Page "Pan flute" Paragraph 6

The formula for calculating the length of a pan flute tube is TL = ( S / F ) / 4 ( the " theoretical length " equals the speed of sound, divided by the desired frequency in hertz, that quantity divided by 4 ).

Because of a property of compression within the tube, the length must be a little shorter to correct flat pitch.

The extra length is helpful for a maker, who can use a cork or plug at the bottom to adjust the pitch.

Some instruments use wax or pellets to tune the fundamental pitch of each tube.

A tube that has a diameter 1 / 10 of its length yields a typical tone colour ( see Timbre ).

An inner diameter range between 1 / 7 and 1 / 14 of the length ( TL ) is acceptable.

A narrow tube will sound " reedy ", while a wide one will sound " flutey ".

If you are a " perfectionist ", multiply the bore diameter by 0. 82 and subtract this value from the tube length.

This compensates for internal compression slowing frequency and the lips partially covering the voicing.

Only tiny adjustments will be needed then to adjust fundamental pitch for air density and temperature.