We have started this discussion as off-topic when discussing the buff stop.
I hope Andrew accepts that I start a new topic, because this is a completely different, and very interesting issue.
We all agree on a basic premise, as rightly written yesterday by Huwsaunders:
“I think that you are right about there not being any evidence of the double pluck having been used historically. However it is a possible registration now and was then,so there is no reason why an 18th century player might not have found it and used it on occasions.”
I intend to demonstrate a stronger statement: that the historical use of the double-pluck, although certainly not impossible, is extremely unlikely.
Since the matter is complex, I will do this in three separate posts, with different arguments.
Put together, they strongly reinforce the thesis.
I will number them, DP1, DP2, DP3, so that answers can refer to my arguments separately.
A first argument I already posted, let me just rephrase it here.
DP1. The double-pluck requires a very accurate action regulation.
This affects the plectra voicing, the jack height and also the dampers position.
While this may not be an issue for two adjacent jack rows, the common discussion is for the English upper manual’s lute 8’ and dogleg 8’: here we have a string being plucked at distant points, with different jack travel and sound amplitude. How difficult it is has already been explained in today’s post by very knowledgeable Carey Beebe.