This piano tuning blog is a companion to our How to Tune a Piano Yourself tutorial. In this blog we expand on the tutorial with new information and perspectives on do-it-yourself piano tuning. If it is your first time here, visit the tutorial first.
Tuning Unisons Video
Piano Technician's Guild has a very instructive video demonstrating tuning unisons. Tuning unisons is the process of making all the two or three strings in a single note match. It sounds easy, but getting these strings to match perfectly with no beats is the skill that a piano tuner works his entire career perfecting. In addition to hearing what a beatless unison should sound like, two other aspects of tuning technique can be observed.
First, as each tuner appears to finish a string, the tuner whacks the key pretty hard once. The idea of the hard hit is to equalize the tension of the string along its length. After striking the key with lesser force while turning the pin, the tuner hits the key hard, then does a lesser test blow or two. If the final test strike still holds tune after the hard strike, then it's in tune and, just as importantly, likely to stay there. Even so, each tuner does this a little differently; the first seems to hit harder than the others.
Second, notice the hammer technique. Some emphasize steady pull, others more of a bump. The final tuner is actually using an impact lever, which is specifically designed for the bump technique.
UPDATE: The video is no longer available on the PTG site, which is unfortunate. The following segment that was part of the video is still available, showing just one tuner:
For more on tuning unisons see this thread:
When unisons are not tuned in unison.
I am having a friendly disagreement with a fellow musician. When tuning a piano, I understood that the three strings had to be "slightly" off set from each other, with the center string being on perfect pitch. This gave the piano a richer sound. My friend says all three strings must be on perfect pitch. I argue that the notes then would sound "flat". Can you tell us who is right? Thank you
Scott replies: The three strings struck by each key are referred to as the "unisons." They should be tuned in pure unison, that is, to the identical frequency. Occasionally in non-technical forum discussions about piano tuning I have seen the notion that the three should be slightly detuned from one another. However, none of the piano tuning references I have read suggest that. If you watch the unisons tuning video referenced in this blog post, you'll hear that the tuner is tuning each string identically. A consistently pure unison is a goal toward which all tuners strive. If anyone should see a detuned unison documented in any piano tuning text, I would like to hear about it. I think the "richer sound" in a properly tuned piano comes from the tuner's skill in detuning the fourths and other intervals to achieve equal temperament, as well as applying the proper stretch for the individual piano.
Check out this blog on piano tuning etc too...
Very useful information. Thank you!