Reed Gapping Overview

When a diatonic harmonica leaves the factory it has a form of generic setup. This generic setup is meant to work for most people. This also means that it will probably not be optimal for you. Depending on your playing style you may need to do reed gapping to get a perfect harmonica for your style. In this article I give an overview of setting the reed gap and the effects it will have.

What is reed gapping?

The reed gap is the distance between the tip of the reed and the reed plate when the reed is at rest. This distance will decide how the reed respond to different air pressures when you start playing a note. If the reed gap is set very low, the reed must be started with very low air pressure. After the vibrations starts the volume can increase. The reed will not even vibrate if the air pressure is to high. If the reed gap is set very high, the reed will need high air pressure and lots of air to start vibrating. If there is too little air or too low air pressure the air will just move past the reed and no sound is made.

correct reed gapping

Not too high and not too low.

The reed gap also determines how the harmonica responds to bends, overblows and overdraws. For draw bends the corresponding blow reed need to be set sufficiently low for it to be engaged when the draw happens. The same thing is true for the corresponding draw reed and overblows.

Getting the right balance

Getting the right reed gap is dependent on your playing style. If you play very softly you need the gap to be low. High gap is needed if you normally play forecfully. The right balance for you is when you can play both softly and forcefully on the same harmonica.

If you have sprecific needs you may need different sets of harmonicas for different styles. I remember going to a worskhop a few years ago with Marc Breitfelder who said he has three different sets of harmonicas. A “normal” set, a set for extreme overbends and a set for country harmonica vamping style.

Tools

You don’t need any complicated tools to do reed gapping. You can use a reed lifter tool, your nails or paper clip to gently push the reed upwards or downwards. Very little force is need so be very careful. You are aiming dor very small adjustements so don’t go too much by your eyes. If the action feels right when you play, it is right.

reed gapping tools

Possible tools to use for reed gapping.

Summary

Reed gapping is the modification I think is almost mandatory for all harmonica players. It is not a very complicated modification but you do have to be careful not to bend any reeds. Do it first on old harmonicas until you feel comfortable with it. I think adjusting the reed gap is something that you should consider doing before getting a custom comb even. With the right reed gap you will get a much more playable harmonica suited to your style.

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2 thoughts on “Reed Gapping Overview

  1. I have a Seydel Low C Silver. I felt that I needed to blow real hard to produce sound in the lowest notes so I made narrower gaps in these reeds but then the sound volume was very weak. So I made the gaps a little wider again but I cannot return to the starting point, I get a leaky sound; the note with a ssshh and I can not eliminate it. What can I do?

    • Difficult to answer straight off, sounds like you have a leak somewhere. Not sure what you did to widen the slot, sounds difficult.

      Start by comparing the slot size or how much light escapes around the reed. Easiest i you have a light table but if you don’t the hold the reed plate up against a light. Be sure to look straight so that you are not fooled by holding it at an angle. This may give you an indication of if the slot size is the main problem.

      Also check the reed offset, if it is too high you need lots of air to get the reed vibrating.

      Air may also be escaping between the reed plate and the comb.

      Check the Seydel home page for service technicians in your neighbourhood, that may be a good option if you cannot fix it yourself.

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