Trombones
The trombone is a fully developed facsimile of its earlier prototype, the medieval sackbut. This "noble" instrument did not become established in symphonic instrumentation until Beethoven's time (Fifth Symphony); yet it was used by opera composers dating back to 1565. The true trombone is built with a pair of tubular slides which distinguish it from all other wind instruments, since it is the only one capable of making its own pitch, as does the human voice. Variations of pitch are regulated by the position of the slide, which alters the length of the air column within the tube. Valve trombones, although used in some European orchestras and bands, have not met universal acceptance.
THE TENOR TROMBONE
The tenor trombone in Bb is the one universally used and is non-transposing in all clefs except the treble. The technical aspects of the slide positions are unique with wind instruments. Whereas the other brass instruments produce a cycle of changing fundamentals and harmonic series by means of valve combinations, the trombone accomplishes similar changes by means of slide positions. There are seven positions of the slide for the completion of a chromatic-scale cycle. Figure B-9 lists these fundamentals with each harmonic series and their slide positions.
In the first position, the slide is pulled up tight and then extended proportionately for the other six positions. Adjacent positions can be played almost instantaneously; others, farther apart, require split seconds for their execution. Rapid passages containing awkward slide positions (Fig. B-10) should be avoided since they are not playable with any degree of clarity, style, or good intonation.
THREE TROMBONES
Composers since the time of Gluck have, with few exceptions, consistently written for three trombones as a unit of "harmony instruments." This arrangement has the advantage of spanning the two middle and bottom parts. Up to the twentieth century, these parts were written in the alto, tenor, and bass clefs. With the increased acceptance of the valve trumpet, the alto trombone was gradually discarded in favor of either three tenors or two tenors and a bass. This change removed the necessity for further use of the alto clef, the tenor and bass being adequate for the notation of newer groupings. (Note: The treble clef, as used in some orchestrations of music for school orchestras, is an expedient to facilitate notation for players not familiar with the bass clef; it is not recommended here.)
THE BASS TROMBONE
The bass trombone pitched in F is a perfect fourth lower than the tenor instrument. Its first position has the identical fundamental and harmonic series as that given for the sixth position of the tenor trombone. The bass instrument has about three more feet of tubing than its smaller counterpart, which necessitates the need for increased breath and embouchure control. A separate F attachment is used occasionally to convert the tenor trombone to the equal playing potentials of the larger instrument with identical slide positions.
THE TROMBONES AS A UNIT
All tonguing styles are possible, but the more rapid ones are fatiguing and become sluggish, especially in the lowest register. The deep, full tone of the bass trombone makes it ideally suited to the bass parts of all brass ensemble passages. It is rarely used as a solo instrument unless doubled either in unison or octaves. Extremely rapid notations are less satisfactory than those for the lighter tenor instrument.
Hector Berlioz, in his monumental Treatise on Instrumentation, referred to the trombones as "group instruments." This distinction results from their homogeneous tonal qualities, which vary little throughout their ranges. Any variance which may occur is generally the fault of the player's execution of range extremes.
In the Richard Strauss revision of the Berlioz text, isolated examples are given as evidence questioning the Berlioz premise. In certain contexts the Strauss theory, supporting independent part writing, may have some validity, but it is too specific to be taken generally. The Berlioz observation, made a century ago, to the effect that "a single trombone in an orchestra seems more or less out of place," remains equally valid today as when it was written.
The single trombone parts in the Chopin piano concertos are glaring examples of ineffectual writing. Many passages sound inappropriate, weak, and slightly amateurish. These parts are rarely idiomatic and frequently give the impression of being intended for a kind of brass bassoon. Trombone doubling of adequately scored bass parts and added extraneous harmonic fillers do not increase volume; rather they upset a normal balanced sonority.
The basic weakness of these parts lies in the composer's failure to recognize the trombone's natural affinity for harmony playing. This particular reference is of value in appraising commercial orchestrations designed primarily for theater, school, and amateur ensembles. With these, parts for one trombone are essentially utilitarian, being a combination of doubled bass parts, cues from other instruments, and occasional chord tones and melodic lines. The results are, for the most part, functional rather than artistic. If one trombone is to be included in varying instrumentations, it can approach artistic standards if employed idiomatically with the other brass instruments.
At this point the student orchestrator may acquire an expanded perspective through a study of the parts for two trombones in Beethoven's Sixth Symphony, the Pastoral A comparison with that of the Chopin concertos reveals the extent of differences in approach and understanding between the two composers. The Beethoven score clearly indicates the advantages to be derived from using trombones as "group instruments" for harmony playing. Part writing for three trombones is similarly exploited by Beethoven in his Fifth and Ninth Symphonies.
Orchestrators writing for three trombones should be cognizant of difficulties arising from the possible absence of a bass instrument. It is rarely available for most orchestras other than those of major standing, and its absence can cause considerable distortion to harmonic positions. Low-part writing, designed for a bass trombone, must invariably be played an octave higher if assigned to a third tenor instrument, which automatically alters chord positions. Figure B-ll illustrates the distortions resulting from these inverted parts.
Trombones are particularly well adapted to harmony playing in all categories of homophonic music. Their extra tonal weight as a unit makes them indispensable for increasing the solidity of harmonic factors. The group-harmony method of scoring has been consistently recognized by symphonic composers dating back to the early Classic period. Later composers have enlarged the scope of this method but they have not strayed far from its basic formulas.
In polyphonic music, the trombone's playing potentials are somewhat more limited. They are best reserved for outlining canonic entrances, for emphasis of isolated accented notes, and for occasional statement of principal thematic ideas in peak climaxes. Notation for outlining can usually be derived from the first notes of rapid scale passages, thereby giving harmonic definition. Melodic statement is most successful when confined to notations which allow clear articulation.
Part writing in the softer dynamic levels is particularly felicitous, approximating the sonority of a male chorus. Note the following example uses the less used (nowadays) alto Trombone along with Tenor and Bass Trombone
The long legato slurs indicated in these excerpts are rather exceptional and differ in style from those employed by the other brass instruments. The only true trombone legato is made by a lip slur confined to the note in each harmonic series. These lip slurs can be made only in the upper register. All other legato phrasings are the result of lip slurs combined with changing slide positions. This technique produces a portamento style of legato which is best in moderate tempos.
Unslurred cantabile melodies are played by tonguing each note. These tones can be nicely connected in a characteristic style approaching legato, which is applicable to all dynamics. At the softer levels the tone is solid without harshness, while unisons in the tenor range with louder dynamics are penetratingly virile.
This semidetached style of melody playing, in unisons or octaves, has its peak strength in the middle and upper reaches of the tenor range. The characteristic pungency of parts in this register is sacrificed if doubled by other instruments.
Solo undoubled melody passages of any significant length for the trombone are comparatively rare. This void is particularly noticeable with sustained cantabile melodies of principal thematic interest. The noble tone quality of the instrument is well realized in Example B-21. Other solos of similar character occur in the middle section of the Sibelius Symphony No. 7 and in the Adagio movement of the Saint-Saens Symphony No. 3.
Short thematic solos are, on the other hand, both effective and quite numerous. They have interest and continuity when paired antiphonally with horns or trumpets.
Unison and/or octave passages, with or without doublings in the brass, have assumed an ever-increasing place of importance since the late 1900s. A maximum of sonority, power, and brilliance can be achieved by doubling the trombones in a higher octave with the trumpets. It is a device useful for establishing contrast, melodic emphasis, and tonal weight. Example B-23e illustrates one method of building brass sonority for a crescendo with an ascending melodic line.
The third trombone and tuba occasionally have bass parts when the cellos are diverted to melodic passages and figurations in the tenor register. Such parts usually have a minimum of movement and are frequently doubled by the bassoons. Contrabass doubling occurs less often.
Muted trombones, though commonplace for solo parts or in combination with other instruments, are seldom scored as a three-part soli unit. This is rather surprising, as the timbre of this muted ensemble is capable of unusual possibilities along the lines shown for the trumpets in Example B-15. It is the kind of tone, quality which responds well to light doublings provided that parts are left well exposed.
