Orchestra
Remember how you learned that 管弦楽 means "orchestral music?" Well the group that plays that music is an orchestra.
かんげんがくだん
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
小さな管弦楽団でバイオリンを演奏しています。
I play violin in a small orchestra.