Large voices tend to be less flexible and, for this reason, are often undesirable for madrigal singing. That a voice is large is, in itself, insufficient reason to eliminate it. It is difficult to gain a unity of qualities, however, if one voice is of much greater size or more mature than the rest. If the larger voices are flexible, though, they will be an asset to the ensemble. And, every effort should be made to include outstanding voices. If only one or two voices are so much larger than the rest look for solo opportunities for them with or without the ensembles. Find imaginative ways to include the best singers.
Intonation
Another important consideration is intonation. This is always important to a choral ensemble, but its importance is magnified in a small ensemble. This is one of the most crucial points in the selection of members. If the person has a poor ear or lacks the vocal technique to sing in tune, it is best to leave them out of a madrigal. It may be difficult to omit what may seem to be an outstanding voice quality, but if the person cannot sing in tune, he or she will be a constant problem in rehearsals and performances. Conductors should make intonation one of the most important parts of the selection process.
Blend
This characteristic of good choral singing is also important, but in a different way for a madrigal ensemble than for a choir. Originally, much of the repertoire was performed with one person on a part, singing or perhaps even playing the part on an instrument. If your definition of blend means a "complete merging of all voices," you will probably develop a boring madrigal and may not even like to hear small ensembles. The blend of a madrigal is one of matching qualities rather than the "complete merging of the voices." In a small ensemble it will be possible to hear individual voices. There is nothing wrong with this. An individual flair is important to the success of the ensemble. Yet,
there will be moments when all of the voices will merge as one. Do not be afraid to allow individuality in a madrigal. Be sure that "blend" does not become "bland."
Reading ability
All directors would like to have only good music readers in their ensembles. Unfortunately, this is rarely the case at the amateur level. A director can be only as strict in this regard as the level of the singers allows. It would be useless to require that all students in the madrigal be able to read all of the music at sight if, by doing so, one eliminates all singers from consideration. The ability to learn the music will determine the complexity and amount of repertoire the ensemble will be able to perform. The ability to learn is of more importance than the ability to sight-read. If the singer is so motivated that he takes the music home and learns the part quickly, that person is very close to being as valuable as the one who can accomplish the same thing within the rehearsal. Often, the former will be a more valuable member because of his eagerness to contribute to the ensemble. In any event, be as strict as the situation will allow. If there is a choice between two otherwise equal candidates, choose the one who is motivated to learn the music the quickest.