The wider cups utilised on the larger instruments are there for a reason as they provide the freedom for the lips to vibrate over a greater width, this being necessary for the long-wavelengths associated with lower tones to be established. Cup diameter is measured across the cup at the point where the rim diameter meets the cup body. In general, this is a difficult measurement to establish but, in the PeakTone® model, it is set digitally and, therefore, repeatably to the same exact dimension. The diagram below shows how this is established on the PeakTone mouthpiece model.

To some extent, the cup diameter should be chosen to suit your lips. Thus, if they’re thick, you might well be better off with a slightly larger cup diameter. Having said that, the range of cup diameters in general use tends to be relatively narrow, ranging, on trumpet mouthpieces, from around 16.25 to 17.5 mm. On the trombone, it ranges over a much-greater scale as mouthpieces are made to suit everything from an alto trombone to a contra-bass instrument. A similar feel to a wide cup may be obtained on PeakTone mouthpieces by setting the peak of the mouthpiece rim to the outside of the mouthpiece giving it the feel of a larger mouthpiece without significantly increasing the volume of the mouthpiece chamber.

While wider cups are generally associated with deeper mouthpieces and larger throats, with PeakTone_® mouthpieces_, you may mix and match to suit yourself.

Together with the cup depth, the cup diameter is one of the key factors in determining cup volume. The volume is also affected by the degree of conicity of a mouthpiece’s cup with more conically-cupped mouthpieces having a lower cup volume. The cup diameter has a profound physical effect on the seating of the mouthpiece on the player’s lips and a too wide a cup will fail to provide sufficient support for your lips and prove very challenging to play. It is important, therefore that, if you’re a beginner, that you start off with a mouthpiece with a comfortable width and only begin to experiment with different mouthpieces after attaining a strong and stable embouchure with which minimum pressure is applied to obtain the higher notes.

The active diagram below provides a facility for you to look at how the cup diameter varies as the slider is moved.

<div class="odoko-diagram-sliders">
  <div id="sliders-simple-cup_diameter-cup" data-params="cup_diameter">
  </div>
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When the mouse pointer hovers over the image, immediately to the left of the word Diameter is a button with the letter i on it. Clicking this will bring up an information box which provides some data on the Cup Diameter setting. Clicking it once more will remove the box.

As the slider appears, so will three new images below the slider. The first of these reports on the range of diameters of the current mouthpiece, the second reports on the current diameter setting and the third is a button with a return icon on it and, pressing this will return the cup diameter value to its default setting. the middle icon is an edit button which means that you are able to enter the value for the cup diameter directly in this. Using this button is by far the best to enter precise data for the cup diameter.