RoberTunes wrote:
Low D whistles that I've seen, in general, have their weaknesses at their extremes; their lowest few notes and their highest few notes...
As somebody who went down the Low D whistle rabbit hole a decade ago, and went through around 40 different Low Ds, I found that as whistles get bigger design/voicing issues are amplified. High whistles are almost universally even in their voicing, while with Low Whistles getting such evenness is extremely difficult.
As RoberTunes says the Achilles' Heel of Low Whistles is how the makers decide to balance the high and low notes.
In the Low Ds I played, nearly always the "diagnostic" notes, the notes that told you all you needed to know about how the whistlemaker had balanced and voiced the octaves, were low E and high B.
Many Low Ds have a powerful Bottom D and strong low F#, but it's that note in between, low E, that is often feeble.
And many Low Ds have a civilized 2nd octave, high E, F#, G, and A, but have a high B that's "shouty", loud, harsh, and tricky to blow just right. (I don't worry about notes higher than that, as high B, the highest note a fiddler can play in First Position, is the highest note generally found in trad Irish dance music.)