I get frequent questions from customers regarding the trumpet mouthpiece gap. By “gap,” trumpeters are referring to the distance from the end of the mouthpiece to the beginning of the leadpipe inside the mouthpiece receiver.  For this post I am relying on a very fine article by Cliff Blackburn that appeared in the May 1979 ITG Journal. According to Cliff, there are two basic measurements that are fairly standard for optimum gap adjustment: 1/8 of an inch and 3/16 of an inch.  1/8 of an inch may be the most standard and encourages good response, a warm sound that is well-centered, and provides nice slurring ability.  3/16 of an inch can produce crisper articulation, a well-centered sound, and more resistance than the 1/8 inch position.  Based on input from other players I would assume a lot of trumpeters are seeking to get notes (especially high range) to lock in better by making these minute adjustments. It can also be assumed that adjusting the gap will have no impact upon the intonation of the instrument.


As with any issue regarding the equipment I am using, I think all of the variables have to be considered before getting too consumed with this issue. First, mouthpieces are not created equal. I have 8 mouthpieces from eight different highly respected manufacturers lined up on my desk in front of me as I write this.  None of the mouthpieces are the same length. The actual length of the shank varies from one mouthpiece to the next. These are observations that can be made visually without having to measure. Second, trumpet mouthpiece receivers are not created equal. How a mouthpiece fits in the receiver will vary from manufacturer to manufacturer.  Some manufacturer’s receivers have to be altered to get any brand of mouthpiece to fit properly. Third, the shank of a mouthpiece wears down over time so the fit/gap will change. Finally, if I have to adjust the gap by shortening the shank, the same mouthpiece may not fit so well in my other trumpets; thus, I have to have a different mouthpiece for each instrument or else change/or install alternate receivers on each instrument until the optimum gap is attained with the same mouthpiece.


Assuming a gap of less than 1/8 inch or more than 3/16 is probably not going to produce good results, a first step would be to adjust the gap to 1/8 of an inch.  At that point I can remove metal from the end of the shank in increments as little as 1/64 of an inch at a time until I reach what I feel is optimum performance.  Once a measurement has been made, I am left with some irreversible options to adjust the gap (short of buying a new mouthpiece or mouthpiece receiver); shorten the mouthpiece shank, make the shank more narrow, or remove metal from the inside of the receiver.


Many of my customers ask me to adjust the gap while I have their trumpet in hand. Even with the player’s mouthpiece in hand this can be problematic.  I can adjust it to suit me or adjust it to a dimension that is requested.  In either case this may not be the best position  for the player.  To get a gap position that you will like, it is best for you to be available to play the instrument as the adjustments are being contemplated/performed.


Probably the easiest first step in experimenting with the gap is to first check the fit of the mouthpiece. If it is loose or you can actually move it side to side even though it feels tight otherwise then either the receiver needs adjustment or your shank needs some adjustment. A poorly fitting mouthpiece can cause a lot of performance problems. You can wrap the mouthpiece shank with a thin piece of paper or foil and insert it into the receiver to tighten the fit. By play testing using this method you can set the mouthpiece out different distances (by increasing/reducing the amount of paper/foil utilized) and determine if increasing the gap makes a positive change in the way the trumpet feels and responds.


Finally, I highly recommend the above-mentioned article by Cliff Blackburn to players that wish to fully understand this issue. If you are not a member of the International Trumpet Guild you can gain access to the very large database of journal articles by joining.