crink. It is possible to break a weak agraffe, so put only a slight upwards pressure on the string. Retune the string and check for correct dampening.

As mentioned above, if one unison is high to the other two, you have a choice. The high string can be lowered, or the two lower ones can be raised with the method just shown. If you prefer to lower a high string, take something softer than the wire, a piece of brass or hard wood (not a screwdriver) and gently run it up and down the string using a slight downwards motion. This is a little trickier, and perhaps not as permanent as raising low wires. 

Step no47 Check sostenuto tabs for evenness, adjust knife angle  

The evenness of the sostenuto tabs should already have been checked while performing steps no43 & 44, the dampening lift form the key and lifter rail. If these previous steps were done correctly, all tabs will be in a straight line. If they are not, go back to step no43 and redo, as any change in the height of the damper lever to get good tab alignment will cause problems with the damper lift from the key and lifter rail.  

Adjusting the sostenuto knife angle rather simple. Adjustment is made by varying the length of the sostenuto pedal rod. Looking from the treble side of the piano at the rod, it should be at 5 o’clock in its rest position, 3 o’clock in the raised position. 

Step no48 Adjust sostenuto knife in / out and up / down  

Now that the tabs are perfectly even and the knife angle is adjusted, all that is left is the in/out and up/down adjustment of the sostenuto rod itself. Taken in this order, working on sostenuto systems becomes considerable less painful. If you can’t remember anything else about the sostenuto rod, remember the distance 1/8“. The rod cannot interfere with the normal playing of the piano. All tabs must clear the rod when not using the sostenuto pedal.  On the other hand, when the pedal is played, it must catch and hold firmly any tabs in the raised position. Adjust the rod in/out to give 1/8” clearance between the rod itself (not the knife part of the rod) and the ends of the tabs.

With the sostenuto pedal in the down position...

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