I've talked about tremolo as a musical feature before, this time I want to go into more detail.
First things first, let's sort out the guitarists: I don't mean using the tremolo arm/whammy bar or whatever you want to call it ("handle" as my girlfriend called it - and no she won't be picking up my guitars for a while). The whammy bar creates a vibrato feature, not a tremolo. Vibrato alters pitch.
Amplitude
Tremolo is the act of altering the volume of a note or set of notes. For an electric instrument, the simplest to hear is by regularly turning the volume knob up and down. The notes fade in, fade out, fade in, fade out and so on.
It's a great tool for livening up a piece of music. The previous article on the subject covered some more ways of using it.
Recordings
Tremolo features on a lot of famous recordings. Three extreme examples are:
How Soon Is Now - The Smiths
Crush with Eyeliner - REM
What's the Frequency Kenneth - REM
But it's used more subtlely on many, many more recordings. Think of any country song and listen to the guitar. Many of the 1950s and 1960s guitar recordings had tremolo on them. Think Duane Eddy (although he mixed it with vibrato by using the whammy bar a lot). Lots of Elvis recordings featuring Scotty Moore had tremolo. This situation was accentuated and facilitated by the inclusion of tremolo circuits in the guitar amps, e.g. Vox
Types of effect
The common tremolo effect alters the amplitude or volume of the incoming signal apply a regularly repeating pattern before output. The most common pattern is the sine wave, although some FX units also allow square and sawtooth. The output signal increases, decreases, increases, decreases, etc.
The waveform applied changes how fast the signal reaches the extremes and how long it stays there before beginning the journey to the other extreme.
Depth
If the signal is applied completely at 100% depth, then the output will have no signal at the points when the applied FX is at its lowest point, conversely it will have the maximum volume when the FX is at its highest point.
Lowering the depth introduces a less radical effect, to the point that if the depth were at 0%, then there would theoretically be no difference between the input and output. As with most effects, the most appropriate depth is usually somewhere between the two extremes.
Symmetry
The waveform applied so far has been the same on both sides, i.e. going up and coming down. Altering the phase allows more time for the signal to climb and a quicker fall or vice versa. This is great for imparting a slower or a rushed feeling to the track.
Phase
For a stereo tremolo, the default set-up is to have the signal applied equally, but alternately to each channel. Changing the phase control alters the timing displacement of the second channel compared to the first, which can be used to create panning echoes or dotted note rhythms.
No Depth?
I'd usually use a tremolo inline with the signal, either at the recording stage (e.g. between guitar and amp) or at the mixing stage (as an insert). If there's no depth control, then patch the tremolo into a send and emulate the depth by the relative values of the signal and send faders.
For guitarists, if there's no depth control, then you maybe able to use it in the amp's FX loop if you've got a variable dry/wet mix. This may not work well, since the FX would be placed after the pre-amp. Depends what equipment you're using.
Playing with fingers
A classical guitar tremolo technique involves repeatedly plucking the same string with the first, second and third fingers. This is often a bass and/or melody note plucked with the thumb followed by the three fingers or sometimes a fourth is employed but the fingering changes.
The most famous example is probably Recuerdos De La Alhambra by Francisco Tárrega, although I think Agustin Barrios Mangore's Una Limosna por el Amor de Dios (Alms for the Peace of God) shows the technique more.
Various forms of flamenco use a similar technique, sometimes using the thumb plus four finger notes (not necessarily four fingers, often three fingers with one repeated) to get a 5-tuplet pattern.
Pick
For electric guitar, rapidly repeated picking of the same note gives a tremolo effect that can be used in solos. Do it too often and you'll sound you can't move your fret-hand fingers. Best to intersperse it with other techniques. Check out the Ozzy Osbourne recordings with Randy Rhoads, e.g. Tribute, to get an idea of how to fit it into a solo. He doesn't use it that often, but when he does, it works well. Nowadays, watch Matt Bellamy of Muse. There are plenty of others, but they're not coming to mind right now.
In other forms of music, e.g. drag, it can be the main feature. This is more likely to happen on the lower strings of the guitar, with a springy/slap-back reverb. Think Dick Dale. Although perhaps not part of drag, Miserlou (as featured in Pulp Fiction) is a great example of how a simple riff can lead the track. The repeated picking comes from his experience with an oud (or ud).
Part of a series by Award Sounds offering a selection of creative ideas to kick-start or rejuvenate a composition.