Combos & Effect Devices
Effect Devices
Today’s guitarist, by using some of the growing number of electronic modifiers available, can make dramatic changes to the basic tonal color of an electric guitar. Whether these changes are meaningful musically, or whether they are just effects for the sake of effect, depends strongly on the musical sense of the performer and the viewpoint of the audience. However, the more you know about an effects box, the better your chances of extracting musically satisfying sounds from it. Below are some of the explanations of how electronic modifiers actually work.
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Guitar Effects
A wah-wah is the name in guitar circles for what synthesizer players call
a filter. Filters are similar to amplifiers in that they provide gain,
but they do so in a premeditatedly lopsided way. For example, a lowpass
filter amplifies lower frequencies while reflecting higher frequencies:
conversely, a highpass filter amplifies higher frequencies while rejecting
lower ones. This principle of controlled amplification lies behind the
bass and treble controls you find on hi-fi and guitar amplifiers. Wah-wah
pedals are a third class of filter, called a bandpass filter. This type
of filter puts a large amount of gain at a specific frequency only. By
making the filter tunable (that is, having the ability to put that gain
peak anywhere within the audio frequency range), and varying the running
with a pedal, you obtain the wah-wah effect. Depending on the filter design,
you can sweep over a one octave range, or up to six or more octaves. A
wider sweep range is not necessarily an advantage, as pedal action becomes
more critical.
The name wah-wah derives from the fact that a bandpass filter is similar to the filter inside your own mouth that allows you to make ‘wah’ sounds. One of the first people to use a commercially available wah-wah was Eric Clapton, on “Tales of Brave Ulysses” from the album Disraeli Gears. Jimi Hendrix also used a wah-wah, as evidenced on virtually all his albums. Some players rock the pedal in a rhythmic fashion to accent the tempo, as in the theme from “Shaft,” whereas others use it more as a tone control, rocking the pedal slowly to accent certain guitar notes.
Fuzzboxes
A fuzzbox is another variation on the amplifier theme, but it’s an amplifier
whose gain is set at an abnormally high level. This means that even the
slightest sounds are going to be amplified so much that they overload
the fuzzboxes’ internal amplifier, causing distortion. The greater the
overload, the greater the fuzz effect. This massive gain not only adds
distortion and sustain, but increases the chance of both controlled and
uncontrolled feedback since it amplifies every little vibration the guitar
produces. You don’t necessarily need a fuzzbox to achieve the fuzz sound;
for example, by turning up your amplifier volume to an outrageously high
level, you can force your electronics and speaker to overload, again giving
distortion. In fact, one of the advantages of a fuzzbox is that you can
obtain the sound of a high volume setup at low levels. Like in the studio
or small clubs.
A variation on the normal fuzz is the triggered type. Since fuzztones are so sensitive, they tend to pick up hum, noise, and other extraneous sounds. A triggered fuzz shuts itself off if you are not plucking the strings, or if the guitar note is at the very end of a decay. Although it doesn’t sustain in as predictable a manner as a conventional fuzz, the lack of noise more than offsets this effect for certain styles of playing.
Many bass players have noted that a guitar fuzzbox
doesn’t sound all that good with bass, giving a thin sound. This is because
a fuzzbox generates many high-frequency harmonics, these high frequency
sounds tend to dominate over the original bass bottom, giving that tinny
effect.
Compressors (sustainers)
I prefer the term compressor over sustainer, because there are ways to
sustain a sound other than compression. Compressors are yet another special-purpose
amplifier circuit.
With a conventional amplifier (or preamplifier), the more signal put into it, the more signal you get out of it (up to the point of distortion, that is). A compressor does just the opposite: the more you put in, the less it gives out. Therefore, when you first pluck a guitar string, the compressor tends to reduce the output, and as the string decays, the compressor amplifies more and more to maintain a constant output. This is how it creates sustain. The mark of a good compressor is smooth compression; in other words, it doesn’t sound choppy as it adjusts to the changing signal input. Also, a compressor should have low noise. Because of the large amounts of gain available, a compressor will sometimes think its own noise is a low-level signal and try to amplify it.
Compression is so widely used in recording to limit dynamic range (otherwise, tape machines and disc cutters would not be able to handle the average live performance caused by distortion from the peaks and valleys) that it would be hard to name a record that doesn’t use it. Also, compression gives the illusion of louder volume, since the constant dynamic range gives a much higher average signal level. For this reason, it’s used on TV commercials to make the ads stand out, and many Top-40 type stations compress their overall signal to get the extra talk power.
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