The Gap - Stomvi USA

Description

The correct gap for each mouthpiece/trumpet system
and player cannot be calculated.
It must be discovered through experimentation.
Your goal in adjusting the gap is
to get the highest percentage of notes
in tune with themselves.

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Receiver cut-away showing the "gap"

The Annulus, or "Gap" as it is commonly referred to, is the space (chamber) between the end of a trumpet mouthpiece and the beginning of the leadpipe.

THE GAP IS THE MOST IMPORTANT DIMENSION
THAT CAN EASILY BE ADJUSTED TO:

Make the upper register as easy as possible.
Improve your endurance.
Give you a full, resonant sound full of harmonics, or tonal colors.
Improve the low register.
Ensure the best intonation possible with your mouthpiece, your trumpet, and the way you play.
Give you more sound for less work.

The "gap" affects the pitch center, or slot of every note on the trumpet.
It does this by affecting the intonation of every note.

When the gap is not correct, you must compensate using your chops and air in an effort to make all the notes be in tune and sound as even in possible. This means you are working harder than you need to to play the instrument.

Signs of an incorrect gap:

Some notes are sharp and some notes are flat.
The upper register speaks well, while the low register speaks badly.
The low register speaks well, while the upper register is difficult.
All or some registers feel stuffy.
All or some registers feel too open.

The video below explains what the gap between the mouthpiece and leadpipe is.

The "gap" affects the pitch center, or slot
of every note on the trumpet.
It does this by affecting the intonation of every note.

Signs of an incorrect gap:

Some notes are sharp and some notes are flat.
The upper register speaks well, while the low register speaks badly.
The low register speaks well, while the upper register is difficult to play.

The video below explains what the gap between the mouthpiece and leadpipe is.

Average gap per manufacturer

Gathered through empirical measurement. Your gap may vary depending on age and model.
For reference use only. All measurements in thousandths of an inch (.001).

Coupler Size

Bach

Benge

Blackburn

Blessing

Eastman

Getzen

Larson

Monette

Schilke

Scodwell

Selmer

Stomvi

Yamaha

2.0

0.331"

0.265"

0.333"

0.338"

0.320"

0.365"

0.350"

0.261"

0.314"

0.265"

0.301"

0.275"

0.291"

2.5

0.300"

0.234"

0.302"

0.307"

0.289"

0.334"

0.319"

0.230"

0.283"

0.234"

0.270"

0.244"

0.260"

3.0

0.269"

0.203"

0.271"

0.276"

0.258"

0.303"

0.288"

0.199"

0.252"

0.203"

0.239"

0.213"

0.229"

3.5

0.238"

0.172"

0.240"

0.245"

0.227"

0.272"

0.257"

0.168"

0.221"

0.172"

0.208"

0.182"

0.198"

4.0

0.207"

0.141"

0.209"

0.214"

0.196"

0.241"

0.226"

0.137"

0.190"

0.141"

0.177"

0.151"

0.167"

4.5

0.176"

0.110"

0.178"

0.183"

0.165"

0.210"

0.195"

0.106"

0.159"

0.110"

0.146"

0.120"

0.136"

5.0

0.145"

0.079"

0.147"

0.152"

0.134"

0.179"

0.164"

0.075"

0.128"

0.079"

0.115"

0.089"

0.105"

5.5

0.114"

0.048"

0.116"

0.121"

0.103"

0.148"

0.133"

0.044"

0.097"

0.048"

0.084"

0.058"

0.074"

6.0

0.083"

0.017"

0.085"

0.090"

0.072"

0.117"

0.102"

0.013"

0.066"

0.017"

0.053"

0.027"

0.043"

6.5

0.052"

-0.014"

0.054"

0.059"

0.041"

0.086"

0.071"

-0.018"

0.035"

-0.014"

0.022"

-0.004"

0.012"

7.0

0.021"

-0.045"

0.023"

0.028"

0.010"

0.055"

0.040"

-0.049"

0.004"

-0.045"

-0.009"

-0.035"

-0.01"

Unfortunately, it is not possible to calculate the correct gap for a system or individual. Remember that adjusting the gap is primarily an acoustic phenomenon. It affects the relative intonation of the notes (pitch center).

Because each player pushes their lips into the mouthpiece by a different amount, this alone affects the relative intonation of the mouthpiece/trumpet system. The video to the right shows this in graphical terms.

The video below explains why gap calculations don't work.

The video below explains what is affected when you adjust the gap.

Different gaps using different Flex Couplers