F3 - A -3dB cutoff frequency, in Hz
Fade - The act of minimizing or maximizing the volume of the vehicle stereo to the front or rear, and vice versa.
Fader - A fader is a control that allows you to balance the sound in a four-speaker system from front to rear. When used with a balance control, you can adjust the sound level from front to rear, and from right to left.
Farad (F) - The basic unit of capacitance. A capacitor has a capacitance of 1 Farad when a charge of 1 votl across the capacitor produces a current of 1 ampere through it. Named after Michael Faraday. There are one million micro-farads (mF) in 1 Farad.
Fb - Enclosure resonance (usually for bass reflex systems), in Hz
Fc/ Fcb - System resonance (usually for sealed box systems), in Hz
Federal Communications Commission (FCC) - The U.S. government agency that overseas and regulates electronic communications.
FET - Refer to Field-effect Transistor
Fidelity - A term used to describe the accuracy of the recording, reproduction, or general quality of audio processing.
Field-effect Transistor (FET) - a transistor that uses an electric field to control the electrical behavior of the device. FETs are also known as unipolar transistors since they involve single-carrier-type operation. Many different implementations of field effect transistors exist.
Filter - An active or passive circuit or device designed to block a certain frequency or range of frequencies. Often any electrical circuit or mechanical device that removes or attenuates energy at certain frequencies.
Firewall - Is the part of the automobile body (unibody or body-on-frame) that separates the engine compartment from the passenger compartment (driver and passengers). It is most commonly a separate component of the body or, in monocoque construction, a separate steel pressing, but may be continuous with the floorpan, or its edges may form part of the door pillars.
FLAC - Refer to Free Lossless Audio Codec
Flashing Lights - A term used to describe the interfacing of the vehicle's parking lights, dome light, emergency lights, etc., with a security system so that the lights flash by the security system.
Flat Response - Also referred to as Flat Frequency Response, is an output signal in which fundamental frequencies and harmonics are in the same proportion as those of the input signal being amplified. A flat frequency response would exhibit relatively equal response to all fixed-point frequencies within a given spectrum.
Fletcher Munson Curves - Similar to Equal Loudness Contour curves, this is a drawing of several curves showing how loud the tones of different frequencies would have to be played for a person to say they were of equal loudness. A set of curves that depict the uneven frequency response of human hearing that are extremely dependent upon relative loudness. The curves show the human ear to be most sensitive to sounds in the 2 kHz to 4 kHz area. This means sounds above and below 2-4 kHz must be louder in order to be heard just as loud. For this reason, the Fletcher-Munson curves are referred to as “equal loudness contours.”
Floating Ground - A non-common grounding point. A point of ground that does not share the same ground point as any other component in the vehicle. A singular ground point.
Flux - The flow of magnetic energy in a circuit.
Flux Density - the magnitude of a magnetic, electric, or other flux passing through a unit area.
Flux Capacitor - A Flux Capacitor is typically used to leap through time and other forms of time travel. In our time the Flux Capacitor is known to be powered with Plutonium. The Plutonium is used by the on-board nuclear reactor which then powers the Flux Capacitor to provide the needed 1.21 Gigawatts of Electrical Power. Once properly installed into the time machine the Flux Capacitor will need to reach 88 mph (142 km/h) to activate time travel.
FM - Refer to Frequency Modulation
FM Mono Sensitivity - This figure tells you how well a CD receiver can pick up FM radio signals. The smaller the number, the greater the ability to pick up weaker stations. Expressed in decibel femtowatts (dBf).
FM Stereo Separation - A measure of the ability of an FM tuner to re-create a vivid stereo effect. Measured in dB (decibels), the higher the figure the better.
FOB - Free on Board. The term designating that the purchaser pays freight from the time the shipment is placed aboard a truck or train. Legal title for the goods passes to the buyer at this time and location. Not to be confused with the electronic vehicle key referred to as a fob.
Fob - Refer to Key Fob
Focus Lens - The lens in the optical block of a compact disc player which focuses the laser light onto the surface of the disc.
Focus Servo - The circuit which keeps the laser light correctly focused on the pit area of the disc.
Ford Motor Company - Is an American multinational automaker also known as Ford. It was founded by Henry Ford and incorporated on June 16, 1903.
Free Air - Which means of free air. Air not under restraint (as by pressure or flow). Normal atmospheric air.
Free Air Resonance (Fs) - Driver free air resonance, in Hz. This is the point at which driver impedance is maximum. "This parameter is the free-air resonant frequency of a speaker. Simply stated, it is the point at which the weight of the moving parts of the speaker becomes balanced with the force of the speaker suspension when in motion. If you've ever seen a piece of string start humming uncontrollably in the wind, you have seen the effect of reaching a resonant frequency. It is important to know this information so that you can prevent your enclosure from 'ringing'. With a loudspeaker, the mass of the moving parts, and the stiffness of the suspension (surround and spider) are the key elements that affect the resonant frequency. As a general rule of thumb, a lower Fs indicates a woofer that would be better for low-frequency reproduction than a woofer with a higher Fs. This is not always the case though, because other parameters affect the ultimate performance as well."
Free Air Response - The frequency at which a speaker will naturally resonate.
Free Lossless Audio Codec (FLAC) - An audio format similar to MP3, but lossless, meaning that audio is compressed in FLAC without and loss in quality.
Frequency - The number of occurrences of a particular event within a certain amount of time. In audio and acoustics, frequency specifically refers to the number of complete cycles a vibration or waveform makes in a second, measured in cycles per second, or Hertz (Hz). In sound, frequency determines what we hear as pitch. The longer the wavelength, the fewer the cycles per second, and the lower the pitch.
Frequency Modulation (FM) - A method of sound synthesis in which the frequencies generated by one oscillator (the carrier) are altered by the output of one or more additional oscillators (operators) to create a diversity of harmonically rich sounds.
Frequency Response - A term that describes the relationship between a component’s input and output with regard to signal frequency and amplitude.
Front-stage - This typically refers to the speakers in the front of a vehicles sound-stage. Typically just the front vehicle cabin speakers, as opposed to the cabin rear speakers.
Fs - Refer to Free Air Resonance
Full-range - A speaker designed to reproduce all or most of the sound spectrum within human hearing (20Hz - 20KHz).
Full Wave Rectification - A circuit which converts an AC voltage into a pulsating DC voltage. It uses two diodes of which one conducts during one half cycle while the other conducts during the other half cycle of the applied AC voltage.
Fundamental Frequency - The original frequency component of a harmonic series.
Fundamental Tone - the tone produced by the lowest frequency component of an audio signal.
Fuse - A device designed to provide protection for a given circuit or device by physically opening when the current being drawn through it exceeds its designed rating.
Fusible Link - Designed to perform the same task as a fuse, but resembles a wire. Fusible links are commonly used in ignition switches and other high-current circuits.