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Electric Instruments & Pick Ups

Electric Definitions

1. The return of a portion of the output of a process or system to the input, especially when used to maintain performance or to control a system or process.
2. The portion of the output so returned.
3. Sound created when a transducer such as a microphone or electric violin picks up sound from a speaker connected to an amplifier and regenerates it back through the amplifier.

IMPEDANCE - (Symbol Z) A measure of the total opposition to current flow in an alternating current circuit, made up of two components, ohmic resistance and reactance, and usually represented in complex notation as Z = R + iX, where R is the ohmic resistance and X is the reactance. Also, and analogous measure of resistance to an alternating effect, as the resistance to vibration of the medium in sound transmission.

PICKUP - Takes signals (in the form of magnetic disturbances, pressure, etc.) from the physical world and converts them into current/voltage signals.

PIEZO - Unlike magnetic pickups, piezo elements (which are usually used on most acoustic-electric instruments) transmit sounds into electrical impulses by mechanical pressure on certain crystals (notably quartz or Rochelle salt); alternatively, electrostatic stress produces a change in the linear dimensions of the crystal. The presence of electrical resonances and anti-resonances make the piezoelectric impedance unique. The resonances result from the electrical input signal exciting a mechanical resonance in the piezo element. For each mechanical resonance in the piezo element, a resonance/anti-resonance pair will exist in the impedance. This characteristic piezoelectric impedance can be modeled by an equivalent circuit. Most of Shar's electric instruments have built-in preamps that perform this function. Pickups purchased separately for installation should use an external preamp by Fishman or LR Baggs.

TRANSDUCER - An electrical device, such as a piezoelectric crystal, microphone, or magnetic pickup, that converts input energy of one form into output energy of another.

PREAMP (or PRE-AMPLIFIER) - An electronic circuit or device that detects and strengthens weak signals, as from a radio receiver, for subsequent, more powerful amplification stages.

AMPLIFIER - A device, especially one using transistors or electron tubes, that produces amplification of an electrical signal.

MIDI - An acronym for "Musical Instrument Digital Interface." It is essentially a software language that allows digital instruments or devices to communicate with each other. It is very useful in executing such operations as scrolling through electronic menus, accessing presets on effects processors or "loops" from a digital sampler, synchronization of multiple devices, sequencing, information transfers, and of course digital synthesis (or the accessing of digitally synthesized sounds that are not otherwise available to the instrument being played). In order for a digital instrument to be MIDI compatible, it MUST have at least a “MIDI-output" and ideally a "MIDI-input" as well as a "MIDI-through" port.

Electric instrumentalists often employ the use of various effects units in the form of "stomp boxes," rack mount units, computer software, or effects that are already built into the amplifier (like the Fender Acoustasonic 30 amp). A brief overview of the effects most often used its organized into 5 different categories.

Category 1: Dynamics

COMPRESSOR - The gain of the amplifier is varied to reduce the dynamic range of the signal. This effect is featured on the Fishman Pro EQ Platinum Preamp.

TREMOLO - Tremolo produces a periodic variation in the amplitude (volume) of the note. A sine wave applied as input to a voltage-controlled amplifier produces this effect.

Category 2: Tone

OVERDRIVE and DISTORTION - The signal is amplified past the limits of the amplifier, resulting in clipping. Violinists who have employed the use of overdrive and distortion include Jean Luc Ponty, Vanessa Mae, and Mark Wood.

WAH-WAH - An effect that gives the instrument an almost vocal effect, familiar as the wah-wah pedal. Example: "Eternity's Breath" by the Mahvishnu Orchestra, used by violinist Jean Luc Ponty. Popular in funk and psychedelic rock (i.e. Jimi Hendrix).

RING MODULATION - An audio effect performed by multiplying two audio signals, where one is typically a sine wave or another simple waveform. It is referred to as "ring" modulation because the analog circuit of diodes originally used to implement this effect took the shape of a ring.

EQUALIZER - Adjusts the frequency response in a number of different bands of EQ. Variants include the Parametric EQ, which instead of flatly boosting and cutting frequencies, curves the frequency response to include changes in adjacent frequencies. Preamps by Fishman and LR Baggs also double as equalizers.

CLEAN BOOST (or any other "Booster) - Amplifies some aspect of the instrument's signal output. Generally used for preventing signal loss through long chains of effects units (pedals) and getting overdrive tones out of a tube amp. On stage, used for volume boosts for solos.

TALK BOX - A vowel-tuned wah that actually takes a human voice as the wah control. Peter Frampton made this effect famous with songs like "Show Me The Way."

Category 3: Time-Based

DELAY - First used by Les Paul, e.g. I'm Forever Blowing Bubbles. Modern digital delay units, the first of which was the Eventide Harmonizer, involve sound waves being converted from analog to digital signals, and clocked through large banks of RAM memory. Paul achieved time delay by stretching audiotape between two reel-to-reel tape decks spaced several feet apart.

ECHO - Uses delays to simulate an echo.

CHORUS - Usually short delays to simulate more than one person playing at a time.

FLANGING - Uses very short variable delays to cause a changing comb filter effect.

REVERB - Simulates echoes in stadiums, halls, other performance areas. Even actual surfaces, such as plate metal and metal springs, are sometimes simulated.

Category 4: Frequency

PITCH SHIFTER - Also introduced by the Harmonizer which has a knob on the front to "change your pitch up."

VIBRATO - Vibrato refers to a variation in frequency of a note, for example as an opera singer holding one note for a long time will vary the frequency up and down. A sine wave applied as input to a voltage-controlled oscillator produces this effect.

Category 5: Other Specific Effects

DEFRETTER - Simulates a fretless guitar.

ACOUSTIC GUITAR SIMULATOR - Simulates an acoustic guitar. Example: Boss AC-2.

ROTARY SPEAKER - A Leslie speaker simulation effect. One particular effect of this type (the Uni-Vibe) was made famous by Jimi Hendrix.

ENVELOPE FOLLOWER - Uses the signal amplitude envelope to control one or more effects.

PICKUP SIMULATION - Simulates either a single-coil pickup if the musician has a humbucker or vice-versa.

AMBIENCE MODELING - Creates an ambience through an amalgam of effects.

GUITAR AMPLIFIER MODELING - Models instrument tone to imitate the tone produced by various amplifiers, especially to attain the valve sound with solid-state equipment. These types of effects are usually digital, and can therefore be found as features of effect processors.