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  Jubilee Music Instruments & Crafts,
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TWCalc Tin Whistle Tonehole Calculation Program

TWCalc - Tin Whistle Tone Hole Calculator

TWCalc Manual



TinWhistle Hole Calculator V3.2


This is the TWCALC operation screen.

Example: To make a High-C whistle.

Preliminary Information

1. First you must know the base frequency of the instrument. The base frequency is cycles per second (Hertz) and it is the note that is played when all of the toneholes are closed.

2. The wall thickness of the material that you are going to use is need to help calculate the hole spacing.

3. The inside diameter of the tubing, cane, wood bore that is being used to make the instrument. At this point, you should read up on length/bore ratios. This can be obtained through my Tin Whistle Maker Anthology or Bart Hopkins Air Columns and Toneholes book.

4. You also need the diameter of the embouchure hole or fipple window. Since Tinwhistles usually have square windows, take the length x width to determine the area. Then divide the area by PI, take the square root of the result and multiply by 2. If the fipple window is perfectly square, use the Utility menu 'Round/Square' conversion for quick results.

5. The units for English or Metric can be use as long as the English/Metric button is set to the appropriate units.

6. The base frequency can be chosen from the first note box on the screen. For more familiarity with frequencies, see the note table.

Operation Details.

7. Click the Calculate Frequencies button to put the base note into effect.

8. If you are doing a scale other than the major scale, (Do, Re, Mi, etc), you can set the spacing of the scale where it says 'Scale Sequence'. The numbers of the number of half-steps to each note. If you change this, click the calculate frequencies button again.

9. Enter the Embouchure Hole diameter that you calculated in step 4 under 'Emb. Hole Diameter'.

10. Enter the Wall Thickness from step 2 in the box marked 'Wall Thickness'.

11. Enter the inside diameter of the tubing from step 4 in the box marked 'Bore Inside Diameter'.

12. Click 'Do It'.

13. At this point, the program will calculate initial tonehole data. A box marked 'Adjust Here' is where you will tweak the hole diameters until the spacing of the holes are within the comfort of human hands. You will also have to monitor the cutoff frequency vs frequency graph.

Clicking the 'U' and 'D' buttons will change the size of the drill for the tonehole. Note: Hole number 1 is at the bottom of the whistle. Each time you change a drill size, click 'Do It' to recalculate.

14. At the bottom of the screen, you will see the results area. The Frequency and then the hole spacing. After it, you will find 'Between Centers'. These are convenient for knowing how much space that your fingers will have to stretch. Try to make the instrument uniform for comfort.

15. The cutoff frequency ratio and the graph are useful in predict the quality of each toneholes sound production. High cutoff frequencies are richer sounding because harmonic overtones are more present in the sound. A very cutoff, ratios below 2 can be weak or muffled in sound.

16. Note, the field called index works in conjunction with the 'Prev' and 'Next' menu selections. You can store multiple Tinwhistle designs in the TWCALC worksheet. Maker sure you apply changes with the DoIt button before browsing.

17. You can save your work by clicking the 'File' menu selection and 'Save'.

18. The length of your tube from the block edge in the fipple window to the bottom will be close to the value in 'Cork to End Length'. This value can vary depending on the shape of the fipple window and will change if the window has walls around it. It is best to fine tune the size of the instrument playing the bottom note before drilling the toneholes.

19. The toneholes positions are shown in millimeters and inches. It is more convenient to use millimeters for placing the holes. The holes are measured from the bottom of the tube.

20. So that is the basics.

More information:

Desc: This box is for your documentation, a description of the instrument being built.

Mat'l: This box is for your documentation, the material being used.

Note Name: The official ANSI name and pitch of the note.

Chim. Height: The Effective Chimney Heigh based on wall thickness and hole diameter. Also called 'Te'.

Nom. Lengths: The mathematical length of a piece of pipe to play just that note. Also called 'L'.

Hole Space: The distance between the Nom Lenght of this hole and the hole below it. Also called '2S'.

Local Cutoff: The point where harmonic overtone frequencies taper off in power. Also called 'fc'.

Open Hole Correction: Influences from holes that are open. Also called 'co, cs'.

Closed Hole Correction: The chimney area of the holes that are closed influencing pitch. Also called 'Cc'.

New Hole Positions: Once corrections are taken in account for Open and Closed holes, the program must recalculate several time 'No Iterations' because holes above and below influence a single note. Sort of like the Chicken and the egg. Also called 'L-Co-Cc'.

Cutoff Ratio: This is a ratio of Cutoff Frequency / Frequency. It is best to have a values above two and to have them close alike.

Ratio Deviation: This shows how one Cutoff Frequency deviates from the average.

Cutoff Ratio Deviation: This show how much deviation between the minimum cutoff ratio to the max cutoff ratio.

Avg. Cutoff: The Average cutoff frequency to the group of toneholes.

Air Length: The length of the air column including the amount that goes beyond the bore into open air.

Length/Bore Ratio: The length of the instrument divided by the bore diameter. Usually around 22-30 for whistles.

Cork to End Length: The length of the tubing from the block edge (at fipple window) to the end of the instrument. (Varies with fipple geometry, this program calculates for a typical tinwhistle).

File - Load: Load a whistle profile file from the Hard Disk, the program uses .TWC extension for the files
and they can be loaded into notepad and view or printed out.

File - Save: Save the whistle profile to Hard Disk

File - Print: Print out the test results.

This allow you to enter non-standard frequencies for each tonehole:


Utility Menu:

Utility - Round/Square Conversion: Calculates a square holes width as equivalent area of a round hole.

Utility - Temperature Conversion: Fahrenheit / Celsius conversion.

Utility - Distance Conversion: Feet / Inches / Centimeters Conversion.

Utility - Calculate Air Density: Take Temperature, Air Pressure, Dewpoint and calculates Air Density. Experimental Stuff.


Major Scale, Harmonic Minor, Natural Minor, Melodic Minor, Ahava Raba. Programs in the 'Scale Sequence' automatically for one of these scales. The "Native American" scale shows in the menu but the calculation is not quite right yet.

Help - About: Reveals Version Number of software.

Help - Fractional Drill Sizes: A handy list of drill sizes.

Help - Tubing Sizes: Various Tubing sizes and suppliers.

Emb Correction is for the Embouchure calculations

Speed of Sound, don't change it unless you understand it.

Tonehole Efficiency, defines that the air uses only 61% of the toneholes area.
Holes that are rounded inside can have a higher efficiency.


Next - Index forward to another whistle design page.

Prev - Index back to another whistle design page.




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