Historical clue formulations

• They often end on a low note — 2025-05-31
• Many opera villains, traditionally — 2023-09-09
• Ones playing things low-key? — 2020-05-07
• The lowest of the low — 2017-08-20
• Back row of many a choir — 2015-04-15
• String section members — 2014-04-06
• Quarters of many quartets — 1999-05-06
• Chorus section — 1998-12-13
• Some guitars — 1998-07-15
• The back of the choir? — 1997-06-12
• Choir voices — 1994-04-26