While all played by the same performer, the Trumpet, Cornet, and Flugelhorn are all in different families of brass instruments and all have different sound qualities. Knowing the differences between the three instruments is essential for good band and orchestral writing.
The B-flat Trumpet, B-flat Cornet, and B-flat Flugelhorn all have the same range, but it’s a combination of bore structure and mouthpiece design that give these three instruments wholly different characters.
Conical vs. Cylindrical
In general terms, when a brass instrument has a conical bore, its tone is warmer with fewer upper harmonics. Conversely, when a brass instrument has a cylindrical bore, it’s tone is brighter with more upper harmonics. The exception to this is the Horn, which is a mostly cylindrical bore instrument, but do to other reasons (hand placement, bell position, and extreme bell flare) has a very warm sound.
There’s an old formula that helps to understand the relationships between the instruments. The Trumpet is roughly 2/3 cylindrical and 1/3 conical, the Cornet is roughly 1/2 cylindrical and 1/2 conical, and the Flugelhorn is roughly 1/3 cylindrical and 2/3 conical.
This is a rough idea. Reality isn’t so smooth though. Most modern trumpets are partly conical through their supposed cylindrical bore.
A Historical Perspective
In reality the modern B-flat Trumpet is really a quasi-cylindrical bore Cornet. The old F Tromba had different proportions of roughly 3/4 cylindrical and 1/4 conical and was 1 1/2 times as long as the Cornet.
The F Tromba produced a bright, almost harsh sound, whereas the Cornet was warm and fluid. In the 19th Century, these two instruments were able to coexist as two very different tone colors. This can be seen in the numerous scores that include a pair of B-flat Cornets and a pair of F Trombas.
However, once the trumpeters realized how much easier the Cornet was to play, they started to switch instruments. Their Tromba became smaller and became the Trumpet of today.
The line between the Cornet and the Trumpet started to blur, and slowly the Cornet began to fade away.
The Flugelhorn on the other had was distinct enough to retain a completely separate identity. The modern Flugelhorn is really a soprano tuba with its highly conical bore shape. If it weren’t for the lead pipe and the valve sections, the entire instrument would be conical.
Equally important to the sound of a brass instrument is the design of the mouthpiece. Mouthpiece design can vary wildly between makers, but there are some general rules. Trumpets are designed to play with a cup-shaped mouthpiece. That is, the interior of the mouthpiece is shaped like a cup (in this case, an old-time tea cup) and has what can be described as a c-shaped bowl. The extreme opposite of this is a funnel-shaped mouthpiece. That is, there is no bowl in the interior, rather the sides slope gradually from the rim to the throat. The Horn has the most funnel-shaped mouthpiece of all the brass. Between the Trumpet and the Horn there are almost infinite variations on these themes.
The deeper the cup, the warmer the sound. So a shallow cup, like on a Trumpet, will produce a bright, brilliant sound.
True Cornet mouthpieces are funnel-shaped, though some makers produce mouthpieces that are cup-shaped for the instrument and thus cannot provide the true Cornet sound.
Flugelhorn mouthpieces are like Cornet mouthpieces in that they have a deep funnel cup. However, Flugelhorn and Cornet mouthpieces cannot be interchanged as the diameter of the receiving pipe (the lead pipe) on the two instruments is different.
The Octave Corollary
These three instruments each have counterparts an octave lower that follow the same principals.
Trumpet – Bass Trumpet
Cornet – Baritone Horn
Flugelhorn – Euphonium
A comparison between a Trumpet, Cornet and Flugelhorn, Also demonstrates the differences between a cup and a funnel mouthpiece on Trumpet.
A comparison between a Trumpet and a Flugelhorn