Whistle-making help/hint needed

[Kypfer]

I've made a few whistles and flutes over the last few years ... mostly they work as well as I might have hoped, but my latest project has got me stumped. A Bb tabor pipe ... should be straight-forward, but it insists on playing two notes at the same time, the required harmonic and a somewhat out-of-tune lower sound that I just can't seem to get rid of. The "all holes closed" note is good, but as soon as I open a finger-hole it goes awry. I'm working with a length of bamboo, so it's not perfectly circular and slightly tapered (wide end at the mouthpiece).

Rather than messing about and potentially ruining it completely, I'm hoping someone can make an educated guess at what can cause these symptoms. Finger-holes too small/large ... window too narrow/wide ... ?

Any help gratefully received

[Chris Wall]

Without seeing it I'm just shooting in the dark, but it sounds like a windway/sound edge issue. Often if you make the distance the air travels too far before hitting the sound edge, strange things happen. Try reducing the distance of space the air travels after leaving the fipple. (Making the open rectangle smaller, closing the gap). Width of the window is not nearly as important as length.

Also, make sure the sound edge has a good angle. About 30 degree angle works for most designs.

If none of that works, make sure the bore size of the bamboo is the right size for the key you are going for. No matter how well you do the other parts, bore size has to be right for the length. For a Bb, your inner diameter should be no larger than about 1.6 cm at the larger end. Any larger and bore can start being the problem. 1.4 to 1.5 cm is ideal.

But I think it's a windway issue. Try a longer fipple to close the space in the window and make sure it's the right height so that air hits the edge squarely.

Best of luck!

[Tunborough]

Two notes at the same time, even with some variation in breath pressure? Congratulations... I didn't even know that was possible.

How is the overtone sequence for the all-holes-closed note, as you blow harder? You should get some approximation of Bb, Bb', F', Bb''.

The first thing I'd look for is irregularities around the sounding window, windway, or sounding blade.

[Tommy]

Have you checked for small air leaks in the full length of bamboo?

[Kypfer]

Two notes at the same time, even with some variation in breath pressure? Congratulations... I didn't even know that was possible.

Oh yes ... on a "normal" commercial instrument I can occasionally achieve it by simply blowing slightly too hard (or slightly not hard enough) ... unfortunately on this concoction it's there the whole time unless I blow very extremely hard, at which point it disappears into the third octave.

How is the overtone sequence for the all-holes-closed note, as you blow harder? You should get some approximation of Bb, Bb', F', Bb''..

The sequence of notes appears good, the "basic" Bb is a bit off tune, but I'm led to believe that may be normal and wouldn't affect the "normal" playing of the instrument.

The first thing I'd look for is irregularities around the sounding window, windway, or sounding blade.

Everything "appears" to be OK ... failing any definitive reply I'll start re-shaping and/or re-cutting various aspects of the whistle-head to try to sort it out ... I just didn't want to end up with a load of untidy "epoxy & sawdust" modifications if I could help it. It's quite a nice "rustic-looking" piece of bamboo, so I'd like to use it ... any ordinary piece of stick would have been used as a burnt offering to the whistle gods long ago

[Kypfer]

Have you checked for small air leaks in the full length of bamboo?

Certainly nothing at all obvious, but I must admit I'd not thought of that ... quickly checks whistle ... hmmm, maybe a very slight leak somewhere, I'll look into that, Thanks!