Valves or wind savers as they are more often called are strips of material that are placed on the harmonica reed plate and cover the slot. Typical diatonic, chromatic and orchestral harmonicas have a blow and draw reed in each slot. Generally, only one of the reeds sounds when a player blows or draws on one hole.
Wind savers prevent air from entering the slot of the non-sounding reed by laying flat against the reed plate creating a seal. Wind savers are most commonly used on chromatic and orchestral type harmonicas which have long reeds. Long reed instruments have larger gaps and therefore more space for air to escape. As reeds get higher in pitch (Smaller), there is a corresponding smaller gap and less air loss. Consequently there is a point where the wind saver has minimal advantage and that’s why wind savers are not always placed on every slot.
Wind savers also provide some benefit to the sounding reed because they maximize the air that is used to propel the reed. Wind savers have long been the nemesis of chromatic harmonica players who are understandably distracted when they hear and feel them slapping (Buzzing) against the reed plate. These issues are due mostly to moisture buildup which causes irregular function, but wind savers also curl and crease with use and are easily damaged when the harp is disassembled.
There are several materials that are used for wind savers but the most common are a type of vinyl. Seydel chromatic wind savers have a waffle design which allows for more air circulation underneath making them less prone to moisture related problems. Volumes can and will be written on wind savers but this post is just the basics. Follow-up articles will discuss the use of wind savers in diatonic harmonicas in what is termed “half-valving”
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