It’s not a reference to an aging male opera singer. There’s a little more to old tenor than that.
A 1742 deed among the children of Samuel Sargent of Middlesex County, Massachusetts, references payment being made in “bills of Credit of the old Tenor.” The deed is specifying the consideration being used to purchase the property.

A history of paper money in Massachusetts, while very interesting, is beyond the scope of this blog. However, the “old Tenor” was a reference to a specific issuance of paper money by the colonial government of Massachusetts. The Massachusetts colony first issued paper money in 1690 when it needed to pay soldiers for military action involving Quebec.

An 1863 history of Hadley, Massachusetts discusses the various issues of paper money in Massachusetts.

There is also an “Introduction to Early Massachusetts Currency” on the Colonial Currency website.