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Partials and intonation

As with all brass instruments, progressive tightening of the lips and increased air pressure allow the player to move to different partial in the harmonic series. In the first position (also called closed position) on a B♭ trombone, the notes in the harmonic series begin with B♭ (one octave higher than the pedal B♭), F (a perfect fifth higher than the previous partial), B♭ (a perfect fourth higher), D (a major third higher), and F (a minor third higher).

F marks the sixth partial, or the fifth overtone. Notes on the next partial, for example A♭ (a minor third higher) in first position, tend to be out of tune in regards to the twelve-tone equal temperament scale. A♭ in particular, which is at the seventh partial (sixth overtone) is nearly always 31 cents, or about one third of a semitone, flat of the minor seventh. On the slide trombone, such deviations from intonation are corrected for by slightly adjusting the slide or by using an alternate position. Although much of Western music has adopted the even-tempered scale, it has been the practice in Germany and Austria to play these notes in position, where they will have just intonation (see harmonic seventh as well for A♭).

The next higher partials—B♭ (a major second higher), C (a major second higher), D (a major second higher)—do not require much adjustment for even-tempered intonation, but E♭ (a minor second higher) is almost exactly a quarter tone higher than it would be in twelve-tone equal temperament. E♭ and F (a major second higher) at the next partial are very high notes; a very skilled player with a highly developed facial musculature and diaphragm can go even higher to G, A♭, B♭ and beyond.

The higher in the harmonic series any two successive notes are, the closer they tend to be (as evidenced by the progressively smaller intervals noted above). A byproduct of this is the relatively few motions needed to move between notes in the higher ranges of the trombone. In the lower range, significant movement of the slide is required between positions, which becomes more exaggerated on lower pitched trombones, but for higher notes the player need only use the first four positions of the slide since the partials are closer together, allowing higher notes in alternate positions. As an example, F (at the bottom of the treble clef) may be played in first, fourth or sixth position on a B♭ trombone. The note E (or the lowest E on a standard 88-key piano keyboard) is the lowest attainable note on a 9-foot (2.7 m) B♭ tenor trombone, requiring a full 7 feet 4 inches (2.24 m) of tubing. On trombones without an F attachment, there is a gap between B♭ (the fundamental in first position) and E (the first harmonic in seventh position). Skilled players can produce " falset " notes between these, but the sound is relatively weak and not usually used in performance. The addition of an F attachment allows for intermediate notes to be played with more clarity.