The bluegrass ensemble isn’t a term you’ll find being used much, if any. But I think it well describes what it is when you are talking about the various instruments used in a typical bluegrass band. If you’ve been playing or jamming for a while, you may already know how every instrument and voice fits in and makes for a distinctive sound. But for the sake of those new to the musical genre, here is a brief introduction on what comprises a typical bluegrass band, the roles of each instrument and what is going on between the instruments. 

Bass. We could say ‘This is an important instrument’ to each of the listed instruments here. But I think the bass is the most important of all, accepting the fact that there are at least one or two others involved (a bass by itself isn’t much on melodies, after all). Just like in a marching band with its bass drum beating out a rhythm for all others to follow, the upright bass, or bull fiddle as it is sometimes called, is responsible for keeping the rhythm, as well as keeping the chord progression for the entire band. The actual techniques of playing the bass aren’t as complicated as the other instruments, but the bass is afforded little room for mistakes in rhythm and proper chording. If the banjo player messes up, it may be that few if anyone notices, but let the bass flub-up, and everyone will turn around to look. Although bassists probably get in a good bit of experience in keys such as G, A, C and D, they should be able to navigate well in any key. The bass plays on the on beat. Interestingly, if you go to a bluegrass festival and start jamming, it is often the bass that is the most in demand instrument, not the ever-so-much-more-common banjo or guitar. It’s been my experience that most bassists also seem to be adept at at least one other instrument.

Guitar. If there is any one instrument that is considered indispensable, it is the guitar. It can hold a bass note, and so fill-in for an actual bass, it can play lead, and provide rhythm. Most singers hold forth behind a guitar, although fiddles and mandolins are frequently played by the lead singer in a band as well. You don’t see as many lead singers playing banjo, Dobro, or bass, but it is done. Most often you’ll see a guitar being used as a back-up instrument. A lot of guitarists can also take lead breaks in bluegrass, but not all of them. Guitars are effective at backing up in any key, playing the bass notes on beat and the strum on the off beat. For lead breaks, guitarists seem to prefer  C, D, E and G.

Fiddle. The most tradion-steeped of these bluegrass instruments, the fiddle is a violin, just named differently and setup slightly differently. For that matter,  nothing would stop a violinist from using an instrument setup as a violin from being used here. Fiddles are capable of playing extremely fast (as in Orange Blossom Special) and we even have a special category of old songs expressly meant to be played on the fiddle called (big surprise here…) fiddle tunes. We don’t normally think of the fiddle as a backup instrument, but it does an effective job of that, either by ‘chopping’ chord fragments, or by backup melody lines; they usually play backup chops on the off beat. Fiddlers seem to prefer keys of A and D.

Banjo. Banjos have the widest variety of styles that you’ll find among these instruments, from 2-finger to clawhammer to Scruggs, melodic and single-string,each with their own distinctive sound. Banjos themselves also vary widely and can be modified more than any of the others. Banjos display a considerable amount of syncopation, due to their unusual string configuration, as well as by how they are played, often emphasizing this hard-to-decipher cascade of notes. As with the guitar, banjos tend to play the bass notes on beat and the pinch (strum) on the off beat.

Mandolin. Mandolins are tuned just like the fiddle, GDAE. But since they are played with a pick rather than a bow, chords can be made with three or four courses of strings (a course is when you have identical strings tuned together in pairs; a mandolin has 8 strings in 4 courses instead of 4 strings alone like a fiddle). Mandolins usually supply backup in the form of a chop on the off beat.

Dobro. Perhaps the Dobro is more correctly called a resonator guitar. Gibson Guitar Company has acquired the rights to the name ‘Dobro’ as of 1993. The resonator guitar is simply a guitar that uses a metal cone for the resonator instead of the usual flat wood found on a regular guitar. It is usually played horizontally with a slide and three finger picks, employing much the same techniques as in modern three-finger banjo styles. Resonator guitars have a wonderful sustain, giving a very different effect from the usual brief sustain of banjos. Backing up is usually more along the lines of how a fiddle backs up, rather than how a banjo does it; with smooth and subtle melody or harmony lines during lulls in the singing or other instrumental breaks.