Sound from electric guitar strings is converted to electrical signal by its pickups. This signal is the raw material that amplifiers use to create sound, and it is often fed directly from the guitar to the amplifier. Once the amp has received the signal, an on-board preamplifier boosts the weak signal from the guitar to a usable level. Some guitarists prefer to use separate preamps and amplifiers to better control the final sound tone.
Tonal Modulation
The audio signal passes through a series of modulators, or effects, to color the original tone and make it more pleasing to the ear Many guitarists use outboard effects pedals and processors for this purpose, but the most basic tonal coloring functions are generally handled by the amplifier. During these processes, subtle changes are made to the original signal to introduce more pleasing frequencies or other more obvious effects like delay or chorus.
Amplification and Output
Once the signal has passed through the modulation stage, it is sent through a series of vacuum tubes (similar to television or radio tubes) or digital processors that create copies of the audio signal. Each copy is slightly louder than its source, and after several copies and some signal conditioning, the final audio signal is loud enough to be sent to a speaker.
