The fundamental (1st natural) is not used on the C trumpet. It speaks on lower trumpets, albeit unsatisfactorily.
The natural harmonic series which is actually playable therefore begins with the 2nd natural (C4) and rises to the 8th natural (C6). Highly proficient trumpeters can reach the 11th natural (F6), but this note is not called for in orchestral compositions. Particularly in jazz there are no limits as to how high the regular scales can go – many jazz trumpeters try to produce ever higher notes on the instrument and even to reach the heights of the fourth octave above middle C.
With the valves the trumpet’s range of naturals can be lowered by a total of six half tones to F#3.
Seven different fingerings are used on the trumpet, each of which lowers the harmonic series by a half tone:
The operation of the valves (fingering) lengthens the trumpet’s tube, which in turn results in a lowering of the instrument’s fundamental pitch. The 2nd fingering (operation of the second valve) lowers the trumpet’s pitch to B3, and overblowing produces the series of partials of a trumpet in B and so on. The valve tones are therefore nothing more than the partials of the lower-pitched instrument.
Thus F#3 is the C trumpet’s lowest note. When F#3 is played the tube length increases by about 60 cm from 130 cm to 190 cm. By way of comparison, the horn’s tubing is lengthened from about 386 cm to 550 cm at its lowest pitch. Of course this also means that a column of air has to be vibrated that is 550 cm long. So the trumpet has a relatively consistent tone quality in all registers, whereas the lower register on the horn is harder to play and sounds duller.
By using the tuning slide the trumpet’s range can be further lowered by a half tone, to F3. This note can only be played in exceptional circumstances, however, because the musician needs time to position the slide and return it to its original position before playing the next note, which would otherwise sound out of tune.