Something's goofy here. The post: "Tune A3 to A4, tune F3 to A3. Check F3 to A4" describes the 3rd-10th octave test which is valid for assuring that the A octave is 4:2 (or slightly wide) but is not a confirmation of proper A4 placement. Also, unless you are going to tune with a C fork—in which case you are not tuning A4 to a fork—you do not need to get a C fork. You either set A440 or you set C523.3 (or whatever) but you do not mix and match: Only one tuning fork to a tuning, please! C fork tuning will NOT give you A440, exactly, unless you miraculously miss the C just enough to land A properly, or the piano, miraculously, has precisely the amount of inharmonicity in the temperament area to produce A440 starting with C523.3. You can get acceptably close and many fine tuners use the C fork, raging debate notwithstanding. But the modern trend, as taught and published, is to use an accurate A440 fork (or pitch source). As George Defebaugh said, other musicans will NOT likely ask to hear the piano's C, they will ask for the A. In any event, let's get practical ... First, the F21 check is to see how well you have placed the A by ear only. It is NOT a "tuning" interval, in the sense that you tune one note to another. So generally, you don't want or need F2 (F21) sounding while you are moving A4. BUT if you must, here is a cheat: Use a mute between F21 and F#22 (or E20) so that the F21 key is held down but not played. Play A4 forcefully and hold it. On many pianos, the sympathetic vibration of the 5th partial of the F will be strong enough to give you a ghost tone that you can tune to match the beat rate that the fork makes with the F. The fork, however, will not be strong enough to ghost the F; the A4 key will be (maybe). I don't think anybody seriously tunes with this ghost but it's instructive to try. What to do: Learn to get tune A4, accurately, with your ear and and the fork—then use the F2 17th as a test, comparing its beat rate with A4 and with the fork. It's really not that tough to get within a 1/2 cent or so just listening to A4 and the fork; the RPT test gives you a 2.999999 cent latitude. Do NOT use F3 in any phase of setting or checking A4 to the fork. Read this carefully: The F3 will have a matching 5th partial with A4 and with the fork. This will be the 2nd partial of A4 and NOT the fundamental. Because of IH, the second partial will ALWAYS be sharp of the fundamental and you will always end up tuning A4 too sharp! The reason that F21 works as a check is that you are comparing the A4 key and the fork with the exact same partial of the F, i.e., its 5th partial. Helpful Note: If you have trouble hearing or counting these check beats, you can tune the F up or down a tad until you get a rate of, maybe, 4 bps, something fast enough, but not too fast to count (feel, hear) accurately. By the way, you can also check your A4/fork tuning use B1 (B15 by key count) as the 7th partial of this note beats against 440 (fork or key). If both B1 and F2 were in tune, the B1 test would beast faster than the F2 test. On some pianos, this use of B1—it's an interval of the 21st, if you'd like to know—can be a great second or alternate check interval; on other pianos, it is hard to hear. Remember, also, that check notes need not be in tune but must be close enough to produce a beat WITH THE PROPER TEST PARTIALS. In other words, the F2, say, could be slightly sharp or flat as long as a good, countable beat is produced. But if that F2 were, say, flat by a fourth, it might still sound "okay" when played with other notes (Lord knows this can happen in the very low bass!) but the pitch, in this case, would actually be a C2 which does NOT have a coincident partial at 440. There is no real mystery about setting the A4. Learn to hear the beat against the fork even when it is very slow, and learn to bring it to a stop. Then check. Then wang the A4 to knock it out of tune and do it all over again until you can wang A4 and it is still in tune. Check, check, check. The only "tricky" part hear is that the fork also has an overtone series so you must learn to hear the lowest, slowest pitches and beats and ignore anything faster in the background (usually 2nd partials). The better (heavier) the fork, the stronger the tone of the 440 fundamental—which is good; but also, usually, the overtones are stronger too, which can fool you. As always, if old-hand aural tuners find me in error, please scream, yell, rant, and ridicule right away, lest false ideas be perpetuated. Alan Barnard Salem, Missouri
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