Gear Glossary

AC: Alternating current; a form of electric current that oscillates with a specific frequency. AC most commonly refers to the current that comes from electrical outlets, but a musical signal travelling through a cable is AC, analogous (in amplitude and frequency) to the sound waves we hear. Compare DC.

Active electronics: Amplification circuitry built into an instrument, requiring a source of power (usually a 9-volt battery). In an active pickup, the circuitry is built into the pickup housing. Compare passive electronics.

Alnico: A combination of aluminum, nickel, and cobalt, commonly used to make pickup magnets.

Analog circuit: A circuit that carries an AC signal whose waveform is analogous (in frequency and amplitude) to the sound wave it represents. Compare digital.

Balanced line: A signal cable or output jack that uses 3-pronged XLR connectors to reduce noise. Two of the prongs carry signals that are identical but 180 degrees out of phase. At the end of the line, the reverse-phase signal is brought back in phase and added to the other signal; this cancels out noise picked up along the line, but doesn't affect information that was in the line at the beginning.

Biamping: An amplification method in which a signal is split into two signals (one predominantly low frequencies and the other predominantly high frequencies), each signal going to a separate power amplifier. A bi-amped signal tends to sound clearer than a mono-amped signal.

Ceramic: A mixture of metal and a clay-based substance, commonly used to make pickup magnets.

Chorus: A delay-based effect that simulates two or more instruments playing in unison. See Gadgets & Gizmos, July/Aug '93.

Combo amp: A preamp, power amp, and speaker cabinet in a single unit.

Compressor: An effect that reduces dynamic range. A compressor often makes a bass sound punchier by putting each note more or less at the same volume. See Gadgets & Gizmos, July/Aug '93.

Crossover: A circuit that divides the audio spectrum into two or more parts; these parts can be amplified separately and sent to separate amplifiers or speaker systems. See biamping.

Cryogenic treatment: A process of slowly cooling strings to extremely low temperatures, in order to increase string longevity and reduce micro-irregularities in the metal.

dB: See decibel.

DC: Direct current; a steady stream of electrons, such as the current produced by a battery. Compare AC.

Decibel: A unit that expresses amplitude, loudness, or intensity.

De-esser: A circuit designed to reduce excessive sibilance ("s" sounds) when using a microphone.

Digital circuit: A circuit that converts a signal into a number-based digital signal, performs mathematical calculations on the digital signal (such as creating reverb effects), and converts the signal back into a waveform-based analog signal. Compare analog circuit.

Direct box: A device that takes the signal from your bass and converts it to low-impedance balanced line, which can then be sent to a recording console or PA mixer.

Driver: Another word for speaker: the sound-producing unit (cone, voice coil, magnet, and frame) that is mounted in a speaker cabinet or enclosure. Note: Sometimes the word "speaker" is also used interchangably with "cabinet" or "enclosure."

Dynamic range: The range of loudness, in decibels, that an instrument, amp, or other device can handle. It's the difference between the quietest possible signal (where the signal and the "noise floor" are at the same level) and the loudest (where significant distortion sets in).

Effects loop: A set of jacks that breaks the circuit of a preamp or amplifier and lets you add a device (such as an effect box) inside the signal chain of the unit. An effects loop normally consists of a "send" jack, which outputs a signal, and a "return" jack, which receives the signal and thus completes the circuit.

Enclosure: See speaker cabinet.

Envelope follower: An effect that rolls off high frequencies as the signal level decreases. The sound is similar to that of a wah-wah pedal, since EQ sweeps follow the decay of each note.

Equalizer: An effect, often built into amps, that lets you boost or cut certain bands of the frequency spectrum, thus changing the tone. See Gadgets & Gizmos, July/Aug '93.

Exciter: A circuit designed to make a signal sound more clear, punchy, bright, or loud, without the use of ordinary EQ or gain.

Expander: A circuit that increases dynamic range by making the loudest notes louder and the softest notes softer.

Flanger: A delay-based effect that produces a "whooshing" sound that sweeps across the frequency spectrum. See Gadgets & Gizmos, July/Aug '93.

Flatwound strings: Strings made of a core wrapped with a flat, ribbon-like winding material. Compared to roundwounds, flatwounds produce less finger noise, but they tend to be dull-sounding. See The Controversial World Of String Design.

Folded horn: A speaker cabinet design that reflects and then projects sound into a room. On their own, folded horns produce loud, deep bass, but not much highs--so they require additional high-end drivers (sometimes built into the cabinet). See Cabinet Basics 101.

Graphite: A form of carbon used in instrument construction. Graphite fiber, when set into resin, has a high stiffness-to-weight ratio and provides strength and stability to bass necks.

Groundwound strings: Roundwound strings that have been ground or burnished to reduce finger noise and fret wear. See The Controversial World Of String Design.

Half-rack: A format for mounting equipment. Two half-rack units mounted side by side take up one space in a standard 19" rack.

Half-round strings: See groundwound strings.

Head: A preamp and power amp in a single unit. Sometimes called a top or brain.

Hertz: A unit that expresses frequency; 1Hz is equivalent to one waveform cycle per second.

Highpass filter: A component of a circuit that lets high frequencies pass but cuts low frequencies.

Humbucking pickup: A pickup that cancels electromagnetic noise (hum) by using two coils wired out of phase and two magnets oriented with opposite polarities. See Selecting A Pickup, April '95.

Hz: See hertz.

Impedance: The AC equivalent of DC resistance; impedance can be thought of as a load on a signal. It's important to consider impedances when connecting any two electronic devices, such as amp and speaker or pickup and amp.

J pickup: A bright-sounding bar-shaped pickup associated with the Fender Jazz Bass. J pickups usually have a single coil, but some J's are double-coil humbuckers. See Selecting A Pickup April '95.

Limiter: An effect that sets a maximum output level. If a signal is limited, once the limiter's threshold level is reached, increased input won't result in increased output. See Gadgets & Gizmos, July/Aug '93.

Lowpass filter: A component of a circuit that lets low frequencies pass but cuts high frequencies.

MIDI: Musical Instrument Digital Interface--the digital language that MIDI-equipped devices use to communicate with one another. Bassists can use MIDI to automate effect-program changes or to drive synth modules with a MIDI bass controller.

MIDI controller: Any musical instrument that produces MIDI signals.

Multi-tap delay: A delay that produces multiple independent echoes rather than one echo.

Neck-through-body design: An instrument-building method in which the neck passes all the way through the body, and the body is actually two "wings" glued onto the side of the neck block.

Noise gate: A circuit that reduces the output level when no signal is coming through, thereby reducing noise and increasing the signal-to-noise ratio.

Onboard: Built into an instrument.

Overdrive: A circuit that boosts signal and/or adds distortion.

P pickup: A warm-sounding pickup (split into two staggered halves) associated with the Fender Precision Bass. See Selecting A Pickup, April '95.

Parametric EQ: An equalizer that lets you specify the frequency band(s) it is affecting. See Gadgets & Gizmos, July/Aug '93.

Passive electronics: A circuit that requires no external power source. Compare active electronics.

Peak EQ: A type of EQ band with a frequency center that can be cut or boosted, with reduced effect on surrounding frequencies. Compare shelving EQ.

Phantom power: A feature of an amplifier, mixer, etc., that sends DC current to the active electronics of a microphone, instrument, or other device.

Phaser: A delay-based effect that produces a liquid, shimmering sound. See Gadgets & Gizmos, July/Aug '93.

Phenolic: A synthetic resin commonly used in fingerboards. Also called ebonol.

Pickup: A device that turns the mechanical energy of string vibration into electrical energy (an AC signal).

Piezoelectric pickup: A non-magnetic pickup, commonly used in upright basses and acoustic bass guitars and occasionally in electrics. The mineral-crystal substance in a piezoelectric generates a voltage potential when vibrated or stressed. Piezoelectrics, which have high impedances, need to be buffered by an appropriate preamp in order to produce a good sound. See 10 Transducers for Acoustic Upright Bass, June '96.

PJ configuration: A pickup arrangement in which a P pickup is near the neck and a J pickup is near the bridge.

Pot: Short for potentiometer, a variable resistor used in tone and volume controls.

Preamp: An amplifier circuit that takes the signal from an instrument (or in the case of an onboard preamp, a pickup or set of pickups) and alters its impedance and/or amplitude, thereby preparing the signal for a power amp. Preamps may also include EQ sections, compressors, effects loops, etc. See Bass Amp Basics, July '92.

Pre-post switch: A feature, sometimes found on preamps, that lets you bypass the EQ section, giving you a "pre-EQ" output signal.

Programmable: Capable of storing user-customized data, such as EQ settings or effect configurations.

Quarter-round strings: See groundwound strings.

Rackmount: Designed to be installed in a standard 19"-wide equipment rack.

Rackmountable: Capable of being installed in a standard 19"-wide equipment rack, but designed to be used elsewhere also (such as on a tabletop or floor).

Relief: The slight up-bow that a neck needs to avoid fret buzz.

Reverb: An effect that simulates the sound of playing in a room or hall. See Gadgets & Gizmos, July/Aug '93.

RMS: Root mean square. "Watts RMS" is a unit that expresses average power along a waveform, rather than at its peaks and troughs. RMS values represent true amplifier power output; figures that use terms such as "peak power" can be deceptively large.

Roundwound strings: Strings made of a core wrapped with a round winding material. Roundwound strings are bright but squeaky, and they tend to wear down frets and fretless fingerboards. Compare flatwound and groundwound strings. See The Controversial World Of String Design.

Scale length: The distance from an instrument's nut to its theoretical bridge position.

Sealed cabinet: A speaker cabinet without a vent (an opening or hole); compare vented cabinet. Sealed cabinets can handle large amounts of power and have excellent "damping" (controlled cone movement), but aren't very efficient. Sometimes called infinite baffle. See Cabinet Basics 101.

Shelving EQ: A type of EQ band (usually the lowest or highest one) which cuts or boosts all frequencies past a central frequency, with reduced effect on frequencies toward the mid bands. Compare peak EQ.

Shielding: The use of a grounded conductor surrounding the circuitry of an instrument, the wires inside a cable, or anything else that carries an electrical signal. Pickups, instrument control cavities, and audio cables should all be shielded to reduce electrostatic noise.

SMPTE: A protocol for highly precise and accurate synchronization among audio devices such as sequencers and tape machines, or between audio and video devices. (Stands for the Society of Motion Picture and Television Engineers.)

Soapbar pickup: Generic term for any rectangular humbucking pickup.

Soft-key control: The use of several buttons underneath an LCD display; the function of each button is shown by the display. Depending on the mode of the unit, the LCD can give several functions for each key, thus giving access to many parameters with just a few front-panel controls.

Solid-state circuitry: Circuitry using transistors instead of vacuum tubes to amplify signals. Compare tube.

Speaker cabinet: A unit that contains one or more drivers; speaker cabinets are often built to control and optimize the sound of the driver(s). Also called an enclosure or speaker system. See Cabinet Basics 101.

Speaker cabinet configuration: A figure that describes the size and number of drivers in a cabinet. A 1x15 cabinet contains a single 15" driver, a 4x10 contains four 10s, etc.

Subwoofer: A cabinet designed to handle very low frequencies.

True diversity: A wireless-system design in which two receivers add their signals to reduce drop-outs and other undesirable effects.

Truss rod: A rod inside an instrument neck that, when properly adjusted, counteracts the tendency for string tension to bow the neck.

Tube: An amplifier component made of glass, often used in instrument amps. Also called a vacuum tube or valve. Many players prefer the "tube sound" over the sound of solid-state amps, though tube amps tend to be larger, heavier, and more fragile than solid-state amps.

Tweeter: A small driver designed to handle high frequencies.

Vented cabinet: A speaker cabinet with a "port" (hole) in one of its walls. Vented cabinets are more efficient than sealed cabinets, but the speakers blow more easily. Also called ported cabinet. Compare sealed cabinet, and See Cabinet Basics 101.

Wah-wah pedal: An effect that adds a narrow boost sweepable across the frequency spectrum, often producing a "talking" or "quacking" sound.

Woofer: A large driver designed to handle low frequencies.

XLR jack: A 3-pronged jack commonly used with microphones and other balanced lines. See balanced line.