# Sticky  Amplifier Information



## lcurle

Todays lesson is on terminology & definitions, enjoy!

*Built-in Crossovers *- Often used to keep high-frequencies from reaching a subwoofer. A low-pass crossover allows only low frequencies to be amplified. A high-pass crossover allows only high frequencies to be amplified. It keeps low bass away from small speakers, so they can play more efficiently.

*Bridged Power* - Bridging a car amplifier, combines the power output of two channels into one channel. Bridging allows the car amplifier to drive one speaker with more power than the amp could produce for two speakers. Because of this high power output, bridging is the best way to drive a single subwoofer. Bridging a car amplifier, combines the power output of two channels into one channel. 

Bridging allows the car amplifier to drive one speaker with more power than the amp could produce for two speakers. Because of this high power output, bridging is the best way to drive a single subwoofer. If the amp is bridgeable, the owner's manual will have directions that tell you how.

Also, keep in mind that most car amplifiers need to see a 4-ohm load when bridged to mono operation. If you want to bridge your amp, you should use one 4-ohm speaker or, if you prefer multiple woofers, wire two 8-ohm speakers in parallel. (Consult your manual before operating your car amp in bridged mode.) 

*Discrete Output Devices *- There are 2-3 basic types of output devices found on car audio amplifiers 1). integrated circuits, 2) bipolar transistors, or MOSFETs. An integrated circuit (or IC) is found only on relatively low-wattage (20 watts RMS per channel or less) amplifiers called "bridged transformerless" amps. An IC can not pass enough current to work on a more powerful amp and is not considered a discrete output device. Bipolar transistors and MOSFETs are found on the output stages of high powered amplifiers. They are fast enough and can handle enough current to send wattage greater than 20 watts per channel to your speakers. Both of these types of transistors are considered discrete output devices. Usually there are two per channel, but some amps feature as many as four per channel. 

*Mono Amplifier* - Mono car amplifiers are single channel amps, well-suited for low-frequency applications. Mono car amplifiers are stable to 2-ohms so you can connect them safely to two 4-ohm woofers wired in parallel.


*MOSFET (Metal Oxide Semiconductor Field Effect Transistor)* - A type of large output transistor used in the final stages of many power amplifiers, and commonly found in most car amplifiers today. Mosfet transistors are most often discrete devices, used with smaller driver transistors and other devices, to convert a small signal to a large one. They are highly stable and efficient, compared to the bipolar types that preceded them.

*Ohm* - The measurement of electrical resistance and system impedance. It is a measure of the degree to which electrons are limited in both velocity and quantity in passing through a circuit. In Impedance measurements, this takes into account, the mechanical resistance inherent in the motion of transducers. The standard is usually 4 ohms for car audio. 

*Parametric* - A type of equalization that permits the center frequency, the filter shape, and the amplitude of each band to be varied. This gives you extremely precise control of the tonal balance in your vehicle. (More versitile than graphic equalizers)

*Preamp Output* - This is the first stage of amplification in which the amplitude of a very low-level audio signal is increased. The first stage of amplification in which the amplitude of a very low-level audio signal is increased.

*RMS Power* - The higher the RMS figure, the louder and cleaner your music sounds. The RMS rating is the maximum the amplifier can put out all day long without distorting. The RMS rating is very important.

*Peak Power *- The peak power rating tells you the maximum wattage a car amplifier can deliver as a brief burst The RMS rating is more important.

*Signal-to-Noise Ratio* - A measurement of noise level in a device compared to the level of the signal. Higher numbers signify a greater difference, which is better.

Speaker input Speaker inputs let you connect an amp to a receiver that lacks RCA preamp outputs. 

*Total Harmonic Distortion (THD)* - The THD is usually expressed in dB. the ratio of (a) the sum of the powers of all harmonic frequencies above the fundamental frequency to (b) the power of the fundamental frequency

*Tri-Way Output -* Car Amplifier setup that powers a pair of stereo speakers and one subwoofer simultaneously from the outputs of a single 2-channel amplifier.


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## jaggerwild

We need a sticky here please guys!


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## carsey

Good stuff

Stickied.


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## jaggerwild

Thank you Carsey ray:


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## lcurle

*Tech Advice - Wire Diagrams*









Bridging an amplifier is a means of combining the power of two channels to drive one speaker. Typically this will double the power of a single channel (i.e. two 50 watt channels would combine to become one 100 watt channel) although some of the top amplifiers will actually quadruple the power of a single channel (i.e. two 50 watt channels would combine to become one 200 watt channel). This is usually the most desirable and you can plan this into your overall design. For example, if you have two subwoofers in your system and you want to drive each of them with 100 watts you can do one of the following.









Parallel wiring involves wiring each speaker positive terminal to the positive speaker output of the amplifier and likewise the negative speaker terminals are wired to the negative speaker output of the amplifier.









Series wiring involves connecting the amplifier's positive terminal to the positive terminal of the first speaker and then connecting the negative terminal of the first speaker to the positive terminal of the second speaker and so on. The final speaker in the chain will have its negative terminal connected to the negative terminal of the amplifier. See the figure below. This wiring scheme is best reserved for multiple subwoofers because any audio artifacts (distortion, frequency attenuation, etc.) caused by the first speaker(s) in the chain will affect the speakers in the chain after it. This is a major problem when mixing multiple speaker types (i.e. woofers with tweeters).









There is often a lot of confusion on how to wire a car audio capacitor (a.k.a. power capacitor or stiffening capacitor). There are two terminals on a car audio capacitor. A positive and a negative. The negative terminal is connected to ground. The positive terminal is connected "in-line" with the car audio amplifier +12 volts terminal. See the diagram below. Ideally the power capacitor should be as close as possible to the amplifier. Within a couple of feet is acceptable. 


















Here's how to wire two capacitors in a system:

NOTE OF CAUTION: Power capacitors store a large amount of energy and they charge very quickly. You must first "charge" your power capacitor using a resistor before connecting it directly to +12 volts. This is done with the a 1k ohm resistor and a voltmeter. The exact value of the resistor is not critical but I would keep it in the 500-1k ohm range. I would recommend getting a 1 watt resistor if possible (your capacitor may have come with a resistor for charging). A lower wattage resistor will heat up too quickly. Also, do not hold the resistor with your bare hand. The current flowing through the resistor will cause the resistor to heat up and you could be burned. A good place to put the resistor is in the main power wire fuse holder. Simply substitute the resistor for the fuse. A diagram for the capacitor charging setup is shown above. You will need to place a voltmeter across the capacitor to monitor the voltage. Once the voltmeter reads 12 volts you can remove the voltmeter and replace the resistor with the power fuse.


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## jaggerwild

*Re: Tech Advice - Wire Diagrams*

Sticky please!


Maybe combine this with other AMP INFO sticky if Lee is OK with it?


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## lcurle

*Re: Tech Advice - Wire Diagrams*

sure, until I come up with more advice for you guys.


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