Power Amplifiers are the key to great sound, at any volume!

There are many reasons to add a high-quality power amp to your system. The ability to play music LOUD is one obvious reason but there's more to it!

If you want lots of earth-shaking bass - good, deep, clean, tight bass - you will need plenty power.

You'll get cleaner sound. Playing music loud with too little power gives rise to distortion. Distortion makes any system sound terrible. There is another downside to distortion. It is distortion, not too much power that destroys speakers. This may sound less than believable, but its true (I've even experienced it myself).

Today's amplifiers give you many different speaker options:

• Traditional 2-speaker, left and right stereo.
• Four channel - For use with 2 pairs of stereo speakers. Usually 2 in the front and 2 in the rear.
• Three Channel (sometimes called tri-mode) in which one amplifier drives a pair of stereo speakers and a subwoofer.
• 5 Channel - Can be used to power 2 pairs of stereo speakers and a subwoofer.

  
  
  

What outputs should I use to provide the audio signal to my amp?
If your head-unit has pre-amp outputs, you should use those to deliver the signal to your amplifier. The pre-amp signal is a low level, low noise signal that gives the cleanest possible sound when fed into an amplifier. If your head-unit does not have pre-amp outputs but your amplifier has speaker level inputs, you can connect your head-units speaker outputs to the speaker-level inputs on the amplifier. If your amplifier does not have speaker-level inputs, you will have to buy a special convertor to convert the speaker-level outputs to a line-level signal that can be fed into the amp. This method will not sound as clean as the direct pre-amp connection.

How should I power the amplifier?
Power Amplifiers generally require a relatively large ammount of current (especially when playing loud). Thus, they are best powered directly from the battery. An inline fuse should ALWAYS be placed as close to the battery as possible. This will protect against any power-line shorts. The thickness of wire needed will depend on the length of the run and the power requirements of the amplifier. The table in the rec.audio.car FAQ will provide you with this information.

Why do Power Amplifiers seem to vary so widely in price?
You might see one amplifer rated at 100 Watts selling for a certain price and then another amplifier rated 500 Watts for the same price. The reason this is so is that some manufacturers rate their amps using misleading techniques. To start with, their are two ratings - Peak power and the more meaningful RMS power. Also, check the frequency response at the rated power (it should be better than 20Hz-20KHz +/-3dB) and the THD at rated power (should be no higher than 0.1%).

What are discrete output devices?
Some amps use relatively cheap integrated circuits to produce power. These are fine in low power amplifiers and head-units, but if you are looking for some reasonable power, look for amps that use high-current discrete output transistors. These are very similar to those used in home audio amplifiers.

As with all autosound components, try to buy an amplifier from a reputable manufacturer; Some are: Rockford Fosgate, Hi-Fonics, Kenwood, ADS, Sony, Pioneer, JBL and Precision Power.

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