I found out today that Michael Praetorius's Terpsichore is written with no indication about what instruments to use. I knew that the Art of the Fugue doesn't have instrumentation either, but I'd always thought that it was unique in that respect.
Are there many other works from the Renaissance or Baroque of polyphonic music with no instrumentation? Was this common practice or are these two pieces just odd?
Non instrument-specific music was standard in the era of Renaissance for several reasons: The number of instruments was far bigger (think of bagpipes, shawms, Gemshorn, hurdy-gurdy, some of these even being built in families) so the chance of a match was smaller.
Printing of scores only got wider use in late 15th/early 16th century and manual copies were expensive: so much of the distribution was playing together and direct teaching/hearing or just the melody was written somehow (the accompagniment was improvised anyway).
As soon as the full range or other capabilities of an instrument was increasingly used, situation became more complicated. A low tone on violin may be producable on a flute too, but the achievable volume is so different, that the balance is shifted.
