PVC flute help needed!

[srijand]

Hello,

My name is Srijan and I'm a singer from India. I've just made my first PVC pipe flute and I'm having some trouble with it and need some help.

I have a 16" long PVC pipe with an internal diameter of 17mm and a wall thickness of 2mm.
I generated my hole distances using the generator at http://people.adams.edu/~rjastalos/Flut ... tomat.html
My flute's bell tone (findamental) is at A 440Hz.

My embouchre hole (diameter 11mm) is at 36mm from the top, and the cork stopper is pushed in so that it is 5mm from the edge of the hole.

I wanted an indian natural intonation tuning (which is a variety of just intonation) in the key of D. I should mention that Bansuri players here play their tonic on the 4th hole (3 holes closed, holes numbered starting near the embouchre moving towards the end of flute) so I needed to have my D on the 4th hole.
The calculations on the website told me that my 4th hole should be at 104mm from the end-of-flute.

Now the weird thing is, my flute plays a lovely C# at the 4th hole where it should play a D! I can't for the life of me figure out why!

Here's a picture of my flute in case it helps: https://drive.google.com/open?id=0B7EDV ... 1pVcGx3clk

The distance from the centre of the embouchure hole to the centre of the 4th hole is exactly 105mm , which, flutomat tells me, should give me a D. But it doesn't. I get a C#.

I also tried to calculate the wavelength of the D note using this length. According to Bart Hopkins' book (musical instrument design) , the wavelength is 4(length+0.3d). So for hole 4, my effective air column length (from embouchre to 4th hole) is about 255mm so the wavelength there comes to 4(255+5.1) which is 260mm or 26cm; which is about 3'5". On referring to the chart at http://www.soundoctor.com/freq.htm I find that the note playing at this hole ought to be just above 330Hz, which would give me an E!! But the note I get is neither an E nor a D, but a C#

What have I gotten wrong? I can't figure this out and any help would be appreciated.

Also, I stuck a makeshift handle in my cork stopper so that I could move it up and down, but changing the position of the stopper doesn't seem to have much of an impact on the pitch of the instrument. Could this be because I'm still new to this and my blowing is inconsistent?

Thanks!
Srijan

[Tunborough]

It looks like you're pretty close, all things considered. You could bring the XXXOOO note in tune by drilling the hole larger, in small increments until it was in tune, but the hole might get too big to play before you got it up to D. This would also affect the tuning of the XXOOOO note, nominally E.

You may have to make another attempt, this time drilling the third hole slightly higher up the tube. Start with the holes a bit under-sized, and then enlarge each one a little at a time until they are in tune, working from the bottom of the tube to the top, hole 6 up to hole 1. Test each note in both octaves.

As I understand it, the cork position serves mainly to bring the two octaves into alignment, rather than overall tuning. For a 17 mm I.D. tube, the recommended starting position of the cork would be 17 mm from the embouchure hole. 5 mm sounds too close, from what I've heard.

[srijand]

That clears most of it up... thank you!
Could you tell me what widening the embouchure hole does? Does it affect the pitch of the flute or only the tone?

[highwood]

It effects the pitch.
Make the hole bigger effectively shortens the tube.

[jemtheflute]

Very important - measure the stopper distance from the centre of the embouchure hole, not the up-tube edge!
The stopper position will not have any significant effect on overall pitch and cannot be used to adjust that - as already stated above, it is used to govern the intonation between the different registers and the "width" of the octaves.

The size of the embouchure hole does affect both overall pitch and scale intonation - a bigger hole will sharpen the upper notes in the octave more than the lower ones.