By Winslow Yerxa

Harmonicas can go out of tune with playing, and even new harps straight from the factory aren’t always in good tune. But you don’t have to accept what you get — you can correct out-of-tune notes.

Harmonica tuning follows straightforward procedures, but it has some ins and outs that you need to know.

Always tune reeds after you’ve done any other reed work, such as embossing the slots, aligning the reeds in their slots, and setting the curvature and offset of the reeds. Any of these other actions can change a reed’s pitch.

The first two things you need to know about tuning are:

  • To lower pitch, you can either remove a small amount of metal from the surface of the reed at its base or add material, such as solder or heavy putty, to the surface of the reed near its tip.

  • To raise pitch, you remove a small amount of metal from the surface of the reed at its tip.

You’ll find that the easiest way to tune a reed is to have direct access to the reeds you want to tune. Diatonic harmonica reeds are mounted on one side of the reedplate, and that’s the side you want facing you.

When you remove the covers from a harmonica, the draw reeds are facing you. However, the blow reeds are inside the comb; to expose them you need to unbolt the reedplates from the comb. You can tune the blow reeds on the comb, but it’s much easier with the reedplates removed. Plus, this way you’re less likely to damage the reeds or push them out of alignment.

To tune a reed, follow these steps:

  1. Support the reed by placing a shim between the reed and the reedplate.

    Metal, thin plastic, or even a piece of stiff paper will work. Just remember to support the reed and not to pry the base of the reed up from the reedplate by using a shim that’s too thick.

  2. Remove metal from the reed by stroking it with a sanding detailer that has a medium-to-fine grit sanding belt.

    The grit number may not be marked on the belt, but you can feel the relative fineness or coarseness of the grit with your finger.

  3. Sand in a small area along the length of the reed.

    Don’t sand across the reed because doing so may create burrs that strike against the slot edge — and any marks across the reed can weaken it. Also, don’t press hard when sanding because pressure can change both the curvature and the offset of the reed.

    When sanding the tip of the reed, the safest procedure is to sand outward toward the tip. (If you sand inward, you may snag the reed and fold it in half.) However, be careful to check for burrs. When you sand near the base of the reed, you can safely sand inward.

  4. Every few strokes, test the tuning by removing the shim, plinking the reed, and then assembling the harp and playing the note.

    [Credit: Photograph by Anne Hamersky]

    Credit: Photograph by Anne Hamersky

Warm reeds vibrate at a lower pitch than cold reeds. Your breath warms reeds up, so it’s a good idea to tune warm reeds. Keep reedplates in an electric heating pad for a short time before tuning and keep them warm while you work.