Now you’re bringing in a different issue, the matter of range. In traditional Irish dance music the highest note that regularly occurs is B in the 2nd octave. A relatively small number of tunes go up to C and/or C# in the 2nd octave.
When I talk about a whistle’s intonation, I only consider the traditional normal range of Bottom D up to B in the 2nd octave.
You put your finger right on it! Exactly so.
If you’re playing a reel up to speed you just don’t have time to tailor your breath on a note-by-note basis in order to fix an out-of-tune scale. You’re relying on the instrument being spot-on, to play spot-on.
And there’s another thing, the thing of expression. I want every note to be right in the middle, so that I can vary my breath for expression and not have some of the notes go too flat or too sharp.
I want ‘needle straight up’ the entire gamut. My Goldie, my Reyburn, my Alba all do that.
Now, people will chime in about Just Intonation v. Equal Temperament. My whistles are all ET. I need them that way due to doing ‘legit’ gigs. If I were to need JI (which in 40 years I’ve not) I could put a bit of tape on the F# hole and another bit of tape on the B hole and Bob’s Your Uncle.
BTW more than one of the Burkes I’ve owned (from High D to Low D and several in between) have had a subtle yet nevertheless odd tuning quirk: B in the low octave is a bit flat, but strangely enough B in the 2nd octave is a bit sharp. This isn’t ideal for many contexts, but it is wonderful for playing along with the uilleann pipes. Concert D uilleann chanters usually have this exact quirk.
I wish you the best of luck with that.
I prefer, whenever possible, to pick up whistles used. There’s really nothing to go wrong or wear out or get out of adjustment with alloy whistles- a friend threw his, in a fit of disgust, down a flight of concrete stairs and his Overton Low D was undamaged.
Two other advantages: you get the whistle right away, and if you don’t like it you can resell it for what you paid for it, a free rental in effect. That is, if you didn’t overpay for it in the first place.
Listening to recordings, in my opinion, is almost useless. You need to get the whistle in your hands to know what it does.
What was a real eyeopener was doing some YouTube comparisons of various Low Ds. In person each had a distinctive unique tone. In the videos they all sounded more or less alike.