Gapping 101

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  • #6734
    AvatarAlan Brinton
    Participant

    After cleaning reeds and reed plates with a toothbrush, I have recently had to regap an entire melodica, my 1970s Suzuki Soprano 25. It took me most of today to get it done to my satisfaction, as I was aiming to make all the notes comparably responsive, rather than simply trying to address an isolated problem or two. After bathing and carefully regapping the Soprano 25, I find it to be a far superior instrument to what it was earlier. We have discussed gapping (or “reed offset”) in relatio the context of several different threads, mainly in relation to choking or failure of specific reeds, but I thought it would be good to start a thread that is dedicated to the topic itself, so here it is.

    I’ll begin by linking an excellent Hohner harmonica workshop that Daren linked earlier, as it’s one of the best sources of information on our topic, and since it presents video of the reed offset process.

    Here are two other very good sources:

    http://www.angelfire.com/tx/myquill/Maintenance.html

    http://www.hohnershop.com/blog/how-to-adjust-your-harmonica-reeds-to-your-personal-playing-style/

    It is worth reviewing all three of these sources carefully prior to a gapping session.

    In my experience, if the reed is intact and a note will not play at all or chokes, the problem is almost always that the gap is too small. The general rule of thumb is that the gap between reed and reed plate should be approximately the same as the thickness of the reed. Typically, at least on a good quality melodica, the reeds of the lower notes are thicker than the reeds of the higher notes, so that as you ascend from the bottom of the keyboard toward the top, the gap should get smaller. An appropriately gapped reed should respond well both when the note is played softly and when it is played loudly. I just tested my whole keyboard once again, and I find that there’s one note, D4, that has an uneven sound when played loudly — loudly relative to my playing, that is. The experts tell us that “right” gapping is relative to the player, which seems correct. So I need to adjust the gap on D4.

    I found that it was necessary to be more aggressive in gapping reeds than I was naturally inclined to be. The reed is a spring, and, as indicated in the video, you need to bend the reed beyond the “rest position” of the spring. In other words, you need to bend it beyond your likely comfort level. A new rest position has to be established. Take note of comments on the video about the importance of pinging in establishing that new position. And, again, notice that the pinging demonstrated in the video is also relatively aggressive.

    I found in today’s gapping session that what worked best for me was to push my left index finger down firmly on the reed at about 1/3 of the way up from the base, and to bend up from the very tip with the corner of a razor blade (rather than wedging a flat surface down to that point under the reed and leveraging up, which places all the stress at that one location). I bent up several times. Then I slid my left finger a bit further up, and repeated the process, with further repetition as necessary. The one experience I have had with breaking a reed off was when the stress was focused on where the base of the reed is attached to the reed plate.

    Disclaimer: In adjusting reed gaps, everyone proceeds at his or her own own risk! But the payoff can be significant.

    I know some others have more gapping experience than I do, and I’m anxious to hear what anyone else has to say on the topic.

    #6735
    AvatarAlan Brinton
    Participant

    Correction: D5. I forgot we’re on the soprano here.

    #6825
    AvatarAlan Brinton
    Participant

    Gapping and Tuning:

    I am now doing more adjustment of gaps during tuning. In recently tuning and gapping some vintage Japanese melodicas, I have observed that opening the gap tends to flatten the note, sometimes rather significantly. I’m convinced now that the first step with a vintage melodica should be cleaning the reeds and reed plates, if necessary. The second step should be a careful check of gapping, with adjustments — which are most likely to involve slightly opening the gaps of notes that choke or show some resistance in being played. Then tuning, which may require some further attention to gapping, since pressure applied in tuning may narrow some gaps. All notes should play freely, even when blown moderately hard. If a particular note requires more air, its reed gap may need to be closed slightly, but this is a more unusual issue than having too small of a gap.

    #7603
    AvatarAlan Brinton
    Participant

    Further Gapping Note:

    If you have a not that’s not sounding properly, opening or closing the gap slightly may rectify the situation. Once you start fooling with a reed, though, it can get confusing and frustrating. You don’t want a significant upward bend from the middle of the reed to the tip, which can be hard to undo. It’s best to make very slight and gradual adjustments, and it seems that each adjustment has to be checked by closing the reed chamber, screwing the top down, and blowing the note. But I have found that pinging the reed in comparison with pinging of the nearby reeds will tell you whether or to what extent the problem has been resolved by a particular adjustment. If there’s a problem with the reed’s gapping (or if the reed is damaged, twisted, whatever), the ping won’t sound right. For example, it will sound dull in comparison with the other reeds, it won’t have the right kind of ring to it, it won’t resonate. It’s like the difference between the sounds you get from a guitar string when you do or don’t press down properly behind the fret.

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