Bob Reeves patented his sleeve system in 1974 (US Patent 3,808,935). This system allows the trumpet player to optimize his/her gap for sound, pitch, and playability or to use the same mouthpiece in different horns that require a different gap.

Once a mouthpiece has been converted for our sleeve system, different sleeves can be used in order to "dial in" the correct gap. Our sleeves vary in diameter in small, but significant, increments thus increasing or decreasing the gap. They are available in half sizes from #1 through #7 (largest gap is #1, smallest is #7).

The change in gap from one sleeve size to the next is .0625" (1/16 inch). Sleeves are available in half sizes allowing for gap adjustments of .0313 (1/32 inch).

Gap Basics

Math-Physics tells us that the gap is a tuning device which adjust the distance (pitch-wise) between the modes (notes).

The correct gap is the one that works. Although some general guidelines can be followed, the proper gap for any individual can only be determined through experimentation. Any formula trying to determine the correct gap does not take into account the player and his/her affect on the resonance frequency of the mouthpiece caused by different lip penetrations.

Remember, it is the effect on the acoustic wave, not the airflow, that is important when determining the correct gap for you.

Think of a coil spring where each coil is a different mode, or note.

In many instances, increasing the gap is like stretching the spring; the distance between the modes increases.

In many instances, decreasing the gap is like compressing the spring; the distance between the modes decreases.

A good way to test the gap you have is by using our paper trick.