measurement marathon part 1: facings

At the moment i have a nice series of alto saxophone mouthpieces. I thought it would we  instructive to measure them and learn from the effect of the differences.

From left to right the mouthpieces under test:

• Meyer 7M medium chamber
• unbranded french?
• Conn Steelay 5 (my favorit)
• Pan American 3
• unbranded 190
• Selmer Goldentone 3
• Yamaha 4c
• Otto Link tone Master 7*
• Selmer Soloist E copies (one red and two blue)
• unbranded
• Brilhart Tonalin
• Selmer CS80 c*

Facing curves

The first measurement  stage was spend on the measurement of the facing curves.

The graphs below show the results.

Horizontal is the length along the facing in mm. Vertical is the opening in hundredths of a millemeter.

The use of a logaritmic vertical scale makes the facing length more clear. The measurements were done in steps of one millimeter along the facing.

Some notable results:

• one unbranded (merkloos) mouthpiece has a very short facinglength.
• Brilhart and Selmer Soloist have the shortest facinglength of the rest.
• most mp's have a smooth curve at the tip end but some old ones (Conn Steelay, Pan American and Selmer Goldentone) show a sudden flattening at the end. 
• Otto Link nad Meyer have the largest tip openings.
• a large tipopening is most of the times combined with a long facing length

I determined a formula for the facing curves that is in fact the segment of a circle with a quite big radius.

The figure above shows a very simple drawing of a mouthpiece and that circle.

The radius of the circle is defined as l_facing/SIN(2*ATAN(h_tip/l_facing)) with:

• l_facing = the facing length
• h_tip = tip opening

I checked for each set of mouthpiece measurement results if the assumption of the radius curve is true. The figure below shows the graphical comparison between the measured values (the red line) for the Brilhart Tonalin and the theoretical values according to the radius formula (the blue line). The green line shows the difference between the two curves multiplied by 10.

In broad terms all measured ranges are quite close to the radius formula. Most deviations are seen at the tip end. Most mouthpieces show a steeper slope in the last 3mm near the tip while some others like the old Conn mouthpieces show a less steeper slope than the one according to the radius curve.