I have two sop. D tuneable whistles,both have tuning problems …sharp in the upper octave. Does the brass slide model have the same problem? I really like the tone but the tuning really is a problem for me. While I’m on the subject, the low G Dixon is one of the sweetest whistles I own…
That’s interesting… I recently got a Dixon Sop. D ‘Duo,’ and the tuning on it is perfect…
I wonder why yours is out… 
Are you pulling the head out about a 1/4 of an inch before you play/tune?? Or are they just out?
dixon does seem to have a tuning problem with his sop D. i got a tunable one (but not the brass slide) 2-3 weeks ago and my experience is the same as yours. i like the sound, i like the feel, but it’s unquestionably sharp in the top register. i’ve tested it against my guitar tuner and tried some alternate fingerings, but there’s really no remedy. i’ve heard some other people say the same. it’s a little hard to figure, because everyone says that the physics of a whistle cause those with a cylindrical bore to be a little flat. that’s why people like michael burke have to jigger with the inside of the bore to get better intonation. that’s the advantage, i guess, with a conical bore. it’s really too bad, because there are a lot of good things about the dixon.
Ditto here. I’ve got a tunable (non-brass) model that’s noticeably sharp on the high notes when I’m playing with others. I love the tone and play it solo at home all the time but I can’t play it with other people.
-Brett
I think it’s a problem with inconsistency. Most of his Ds are ok, but some seem to have a tuning problem for some notes in the 2nd octave [I would have expected notes in the 2nd octave to be flat rather than sharp, though].
I’ve tried many Dixon Ds because I’ve ordered quite a few from Tony at different times for different people, and most were right on pitch. The latest one I ordered, in January, was spot on in its tuning and was a great whistle.
But my very own normal tunable (a few years old) was very slightly flat for the F# and A notes, noticeable mainly in the 2nd octave. I also had some flat 2nd octave problems with my brass slide tunable. I filed the holes bigger or bevelled the outer edges (do it a bit at a time) and now they’re fine.
That’s a potential solution if it’s just one or 2 notes that’s in issue, because the plastic is very soft and easily filed. You might try shifting the tuning slide until the 1st octave was on pitch and the 2nd one flattish in some notes, then start enlarging the relevant holes (if the note per se was flat) or bevelling off the relevant holes’ outer edges (if it was flat in the 2nd octave).
If it’s very flat for most notes, you might want to communicate with Tony. He’s great to deal with.