Thank you so much for the detailed response. So does this sound right:
Up until 670 A.D., no instruments
From 670-1200s A.D., they were extremely rare but there were a few organs here and there.
In the 1300s-1400s A.D., they were becoming more popular, but still aren't the norm among the churches.
So then what happened from the time of the reformation? Did the Romans continue to use them but nobody else did? When did Protestants first use them, and how popular were they? Thanks!
Most of this is from John Price's book which I heartily recommend since you're interested:
-Organs rapidly proliferated during the 15th century and by the 1500s "an organ was found in nearly every important church." In the 16th century there was continued introduction of other instruments and instrumentation became a distinguishing hallmark of the Roman liturgy.
-Many of the proto-Reformers like Wycliffe and Hus decried the use of instruments and encouraged unaccompanied congregational singing. Even Papists who wished for reform within the Roman church like Erasmus complained of the use of instruments
-Luther thought that the reform of worship was of secondary importance and allowed instrumentation. This was not unanimous among the Lutherans as both Melancthon and Carlstadt opposed the use of instruments. Nevertheless, the Lutheran church maintained their use for the most part.
-The Reformed almost universally opposed them. Not just Calvin, but Zwingli (despite being an accomplished musician himself), Bullinger, Beza, Knox, and Pareus too. Even men like Menno Simons (founder of the Mennonites) and prelatists like Robert Horne and John Marbeck opposed the organ and other instruments. In the Church of England, instruments were abolished in the second prayer book (1563)
-The Puritans were uniformly against it. The Westminster standards don't directly address the issue since the Solemn League and Covenant of Scotland and acts of Parliament in England had already abolished them by law.
-This continues into the 17th century. Even Isaac Watts wrote against the use of instruments. The only dissenting voice appears to be of Richard Baxter who thought them indifferent. On this, as in other important matters, he is a poor guide for Reformed theology and practice, however.
-The uniformity begins to breakdown in the early 18th century. There was still widespread opposition but in some churches smaller orchestral instruments begin to be imported from the schoolhouse to the church. The first organ installed in a church of Puritan heritage was in 1770 in First Congregational Church in Providence, Rhode Island. While present in the Anglican churches too, many continued to voice opposition there as well.
-Scottish Presbyterianism finally succumbs in the late 19th century, seemingly under the influence of revivalists like Dwight Moody. Still, many prominent ministers and theologians continued opposing them on both sides of the Pacific such as Spurgeon, John L. Dagg, Dabney, Thornwell, Giradeau, etc.
- In the 20th century revivalism and the piano (and eventually the guitar) won out, as we all can see.
That is the story, briefly, in churches of English and Scottish descent. Price doesn't cover the German and Dutch churches, but their theologians of the orthodox eras were universally opposed to instruments as well following the decisions of their early church synods. Examples would include Wilhelmus a Brackel, Gisbertus Voetius, Abraham Van de Velde, Henrik de C ock, etc. Instruments were introduced there at the earliest in the 18th century.