| The car audio amplifier... its soul purpose is to take a | | | | range |
| low level signal from the source unit and transform it | | | | of them.Distortion: This is often given as T.H.D. or |
| into a high level signal for activating the | | | | total |
| loudspeakers.Amplifiers range in power from about | | | | harmonic distortion. It is the measure of how much |
| twenty watts per channel to over one thousand | | | | an |
| watts per channel. Would you believe that the prices | | | | amplifier will change a signal from the input signal it is |
| range anywhere from fifty dollars to several | | | | given. Figures below 0.1% are negligible and will not |
| thousand dollars depending on features, power | | | | be |
| output and quality! Amplifiers range from one channel | | | | heard. Usually the figure can be in the 3% range |
| of output to as many as eight channels. The most | | | | without |
| common amplifiers are currently two and four channel | | | | being heard but virtually all high quality amplifiers will |
| models.Amplifier Power Ratings | | | | have a T.H.D. below 0.1%.Efficiency: This is the ratio |
| Power amplifiers also have "optional equipment". | | | | of of power input (from the |
| These features include built-in active crossovers, | | | | battery) to power output (to the speakers). A 100 |
| equalizers, signal processing and speaker level inputs. | | | | watt |
| When shopping for an amplifier consider that all | | | | amplifier with an efficiency of 50% would take in |
| power ratings are not created equal. The only true | | | | 200 watts of power from the battery and output |
| measure of an amplifier's power is its continuous | | | | 100 watts of power to |
| power rating or R.M.S. rating ( or root mean square) | | | | the speakers. The other 100 watts of power would |
| and refers to the average power output of the | | | | be wasted |
| amplifiers. Some of the low-quality brands will | | | | as heat. The higher the efficiency of an amplifier the |
| exaggerate or even outright lie about the power | | | | better.Power Output: The rated power output of an |
| output of their amplifiers which is a good reason to | | | | amplifier |
| stick with the well known manufacturers.Car Amplifier | | | | should be given into a four ohm load, all channels |
| Quality: Also keep in mind the quality of the amplifier. | | | | driven |
| A | | | | from twenty to twenty thousand hertz |
| generally good indication of quality build and the | | | | (20Hz-20kHz). Keep in mind that while the low end |
| power | | | | amplifiers are exaggerated in |
| output is the size and the weight of the amplifier | | | | their power output, many high end amplifiers are |
| itself. | | | | under- |
| Better quality amplifiers will usually have a heavier | | | | rated in their power output. These are sometimes |
| and | | | | called |
| larger heatsink versus a low quality amplifier of the | | | | "cheater amps" because they allow a car audio |
| same | | | | competitor to |
| power rating.However there are many top quality | | | | compete in a lower power class while in reality |
| amplifiers that do not follow this rule.Blaupunkt makes | | | | having a |
| a line of amplifiers that have a plastic shell. Because | | | | larger amplifier. This under-rating can be three times |
| of the high efficiency design of those amplifiers a | | | | less |
| heavy heatsink is not required. Also a good indication | | | | than the actual power output.Power Supply: The |
| of an amplifier's true output is the size of the fuse | | | | two most common types are the IC chip and the |
| used.Use your head when buying and keep in mind | | | | MOSFET supply. The IC chip is what is used in most |
| the brand's reputation for quality.If you find yourself | | | | source units (head units) and are only capable of |
| on a budget or lack space for many components | | | | roducing about twenty watts per channel. MOSFET is |
| then the economical thing to do is buy a multi-channel | | | | the more common design and has a smoother sound |
| amplifier with the built in features and processors | | | | than the chip design.Pre-amp Inputs: This is a set of |
| that you desire. By minimizing the number of | | | | jacks (usually RCA jacks) |
| components the chance of noise entering into the | | | | that will accept a low level pre-amp signal from a |
| system is lessened.Some features and aspects of | | | | source |
| amplifiers to consider are:Bridgeable: This feature | | | | or processing unit.Pre-amp Outputs: This is a set of |
| allows a pair of amplifier power | | | | jacks (usually RCA |
| channels to be combined into one channel of greater | | | | jacks) that pass on a low level pre-amp signal to |
| power. | | | | another |
| This is usually used for driving a subwoofer although | | | | amplifier or processing unit. These will sometimes be |
| it | | | | filtered outputs.Separate Gain Controls: This allows |
| will work with any other type of speaker as | | | | the gain of each |
| wellChannels: The more channels an amplifier has the | | | | channel of the amplifier to be set independently of |
| greater | | | | the |
| the installation flexibility it will have. Especially in | | | | other(s).Speaker Level Inputs: For source units that |
| terms of options, future add-ons and upgrades.Class: | | | | do not have |
| This refers to the way the amplifier operates. The | | | | pre-amp level RCA outputs this feature may be |
| three types that are most likely to be encountered | | | | used to take |
| are A, | | | | the signal from the speaker leads of the source unit. |
| A/B, and D. Class A amplifiers are the least efficient | | | | The |
| in | | | | signal will not be as clean as a pre-amp level output |
| terms of power consumption, staying on continually, | | | | but |
| but | | | | will be adequate for most factory upgrade |
| also have better sound in general than A/B | | | | applications.Stability: The measure of how low of an |
| amplifiers. They | | | | impedance load an amplifier can handle (in ohms). Any |
| are very rare in car audio. Class A/B amplifiers are | | | | good quality amplifier |
| more | | | | will be two ohm stable while a rare few will go as |
| efficient than the class A design and are the most | | | | low as a |
| common | | | | quarter of an ohm. Ideally an amplifier should double |
| type. Almost all amplifiers in the car audio market are | | | | its |
| of | | | | power each time the load is halved. For example, a |
| the A/B design. Class D amplifiers are usually | | | | one |
| reserved for | | | | hundred watt amplifier (into a four ohm load) should |
| high power subwoofer amplifiers and can reach | | | | produce two hundred watts into a two ohm load |
| efficiencies | | | | and so on. |
| in the 80%+ range. This design can therefore be | | | | This is most useful when running multiple speakers |
| smaller, | | | | off of a |
| uses less current and produces less heat than the | | | | single amplifier or in sound off competitions that are |
| other | | | | classed by total power output.Tri-Mode Output: This |
| classes.Connectors: This is the method of | | | | feature is available under different |
| attachment used for | | | | names but is the ability of an amplifier to run a |
| wires that are connected to the amplifier, including | | | | stereo |
| speaker and power wires. The most common kind is | | | | pair of speakers and a mono subwoofer (or center |
| the screw terminal strip. This is a series of screw | | | | channel) |
| connectors that can be removed and replaced | | | | from only two channels of the amplifier. Personally, I |
| without compromising the | | | | would not recommend doing this. Instead buy a |
| amplifier. The other main type of attachment is the | | | | good quality |
| "Molex" | | | | four channel amplifier and bridge two of the channels |
| type connector. This method involves a wire harness | | | | for |
| that | | | | the subwoofer.Tube Amplifiers: These are the least |
| plugs into the amplifier after the power and speaker | | | | common amplifiers and are also the most expensive. |
| connections have been made with a crimp or solder | | | | Rather than the traditional |
| connection. If the amplifier is installed in more than | | | | solid state components they use old fashioned |
| one | | | | vacuum tubes. They are said to produce a warmer |
| system these wires can get pretty short over time | | | | sound and a moother midrange than solid state |
| and | | | | designs. For most systems the standard design will |
| become more difficult and even dangerous to work | | | | be more desirable.Armed with this knowledge, you |
| with. A | | | | should now be able to make an informed decision on |
| variation on the two is a harness that the power | | | | your amplifier purchase. Interested in more amplifier |
| and | | | | articles? Check out Putting the "BOOM...BOOM...BOOM" |
| speaker wires screw into. Then the harness plugs | | | | into your system.Enjoy!George Steiner and Judy |
| into the | | | | Steiner from North Carolina have unsuccessfully |
| amplifier. This is probably the most convenient of all | | | | maneuvered through the teenage eons with their |
| connections.Crossover/Filter: A built in crossover can | | | | two daughters. The countless boyfriends with |
| be useful, | | | | modified auto stereo systems broadcasting |
| especially if it is many frequencies of adjustment. A | | | | bone-jarring bass, little room to sit due to the |
| filter is a crossover that only affects one channel, | | | | electronic gagets and non-existant trunks, |
| not | | | | experiences we could have done without! |
| actually splitting frequencies but simply reducing a | | | | |