p - Density of air at STP 1.18 kg/m^3.
P - Refer to Power or Peta
Pa - Refer to Acoustical Power
Pain Generator(s) - A name given to a type of siren that is specifically designed to produce a sound of the proper volume and pitch so as to cause physical pain to a thief's ears.
Pair - Also referred to as pairing, the term is used to describe wirelessly connecting two or more compatible Bluetooth devices to one another. Where numeric keypads are present on one (or both) devices, often a code is required for first time pairing. Once paired, the devices can operate with one another using their established Bluetooth profile(s).
PAL - Refer to Phase Alteration Line
Panic - The name given to the feature of a security system that provides the ability to the operator to cause the system’s siren to sound at will. The panic feature is typically initiated either by pressing a button or buttons on the remote control transmitter by keypad command, by push button, or by toggle switch.
Parallel - Lines, planes, surfaces, or objects, side by side and having the same distance continuously between them.
Parallel Wiring - A circuit in which two or more devices are connected to the same source of voltage, sharing a common positive and negative point, so that each device receives the full applied voltage.
Parallel/Series Wiring - A combination of parallel and series circuits wired together to produce a certain voltage or impedance. This is typically used in wiring subwoofers and speaker voice coils together or individually to offer more options of impedance.
Parametric - A type of equalizer with adjustable parameters such as center frequency and bandwidth (Q) as well as amplitude.
Parasitic Current Draw - A term that describes the amount of current consumed by a circuit when it is not performing any work or otherwise “at rest”. Also refer to Quiescent Current or Standby.
Pascal (PSI) - the SI unit of pressure, equal to one newton per square meter, approximately 0.000145 pounds per square inch, or 9.9 × 10-6 atmospheres.
Passive - A component that does not generate or control electrical current (as opposed to an “Active Device”). In audio applications, this usually refers to a piece of gear that does not include an amplifier as part of its design. For example, active speakers are self-powered, while passive speakers require an external amplifier in order to reproduce sound.
Passive Arming - The ability of some security systems to arm without requiring any direct action from the operator of the vehicle
Passive Radiator - a device that looks just like an ordinary driver, except it has no magnet or voice coil. A radiator is usually a highly compliant device, with a similar cone material and surround found on regular active drivers. The radiator must usually be at least as large (or larger) than the driver it is aligned with. The passive radiator is tuned to Fb and used in place of a port, providing bass reinforcement for the driver in a similar fashion as any regular ported box. A clear advantage of the radiator is the absence of port noise, and some audiophiles claim the radiator provides a better sounding bass than a ported enclosure. Disadvantages include difficulty in tuning, and the extra required baffle area for the radiator. Most radiators can be tuned with either weights or silicone, adding material in a balanced manner until Fb is attained.
Passive Crossover - uses inductors (coils) and capacitors to direct proper frequencies to appropriate drivers. These crossover systems can be simple (First Order = 1 component @ -6 dB/octave slope) to complex (Fourth Order = 4 components @ -24 dB/octave slope).
PDA - Refer to Portable Navigation Device
Pe - Term referring to electrical power
Peta (P) - A prefix meaning 1015 or 1,000,000,000,000,000
Peak Power - Peak power is measured during a brief musical burst, such as a sudden drum accent. Some manufacturers display peak power ratings on the face of their products. The RMS power rating is more significant, and we recommend using it for comparison purposes.
Phase - The relative position of two sound waves with respect to each other.
Phase Alteration Line - This describes the color television broadcast standard used in many Western European countries (except France), the Middle East, and parts of Africa and South America.
Phase Cancellation - Is an acoustic phenomenon in which two or more “out of phase” sound waves result in weakened or lost frequencies. When two identical frequencies are cycling 180° opposite each other, complete phase cancellation occurs. Also referred to as wave cancellation.
Phase Shift - Frequency interaction in the crossover region of passive crossovers which can cause some frequencies to be delayed with respect to other frequencies.
Photo Detector (photo diode) - A semiconductor device which provides variations in current as a function of light intensity.
Phone Book Access Profile (PBAP) – This profile makes information from the mobile’s phone book available in the hands-free car kit and is part of the enhancements to the Hands-Free Profile (HFP 1.5V or higher). This includes common features from the mobile phone such as enhanced call control, phone status indicators, response and hold, and information about the subscriber number linked via the phone’s address book. Audio quality is also enhanced over HP (talk and listen only) profile, which is a viable selling point for more premium kits and where an installer must consider microphone placement and how the audio will be heard from the caller (through existing speakers or via separate, stand alone speakers).
Piezo Electric Tweeter - A very efficient, highly directional tweeter which operates without a crossover or magnet. Driver creates sound when a quartz crystal receives electrical energy.
Pink Noise - Sound with all frequencies perceptible to the human ear reduced to an equal energy level.
Pink Noise Generator - A device used to generate pink noise that usually includes a calibrated microphone.
Pinswitch - A simple spring-loaded mechanical switch used in many different vehicles designed to turn on interior lights when doors are opened. Pinswitches are also used in the installation of most security systems in the hood or trunk/hatch as a means of triggering the system should these points be opened
Pit - One of the depressions that represents data in a compact disc. May also be referred to as bumps, this is what the pick up sees.
Plate Speaker - A speaker that has two drivers mounted side by side on a flat surface.
Plastic Optical Fiber (POF) - Also known as Polymer Optical Fiber, it is an optical fiber that is made out of polymer. Similar to glass optical fiber, POF transmits light (for illumination or data) through the core of the fiber. Its chief advantage over the glass product, other aspect being equal, is its robustness under bending and stretching.
Plexiglas - a solid transparent plastic made of polymethyl methacrylate (the same material as perspex or Lucite).
PND - Refer to Portable Navigation Device
POF - Refer to Plastic Optical Fiber
Polarity - A very simple concept. Any electrical signal has polarity, and it is a reference to the signal's position or voltage above or below the median line. A device which inverts the polarity of a signal will simply swap positive voltage to negative voltage and vice versa
Pole Mount - A common automotive speaker design with the high frequency driver mounted on a center pole. Newer designs mount the high frequency driver in the same location above the lower frequency driver with a bridge. This prevents problems such as dust and dirt from entering at the base of the pole.
Polyfill (Poly-fil) - is typically nondirectional weaved padding made from polypropylene fibers that maybe used inside loudspeaker enclosures to cushion the back wave. This provided cushion to the back wave tricks the subwoofer into operating as if the enclosure has more inner air volume than it truly offers. Polyfill is ideal in applications when there is not enough space for a needed larger enclosure or when the enclosure used simply does not offer the inner air volume needed for the sub to operate efficiently.
Polypropylene - Also known as polypropene is a thermoplastic polymer used in a wide variety of applications. In the Car Audio world its main uses are in speaker and subwoofer diaphragms, electrical tape, and also as fibers in the case of Poly-fil. It is typically manufactured using the injection molding technique.
Positive Polarity - A reference to the signal's position or voltage above the median line.
Portable Navigation Device (PND) - Also referred to as a Personal Navigation Device or Personal Navigation Assistant, is a portable electronic product which combines a positioning capability (such as GPS) and navigation functions. Some PNA devices are PDAs with limited features and can be unlocked.
Ported Enclosure - A type of speaker enclosure that uses a duct or port to improve efficiency at low frequencies. Excellent design for lower power systems, as the port often adds up to +3 dB to low frequency efficiency. F3 can be set considerably lower with proper design, although low frequency roll-off is generally -24 dB/octave. Good transient response with proper tuning, although the driver loses damping below the tuning frequency. Excellent power handling about Fb, but source material or frequencies below Fb cause the driver to progressively perform as if it were not enclosed at all. Due to this, ported enclosures without a low frequency filter may have lower power handling compared to other designs. More difficult to properly build and tune than a sealed enclosure, with several "optimum" alignments available depending upon the Qts of the driver.
Potentiometer - Often thought of as a fancy word for “knob,” a potentiometer is basically any mechanism that controls input or output voltage by varying amounts (for example, panning a signal left/right, volume control, or the amount of signal sent to an aux send or bus. Potentiometers can be knobs or faders, meaning that almost every control on a console that isn’t a button or switch is a potentiometer. However, many engineers commonly refer to faders as “faders” and knobs as “pots.”
Power (P) - The time rate at which work is done or the rate at which energy is used. Basic equations for Electrical Power are: P = V^2/R or P = I^2*R.
Power Cell - A single unit for producing DC electricity by electromechanical or biochemical action. A common 12.66V vehicle battery is composed of a number of individual cells connected together. Each cell is typically rated at 2.11 volts; a common automotive battery is composed of six separate two-volt sells.
Power Handling - Total system power refers to the total power consumption of the unit, rather than the power handling of the speakers or the power output of the amplifier. In some cases, an audio device may be measured by the total system power of all its loudspeakers by adding all their peak power ratings. Also often referred to and noted as RMS or Dynamic Watts.
Power Line Noise - A varying AC ripple that is found riding on a DC voltage. It is recognized by a whining that varies with engine speed.
Power Windows - The feature where the opening and closing of the vehicle’s windows is performed by some mechanical means other than human power. Power windows are typically operated by electric motors.
Power Supply Capacitor - A polarized, large value capacitor specifically intended to stabilize supply voltage during periods of peak current demand. Also called a “Stiffening Capacitor”.
Pre-amp Fader - A circuit that allows effective level control of two amplifiers, built in and external without loss of power.
Preampilfier (Preamp) - A low-noise amplifier designed to take a low-level signal (for example, from a microphone) and bring it up to normal line level before sending it into the mixing console.
Prefab Enclosure - Refer to Prefabricated Enclosure
Prefabricated Subwoofer Enclosure (Prefab Enclosure) - A style of subwoofer enclosure that is built in mass amounts for many different types and specifications of subwoofers. Many times a less expensive route.
Presence Frequencies - The range of audio frequencies between 4 kHz and 6 kHz that when boosted, can increase the sense of presence, especially on voices.
Preset - A factory programmed set of parameters on a synth, signal processor, plug-in or other electronic device.
Professionalism - The competence or skill expected of a professional.
Protons - These make up part of the nucleus of a ll atoms except hydrogen, whose nucleus consists of a single proton. In neutral atoms, the number of protons is the same as the number of electrons. In positively charged atoms (as in electricity conductive materials), the number of protons is greater than the electrons outnumber protons.
Proximity Sensor - A common term for a spatial-type sensor that can be either the radar, or infrared type. Also refer to Spatial Sensor.
PSI - Refer to Pascal or Pound per Square Inch
Pulsed Output - An output of a security system usually used to flash parking lights or honk horns; it is pulsed or turned on and off by the security system. In some cases an output may be programmable to behave this way when activated.
Pulse Width Modulation (PWM) - A fancy term for describing a type of digital signal. Pules width modulation is used in a variety of applications including sophisticated control circuitry.
Push-Pull Configuration - Refer to Isobaraic
PWM - Refer to Pulse Width Modulation