If I understand correctly the instrument pictured is the one I will be getting shortly. I will post my experiences with it (on this thread I think).
John
Hi Gerardo, the inner bore remains consistant. the wall thickness of the tube is tapered. this is an evolution of my own experiments based on many silent sit ins on forum threads, alot of research and finally what actually works. The thickness of the tube does effect the volume and transition of octaves. This has to do with negative and positive pressure from inside the tube and outside the tube through the tone holes depth. A thick wall at the E note allows you to push more air increasing the volume before breaking into the second octave…while a thinner wall gave a weaker E and did not take much air to break the octave transition…these are not theories but actual back to back experiments with two separate tubes utilizing one whistle head…
The thickness of the tube wall itself can infact be graded to equalize a whistle one way or another…while this whistle was already not to bad…the upper register got a little loosening by taking away some material. So by removing material at the higher notes the air requirment is less and that means screaming B’s and C’s are turned down…While again I never considered this a problem with the lochlan, just for the record though, everything can be improved just a little bit!.It’s quite interesting actually!..
This is a correct way of thinking.
I am involved in trumpet modification and building of basic instruments and the acoustics are all to do with standing waves.
Mass (i.e. wall thickness) is an issue.
Adding or removing mass in certain areas improves the pitch and makes the response more even (on any wind instrument)
Interesting design. How on earth do you keep that whistle from crawling up the tool bit without a steady rest, when machining that far from the chuck??
I doubt it. Whistles are not brasswinds; there’s no closed system end-stopped resonating length. The tube does not vibrate to any significant degree, and empirically, instruments made of materials with very different mass and density may sound virtually identical. The effects of fipple geometry and tone hole placement are determinative.
Chimney depth is another matter, for response and intonation. And it looks like Greg has come up with an interesting approach to controlling chimney depth per note - which is what he describes. Fascinating stuff, Greg.
Interesting. Now that you have a target for each tone hole, could you turn between centers and offset one of the centers to turn a nice even taper? Or is the delta between the tone holes such that a straight taper won’t get you where you need to be?
Thanks MT, But I have to give credit to all the contributing members of the board who brought such interesting topics to the surface…all I have done is collected very valuble information from the very knowledgeable members of this board improving my own design…in any case there’s strength in numbers, thanks to the board and everyone involved!
Thanks Carey, your right in offsetting centers…for a nice straight taper from the highest note to the lowest…my telescopic look just makes for easier machining…though a nice straight taper would look very cool!
Now you’ve got me wondering how to bore the ID with a taper, and leave the OD constant. Two possibly constructive techniques at once - a tapered bore AND a tapered wall. Offset steady rest? Hmmm… would need a thrust bearing to keep everything tight while boring. Maybe just a nice tapered reamer. Could be fun to play with.
really, the possibility sounds pretty cool, …in respect to this I think it was a shaw low D,…I noticed the E tone hole was built up to add thickness…I gather it was to increase the strength of the low E
I’ve made tapers buy using telescoping brass tubing and the inner tube is sliced longways diagonally - do so creates a tapered change in area as you proceed down through the bore where more and more of the the diagonally sliced off tube contributes to decreasing bore area.
gregrussell - that’s a good observation. I looked at the numbers and I see that your change of the wall thickness on the lower toneholes (chimney) would cause the original hole to move up closer if diameter is maintained - then you can thus use a bigger tonehole instead with a reasonable stretch to the next hole and have higher cutoff frequency on that low-E.
Higher cutoff frequency makes the Low-E sound clean altogether and not strangled sounding in the second octave.
Offset steady rest? Hmmm… would need a thrust bearing to keep everything tight while boring. Maybe just a nice tapered reamer. Could be fun to play with.