How I tuned my pitch pipe

Bought a vocal pitch pipe last year and it really is a good example of what you pay is what you get. At its ultra cheap price (RM20 = US$5.50 approx), this China-made pipe (manufacturer website in Chinese available here) has several notes in its 13-pitch C-C range off-key. Here's how I re-tuned the pipe to correct notes/frequencies the simple way.

Materials required

1. Out-of-tune pitch pipe (duh!)
2. Small pliers, unless your fingers are small/strong enough to hold the nut
3. Jeweller's or any small screwdriver
4. UHU glue (or any other tacky glue)
5. PC with Audacity installed (or keyboard) to generate reference tones

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Open the pitch pipe first by removing the mouthpiece (if it has one) by gently lifting from the bottom nut-side of the pipe. Once free from the bolt, slide the mouthpiece off.

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Unscrew the solitary screw holding the pieces together to end up with the three sections. The black plastic piece is the air chamber that directs your breath into the correct pipe. The middle piece has the reeds that vibrate to create a note not unlike a normal whistle. The top metal piece basically forms a resonating chamber to amplify the note and also allow for air to escape without vibrating other reeds.

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Each piece has a notch/pin to guide them into proper position for reassembly later. You can use a marker to mark the notes on the middle piece just in case you get confused - else look for the changes in reed lengths. A sudden change in the lengths indicate the C-C octave jump.

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To retune, first I generated the correct notes in Audacity using the built-in tone generator. The correct frequencies for the 13 pitches requires are as follows (in ascending order)

Note	Frequency (Hz)
C	261.63
C#/Db	277.18
D	293.67
D#/Eb	311.13
E	329.63
F	349.23
F#/Gb	369.99
G	391.99
G#/Ab	415.31
A	440.00
A#/Bb	466.16
B	493.88
C’	523.25

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Using these tones, I found out that the notes C to F were too sharp. To 'flatten' them, I just used a tiny drop of UHU glue on the reed itself. UHU glue works very well here because it becomes tacky after a while to allow for changes before it hardens completely. If a note is too flat, you can 'sharpen' either by filing off a little (miniscule) amount from the reed. Else, a quick fix would be just to shorten the length of the affected reed by taping duct tape near the secure end to 'shorten' the reed.

After corrections, do a quick test blow on the note to check with the reference tones. If too flat, take the screwdriver (or small blade/pin) to scratch off a little glue. If too sharp add more glue. Repeat until correct tone is acquired. Continue with the rest of the notes until all are tuned or corrected. Leave the part to dry overnight when complete.

Once dry, reassemble the pieces following the notch and screw the bolt back into place. Slide in the mouthpiece and test again. If everything goes to plan, the pipe should be in pitch now.

[Note: Another way to do this is to use a small nail file to thin down the reeds or 'sharpen' the note and a little solder to lower the note but this would be even more troublesome as mistakes are not so easily rectified]

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