Electric guitars depend on electromagnetic pickups and amplifiers to produce their sound, and the very fact that they are electrical makes it possible to modify the sound electrically/electronically. The guitar and amplifier themselves have volume and tone controls, but add to this the effects you can produce with guitar pedals and the variety of sounds becomes staggering. This simple guide to guitar effects pedals will show you whats available.
All guitar effects pedals are variations of 4 main effects:
distortion/overdrive,
dynamics,
reverb/delay and
pitch modulation.
The first 2 work by reshaping the electrical signal, the second two by augmenting (enhancing) it.
Signal reshaping (distortion/overdrive and dynamics)
Vacuum tube amplifiers were originally used for processing guitar output. They had a maximum amplification like any amplifier, above which they clipped the tops off the waveforms. The distortion was found to be pleasant to many musicians so this distortion/overdrive effect became popular. Nowadays, the same effect can still be produced using a vacuum tube (the old way) and many people think this is preferable, as tubes gradually round off the peaks. Solid state (tubeless) modern devices will work by chopping off the peaks, which produces a harsher distortion than tubes. A popular example of a distortion pedal was the fuzz box.
So a circuit which prevents output signal from reaching a set limit by clipping is distortion. But you can also get the same effect by reducing the signal amplification, which is a compression. This reduces or compresses the gain of high amplitude signal. By setting the gain high on one of these effects pedals, you can get amazingly great sustain. Ring modulation takes the guitar signal and adds a second from a source or oscillator, and the output is the combined sum and difference. Pitch Shifters are microprocessor-based devices which shift the frequency base of the guitar signal. This requires a lot of processing power as it takes the sound and reconstructs it at a different frequency.
Signal augmentation The second way that guitar effects pedals work is by augmenting the signal. For example, flanging takes two copies of the signal, phase shifts one of them and mixes the results together. It comes from old reel-to-reel tape practices and creates a characteristic swirling sound. Phasing also produces a swirling sound, but without the frequency shifts. Chorus involves splitting the two signals even further apart, so that theyre more than a cycle apart in phase, when you can hear two distinct signals. Its less pronounced than flanging and phasing, and tends to thicken the sound, a little like reverb, the next effect.
Reverb adds back in copies of the original signal with time delays so short they cant be separately heard. Delay and echo both have enough delay so the delay is distinguishable to your ear.
All these effects come from the two core methods of reshaping the sound signal or augmenting it. The theory is all very well, but if youre interested in effects pedals, you need to go and try some and really get a feel for what sound you like. Pedals nowadays can create just about any sound you want, and they also come combined into sets called multi-effects pedals. With these you can combine effects for almost limitless combinations of sound.
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