The foundation of bluegrass backup (often called rhythm)
is three instruments: the bass, the guitar, and the mandolin.
The basic bluegrass rhythm pattern is a boom-chick boom-chick
pattern. The boom here is often called the beat, and
the chick is called the back-beat. A simple bluegrass
bass pattern is simply to play the tonic of the chord on the
beat and the 5th of the chord on the backbeat. The guitar
typically plays a single bass note on the beat (boom) and
brushes the strings of the chord on the backbeat (chick).
The mandolin plays either not at all or a very light chord
stroke on the beat (boom), and then a sharp chop on
the backbeat (chick). A mandolin chop is performed by striking
the strings of the chord quite hard, but then almost instantly
damping the strings to stop the sound. The result is a short,
percussive sound which is just barely identifiable as the
When done correctly, the effect of a good rhythm section
is remarkable. On the beat (boom), you get the tonic from
the bass fiddle and the bass strings of the guitar, setting
the pace for the music. Then, immediately following, you get
the dramatic counter-sound of the backbeat (chick) with the
roar of the full guitar chord accented by the percussive chop
of the mandolin.
So what about the other instruments? Well, potentially the
most wonderful and certainly the most dangerous backup instrument
is the banjo. One basic form of banjo backup is vamping. This
is basically just a banjo version of the mandolin chop, and
it is used pretty much in the same way -- that is to punch
up the backbeat. It is used in this way with the mandolin
to backup other leads, and it is used to backup the mandolin
when the mandolin has the lead. The other form of backup for
the banjo is to use the same syncopated three-finger rolls
which are used for a banjo lead. This can be very effective,
but it can also be terrible when it conflicts or competes
with other instrument or vocal leads. The best rule of thumb
here is that, if you are a banjo player, go out of your way
to learn syncopated backup techniques, and then, when you
really know them well, use them very selectively and occasionally.
The reason for this is that the banjo is such a loud, in-your-face
instrument that it can interfere with, rather than backing
up, the lead.
Almost equal in power and danger to the banjo is the fiddle.
Fiddle backup is generally done by playing short tasteful
riffs, usually referred to as "fills", that compliment
the vocals as a breath is taken between lines or at the end
of a verse or chorus. Next time you listen to your favorite
bluegrass album listen to how the backup instruments come
in and out. Something to keep in mind is that it's often said
"It's more important to know when not to play than when
to play". Another way to put it is, "sometimes less
is more". This idea of playing during the "breaths"
can also apply to playing fills between the lines of another
instruments lead break.
Other advanced techniques that compliment another instrument's
lead break are playing a harmony (the same way that a vocalist
sings a harmony) or playing a counter-part lead that contrasts
with, but at the same time compliments, the lead. Always remember
that these backup techniques should be lower in volume so
as to never overpower or take away from another's lead. Also,
some fiddle players replicate the mandolin chop or banjo vamp
by a sharp abrupt stroke on the strings using the frog end
of the bow. If other instruments are already providing the
backbeat, then it is not that interesting for the fiddle to
provide this element. A fiddle can also add fullness by playing
slow moving "string" parts consisting of half or
whole notes. This is particularly effective in slower songs.
One final word about loudness. It is really important to
adjust the level of the backup to match the level of the lead.
Since the level of the lead often changes dramatically during
a song, you must change too. A banjo at full cry can be very
loud, and you may need to play flat out to blend. On the other
hand, a soft voice or a guitar lead may be very soft,
and you will need to cut way back. The basic rule is always
listen to the music, not just to what you are playing
but what the whole jam session is playing, and continuously
adjust. The music will sound better, you will enjoy it more,
and the other jammers will enjoy you more.