JSmith Mouthpiece Model Numbering System

Every JSmith Mouthpiece model name is a precise breakdown of its playing characteristics. A model such as 500ASL tells you exactly how the mouthpiece is built and how it will perform.

Example Model: 500ASL

Rim Size (First 3 Digits) — 500

The three-digit number represents the rim radius in thousandths of an inch.

  • 500 = .500" rim radius

  • This equals a 1.00" rim diameter

  • Larger numbers = larger rim diameters

  • Smaller numbers = smaller rim diameters

Cup Depth (First Letter) — A

The first letter indicates relative cup depth, which influences tone color, response, and endurance.

Cup depths progress in controlled increments:

A → A+ → B → B+ → C → C+ → D → D+

  • A = Shallowest (bright, quick response, high efficiency)

  • Middle letters = balanced all-around designs

  • D+ = Deepest (darker tone, broader sound, more volume potential)

  • Some instruments allow for a shallower ‘alpha’ cup shown as “α” or deeper model cups depending on the instrument

Throat & Backbore Shape (Second Letter)

The second letter defines the openness and contour of the throat and backbore, which directly affects airflow, resistance, projection, and how the mouthpiece “slots.”

Resistance / Openness Scale:

R → R+ → S → S+ → T

  • R = Tightest
    Highest resistance, very focused core, strong control and efficiency

  • R+ = Moderately tight
    Slightly more airflow than R, while maintaining a compact, centered feel

  • S = Medium / Balanced
    Even blend of resistance and openness, versatile response

  • S+ = Moderately open
    Freer blow than S with increased projection and breadth

  • T = Most Open
    Maximum airflow, broad sound, powerful projection, least resistance

Some instruments also offer a tighter “Q” throat

Instrument Designation (Third Letter) — L

The final letter identifies the instrument type the mouthpiece is optimized for.

  • L = Large bore tenor trombone

Certain instruments like Small bore tenor trombone and trumpet do not have this letter to avoid conflicts with other instruments

Putting It All Together

500ASL =

  • 1.00" diameter rim

  • Shallow “A” cup for clarity and efficiency

  • “S” throat/backbore for balanced airflow

  • “L” Designed for large bore tenor trombone

This naming system allows players to move between models with confidence, making precise adjustments to rim feel, depth, resistance, and instrument compatibility without guesswork.