# 4 Ohm Stable – The lowest impedance accepted by the amplifier will be 4 Ohm, which won’t be a problem, as most automotive speakers are 4 ohm impedance. 2 Ohm Stable – Amplifiers capable of powering speakers at lower impedance produce more power. This amp can comfortably power speakers with all channel(s) being used at a 2 ohm load. 1 Ohm Stable – An amplifier that is capable of delivering power at a 1 ohm load is usually reserved for serious subwoofers that can take the power. Please note this particular amp needs a healthy electrical system that is capable of delivering the current the amp demands. A Accessory (position) – Refers to the position of the key in the ignition switch; A wire showing 12 Volts (+) when in this position. Acoustics – The study of sound. The science of production, effects and transmission of sound waves through various mediums, and the effects of absorption, diffraction, interference, reflection, and refraction. Alternator – A device that is turned by a motor to produce AC voltage, which is then rectified (turned into DC) and used to supply voltage to the vehicle’s electrical system. Alternator Whine – A whining that is heard when the RPM of an engine increase – usually the result of a voltage differential created by more than one ground path or a poor ground path (ground loop). American Wire Gauge (AWG) – A standard of the dimensional characteristics of wire used to conduct electrical current or signals. AWG is identical to the Brown and Sharpe (B & S) wire gauge. Amplifier – Simply put, an amplifier (amp) is a device for increasing the power of a signal. The “head” unit (such as a radio or CD player) in a car has limited power and typically does not have the power to operate additional or larger speakers. When adding aftermarket components, an amplifier is often necessary to provide additional output to the speakers and subwoofers. Basically the amplifier acts as the power source for the car sound system by modulating the power generated by the car battery to allow the speakers to reach their full potential. The “gain” of an amplifier is the ratio of output to input power or amplitude, and is usually measured in decibels (dB). Amplifier, Class A/B – Class A/B amplifiers have been long known for their ability to produce great quality (Class A portion) while having efficiency better than pure Class A amplifiers. We designed specific circuitry that reduces distortion further and increasing the sound quality and power. Amplifier, Class D – In simple terms, a Class D amplifier is an electronic amplifier where the power devices, usually MOSFETs, are operating as binary switches, being either fully on or fully off. The speed of the switches must be much higher than the desired frequencies of the input signal. The amplifier uses Pulse Width Modulation (PWM) to convert the input signal to a series of pulses, which in turn drive the power devices, which deliver a changing voltage into a fixed load such as a subwoofer. The high frequency switching produces undesirable frequencies which are removed by a low pass filter, leaving only those relevant to the input signal. Class D is sometimes misinterpreted as being synonymous with “digital,” but that is not the case. All Class D amplifiers are not digital, but the term is often used for Class D amplifiers with significant amounts of digital processing in them. Class D amplifiers are noted for their very high efficiency, so they are often used where a high level of power is required, such as driving large subwoofers. Practically, efficiencies of over 90% are achievable, thus reducing the amount of heat produced. Because of their efficiency, they require a smaller heat sink which reduces size and cost. Class D amplifiers are used in many applications, including powered subwoofers, powered speakers, mobile applications (to save battery power), and bass amplifiers. While early Class D amplifiers were used mainly for subwoofers, advances have produced high power, low distortion units covering the entire audio band. Amplifier, Power – An amplifier designed for driving loudspeakers and having a higher power output than a line amplifier or preamplifier. Amplified Subwoofer – Because of the large amount of power required to drive subwoofers and produce the low frequency sound, car subwoofers must have at least one amplifier to provide enough power for the subwoofers to operate as designed. If space is a concern, powered subwoofers are available in which the enclosure has both an amplifier and a subwoofer. The performance capabilities of the amplifier and subwoofer must be matched to avoid damage to the system. Auto Loud – Automatically provides low frequency boost for listening at low levels. Auto Memory – A tuner feature that automatically finds the strongest stations in the local area, and places them in preset memories B Balance – The relative volume level between two channels, usually the left and right channels. Balance may also refer to the relative volume between front and rear channels of an audio system. Basket – The rigid frame of a speaker that supports all of its components. Bass – The low audio frequency range typically below 500 Hz (hertz). Bi-Amplification – The use of two amplifiers: one for the amplification of lower (bass) frequencies, and the other for higher (midrange and treble) frequencies. The audio signal from the head unit or pre-amplifier is passed through an electronic crossover and divided into two separated signals. These signals are sent to the respective amplifiers and their outputs are sent to the respective speakers (bass to woofers, midrange and treble to mids and tweeters through the use of passive crossovers). Tri-Amp is the use of three amplifiers in the same manner with the audio signal divided into three separate bands of frequency by the electronic crossover and so on. Bottom End – Bass response; referring to the sound qualities of the lowest frequency ranges of a speaker or audio system. Bridgeable – An amplifier when can be bridged to gain more power from the channels available. Usually the power is 2x what the normal power would be on each channel. Bridging an amp is a great way to utilize it when need to power a subwoofer when monoblock amp is not used. Please note, when bridging an amp the final speaker impedance must be no less than 4 Ω. Built-In Amp – The systems that have built-in amps will not require any additional equipment to get it connected to your existing audio system. The amplified system will need a source input and power, and you’re ready to hear your new improved addition of audio. Built-in LED – Utilizing the latest illumination technology, LED’s highlight the product and also gives a brilliant accent to it as well. C Capacitor – 1 (polarized): An electrical circuit element used to store charge temporarily, consisting in general of two metallic plates separated by a dielectric. 2 (non-polarized): A crossover component used to filter out lower frequencies and allow higher frequencies to pass. Crossover Filter – The on-board crossovers enable you to tailor the audio in your vehicle precisely. All speakers are not created equal, nor do they play equally. Each type of speaker is designed to play a certain band of frequencies. That’s where a crossover does it job, it filters out frequencies to speakers that weren’t designed to play them. There are two types of crossovers, a Passive and Active. Passive crossovers rely on components that do not require an external power circuit, and will connect in between the source unit and speaker. An Active crossover will require power to function. It’s generally more adjustable than passive, and is what is on board on our amplifiers. This equates to a better sounding audio system and longevity to your speakers. The rate at which a crossover functions is measured in “dB per octave”; generally a steeper slope is better for speakers because they can be “filtered” at a lower frequency. Clipping – Audible distortion that occurs when continuous power-to-peak power capabilities (headroom) are exceeded. “Turn it down!” Coaxial – A speaker composed of larger cone for low range frequencies and a smaller cone or tweeter for higher frequencies aligned on the same axis. A crossover network is necessary to route the proper signals to each driver. These may be passive (usually included). If the speakers are bi-amplified, an active crossover will be used to route the proper range of frequencies to the respective amplifier channels. Cone – The most common shape for the radiating surface of a loudspeaker – the part that moves air. Constant 12 V (+) – A lead, wire, or connection point that shows positive 12 volts regardless of ignition key position or any other switch; Positive terminal of 12 volt battery. Crossover Frequencies – The frequencies at which an active or passive crossover network divides audio signals, expressed in Hertz (Hz). Crossover Network – A unit that divides the audio spectrum into two or more frequency bands, the two types are active and passive. Current – The rate of flow of electricity, measured in amperes (amps). D DAC (D/A) – Digital to analog converter – a component or circuit that is used to derive or convert an analog signal from a digital one. Damping – The reduction of the magnitude of resonance by the use of some type of material. Damping Factor – The ratio of rated load impedance to the internal impedance of an amplifier -the higher the value, the more efficiently an amplifier can control unwanted movement of the speaker coil. A high damping factor is crucial for large speakers that reproduce bass. Damping factor is calculated by dividing the load (speaker) impedance by the impedance of the amplifier. Thus, a given amplifier’s damping factor will decrease as the speaker’s impedance decreases. This means an amp running at 4 ohms will provide tighter bass than at 2 ohms. dBr – A unit of measurement that indicates the decibel level relative to a reference level. Decibel (dB) – The basic unit of measurement in electronic and acoustic work – a logarithmic scale to express the difference between two values (the ratio of loudness) – the threshold of hearing is 0 dB. One dB SPL is the smallest audible difference in sound level. Named for A.G. Bell Deutsche Industrie Normen (DIN) – German (European) industrial standards. DIN size refers to the stereo size that fits most European automobiles. Digital Output – An output where the signal is in digital form to allow external processing before being converted to an analog signal Directional/Directionality – The angle at which a speaker disperses sound. Higher frequencies are narrower than lower frequencies. Tweeters are more directional than woofers. Discharge – In a capacitor, it’s the release of stored energy to a load. In a battery, it’s the conversion of chemical energy to electrical energy. Dispersion – Distribution of sound from a speaker. Distortion – Sound that is modified or changed in some way – measured as a percentage of the whole signal. Diversity Tuner – An FM tuning method which employs two antennas. The tuner can switch between the two antennas in order to attain better reception. DMM – Digital Multimeter – gives a precise reading of voltage, current, or resistance (ohms) Dome – A convex speaker shape usually used for tweeters. Double DIN – Twice the height of the standard DIN dimensions; width is standard DIN width. Driver – Synonymous with loudspeaker – The term also refers to a loudspeaker being coupled to a horn for acoustic coupling and controlled dispersion of sound. Driver Volume – the amount of enclosure airspace that is displaced by the speaker itself Dual Mode – An amplifier configuration in which both a stereo speaker pair and mono speaker system (usually a subwoofer) are simultaneously powered by a stereo amplifier Dust Cap – Part of the speaker that keeps foreign material from falling into the voice coil, which could hinder the speaker’s movement. Dynamic Range – The difference between the softest and loudest portions of sound that an amplifier or recorder can reproduce within an acceptable range of distortion – Expressed in decibels, the higher the number the better. E Efficiency – The ratio of energy output to total energy input, expressed as a percentage. With speakers, this refers to the ratio of total acoustic watts radiated to total electrical watts input. Enclosure – A box housing a speaker to separate the front sound waves from the rear sound waves. Enclosure [Sealed] – The subwoofer driver will operate in a sealed enclosure that will yield solid, tight bass. You can purchase a pre-fabricated enclosure or build one to suit your installation needs. It’s a relatively easy enclosure to build and is the smallest enclosure the subwoofer is designed for. Enclosure [Ported] – A ported enclosure is easy to spot because of the vent or port. It has a benefit over the sealed enclosure, which will output an extra 3-4dB. The enclosure is bigger, but will give you chest thumping bass with authority. An amplifier with a subsonic filter is recommend to properly tune this enclosure, so you get the most out of it. Enclosure Volume – the total amount of internal airspace of an enclosure – this includes the net, driver and vent volumes. Equalization – The process of changing the frequency balance of a signal so acoustical energy is proportional to the electrical input (or any type of relative frequency adjustment). Equalizer – A component designed to alter the frequency balance of an audio signal. F Fader – The control that adjusts the relative volume levels of front and rear speakers in a four speaker system or the front and rear pre-amplifier outputs. Farad – The basic unit of capacitance. A capacitor has a value of one farad when it can store one coulomb of charge with one volt across it. Fb – measured in Hz – the resonant frequency of the air in a port and the stiffness of the air in a ported system – also known as the tuning frequency of a vented enclosure. Fidelity – The term used to describe the accuracy of recording, reproduction, or general quality of audio processing. Fixed DIN Mount – A DIN head unit mounting system whereby no part or component is removable for security purposes Flat Frequency Response – Term for a circuit or audio system which will pass audio signals that will vary by no more than ± 1 dB usually between 20 Hz and 20 kHz unless otherwise specified. FM Stereo Separation – The FM tuner demodulator’s ability to separate left and right channel signals of FM stereo broadcast – measured in decibels, the higher the number the better. Free Air Response – The frequency at which a speaker will naturally resonate. Frequency – The number of wavelengths which pass a specific point in a specific time period, measured in Hertz (Hz) – cycles per second. Frequency Response – The lowest and highest parts of the frequency spectrum that can be reproduced by an audio component within specific limits and tolerances. Fs or Fo – measured in Hz – the frequency at which a speaker naturally resonates in free air Fuse – A device that protects electric circuits by interrupting power in a circuit when an overload occurs – rated in amperes (amps). G Gain – The amount of amplification used in an electrical circuit. Gauge (wire) – The diameter of a wire. The higher the number, the thinner the wire. Graphic (equalizer) – Refers to a type of equalizer with sliding controls that create a pattern representing a graph of frequency response changes. Ground – An electrical line with the same electrical potential as the chassis of the vehicle, most commonly negative 12 volts DC. Ground Loop – The condition created when two or more paths for electricity are created in a ground line, or when one or more paths are created in a shield or an audio cable. This can create undesirable noise such as a high pitched whine when the vehicle is running or pops and clicks when other devices are used in the vehicle. Ground Potential – In an automobile this is the electrical potential of the vehicles chassis, specifically the chassis of the alternator when the vehicle is running. A circuit, terminal or chassis is said to be at ground potential when it is used as a reference point for other potentials in the system. H Hertz (Hz) – The unit of measurement for frequency. 1 Hz is equal to 1 cycle per second. High Frequency Driver – A loudspeaker specifically designed to reproduce short, high-frequency wave lengths. The driver typically has a small, lightweight diaphragm. Tweeter. High Level Input – An input configured to accept speaker level signals. High Pass Filter – A network of elements used to attenuate all frequencies below a predetermined frequency. Frequencies above the cutoff point pass without any effect. Highs – Term which refers to a set of speaker components used to reproduce frequencies above 500 Hz as in a set of separates. Highs may also refer to tweeters which are used to reproduce frequencies usually above 2.5 kHz. Not bass. High and Low Level Inputs – Having both of these types of inputs allows owners to add an amplifier to virtually any factory, premium factory, or aftermarket source unit. High level also known as speaker level inputs simply accepts the outputs from a source unit as a signal. Low level also known as “RCA” accepts a pre-amp output signal from the pre-amp outputs of head units. I Imaging – The reproduction of sound accurately so that the listener can imagine the original environment and placement of the original sound sources accurately within within that environment. The better the imaging the more analogous the reproduced sound will be to the original. Impedance – The opposition to the flow of alternating current (AC) in an electrical circuit. Measured in ohms () – the combined effect of resistance, capacitance and inductance. Infinite Baffle – A loudspeaker baffle of infinite space that has no openings for the passage of sound from the front to the back of the speaker. Also a sealed enclosure where the internal volume is greater than the Vas of the driver Input Sensitivity Control – Adjusts the amount of input signal being fed to the amplifier stage to reduce distortion. Intermodulation Distortion (in loudspeakers) – Is the distortion generated in single cone speakers when the cone is reproducing a high and low frequency simultaneously. The high frequency peaks will be flattened off if the low frequency is distorted in any way. IPX Rating – IPX is a standard of which tells you how resistant a certain product is against the elements. It can vary from a light spray or dust to complete submersion in water. Products that have been tested and rated have been designed for the user in mind. ISO-DIN Mounting – Refers to a mounting system in which the head unit is mounted behind the dash panel with side brackets, employing factory installed trim panels (flush mounting). K Kilohertz (kHz) – 1 kHz = one thousand hertz or 1,000 times per second. Formerly kilocycles (kc) Kirchoff’s Current Law (KCL) – A law stating that the total current entering a point or junction in a circuit must equal the sum of the current leaving that point or junction. Kirchoff’s Voltage Law (KVL) – (KVL) A law stating that the voltage supplied to a DC circuit must equal the sum of the voltage drops within the circuit. L Liquid Crystal Display (LCD) – A type of digital display made of a material that changes reflectance or transmittance when an electrical field is applied to it. Load – The electrical demand of a process, expressed in current (amps), power (watts), or resistance (ohms). Loudness Control – Intended to boost low frequencies at lower volume levels and should not be used at high volume listening levels. Loudspeaker – An electro acoustic transducer which converts electrical audio signals at its input to audible waves at its output – may also refer to a given driver of a multiple speaker system and not to the whole speaker system as might a speaker. Low Frequency Driver – A loudspeaker specifically designed to reproduce long, low-frequency wave lengths. The driver typically has a large cone, magnet structure, and voice coil. Woofer. Low Pass Filter – A network of elements used to attenuate all frequencies above a predetermined frequency. Frequencies below the cutoff point pass without any effect. Lows – Term which refers to a set of speaker components used to reproduce frequencies below 500 Hz as in a set of woofers – may also refer to the low frequency drivers of a set of separates. Not treble. Low Profile – The low profile of the driver can fit it many depth constrained spaces that are in many modern vehicles. We have designed the drivers motor, suspension, and cone to allow for audio performance that isn’t compromised because of the lack of basket depth. M Magnetic Structure – The part of loudspeaker comprising the magnet, pole piece, back plate and top plate Midrange Driver – A midrange driver is a speaker that produces sounds in between the low frequencies of a woofer and the high frequencies of a tweeter. Typically the frequency range is from about 300 to 5000 Hz. They are often used in three-way multi-driver speaker systems to complement the low frequency woofers and the high frequency tweeters. As it turns out, midrange drivers produce the most significant part of the sound spectrum, containing most of the fundamental sounds of musical instruments and the human voice. These are the sounds most familiar to the human ear. Mid-range speakers are often found in televisions, where talking is of paramount importance. Since these frequencies are so important, the human ear is readily able to detect any distortion or lack of clarity. A mid-range driver should be capable of low-distortion reproduction of sound with adequate volume. Fortunately, because the ear is so sensitive to these sounds the power needed to drive a midrange driver can be low. Mid-range drivers come in different types, but are usually cone types or, less commonly, dome types, or compression horn drivers. Typically the cone is made of paper, although a wide range of other materials is also used. MOSFET – A complete discussion of MOSFET is quite complicated and involves some rather ugly mathematics, so we’ll stick to the essentials relevant to car audio. Basically, MOSFET is the acronym for a “metal oxide semiconductor field-effect transistor” designed to handle significant power levels. A MOSFET can be considered to be a voltage-controlled switch. They are typically used in Class D audio amplifiers where there is rapid switching off and on in response to the input signal from a head unit such as a radio. The switching rates are very high, far above human hearing, and the amplified signal is filtered to remove the high frequency part of the signal to maintain the fidelity of the output signal. MOSFET has the property of having good efficiency at low voltages (less than 200 V). In the context of amplifiers, a MOSFET amplifier can drive speakers to kilowatt power levels with good clarity and fidelity, which is especially useful for power hungry speakers such as subwoofers. Because of the efficiency of MOSFETs they produce less heat and require less cooling, which allows reduction in size and cost due to smaller heat sinks to handle the temperature. MOSFET is not confined to amplifiers, and MOSFET circuits are the design of choice in most microchips manufactured today. Multi-meter – A common term used to describe a VOM (voltage ohm meter). A multi-meter usually has the ability to measure volts, resistance (ohms), and amperes or milli-amperes. N Net Volume – the amount of airspace within an enclosure (not including the airspace taken up by bracing, vents, or the speaker itself) Nominal Impedance – The minimum impedance a loudspeaker presents to an amplifier, directly related to the power the speaker can extract from the amplifier. O Octave: The interval of eight diatonic degrees between two musical tones. The doubling or halving of frequencies.40Hz is an octave higher than 20Hz. Ohm – The unit of electric resistance and impedance – one ohm is the resistance value through which one volt will maintain a current of one ampere. Ohm’s Law – Current in a circuit is directly proportional to the voltage, and inversely proportional to resistance. It also includes the relationships of watts to amps, volts and ohms. Oversampling – Doubling or quadrupling (or by even a higher factor of 2 squared) the sampling frequency during the digital to analog process to obtain a high frequency for digital filtering P Parallel Circuit – A circuit configuration in which the same voltage is applied to all components, with current divided among the components according to their respective resistances or impedances. Example: All positive leads of two or more speakers connected together and all negative leads connected together. Parametric – A type of equalizer with adjustable parameters such as center frequency and bandwidth (Q) as well as amplitude. Phase – The relative position of two sound waves with respect to each other. Phase Control – This control feature allows the user to adjust the phase so all audio signals are playing together, the way it’s intended rather than against each other. Bass notes when absent, are very obvious and a quick adjustment to the Phase will remedy that. Phase Shift – Frequency interaction in the crossover region of passive crossovers which can cause some frequencies to be delayed with respect to other frequencies. 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. Plug & Play – Plug and play systems are the fastest way to get your music heard. Usually the install is completed by simply plugging in the power. The audio source will be your mobile phone or device and you’re ready to hear music. Power Handling Capability – measured in RMS – The maximum amount of power that can be safely accommodated without damage in a speaker system. This will vary depending on frequency and length of time the signal is applied. Pre-Amp Output – This feature allows you to connect and expand your audio system with external devices (i.e. Amplifiers, Processors) through RCA connections. A unit is capable of having up to three pre-amp outputs, front, rear, and subwoofer. Some units might have one or two outputs, but you can still use those outputs for complete system building. Pre-amp Fader – A circuit that allows effective level control of two amplifiers, built in and external without loss of power. Protection – Protection is key when the things get a little too hot or a speaker fails. In the event when an amp gets too hot, the thermal protection circuit turns on and allows the amp to cool down before turning back on. If a speaker fails, the protection circuit will automatically cutoff power to the output and remain in that state until the short if removed. These safety features allow you to have peace of mind and know the amplifier is monitoring conditions constantly. Q Q – The ratio of reactance to resistance in a series circuit, or the ratio of resistance to reactance in a parallel circuit. Qes – The Q of a driver at its free air resonance considering only its electrical losses. Qms – The Q of a driver at its free air resonance considering only its mechanical losses. Qtc – The measurement of a speaker and enclosure working together as one, or the total Q of a woofer and sealed enclosure at the system’s resonant frequency considering all resistive losses. Qts – The measurement of the speaker as a motor taking into consideration all mechanical and electrical losses – the total Q of a woofer at Fs, considering all driver resistances. R Rear Camera Input – When the vehicle is put into reverse, the camera (camera sold separately) will trigger and allow you to have an view of what’s directly behind your vehicle. Certain models will allow for direct viewing while towing a trailer. A safety feature that will improve rear view visibility Remote Turn On Lead – The lead from the head unit which supplies a signal (12V+) to the “remote turn on” lead of the amplifier turning the amplifier on when the head unit is turned on, and allowing the amplifier to be mounted in a location out of reach of the user. This is NOT the amplifier’s main source of power. Resonance – Pitch – When you tighten a drum, you raise its resonance. Resonant Frequency – Frequency at which there is a response peak, due to a specific interaction of inductive and capacitive circuitry in an audio devise or system. RF Modulator – A device that converts a signal (typically audio and/or video) into a radio frequency RMS – Power transferred from an amplifier to a speaker is measured in watts. Power ratings are an indication of the power the amplifier can supply. Amplifier power can be measured in different ways. For example, there is peak power output, which represents the amount of power which can be produced for a very brief period of time. However, for amplifiers the general convention is to measure the RMS (“root mean square” – see below) power. This is the maximum output of the amplifier using a continuous sine wave input signal at the onset of clipping. Clipping is basically the level of power at which you cause an arbitrary amount of total harmonic distortion (THD). RMS power ratings are sometimes referred to as “continuous power ratings.” Since music signals are not sine waves, the RMS power is actually only an approximation of the power, but it is a reasonable way to compare amplifiers. The RMS power rating should be viewed as the maximum power produced by an amplifier within an acceptable range of THD in a particular band of frequencies, typically 20Hz to 20kHz for music amplifiers. Root mean square (RMS). Okay, now for the mathematically inclined. The root mean square is a statistical measure of the magnitude of a quantity which can vary in value. It is particularly useful when a varying quantity can be either negative or positive, as is the case with sine waves. To calculate the RMS value you square the value of each quantity, or each value in a continuously varying quantity. The squared values are then added and the mean (for practical purposes the arithmetic average) is calculated. The square root of the mean is then the RMS value. In essence it is the square root of the mean of the squares. Aren’t you sorry you asked? S s – A description of the shape of the pass band. S values range from .4 to 1. An s value of .7 is considered ideal due to its flat frequency response. S Factor – the bandpass enclosure’s frequency response in the pass band – it is a general indicator of bandwidth. Sealed Enclosure – A type of speaker enclosure that does not allow the pressure generated by the back wave of the speaker to leave the enclosure. Sealed Volume – The amount of enclosure airspace on one side of a woofer in a bandpass system, that acts as a sealed enclosure. Sensitivity (loudspeaker sensitivity) – The sound pressure level a speaker produces when fed by a given input power, measured at a specific distance on axis directly in front of the speaker (Typically specified in dB SPL at 1 meter with 1 watt of input signal). Separates – A speaker system with more than one type of driver. The most common type of separates system is a set containing two high frequency drivers (tweeters), two lower frequency drivers (mids or woofers), and two crossover networks (filters). Separation – The degree to which left and right channels in a stereo signal can be kept apart. Series Circuit – A circuit configuration in which a single current path is arranged among all components: connecting the positive speaker output of an amplifier channel to the positive terminal of speaker # 1, the negative terminal of # 1 to the positive terminal of speaker # 2, and the negative terminal of # 2 to the negative output of the same amplifier channel is a series connection. Signal to Noise Ratio – S/N – The ratio of the desired signal level to the level of unwanted noise (measured in decibels). Signal-to-Noise Ratio 10.0 dB 20.0 dB 30.0 dB 40.0 dB 50.0 dB 60.0 dB 70.0 dB 80.0 dB Times Signal is Greater than Noise 3.16 10.00 31.62 100.00 316.20 1,000.00 3,162.00 10,000.00 Slope – The rate of boost or attenuation expressed in decibels of change per octave. Sound Pressure Level (SPL) – An acoustic measurement of sound energy, typically expressed in dB SPL. Theoretically, 0 dB SPL is the threshold of human hearing at 1 kHz, while 120 dB is the threshold of pain. Sound Stage – The area that appears to be occupied by sonic images. as with a real stage, a sound stage should have depth, height, and width. Speaker – A transducer which converts electrical energy into acoustical energy (sound). SPLo – measured in dB – the speaker’s reference efficiency measured with 1 watt input at a distance of 1 meter from the center of the cone. Strapping Capability – Two amplifiers can be “linked” together to make double the power at high impedance (2 Ω) The benefits are less electrical current needed than 2 individual amps at 1 Ω, and only a single set of signal RCA cables. Selectable LP Slope – Having this feature on subwoofer amp is priceless. It allows you to choose a 12dB or 24dB slope, allowing you to further tune your subwoofer system precisely. A slope simply dictates how sharp the rate at which the crossover cuts off. Steering Wheel Controls (SWC) – Boss Audio head units have the ability to interface to your vehicles SWC, allowing you to control functions of the radio right from the steering wheel. An interface module might be needed however based on your vehicle make/model. Stereophonic (stereo) – Consisting of two or more audio channels in an audio system during recording and playback to give a more natural distribution of sound. Subwoofer – A subwoofer (or sub) is a loudspeaker used for very low-frequency sounds with great power, frequencies known as the “bass.” The typical frequency range for a subwoofer is about 20–200 Hz for consumer products. Subwoofers are intended to augment the low frequency range of loudspeakers (see “midrange speakers” and “tweeters”) which are designed to cover higher frequency bands and which typically do not handle low frequencies well. The combination of speakers provides greater depth to the overall sound of the music. Subwoofers are often quite large, with 10″ to 15″ subwoofers common. For best performance typically subwoofers are placed in a loudspeaker enclosure capable of resisting deformation while withstanding the air pressure caused by the power of the low frequencies. Supertweeter – A high frequency driver designed to reproduce very high frequencies, typically over 10 kHz. Subsonic Filter – A subsonic filter is fancy word for “High-Pass” filter. That being said, it’s a high-pass for the subwoofer. This is especially true when you have the sub loaded in a ported enclosure, where the port will start to make noise. The subsonic filter tuned around the lowest frequency the subwoofer or port will play making a bit more efficient rather it trying to reproduce frequencies that it can’t. Subwoofer Level Control – An added feature on our amps, allows you control level of the subwoofer from an included mountable wired remote. The RJ45 style plug connects to the amplifier and remote. Switchable Input Sensitivity – In order to properly adjust the input sensitivity of an amp, the output level must be within the range of the input of the amplifier. Our selectable input gives you the freedom to connect the amp to any source unit and have peace of mind it will be within range to properly use the volume settings on your source unit the way it was designed. Switchable Tuner – Different countries around the world have requirements for broadcasting radio frequencies. Our radios have a selectable tuner area that allows you to receive radio broadcasts no matter where you are in the world. (US, EU, Asia, ORIT, Americas) T Threshold of Pain (in dB SPL) – The minimum value of sound pressure of a given frequency that will cause pain to a listener 50% of the time: Discomfort begins at 118 dB SPL. Actual pain starts around 140 dB SPL within the frequency range between 200 Hz and 10,000 Hz. Total Harmonic Distortion (THD) – The noise referenced to signal in decibels (dB) as a percentage. Noise referenced to Signal -10.0 dB -20.0 dB -30.0 dB -40.0 dB -50.0 dB -60.0 dB -70.0 dB -80.0 dB Percent Distortion 31.6% 10.0% 3.16% 1.00% 0.316% 0.100% 0.0316% 0.0100% Tuner – A component (or section of one) that receives radio signals and selects one broadcast from many. Tweeter – A tweeter is a speaker that reproduces only higher audio frequencies. The name is derived from the high pitched sounds made by some birds, especially in contrast to the low woofs made by many dogs after which low-frequency drivers are named (woofers). The average tweeter outputs frequencies from approximately 2,000 hertz (Hz) to 20,000 Hz, which is considered to be the upper limit of human hearing. Because a tweeter is limited to high frequencies, it is combined with speakers that reproduce other frequencies to produce a full range of audible sound. Typically tweeters use a voice coil suspended in a fixed magnetic field. When current from an amplifier is applied to the coil, a varying magnetic field is generated. The coil works against the magnetic field of a fixed magnet which is part of the tweeter. As the coil is forced to move it moves a diaphragm attached to it. The mechanical movement of the diaphragm is determined by the signal supplied by the amplifier. The movement of the diaphragm vibrates the air, which causes audio waves which we hear as high sounds. The material used in the tweeter effects the type of sound produced. Generally, tweeters made of soft materials, like polypropylene, textile blends, or silk will give a sound that’s refined and somewhat mellow, whereas hard materials, like metal, ceramics, or graphite, produce highs that are bright and snappy. Dispersion is the extent to which the tweeter yields sound over a given area; that is, the area in which the sound is best heard. Dispersion is a major concern in tweeters because high frequency sound is much more directional than the low frequencies produced by woofers. Piezo (piezoelectric) describes the ability of certain crystal lattices to respond by flexing in proportion to the amplitude and frequency of an incoming signal. Piezo tweeters are very efficient drivers. A diaphragm is the sound-producing element in a tweeter and is the surface that produces the sound. It can be driven by several technologies, including piezo or conventional dynamic diaphragm. – Cone Tweeter Cone tweeters are noteworthy for being the most economical but having a limited dispersion pattern. They are similar in style to woofer cones but adapted for the production of high frequency sound. They are infrequently used now, having been largely replaced with domes. – Dome Tweeter Dome tweeters are the most common type. They are more accurate than cone tweeters and have low distortion and a much wider dispersion pattern. Typical dome materials can be soft or hard, and include metals such as neodymium or titanium for extended high frequency response, plastics such as Mylar, or even silk for smoother sound. Combinations of materials are also used. They can be also powered by a magnet and coil diaphragm, or by a piezo driver. All have relatively low mass and high power handling capabilities. – Bullet Tweeter A bullet tweeter is a type of dome tweeter in which there is a large passive, bullet-shaped device above the center that expands the dispersion angle of the sound so that it covers a greater area with a relatively small driver. – Horn Tweeter Horn tweeters have a relatively small emitter at the apex of a “horn” shape. This is an effective and powerful way of radiating high frequency, but they tend to be very directional and may lack the extended range of the dome tweeters. They are also powered by a magnet and coil diaphragm, or by a piezo driver. Some versions with wider dispersion can be used in car audio applications. High frequency drivers in horns are often referred to as “compression drivers.” This type is more efficient than other types and can be used to reduce the amount of thermal stress on a voice coil. U Unloading – The tendency of an enclosure to produce no spring or pressure on the woofer. Unloading produces an uncontrollable over-excursion of the woofer cone (it vibrates out of control); the speaker will exhibit low power handling at lower frequencies. V Vas – Volume Acoustic Suspension – a measurement in liters or cubic feet of the volume of air that is equal to the compliance of the speaker’s total suspension. Vb – measured in inches3, feet3, or liters3 – the internal volume of air of a given enclosure. Vd – the volume of air displaced by the speaker’s cone during an Xmax displacement. Vent Dimensions – vent diameter X (by) vent length. Vent Volume – the amount of enclosure airspace that is displaced by the vent Vented Volume – the amount of enclosure airspace on one side of a woofer in a bandpass system that acts as a vented enclosure Video Output – If you have additional video monitors, the video output can be connected to the additional monitors, giving you an expanded video throughout your vehicle. Volume – measured in inches3, feet3, or meters3 – length x width x height VOM – Volt-Ohm-Meter – multimeter that measures voltage, resistance (ohms), amperes, and milliamperes Voice Coil [single] – A subwoofer with a single voice coil has an impedance of 4 Ω. It can be powered by an appropriately matched amplifier, or be combined with several other single voice coil subwoofers wired in a series or parallel configuration. Usually a single voice sub is perfect for low to medium powered applications Voice Coils [dual] – A subwoofer with dual voice coils offers a couple of advantages over a single coil. You will have more wiring configurations. If you add additional subwoofers, wiring configurations can be matched to amplifiers easily to access the power needed. Power handling goes up as well since there an additional coil to power. Dual voice coils subwoofer will work in medium to high power applications. Voice Coil [3ohm] – Our 3 Ohm voice coil is compatible with all automotive head units. We use a specially designed coil to for extra sensitivity to the speaker, leading to increased output. W Watt (wattage) – A measurement of real power – The product of voltage and current in a resistive circuit Woofer – A loudspeaker made to reproduce the lower range of the audio spectrum (bass), in a 2-way or more complex speaker system. X Xmax – measured in inches or millimeters – the maximum linear cone excursion of a driver.