There is no standard collective nouns for 'instrumentalists', however, the collective noun for musicians will work:a band of instrumentalistsan orchestra of instrumentalists
a quintet
NONEt
An octet.
A group of six singers or six instrumentalists.
yes they do
mariachi's
manage the bands finances and sorts out the instrumentalists
mariachi's
Duet
A dramatic work in one or more acts, set to music for singers and instrumentalists.
An opera is a dramatic work in one or more acts, which is set to music for singers and instrumentalists.