Yesterday i finished making an A whistle.
The inner diameter was exactly the same as my Overton A, so i set out to copy the fipple and hole measurements from that.
I discovered a similar problem as with my now deceased Low E attempt (i gave up on that one):
After making the fipple and cutting the lenth of the tube to pitch I have a whislte with a good sounding, strong bell note. The balance between the octaves is also good.
Then when drilling the holes I find that they can only be in pitch with far less breath pressure.
So the holes on my home made A are much smaller than on the Overton, even though all the measurements are the same.
CAn anyone shine a light on the question how to keep the strong bell note, and have equally strong tones on the other holes with the same (or slightly increasing) breath pressure.
Is there a formula to calculate hole spacing for any particular tube size/diameter?
There is a very handy calculator for simple flutes on-line. It works as well for whistles, if you calculate the area of the square fipple hole to the same area as the flutes round embrochure and place the sharp edge of the fipple right at the measure for the distance between the fipple hole and the 1st tone hole. I would recommend that you put in a big tuning slide to help you fudge the length to the bell note if necessary.
To get strong notes from top to bottom, using the Flutomat or P. Hoekje’s spreadsheet: You must pay attention to a variable called “Local Cutoff Frequency”. This number must exceed the highest pitch that you want the tonehole to reach. If not, it will sound muffled.
Example, if the tonehole plays 440Hz and you want the instrument to play in both octaves, the “Local Cutoff” must be higher than 880 Hz for it to work properly.
Some say that the cutoff frequencies must all be the same for each hole. That is nearly impossible to get just right. It is best to have the cutoffs follow some acute sloped linear function. (Graph it Excel!)
Daniel is very knolagable about woodwind calculation and is one of the most informed amateur whistlesmiths I know. He is,of course,trying to tell you that a balance must be struck between the upper and lower octave calculations.
I believe,from your above comments,that you have a problem with “Acoustic Impedance”. When you get a solid bell note in your “toneholess” stage there isn’t any open toneholes to rob the acoustic energy.
If you plug the end of the bore with a coin shaped plug after toneholes are added and drill it out until a solid bell note returns,you will have corrected your “backpressure” or “acoustic impedance” problem.It sometimes takes only a small “ring” to make a big difference in tone.
Calculating for a narrow bore will also help in a final product. Flute/Whistle bores can average between 28 and 35 times the bore diameter. Shorter flutes/whistles display more “flutey” harmonics but longer bores have greater range and better acoustic impedance.
If you plug the end of the bore with a coin shaped plug after toneholes are added and drill it out until a solid bell note returns,you will have corrected your “backpressure” or “acoustic impedance” problem.It sometimes takes only a small “ring” to make a big difference in tone.
Hello Thomas,
Thank you for your reply.
I just want to make sure I understand coorectly. Do you mean to lessen the inner diameter of the tube at the end of the whistle?
Calculating for a narrow bore will also help in a final product. Flute/Whistle bores can average between 28 and 35 times the bore diameter. Shorter flutes/whistles display more “flutey” harmonics but longer bores have greater range and better acoustic impedance.
Thomas Hastay.
Do you mean to calculate for a narrower bore than what you are actually using?
Sorry if I got you wrong…
I’m learning a lot here.
Thanks again,
I used the Flutomat to make a G flute last night. It took about 20 minutes. And the things is dead on tune in both octaves(all credit to the formula, not my craftmanship). I still have to clean up the holes a bit and sharpen the embrochure, it’s hard to get the low notes started.
Added benefit is that my wife is pleased that I’m satisfying my WhOA with the plastic in the basement instead of the plastic in my wallet.
Cheers,
jb
this worked, much closer than expected, but while making a low G flute (holes are easier than fipples), after the second octave on the bell note, I get a D. two and a half octaves, any use for this? Is there a web page explaining the physics of this one?
Yes Jeroen,I do mean reducing the inner diameter at the bore end of the whistle.
I also mean calculating a bore to be more than 32 times the bore diameter will improve the “end product”(or more narrow than the one you are using). A concert silver flute is approximately 33 times the bore diameter in length.
I’m sorry for this tardy reply.
Thomas Hastay.
[ This Message was edited by: Thomas-Hastay on 2001-11-05 16:01 ]
