A Welsh male voice choir is made up of four sections. There are two groups of tenors, known as the Top Tenors and Second Tenors, and two groups of basses, known as the First Bass and Bottom Bass (or sometimes Baritone and Second Bass).
The Top Tenors sing the highest part and usually lead the melody.  For those of you who are more musically-minded, the typical tenor range extends roughly from the C below middle C on the piano to the C one octave above middle C, although it is pretty unusual for the tenors to be asked to sing that high.  The famous top note in Puccini's "Nessun Dorma" is the B above middle C, just to give you an idea of how high top C is!
When you see the Fron Male Voice Choir on stage, the Top Tenors are usually on the centre-left, the First Basses are on the centre-right with the Second Tenors far left and Bottom Basses far right.  Of course, this arrangement can change depending on the venue. For example, at our very popular Christmas concert at the New Vic Theatre in Newcastle-under-Lyme, where the auditorium is in the round, the choir is arranged in a circle around the piano.  
The Second Tenors fill the sound between the Top Tenors and the baritones lending support to both sections. They are capable of singing almost as high as the top tenors but can also reach down the B below middle C - notes normally sung by the First Basses. Second Tenors most usually sing complex harmonies rather than the melody - not an easy task.
The First Bass (or baritone ) vocal range falls somewhere between the Bottom Bass and Second Tenor, typically from around the A below middle C to the F above. It is considered the natural voice for most men.  An important section, it contributes greatly to the rich fullness of sound the choir generates and the overall harmonies produced. 
The Bottom Bass (or second bass) is the powerhouse section of the choir and, because most of the time they are singing the root of the chord, they provide the essential platform above which the other voices can weave their harmonies. Their vocal range extends from around the second E below middle C to the E above middle C. However, a Bottom Bass not only has to be able to reach these low notes, but he also has to be able to produce them with sufficient power and tone needed to produce the authentic sound of a Welsh Male Voice Choir such as the Fron.  Look out for the basses singing the bottom D at the end of the Russian Hymn Spaseniye Sodelal and feel the rumble!