At first glance these arrangements are an easy answer to all the problems of a volunteer ensemble, and with a little forethought and planning, they can be tremendous tools. There are some definite pitfalls and some definite tricks of the trade. Also, as technology makes music arranging more accessible and less time consuming, there are some lures that I have seen trap many arrangers.

One of the first pitfalls of flexible instrumentation arranging is the misconception that with this music, any combination will work. For an example, let us pretend that we are using a variable instrumentation quartet. Entire Hymnals have been formatted like this. The basic concept is simple: Arrange for SATB, transpose each part for each instrument, and there you have it! - The perfect violin, trumpet, saxophone, bassoon quartet! For any instrumental group, there must be some basic consistency. A good starting point would be to keep the instrument families together. The Hymnal arrangements work great for a brass, string, or woodwind core group. With a core group, adding on additional parts is a snap.

The other pitfall with the same arrangements is getting the wrong instruments on the wrong voice parts. Keep in mind the Vocal Range of each instrument:

Soprano	Trumpet	Flute/Oboe	Violin
	(Horn)	(Clarinet)
Alto	Horn	Clarinet/Oboe	2nd Violin
	(2nd Trumpet)	(2nd Flute)	(Viola)
	(Trombone)
Tenor	Trombone	Clarinet/Bassoon	Viola
	(Horn)	('Cello)
Bass	Trombone	Bassoon	'Cello
	Euphonium	Bass clarinet	(Viola)
	Tuba	Bass

This chart is by no means exhaustive. It also does not mean that the instruments listed cannot assume other roles. As an arranger, the vocal range of each instrument must be high on the list of priorities. A professional Tuba player once remarked about a particular arrangement "To put the melody in the Tuba is the mark of an amateur." This doesn't mean that it is wrong in all cases, but when a rule is broken, it must be supported by solid orchestration, which rules out the idea of Flexible Instrumentation. Many of the great composers have had a melody in the Tuba, but their works are for a complete orchestra, not whomever attends the Titipu Town Band. The object is to avoid a naturally low instrument playing above a naturally high instrument.

The vocal ranges of each instrument do have some flexibility. Generally, all the voices will adapt to the adjacent voice part. That is, a soprano instrument can play an alto part, an alto can play either soprano or tenor, a tenor can play either alto or bass and a bass instrument can play the tenor line. By this generalization, it is clear that the inner voices are where the real flexibility lies. Another way to illustrate this point: Check the hymnals. For example, in most hymns, the ATB parts are within the practical range of the horn or trombone, or the SA parts are within the range of a flute. True, an alto line might get a little high for the average trombone player, but it is not out of the question.

One of the next considerations is the actual range of the instrument group for which you are writing. Continuing the thread of a hymnal arrangement for flexible instrumentation quartet, we find that we have all the instruments now assigned to their principal voice and all possible alternate voices. Using Coda Music Technology's Finale or any other software, we hit the "transpose" buttons and start cranking out parts. Great! But beware! I have seen pieces in print from major publishers with viola parts written with low B flats, and I am certain they did not intend scordatura. I have made the mistake myself of transposing a second trumpet part for horn and not accounting for the extreme range that caused some less-than-kind remarks from a well-meaning, but worn out horn player!

This leads to the next issue - that of characteristic sounds. Try this exercise: Think of the sound of a flute playing below the bass clef staff. Then, think of a trombone playing above the treble staff. Think of the sound of any instrument playing an octave or so out of its range. Most likely, the sounds you hear in your head are at very least not very pretty, and in some cases, not even imaginable. Characteristic range, simply put, is the range where an instrument is most commonly heard. Just because a trombone player can play as high as a horn doesn't mean that it is necessarily a good idea. Back to the flexible quartet hymns, the alto part that the trombone player can play would probably sound much better down an octave.

Another issue with flexible instrumentation is that not all parts are flexible! For example, much of the church orchestra music currently on the market is clearly written around the first trumpet part. A well-known arranger has stated repeatedly at numerous clinics "The first trumpet chair is the hot seat!" The flexible instrumentation brass quintets from Highland Music Press must have a trumpet on top (part 1) and a definitively bass instrument on the bottom (part 5). Parts 2, 3 and 4 are generally for whatever brass instruments you have available, keeping in mind the vocal categories of the instruments on hand.

In summary, the primary consideration when writing for flexible instrumentation must be the vocal part of the instruments in question. The technology that can spit out parts as fast as you can write them is no substitute for competent arranging. As the parts are generated, review them with an eye (ear) for characteristic sound. If you can't hear it, don't expect someone else to play it.