The euphonium is closely related to the tuba, think of it like a younger cousin. The section bridges the gap between the tone and quality of the trombone and tuba sections in the wind band. The euphonium plays a soloistic role in the wind band and marching bands, however, unfortunately, there isn't much opportunity for the instrument in the orchestral world beyond a handful of works.
The euphonium has a conical bore like the tuba and horn, which produces a beautiful mellow tone quality. The name "euphonium" is from the root word "euphony" which means "pleasing to the ear".
Euphonium vs. Baritone
Typically, the euphonium refers to a four-valve medium or large bore instrument with a bell that points straight up. These instruments look like small tubas. This is the instrument that the serious player aspires to. Four-valve instruments can either have all four valves on top or can have three on top, with the 4th valve on the side.
The baritone is a slightly smaller instrument, with three-valves and a small shank mouthpiece. The bells can be upright or forward-facing. These are often the best choice for a beginner.
Both instruments are B-flat non-transposing. The fundamental pitch is Bb.
Notice the 4th valve on the side, played with the left hand
The Compensating System.
The compensating system is designed to help solve intonation problems inherent in any brass instrument. This is highly important on euphoniums since it isn't as easy as "kicking a slide" like on a trumpet.
The compensating system adds an additional loop of tuning to each valve which is only used when the fourth valve is engaged. Not all four valved instruments are compensating--these are typically intermediate models. Another thing to look for are the valves, compensating valves are longer to accommodate the extra valve ports.
*Notice the extra tubing associated with the compensating system on this euphonium, this greatly improves intonation since we can’t “kick” slides like on a trumpet.
When standing, the weight of the instrument must be supported by the left hand/arm. The left hand cradles the instrument holding it around the 3rd valve slide.
When seated, the bottom of the instrument can rest on the lap or be cradled by the left hand. A folded towel can help support the instrument at the correct height.
Things to look for:
Is the mouthpiece lining up with the embouchure? Young students become accustomed to the instrument resting on their laps, as they grow you'll see them compress their neck down to play. Use the towel to raise up the instrument to the correct height.
Students are tempted to hold the lead-pipe with their left hand. Don't do it!
Play with good right hand posture. Think about holding a golf ball in their valve hand. Valves should be played with the fingertips, not the first knuckle. Watch the thumb placement, the bar or ring should rest near the thumb pad, not the thumb-pit.
From the UWSP Honor Band 2020 Masterclass: Seth Mahoney, Holden Midyett, Elijah Schuh, Caleb Deleske, and Dr. Lawrence.