An effects processor, or FX processor, is a digital device that changes the signal of an electric guitar to add special effects. It is usually used as a preamp device that sends the processed signal to the guitar's amplifier, but an effects processor can also be built into a personal headphone amp. Though some amplifiers can create effects like overdrive, distortion, echo, tremolo and reverb, in most cases the effect must be "dialed" manually. In a live show a guitarist must switch from one effect to another in the course of a beat. While some amps provide a remote foot pedal, a digital processor can change between several effects instantly with the stomp of a foot.
Many people are familiar with "effects pedals." A simple effects pedal might only produce one effect —- for instance, distortion. Stomping on the pedal once will turn distortion on, while stomping again turns it off to revert to the "clean" amplified sound. If the amp is set to produce its own effect, such as overdrive, the guitarist can easily switch between two effects.
A programmable effects processor can produce from dozens to over 100 special effects. It might include up to three or more pedals, and the guitarist can cycle through the "digital patches" silently by depressing a pedal while watching a LED screen. Utilizing "user patches" to copy needed effects, the processor can be programmed in advance to store desired effects near each other.
Another advantage of an effects processor is that one can create unique patches by applying compression, echo, gain, reverb and more to existing patches. Many models also include amp and cabinet modeling to emulate the sound of various famous amplifiers and cabinet combinations. Some even create acoustic environments like "Concert Hall," "Club" or "Arena."
An effects processor usually includes an on board digital tuner, and virtually all models provide a line-in jack for playing along with your favorite music. To help you learn riffs, some can digitally record a small section of a song to be played back at slower steps without changing the pitch. You can figure out the lick, practice along, and increase the tempo until you can play it at normal speed. The processor is also a great tool for the personal recording studio, and many digital recorders now include an effects processor. Processors are also included in several headphone amps.
To stay inspired to write or play, beginners can use an effects processor to gain the same wide range of acoustic capabilities the pros have at a nominal price almost anyone can afford. These processors are available online and nearly everywhere guitars are sold. Features range between manufacturer and models, so shop before buying. Prices range from US$99 to US$300 or more, depending on make, model and features.