About the steel pan instruments
The steel pan family, like all other families of musical instruments including the voice, covers a wide range of notes. Each instrument has a different role similarly to the instruments in a classical orchestra or jazz band.
Lead ('tenor') Pan - highest range, single barrel; traditionally plays the melody in steel band arrangements
Double Tenor Pan - next highest range, comprised of two barrels. May play the melody, or a harmonized version of the melody, or may 'strum' chords beneath the melody.
Double Seconds Pan - slightly lower than the Double Tenors, also comprised of two barrels. Often strums chords, but may play melody, harmony or other parts of an arrangement. This is the instrument favoured by many solo (unaccompanied) pan artists such as Robert Greenidge and Len 'Boogsie' Sharpe.
Guitar pan - made up of two pans with less notes than the double seconds. Used mainly to strum chords or play the harmony horn section.
Cello pan - usually three (also known as Treble Guitars) or four barrels (also known as Tenor Bass), set in a semicircle, comprise this instrument. These fill a variety of roles in a steel band, ranging from bass lines, to strums, to the melody.
Quadrophonics - a sister instrument to the 'cello pan; however, rather than having the drums arranged side-by-side in a semicircle, two of the drums are set flat in front of the player, while the two remaining barrels are set vertically.
Bass pan - as the name would indicate, the lowest-ranged instrument in the steel band. Due to the size of the notes used on this instrument, there may be as few as three different pitches on each barrel, requiring the use of six, eight, or even more barrels to complete a single instrument. The traditional role of this instrument is bass lines, but arrangers such as Cliff Alexis, Ray Holman, Robert Greenidge, and Len 'Boogsie' Sharpe (among others) will often assign the melody or countermelodies in the bass instruments, at some point in their arrangements.
The Engine Room
Steel bands are usually embellished with a rhythm section (known as an 'engine room'), including drum kit, congas, iron (brake drum), cowbell, maracas, tambourine, woodblock and any other percussion instrument which suits the arranger's purpose.
Typical note layouts of the steel pan instruments
As a classical orchestra has strings, wind and percussion, an all steel percussion orchestra has different sections for specific musical elements in the chromatic scale. Click image to view range.