The Gap

Discussion in 'Trumpet Discussion' started by thompa, Oct 19, 2009.

  1. thompa

    thompa New Friend

    Jun 17, 2009

    Does anyone here have any experience or knowledge about the gap between the mouthpiece and the leadpipe? I have heard players talk about this and that it might be a good idea to look into.

    So if anyone here have been messing around with that; what is the main
    purpose of this and what did YOU find out? Did some aspects of your playing become easier or was there hardly any change?

  2. dhbailey

    dhbailey Piano User

    Jul 28, 2009
    New Hampshire
    I believe the Bob Reeves mouthpiece page has information on that but it seems to be down right now so I'm not sure.

    It's another area of "trumpet voodoo" which has no single right answer which works for everybody. Some people it's not an important issue, others feel there should be no gap, others feel there should be a slight gap, still others feel there should be a larger gap. Each has their claims for why their decision is best.

    If you want to experiment, you can cut a business card and wrap it around the shank of the mouthpiece and insert it into the trumpet. This will prevent the mouthpiece from going in as far as usual and will thus give you a larger gap. See if you notice a difference and then if you like or dislike the difference.

    It's like heavy bottom caps -- some people like them, some hate them, some notice no difference. Personally, I've found that my horn responds better with a heavy cap on the bottom of valve 3, a medium cap on the bottom of valve 2 and a normal weight cap on the bottom of valve 1, all with a neoprene O-ring which keeps them snug without actually pinching against the brass of the casing.

    I would never suggest that anybody else follow my example because I can only state positively that it makes a difference on my trumpet with regard to slotting of notes, but for all I know it could be in my head and I'm just playing better because I think those bottom caps make a difference. I don't think that's it, because every so often I go back to the normal valve caps and the horn isn't as easy to play with them. My son (who is a trumpet major in college) notices the difference also.

    The same will be true for questions about the mouthpiece gap. Some people probably do notice a difference, but there's no way that adjusting the gap will be right for everybody. Be careful about becoming bogged down in these sorts of issues and remember that long before people began obsessing about different weight bottom caps and mouthpiece gaps and one-piece bells and side-seam bells and other issues, there has always been great trumpet playing using the "old" technology.
  3. walldaja

    walldaja Pianissimo User

    Feb 25, 2008
    Kokomo, IN
    The ITG has several articles about it on the following web page
    mouthpiece gap - Google Search

    Short answer is the average gap is about 1/8" and as you reduce the gap you lower the playing resistance of the horn. If you increase the gap, you increase the resistance.

    The new Harrison Wedge mouthpiece comes with five different length shanks so you can play with the gap. One shank is standard and then there are two that shorten the shank and two that legnthen the gap. See Dr Dave's website for more information Harrison Wedge Mouthpiece

    I would use a small piece of paper vice a card for a closer leak free tolerance.
  4. rowuk

    rowuk Moderator Staff Member

    Jun 18, 2006
    I have played with gap extensively. It is a small inefficiency introduced into the instrument to modify intonation and blow. The actual effects are quite modest, but seem to, like most geeky things, get blown WAY out of proportion.

    On one of my horns, it made a difference of about 10 cents (100 cents is a half tone) on the G on top of the staff. The note was previously slightly sharp and after the gap was increased, spot on. I noticed no other change on that horn.

    For the geek, the actual function is a step in the bore close to the mouthpiece. in cylindrical tubing, the length is significant to determine where the resonant nodes fall. Irregular shapes have resonant nodes based on volume. There is also some turbulence at such a step. Both effects "move" the pressure nodes in the horn very slightly. Depending on the design of the horn, that can change the efficiency and frequency of a certain range on the instrument. On a cornet of mine, changing the gap produced no noticable difference in the response of the instrument for any note up to G above high C.
  5. gzent

    gzent Fortissimo User

    Nov 5, 2003
    Rochester, MN
  6. thompa

    thompa New Friend

    Jun 17, 2009
    Thank you guys for all the info!

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