The Right Amplifier For Your System
Continued from this article. Part two.
Ohms not Gnomes
When choosing an amplifier, it is important to match the nominal impedance of the speakers with the performance capability of the amplifier. Nominal Impedance is the average load a speaker or subwoofer presents to an amplifier. This is measured in ohms. (Ohms are the measurement of electrical resistance.)
Most amplifiers are typically capable of 2 ohms stereo (unabridged outputs) and 4 ohms mono (bridged output). Higher performance amplifiers, typically 2-channel and mono-block (single channel) dedicated subwoofer amplifiers, are capable of dealing with lower impedances up to and exceeding 0.5 ohms! Choose an amplifier that meets your minimum requirements for impedance load. Always refer to the manufacturers spec and not what an enthusiast will say it can do. This will ensure the longevity of your amplifier.
Power per channel
Power is the most important feature of an amplifier. It determines how loud your stereo can play as well as how much power it will draw from your electrical system. There are many misconceptions about power. The most common myth is that overpowered speakers will break more often than underpowered speakers. This is false. One of the most common causes of speaker failure is damage due to amplifier distortion (amplifier clipping). An under powered amplifier will most likely be driven into clipping hard which will result in blown speakers or worse, a blown amplifier. When deciding on an amplifier it is best to match the power of the amplifier to the RMS power rating of the speakers. This will give you the maximum safe output of the speakers. Make sure the amplifier’s power rating meats CEA 2006 standards. At a minimum, choose an amplifier that can deliver one half the rated RMS power handling of your midrange and tweeters. For subwoofers, the goal is to balance the output of the subwoofer with the rest of the system. Choose an amplifier that has at least one-quarter the RMS (continuous) power handling of the subwoofer. In most situations, you will not need to exceed the RMS power handling of the subwoofer to balance the system. If high bass out put is your goal, pick an amplifier that can deliver the peak power handling of the subwoofer. Peak power handling is the amount of power a woofer can safely handle for brief moments. In any situation, never exceed the Peak power rating of the subwoofer.
Internal Crossovers and Signal Processing
Today, most every amplifier includes internal crossovers or additional signal processing. Signal processing varies between simple high-pass or low-pass crossovers to full adjustable digital crossovers with time alignment and 31 band equalizers. For amplifiers driving midrange and tweeters, make sure the high-pass crossover has the frequency adjustment range suitable for your application. If you plan a three way system with separate amplifiers for the tweeter, midrange and woofer, make sure the crossover range fits the recommended frequency range for the speakers. For subwoofer amplifiers, amplifiers with a bass boost or better a subsonic filter. (A subsonic filter is the a circuit the protects subwoofers for excessive low-frequency excursion) Make sure the amplifier you choose has at least the electronic crossovers you need to properly control the system. Additional controls and adjustments make for a more flexible and potentially better sounding system.
Conclusion
There are other important factors such a good warranty and build construction to take in to consideration as well. And, of course, amplifier looks are always important. If you need additional assistance, rely on your local car audio stereo shops for expert advice. They have the latest information of what is hot and not. Plus they will be able to recommend amplifiers based on their observed reliability. Choosing an amplifier that is perfect for your needs can be a challenging task. But the results will be worth the effort.
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